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Document and Entity Information - USD ($) $ in Millions	12 Months Ended
Document and Entity Information - USD ($) $ in Millions	Dec. 31, 2018	Feb. 14, 2019	Jun. 29, 2018
Document Information [Line Items]
Entity Registrant Name	CASELLA WASTE SYSTEMS INC
Entity Central Index Key	0000911177
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-K
Document Period End Date	Dec. 31, 2018
Document Period End Date	2018
Document Fiscal Period Focus	FY
Amendment Flag	false
Trading Symbol	CWST
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Public Float			$ 1,017
Class A Common Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		45,510,572
Class B Common Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		988,200

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
CURRENT ASSETS:
Cash and cash equivalents	$ 4,007	$ 1,995
Account receivables - trade, net of allowance for doubtful accounts of $931 and $809, respectively	74,937	65,953
Refundable income taxes	2,254	522
Prepaid expenses	7,345	8,299
Inventory	6,542	6,534
Other current assets	2,008	1,077
Total current assets	97,093	84,380
Property, plant and equipment, net of accumulated depreciation and amortization of $878,701 and $811,474, respectively	404,577	361,547
Goodwill	162,734	122,605
Intangible assets, net	34,767	8,149
Restricted assets	1,248	1,220
Cost method investments	11,264	12,333
Deferred income taxes	9,594	11,567
Other non-current assets	11,133	13,148
Total assets	732,410	614,949
CURRENT LIABILITIES:
Current maturities of long-term debt and capital leases	2,298	4,926
Accounts payable	57,289	47,081
Accrued payroll and related expenses	10,969	12,183
Accrued interest	2,415	2,093
Contract liabilities	3,074	1,823
Current accrued capping, closure and post-closure costs	11,633	3,035
Other accrued liabilities	23,819	17,428
Total current liabilities	111,497	88,569
Long-term debt and capital leases, less current portion	542,001	477,576
Accrued capping, closure and post-closure costs, less current portion	61,442	59,255
Deferred income taxes	2,519	2,305
Other long-term liabilities	30,783	25,106
COMMITMENTS AND CONTINGENCIES
Casella Waste Systems, Inc. stockholders' deficit:
Additional paid-in capital	373,716	356,638
Accumulated deficit	(388,669)	(395,107)
Accumulated other comprehensive (loss) income, net of tax	(1,308)	184
Total stockholders' deficit	(15,832)	(37,862)
Total liabilities and stockholders' deficit	732,410	614,949
Class A Common Stock
Casella Waste Systems, Inc. stockholders' deficit:
Common stock	419	413
Class B Common Stock
Casella Waste Systems, Inc. stockholders' deficit:
Common stock	$ 10	$ 10

CONSOLIDATED BALANCE SHEETS (Parenthetical) $ in Thousands	12 Months Ended
CONSOLIDATED BALANCE SHEETS (Parenthetical) $ in Thousands	Dec. 31, 2018 USD ($) vote $ / shares shares	Dec. 31, 2017 USD ($) vote $ / shares shares
Accounts receivable - trade, allowance for doubtful accounts \| $	$ 931	$ 809
Property, plant and equipment, accumulated depreciation and amortization \| $	$ 878,701	$ 811,474
Class A Common Stock
Common stock, authorized shares (in shares)	100,000,000	100,000,000
Common stock, par value (in dollars per share) \| $ / shares	$ 0.01	$ 0.01
Common stock, issued shares (in shares)	41,944,000	41,298,000
Common stock, outstanding shares (in shares)	41,944,000	41,298,000
Common stock, votes (in votes per share) \| vote	1
Class B Common Stock
Common stock, authorized shares (in shares)	1,000,000	1,000,000
Common stock, par value (in dollars per share) \| $ / shares	$ 0.01	$ 0.01
Common stock, issued shares (in shares)	988,000	988,000
Common stock, outstanding shares (in shares)	988,000	988,000
Common stock, votes (in votes per share) \| vote	10	10

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement [Abstract]
Revenues	$ 660,660	$ 599,309	$ 565,030
Operating expenses:
Cost of operations	453,291	405,188	381,973
General and administration	84,791	79,243	75,356
Depreciation and amortization	70,508	62,102	61,856
Southbridge Landfill closure charge, net	8,054	65,183	0
Expense from acquisition activities and other items	1,872	176	0
Environmental remediation charge	0	0	900
Contract settlement charge	2,100	0	0
Development project charge	311	0	0
Total operating expenses	620,927	611,892	520,085
Operating income (loss)	39,733	(12,583)	44,945
Other expense (income):
Interest income	(273)	(273)	(290)
Interest expense	26,294	25,160	38,942
Loss on debt extinguishment	7,352	517	13,747
Impairment of investments	1,069	0	0
Other income	(745)	(935)	(1,090)
Other expense, net	33,697	24,469	51,309
Income (loss) before income taxes	6,036	(37,052)	(6,364)
(Benefit) provision for income taxes	(384)	(15,253)	494
Net income (loss)	6,420	(21,799)	(6,858)
Less: Net loss attributable to noncontrolling interests	0	0	(9)
Net income (loss) attributable to common stockholders	$ 6,420	$ (21,799)	$ (6,849)
Basic earnings per share attributable to common stockholders:
Weighted average common shares outstanding (in shares)	42,688	41,846	41,233
Basic earnings per common share (in dollars per share)	$ 0.15	$ (0.52)	$ (0.17)
Diluted earnings per share attributable to common stockholders:
Weighted average common shares outstanding (in shares)	44,168	41,846	41,233
Diluted earnings per common share (in dollars per share)	$ 0.15	$ (0.52)	$ (0.17)

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 6,420	$ (21,799)	$ (6,858)
Other comprehensive (loss) income, before tax:
Interest rate swap settlements	(361)	(410)	0
Interest rate swap amounts reclassified into interest expense	363	421	0
Unrealized (loss) gain resulting from changes in fair value of derivative instruments	(1,476)	267	0
Unrealized gain (loss) resulting from changes in fair value of marketable securities	0	59	(75)
Other comprehensive (loss) income	(1,474)	337	(75)
Tax effect related to items of other comprehensive (loss) income	0	85	0
Other comprehensive (loss) income, net of tax	(1,474)	252	(75)
Comprehensive income (loss)	4,946	(21,547)	(6,933)
Less: Net loss attributable to noncontrolling interests	0	0	(9)
Comprehensive income (loss) attributable to common stockholders	$ 4,946	$ (21,547)	$ (6,924)

CONSOLIDATED STATEMENT OF STOCKHOLDERS' DEFICIT - USD ($) shares in Thousands, $ in Thousands	Total	Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interests	Class A Common Stock	Class A Common Stock Common Stock	Class B Common Stock	Class B Common Stock Common Stock
Beginning balance at Dec. 31, 2015	$ (21,597)	$ 344,518	$ (366,459)	$ 7	$ (74)		$ 401		$ 10
Beginning balance (in shares) at Dec. 31, 2015							40,064		988
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(6,858)		(6,849)		(9)
Other comprehensive (loss) income	(75)			(75)
Issuances of Class A common stock	528	523					$ 5
Issuances of Class A common stock (in shares)							508
Stock-based compensation	3,393	3,393
Contributions from noncontrolling interest holder	59				59
Ending balance at Dec. 31, 2016	(24,550)	348,434	(373,308)	(68)	(24)		$ 406		$ 10
Ending balance (in shares) at Dec. 31, 2016						40,572	40,572	988	988
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(21,799)		(21,799)		0
Other comprehensive (loss) income	252			252
Issuances of Class A common stock	1,779	1,772					$ 7
Issuances of Class A common stock (in shares)							726
Stock-based compensation	6,432	6,432
Other	24				24
Ending balance at Dec. 31, 2017	(37,862)	356,638	(395,107)	184	0		$ 413		$ 10
Ending balance (in shares) at Dec. 31, 2017						41,298	41,298	988	988
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	6,420		6,420		0
Other comprehensive (loss) income	(1,474)			(1,474)
Issuances of Class A common stock	1,017	1,012					$ 5
Issuances of Class A common stock (in shares)							496
Stock-based compensation	8,445	8,445
Issuance of Class A common stock - acquisition	7,622	7,621					$ 1
Issuance of Class A common stock - acquisition (in shares)							150
Ending balance at Dec. 31, 2018	$ (15,832)	$ 373,716	$ (388,669)	$ (1,308)	$ 0		$ 419		$ 10
Ending balance (in shares) at Dec. 31, 2018						41,944	41,944	988	988

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash Flows from Operating Activities:
Net income (loss)	$ 6,420	$ (21,799)	$ (6,858)
net income (loss) to net cash provided by operating activities:
Depreciation and amortization	70,508	62,102	61,856
Depletion of landfill operating lease obligations	9,724	9,646	9,295
Interest accretion on landfill and environmental remediation liabilities	5,708	4,482	3,606
Amortization of debt issuance costs and discounts on long-term debt	2,449	2,692	3,881
Stock-based compensation	8,445	6,432	3,393
Environmental remediation charge	0	0	900
(Gain) loss on sale of property and equipment	(492)	49	(574)
Southbridge Landfill non-cash closure charge	16,179	63,526	0
Southbridge Landfill insurance recovery for investing activities	(3,506)	0	0
Non-cash expense from acquisition activities and other items	757	0	0
Development project charge	311	0	0
Loss on debt extinguishment	7,352	517	13,747
Impairment of investments	1,069	0	0
Deferred income taxes	1,250	(15,525)	583
Changes in assets and liabilities, net of effects of acquisitions and divestitures:
Accounts receivable	(5,833)	(4,664)	(1,029)
Accounts payable	9,091	2,084	76
Prepaid expenses, inventories and other assets	535	(1,404)	(2,256)
Accrued expenses and other liabilities	(9,133)	(600)	(6,186)
Net cash provided by operating activities	120,834	107,538	80,434
Cash Flows from Investing Activities:
Acquisitions, net of cash acquired	(88,918)	(5,056)	(2,839)
Additions to property, plant and equipment	(73,232)	(64,862)	(54,238)
Payments on landfill operating lease contracts	(7,415)	(7,240)	(7,249)
Proceeds from property insurance settlement	992	0	0
Proceeds from sale of property and equipment	870	711	1,362
Net cash used in investing activities	(164,197)	(76,447)	(62,964)
Cash Flows from Financing Activities:
Proceeds from long-term borrowings	634,700	185,500	604,850
Principal payments on long-term debt	(584,223)	(216,966)	(608,198)
Payments of debt issuance costs	(5,573)	(1,452)	(8,146)
Payments of debt extinguishment costs	0	0	(7,219)
Proceeds from the exercise of share based awards	471	1,278	128
Net cash provided by (used in) financing activities	45,375	(31,640)	(18,585)
Net increase (decrease) in cash, cash equivalents and restricted cash	2,012	(549)	(1,115)
Cash, cash equivalents and restricted cash, beginning of period	1,995	2,544	3,659
Cash, cash equivalents and restricted cash, end of period	4,007	1,995	2,544
Supplemental Disclosures of Cash Flow Information:
Interest	23,523	25,029	42,712
Income taxes, net of refunds	105	146	274
Supplemental Disclosures of Non-Cash Investing and Financing Activities:
Non-current assets acquired through long-term obligations	7,092	3,564	$ 2,299
Southbridge Landfill
net income (loss) to net cash provided by operating activities:
Southbridge Landfill non-cash closure charge	6,012	0
Development project charge	0	$ 9,149
Cash Flows from Investing Activities:
Proceeds from property insurance settlement	$ 3,506

BASIS OF PRESENTATION	12 Months Ended
BASIS OF PRESENTATION	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
BASIS OF PRESENTATION	BASIS OF PRESENTATION Casella Waste Systems, Inc. (“Parent”), its consolidated subsidiaries and any partially owned entities over which it has a controlling financial interest (collectively, “we”, “us” or “our”), is a regional, vertically integrated solid waste services company that provides collection, transfer, disposal, landfill, landfill gas-to-energy, recycling and organics services in the northeastern United States. We market recyclable metals, aluminum, plastics, paper and corrugated cardboard, which have been processed at our recycling facilities, as well as recyclables purchased from third-parties. We manage our solid waste operations on a geographic basis through two regional operating segments, our Eastern and Western regions, each of which provides a full range of solid waste services, and our larger-scale recycling and commodity brokerage operations through our Recycling segment. Organics services, ancillary operations, along with major account and industrial services are included in our Other segment. The accompanying consolidated financial statements, which include the accounts of the Parent, our wholly-owned subsidiaries and any partially owned entities over which we have a controlling financial interest, have been prepared in accordance with generally accepted accounting principles in the United States (“GAAP”) pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”). All significant intercompany accounts and transactions are eliminated in consolidation. Investments in entities in which we do not have a controlling financial interest are accounted for under either the equity method or the cost method of accounting, as appropriate.

ACCOUNTING CHANGES

12 Months Ended

Dec. 31, 2018

Accounting Changes and Error Corrections [Abstract]

ACCOUNTING CHANGES



Standard	Description	Effect on the Financial Statements or Other Significant Matters
Accounting standards updates ("ASU") that were adopted effective January 1, 2018
ASU 2017-12: Derivatives and Hedging (Topic 815)	Requires that an entity align its risk management activities and financial reporting for hedging relationships through changes to both the designation and measurement guidance for qualifying hedging relationships and the presentation of hedge results. This guidance expands and refines hedge accounting for both financial and commodity risk components and aligns the recognition and presentation of the effects of the hedging instrument and the hedged item in the financial statements.	The adoption of this guidance affects the designation and measurement guidance for qualifying hedging relationships and the method of presenting hedge results, including the addition of a tabular disclosure related to the effect on the income statement of fair value and cash flow hedges and no longer measuring and reporting hedge ineffectiveness. We early adopted this guidance using a modified retrospective approach effective April 1, 2018 with an initial application date of January 1, 2018 with no adjustment to Accumulated Deficit. See Note 10, Long-Term Debt and Capital Leases for additional disclosure.

ASU 2017-09: Compensation - Stock Compensation (Topic 718)	Requires that an entity should account for the effects of a modification to an award unless all of the following conditions are met: the fair value of the modified award is the same as the fair value of the original award immediately before the original award is modified; the vesting conditions of the modified award are the same as the vesting conditions immediately before the original award is modified; and the classification of modified award as an equity instrument or a liability instrument is the same as the classification of the original award immediately before the original award is modified.	The adoption of this guidance could affect equity compensation expense and net income if there is a modification of an award.



ASU 2016-18: Statement of Cash Flows (Topic 230)	Requires that an entity should explain the change during the period of cash, cash equivalents, and amounts generally described as restricted cash or restricted cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows.	The adoption of this guidance is retrospective to each period presented. As a result of this adoption, we reclassified $1,347 of restricted cash from net cash used in investing activities in fiscal year 2016.

ASU 2016-01, as amended through March 2018: Financial Instruments - Overall (Topic 825-10)	Requires the following: (1) equity investments (except those accounted for under the equity method of accounting, or those that result in consolidation of the investee) to be measured at fair value with changes in fair value recognized in net income; (2) entities to use the exit price notion when measuring the fair value of financial instruments for disclosure purposes; (3) separate presentation of financial assets and financial liabilities by measurement category and form of financial asset; and (4) the elimination of the disclosure requirement to disclose the method(s) and significant assumptions used to estimate the fair value that is required to be disclosed for financial instruments measured at amortized cost.	The adoption of this guidance resulted in a cumulative-effect adjustment to Accumulated Deficit, recognition of the change in fair value of certain equity investments in net income, and enhanced disclosure. The adoption of this guidance did not have a material impact on our consolidated financial statements.

ASU 2014-09, as amended through November 2017: Revenue from Contracts with Customers (Topic 606)	The core principle of the guidance is that using a five step methodology an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. The standard also requires enhanced qualitative and quantitative disclosure regarding revenue recognition from customer contracts.	We adopted the guidance using the modified retrospective approach effective January 1, 2018 with no adjustment to Accumulated Deficit. We adopted the standard through the application of the portfolio approach. We selected a sample of customer contracts to assess under the guidance of the new standard that were characteristically representative of each portfolio. Upon completion of our review, the guidance did not result in a significant change to the timing of revenue recognition. We identified certain immaterial sales commissions, which represent costs of obtaining a contract, that should be capitalized as contract acquisition costs under the guidance and amortized to general and administration expense over the expected life of the customer contract. Based on the immateriality of these sales commissions, no adjustment to Accumulated Deficit nor the accounting of these costs was deemed necessary. See Note 4, Revenue Recognition for additional disclosure.



Standard	Description	Effect on the Financial Statements or Other Significant Matters
Accounting standards that are pending adoption at December 31, 2018



ASU 2018-16: Derivatives and Hedging (Topic 815)	Allows an entity to use the overnight index swap ("OIS") rate as a benchmark interest rate for hedge accounting purposes in conjunction with ASU 2017-12: Derivatives and Hedging.	The adoption of this guidance is not expected to have a material impact on our consolidated financial statements as we do not have any hedges that use the OIS as a benchmark interest rate. This guidance is effective January 1, 2019 because we early adopted ASU 2017-12: Derivatives and Hedging, with an initial application date of January 1, 2018.

ASU 2017-04: Intangibles - Goodwill and Other (Topic 350)	Requires that when an entity is performing its annual, or interim, goodwill impairment test, it should compare the fair value of the reporting unit with its carrying amount when calculating its impairment charge, noting that the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. Additionally, if applicable, an entity should consider income tax effects from any tax deductible goodwill on the carrying amount of the reporting unit when calculating its impairment charge.	As of December 31, 2018, we did not record a goodwill impairment charge related to our annual goodwill impairment test because at that time the fair value of each reporting unit exceeded its respective carrying value. Upon adoption, if the carrying value of any of these reporting units exceeds the fair value when we perform a goodwill impairment test, we would record an impairment charge equal to the amount by which the carrying value exceeds its fair value. This guidance is effective January 1, 2020 with early adoption permitted for interim or annual goodwill impairment tests performed after January 1, 2017.



ASU 2016-02, as amended through December 2018: Leases (Topic 842)	Requires that a lessee recognize at the commencement date: a lease liability, which is the obligation of the lessee to make lease payments arising from a lease, measured on a discounted basis; and a right-of-use asset, which is an asset that represents the lessee’s right to use, or control the use of, a specified asset for the lease term.	We adopted the guidance using the prospective optional transition method effective January 1, 2019, which allows us to elect not to restate comparative periods and recognize the effects of applying this guidance as a cumulative-effect adjustment to retained earnings as of January 1, 2019. Upon adopting this guidance, we will recognize a right-of-use asset and a lease liability for leases classified as operating leases with a term in excess of 12 months in our consolidated balance sheet. As a part of the implementation, we have applied the practical expedient package. The practical expedient package allowed us to: 1) not reassess lease classification for existing leases; 2) not reassess whether a contract contains a lease for existing contracts; and 3) not reassess initial direct costs for existing leases. With the assistance of third-party resources, we designed internal controls over the adoption of this guidance and implemented a third-party enterprise lease management software solution. In conjunction with this, we have modified our lease policy and internal business process to effectively manage and account for leases as well as support recognition and disclosure under the new standard. As of January 1, 2019, we expect to recognize a right-of-use asset for operating leases of between approximately $106,000 and $121,000 and a corresponding lease liability of between approximately $76,000 and $91,000 with the difference primarily associated with prepaid amounts for certain landfill operating leases that will be reclassified from property, plant and equipment. We do not expect to recognize a material cumulative effect adjustment to retained earnings and we do not expect the adoption of this guidance to have a material impact on our consolidated statements of operations or our consolidated statements of cash flows. We also do not expect that the adoption of this guidance will have a material impact on the accounting for our finance leases. This guidance will require additional disclosures over leases in order to comply with the standard.

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

Management’s Estimates and Assumptions

Preparation of our consolidated financial statements in accordance with GAAP requires management to make certain estimates and assumptions. These estimates and assumptions affect the accounting for and recognition and disclosure of assets, liabilities, equity, revenues and expenses. We must make these estimates and assumptions because certain information that we use is dependent on future events, cannot be calculated with a high degree of precision given the available data or simply cannot be readily calculated. In some cases, these estimates are difficult to determine, and we must exercise significant judgment. In preparing our consolidated financial statements, the estimates and assumptions that we consider to be significant and that present the greatest amount of uncertainty relate to our accounting for landfills, environmental remediation liabilities, asset impairments, accounts receivable valuation allowance, self-insurance reserves, deferred taxes and uncertain tax positions, estimates of the fair values of assets acquired and liabilities assumed in any acquisition, contingent liabilities and stock-based compensation. Each of these items is discussed in more detail elsewhere in these notes to consolidated financial statements, as applicable. Actual results may differ materially from the estimates and assumptions that we use in the preparation of our consolidated financial statements.

Cash and Cash Equivalents

We consider all highly liquid investments purchased with original maturities of three months or less to be cash equivalents.

Concentrations of Credit Risk

Financial instruments that potentially subject us to concentrations of credit risk consist of cash and cash equivalents, restricted investment securities, accounts receivable-trade and derivative instruments. We maintain cash and cash equivalents and restricted investment securities with banks that at times exceed applicable insurance limits. We reduce our exposure to credit risk by maintaining such deposits with high quality financial institutions. Our concentration of credit risk with respect to accounts receivable-trade is limited because of the large number and diversity of customers we serve, thus reducing the credit risk associated with any one customer group. As of December 31, 2018, no single customer or customer group represented greater than 5% of total accounts receivable - trade. We manage credit risk through credit evaluations, credit limits, and monitoring procedures, but generally do not require collateral to support accounts receivable - trade. We reduce our exposure to credit risk associated with derivative instruments by entering into agreements with high quality financial institutions and by evaluating and regularly monitoring their creditworthiness.

Accounts Receivable – Trade, Net of Allowance for Doubtful Accounts

Accounts receivable – trade represent receivables from customers for collection, transfer, recycling, disposal and other services. Our accounts receivable – trade are recorded when billed or when related revenue is earned, if earlier, and represent claims against third-parties that will be settled in cash. The carrying value of our accounts receivable – trade, net of allowance for doubtful accounts represents its estimated net realizable value. Estimates are used in determining our allowance for doubtful accounts based on our historical collection experience, current trends, credit policy and a review of our accounts receivable – trade by aging category. Our reserve is evaluated and revised on a monthly basis. Past due accounts receivable - trade are written off when deemed to be uncollectible.

Inventory

Inventory includes secondary fibers, recyclables ready for sale, and parts and supplies. Inventory is stated at the lower of cost (first-in, first-out) or market.

Property, Plant and Equipment

Property, plant and equipment is recorded at cost, less accumulated depreciation and amortization. We provide for depreciation and amortization using the straight-line method by charges to operations in amounts that allocate the cost of the assets over their estimated useful lives as follows:



Asset Classification		Estimated Useful Life
Buildings and improvements		10-30 years
Machinery and equipment		5-10 years
Rolling stock		5-10 years
Containers		5-12 years
Furniture and Fixtures		3-8 years

The cost of maintenance and repairs is charged to operations as incurred.

Landfill development costs are included in property, plant and equipment. Landfill development costs include costs to develop each of our landfill sites, including such costs related to landfill liner material and installation, excavation for airspace, landfill leachate collection systems, landfill gas collection systems, environmental monitoring equipment for groundwater and landfill gas, directly related engineering, capitalized interest, on-site road construction, and other capital infrastructure. Additionally, landfill development costs include all land purchases within the landfill footprint and the purchase of any required landfill buffer property. Under life-cycle accounting, these costs are capitalized and charged to expense based on tonnage placed into each site.

See the “Landfill Accounting” accounting policy below for additional disclosure over the amortization of landfill development costs and Note 7, Property, Plant and Equipment for disclosure over property, plant and equipment.

Landfill Accounting

Life Cycle Accounting

Under life-cycle accounting, all costs related to acquisition and construction of landfill sites are capitalized and charged to expense based on tonnage placed into each site. Landfill permitting, acquisition and preparation costs are amortized on the units-of-consumption method as landfill airspace is consumed. In determining the amortization rate for each of our landfills, preparation costs include the total estimated costs to complete construction of the landfills’ permitted and expansion capacity.

Landfill Development Costs

We estimate the total cost to develop each of our landfill sites to its remaining permitted and expansion capacity (see landfill development costs discussed within the “Property, Plant and Equipment” accounting policy above). The projection of these landfill costs is dependent, in part, on future events. The remaining amortizable basis of each landfill includes costs to develop a site to its remaining permitted and expansion capacity and includes amounts previously expended and capitalized, net of accumulated airspace amortization, and projections of future purchase and development costs including capitalized interest. The interest capitalization rate is based on our weighted average interest rate incurred on borrowings outstanding during the period. Interest capitalized during the fiscal years ended December 31, 2018 ("fiscal year 2018"), December 31, 2017 ("fiscal year 2017") and December 31, 2016 ("fiscal year 2016") was $140, $295 and $273, respectively.

Landfill Airspace

We apply the following guidelines in determining a landfill’s remaining permitted and expansion airspace:

Remaining Permitted Airspace. Our engineers, in consultation with third-party engineering consultants and surveyors, are responsible for determining remaining permitted airspace at our landfills. The remaining permitted airspace is determined by an annual survey, which is then used to compare the existing landfill topography to the expected final landfill topography.

Expansion Airspace. We currently include unpermitted expansion airspace in our estimate of remaining permitted and expansion airspace in certain circumstances. To be considered expansion airspace all of the following criteria must be met:


•	we control the land on which the expansion is sought;


•	all technical siting criteria have been met or a variance has been obtained or is reasonably expected to be obtained;


•	we have not identified any legal or political impediments which we believe will not be resolved in our favor;


•	we are actively working on obtaining any necessary permits and we expect that all required permits will be received; and


•	senior management has approved the project.

For unpermitted airspace to be included in our estimate of remaining permitted and expansion airspace, the expansion effort must meet all of the criteria listed above. These criteria are evaluated annually by our engineers, accountants, lawyers, managers and others to identify potential obstacles to obtaining the permits. Once the remaining permitted and expansion airspace is determined in cubic yards, an airspace utilization factor (“AUF”) is established to calculate the remaining permitted and expansion capacity in tons. The AUF is established using a process that considers the measured density obtained from annual surveys. When we include the expansion airspace in our calculation of remaining permitted and expansion airspace, we include the projected costs for development, as well as the projected asset retirement costs related to final capping, closure and post-closure of the expansion airspace in the amortization basis of the landfill.

After determining the costs and the remaining permitted and expansion capacity at each of our landfills, we determine the per ton rates that will be expensed as waste is received and deposited at each of our landfills by dividing the costs by the corresponding number of tons. We calculate per ton amortization rates for assets associated with each final capping event, for assets related to closure and post-closure activities and for all other costs capitalized or to be capitalized in the future for each landfill. These rates per ton are updated annually, or more frequently, as significant facts change.

It is possible that actual results, including the amount of costs incurred, the timing of final capping, closure and post-closure activities, our airspace utilization or the success of our expansion efforts, could ultimately turn out to be significantly different from our estimates and assumptions. To the extent that such estimates or related assumptions prove to be significantly different than actual results, lower profitability may be experienced due to higher amortization rates, higher final capping, closure or post-closure rates, or higher expenses. Higher profitability may result if the opposite occurs. Most significantly, if it is determined that the expansion capacity should no longer be considered in calculating the recoverability of the landfill asset, we may be required to recognize an asset impairment. If it is determined that the likelihood of receiving an expansion permit has become remote, the capitalized costs related to the expansion effort are expensed immediately.

Final Capping, Closure and Post-Closure Costs

The following is a description of our landfill asset retirement activities and related accounting:

Final Capping Costs. Final capping activities include the installation of liners, drainage, compacted soil layers and topsoil over areas of a landfill where total airspace has been consumed and waste is no longer being received. Final capping activities occur throughout the life of the landfill. Our engineering personnel estimate the cost for each final capping event based on the acreage to be capped, along with the final capping materials and activities required. The estimates also consider when these costs would actually be paid and factor in inflation and discount rates. The engineers then quantify the landfill capacity associated with each final capping event and the costs for each event are amortized over that capacity as waste is received at the landfill.

Closure and Post-Closure Costs. Closure and post-closure costs represent future estimated costs related to monitoring and maintenance of a solid waste landfill after a landfill facility ceases to accept waste and closes. We estimate, based on input from our engineers, accountants, lawyers, managers and others, our future cost requirements for closure and post-closure monitoring and maintenance based on our interpretation of the technical standards of the Subtitle D regulations and the air emissions standards under the Clean Air Act of 1970, as amended, as they are being applied on a state-by-state basis. Closure and post-closure accruals for the cost of monitoring and maintenance include site inspection, groundwater monitoring, leachate management, methane gas control and recovery, and operation and maintenance costs to be incurred for a period which is generally for a term of 30 years after final closure of a landfill. In determining estimated future closure and post-closure costs, we consider costs associated with permitted and permittable airspace.

Our estimated future final capping, closure and post-closure costs, based on our interpretation of current requirements and proposed regulatory changes, are intended to approximate fair value. Absent quoted market prices, our cost estimates are based on historical experience, professional engineering judgment and quoted or actual prices paid for similar work. Our estimate of costs to discharge final capping, closure and post-closure asset retirement obligations for landfills are developed in today’s dollars. These costs are then inflated to the period of performance using an estimate of inflation, which is updated annually (1.5% as of December 31, 2018). Final capping, closure and post-closure liabilities are discounted using the credit adjusted risk-free rate in effect at the time the obligation is incurred. The weighted average rate applicable to our asset retirement obligations as of December 31, 2018 is between approximately 8.7% and 9.8%, the range of the credit adjusted risk free rates effective since the adoption of guidance associated with asset retirement obligations in the fiscal year ended April 30, 2004. Accretion expense is necessary to increase the accrued final capping, closure and post-closure liabilities to the future anticipated obligation. To accomplish this, we accrete our final capping, closure and post-closure accrual balances using the same credit-adjusted risk-free rate that was used to calculate the recorded liability. Accretion expense on recorded landfill liabilities is recorded to cost of operations from the time the liability is recognized until the costs are paid. Accretion expense on recorded landfill liabilities amounted to $5,556, $4,401 and $3,606 in fiscal years 2018, 2017 and 2016, respectively.

We provide for the accrual and amortization of estimated future obligations for closure and post-closure based on tonnage placed into each site. With regards to final capping, the liability is recognized and the costs are amortized based on the airspace related to the specific final capping event.

See Note 9, Final Capping, Closure and Post-Closure Costs for disclosure over asset retirement obligations related to final capping, closure and post-closure costs.

We operate in states which require a certain portion of landfill final capping, closure and post-closure obligations to be secured by financial assurance, which may take the form of surety bonds, letters of credit and restricted investment securities. Surety bonds securing closure and post-closure obligations at December 31, 2018 and December 31, 2017 totaled $201,177 and $164,893, respectively. Letters of credit securing closure and post-closure obligations as of December 31, 2018 and December 31, 2017 totaled $0 and $0, respectively. See Note 6, Restricted Assets for disclosure over restricted investment securities securing closure and post-closure obligations.

Landfill Operating Lease Contracts

We are party to four landfill operation and management agreements. These agreements are long-term landfill operating contracts with government bodies whereby we receive tipping revenue, pay normal operating expenses and assume future final capping, closure and post-closure obligations. The government body retains ownership of the landfill. There is no bargain purchase option and title to the property does not pass to us at the end of the lease term. We allocate the consideration paid to the landfill airspace rights and underlying land lease based on the relative fair values.

In addition to up-front or one-time payments, the landfill operating agreements may require us to make future minimum rental payments, including success/expansion fees, other direct costs and final capping, closure and post-closure costs. The value of all future minimum rental payments is amortized and charged to cost of operations over the life of the contract. We amortize the consideration allocated to airspace rights as airspace is utilized on a units-of-consumption basis and such amortization is charged to cost of operations as airspace is consumed (e.g., as tons are placed into the landfill). The underlying value of any land lease is amortized to cost of operations on a straight-line basis over the estimated life of the operating agreement. See Note 7, Property, Plant and Equipment for disclosure over depletion of landfill operating lease contracts.

Leases

In addition to landfill operating leases, we lease property and equipment in the ordinary course of our business. Our leases have varying terms and may include renewal or purchase options, escalation clauses, restrictions, lease concessions, capital project funding, penalties or other obligations that we consider in determining minimum rental payments. Leases are either classified as operating leases or capital leases, as appropriate.

Operating Leases. Many of our leases are operating leases. This classification generally can be attributed to either (i) relatively low fixed minimum rental payments or (2) minimum lease terms that are much shorter than the assets’ economic useful lives. We expect that, in the normal course of business, our operating leases will be replaced by other leases, or replaced with fixed asset expenditures.

See Note 11, Commitments and Contingencies for disclosure over future minimum lease payments related to our operating leases.

Capital Leases. We capitalize assets acquired under capital leases at the inception of each lease and amortize them to depreciation expense over the useful life of the asset or the lease term, as appropriate. The present value of the related lease payments is recorded as a debt obligation.

See Note 10, Long-Term Debt and Capital Leases for disclosure over our future maturities of debt, which includes capital lease payments.

Effective January 1, 2019, we adopted ASU 2016-02, as amended through December 2018: Leases (Topic 842). See Note 2, Accounting Changes for additional disclosure over our adoptions of this guidance.

Goodwill and Intangible Assets

Goodwill. Goodwill is the excess of our purchase cost over the fair value of the net assets of acquired businesses. We do not amortize goodwill, but as discussed in the “Asset Impairments” accounting policy below, we assess our goodwill for impairment at least annually.

See Note 8, Goodwill and Intangible Assets for disclosure over goodwill.

Intangible Assets. Intangible assets consist primarily of covenants not-to-compete and customer lists. Intangible assets are recorded at fair value and are amortized based on the economic benefit provided or using the straight-line method over their estimated useful lives. Covenants not-to-compete and customer lists are typically amortized over a term of no more than 10 years.

See Note 8, Goodwill and Intangible Assets for disclosure over intangible assets.

Investments in Unconsolidated Entities

Investments in unconsolidated entities over which we have significant influence over the investees’ operating and financing activities are accounted for under the equity method of accounting. Investments in affiliates in which we do not have the ability to exert significant influence over the investees’ operating and financing activities are accounted for under the cost method of accounting. As of December 31, 2018 and December 31, 2017, we had no investments accounted for under the equity method of accounting.

We monitor and assess the carrying value of our investments throughout the year for potential impairment and write them down to their fair value when other-than-temporary declines exist. Fair value is generally based on (i) other third-party investors’ recent transactions in the securities; (ii) other information available regarding the current market for similar assets and/or (iii) a market or income approach, as deemed appropriate.

When we assess the carrying value of our investments for potential impairment, determining the fair value of our investments is reliant upon the availability of market information and/or other information provided by third-parties to be able to develop an estimate of fair value. Considerable judgment is required in interpreting market data to develop the estimates of fair value. Accordingly, our estimates are not necessarily indicative of the amounts that we, or other holders of these investments, could realize in a current market exchange. The use of different assumptions and/or estimation methodologies could have a significant effect on the estimated fair values. The estimates of fair value could differ significantly from the amounts presented. See “Asset Impairments” accounting policy below.

Fair Value of Financial Instruments

Our financial instruments may include cash and cash equivalents, accounts receivable-trade, restricted investment securities held in trust on deposit with various banks as collateral for our obligations relative to our landfill final capping, closure and post-closure costs and restricted cash reserved to finance certain capital projects, interest rate derivatives, trade payables and long-term debt. Accounting standards include disclosure requirements around fair values used for certain financial instruments and establish a fair value hierarchy. The three-tier hierarchy prioritizes valuation inputs into three levels based on the extent to which inputs used in measuring fair value are observable in the market. Each fair value measurement is reported in one of three levels: Level 1, defined as quoted market prices in active markets for identical assets or liabilities; Level 2, defined as inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities; and Level 3, defined as unobservable inputs that are not corroborated by market data.

See Note 10, Long-Term Debt and Capital Leases and Note 13, Fair Value of Financial Instruments for fair value disclosure over long-term debt and financial instruments, respectively. See the “Derivatives and Hedging” accounting policy below for the fair value disclosure over interest rate derivatives.

Business Combinations

We acquire businesses in the waste industry, including non-hazardous waste collection, transfer station, recycling and disposal operations, as part of our growth strategy. Businesses are included in the consolidated financial statements from the date of acquisition.

We recognize, separately from goodwill, the identifiable assets acquired and liabilities assumed at their estimated acquisition-date fair values. We measure and recognize goodwill as of the acquisition date as the excess of: (a) the aggregate of the fair value of consideration transferred, the fair value of any noncontrolling interest in the acquiree (if any) and the acquisition date fair value of our previously held equity interest in the acquiree (if any), over (b) the fair value of net assets acquired and liabilities assumed. If information about facts and circumstances existing as of the acquisition date is incomplete by the end of the reporting period in which a business combination occurs, we will report provisional amounts for the items for which the accounting is incomplete. The measurement period ends once we receive the information we were seeking; however, this period will not extend beyond one year from the acquisition date. Any material adjustments recognized during the measurement period will be recognized retrospectively in the consolidated financial statements of the current period. All acquisition related transaction and restructuring costs are to be expensed as incurred.

See Note 5, Business Combinations for disclosure over business acquisitions.

Environmental Remediation Liabilities

We have recorded environmental remediation liabilities representing our estimate of the most likely outcome of the matters for which we have determined that a liability is probable. These liabilities include potentially responsible party investigations, settlements, certain legal and consultant fees, as well as costs directly associated with site investigation and clean up, such as materials and incremental internal costs directly related to the remedy. We provide for expenses associated with environmental remediation obligations when such amounts are probable and can be reasonably estimated. We estimate costs required to remediate sites where it is probable that a liability has been incurred based on site-specific facts and circumstances. Estimates of the cost for the likely remedy are developed using third-party environmental engineers or other service providers. Where we believe that both the amount of a particular environmental remediation liability and timing of payments are reliably determinable, we inflate the cost in current dollars until the expected time of payment and discount the cost to present value.

See Note 11, Commitments and Contingencies for disclosure over environmental remediation liabilities.

Self-Insurance Liabilities and Related Costs

We are self-insured for vehicles and workers’ compensation with reinsurance coverage limiting our maximum exposure. Our maximum exposure in fiscal year 2018 under the workers’ compensation plan was $1,000 per individual event. Our maximum exposure in fiscal year 2018 under the automobile plan was $1,200 per individual event. The liability for unpaid claims and associated expenses, including incurred but not reported losses, is determined by management with the assistance of a third-party actuary and reflected in our consolidated balance sheet as an accrued liability. We use a third-party to track and evaluate actual claims experience for consistency with the data used in the annual actuarial valuation. The actuarially determined liability is calculated based on historical data, which considers both the frequency and settlement amount of claims. Our self-insurance reserves totaled $15,040 and $14,480 as of December 31, 2018 and December 31, 2017, respectively. Our estimated accruals for these liabilities could be significantly different than our ultimate obligations if variables such as the frequency or severity of future events differ significantly from our assumptions.

Income Taxes

We use estimates to determine our provision for income taxes and related assets and liabilities and any valuation allowance recorded against our net deferred tax assets. Valuation allowances have been established for the possibility that tax benefits may not be realized for certain deferred tax assets. Deferred income taxes are recognized based on the expected future tax consequences of differences between the financial statement basis and the tax basis of assets and liabilities, calculated using currently enacted tax rates. We record net deferred tax assets to the extent we believe these assets will more likely than not be realized. In making this determination, we consider all available positive and negative evidence, including scheduled reversals of deferred tax liabilities, projected future taxable income, tax planning strategies and recent financial operations. In the event we determine that we would be able to realize our deferred income tax assets in the future in excess of their net recorded amount, we will make an adjustment to the valuation allowance which would reduce the provision for income taxes.

We account for income tax uncertainties according to guidance on the recognition, de-recognition and measurement of potential tax benefits associated with tax positions. We recognize interest and penalties relating to income tax matters as a component of income tax expense.

On December 22, 2017, the Tax Cuts and Jobs Act (the “Act”) was enacted. The Act, which is also commonly referred to as “U.S. tax reform,” significantly changes United States corporate income tax laws by, among other things, reducing the US corporate income tax rate from 35% to 21% starting in 2018.

See Note 15, Income Taxes for disclosure related to income taxes, including the effect of the Act on income taxes.

Derivatives and Hedging

We account for derivatives and hedging activities in accordance with derivatives and hedging accounting guidance that establishes accounting and reporting standards requiring that every derivative instrument (including certain derivative instruments embedded in other contracts) be recorded in the balance sheet as either an asset or liability measured at its fair value. The guidance requires that changes in the derivative’s fair value be recognized currently in earnings unless specific hedge accounting criteria are met.

Our objective for utilizing derivative instruments is to reduce our exposure to fluctuations in cash flows due to changes in the commodity prices of recycled paper and adverse movements in interest rates.

Our strategy to hedge against fluctuations in the commodity prices of recycled paper is to enter into hedges to mitigate the variability in cash flows generated from the sales of recycled paper at floating prices, resulting in a fixed price being received from these sales. We evaluate the hedges and ensure that these instruments qualify for hedge accounting pursuant to derivative and hedging guidance. Designated as highly effective cash flow hedges, both the effective and ineffective portion of the change in the fair value of these derivatives is recorded in our stockholders’ deficit as a component of accumulated other comprehensive income (loss) until the hedged item is settled and recognized as part of commodity revenue. If the price per short ton of the underlying commodity, as reported on the Official Board Market, is less than the contract price per short ton, we receive the difference between the average price and the contract price (multiplied by the notional tons) from the respective counter-party. If the price per short ton of the underlying commodity exceeds the contract price per short ton, we pay the calculated difference to the counter-party. The fair value of commodity hedges are obtained or derived from our counter-parties using valuation models that take into consideration market price assumptions for commodities based on underlying active markets. We were not party to any commodity hedge contracts as of December 31, 2018.

Our strategy to hedge against fluctuations in variable interest rates involves entering into interest rate derivative agreements to hedge against adverse movements in interest rates. For interest rate derivatives deemed to be highly effective cash flow hedges, both the effective and ineffective portion of the change in fair value of these derivatives is recorded in our stockholders’ deficit as a component of accumulated other comprehensive income (loss) and reclassified into earnings through interest expense in the same period or periods during which the hedged transaction affects earnings.

See Note 13, Fair Value of Financial Instruments for fair value disclosure over derivative instruments and Note 10, Long Term Debt and Capital Leases for further disclosure over interest rate derivatives. We also early adopted ASU 2017-12: Derivatives and Hedging (Topic815) with an initial application date of January 1, 2018. See Note 2, Accounting Changes for further disclosure.

Contingent Liabilities

We are subject to various legal proceedings, claims and regulatory matters, the outcomes of which are subject to significant uncertainty. We determine whether to disclose or accrue for loss contingencies based on an assessment of whether the risk of loss is remote, reasonably possible or probable, and whether it can be reasonably estimated. We analyze our litigation and regulatory matters based on available information to assess the potential liabilities. Management’s assessment is developed based on an analysis of possible outcomes under various strategies. We accrue for loss contingencies when such amounts are probable and reasonably estimable. If a contingent liability is only reasonably possible, we will disclose the potential range of the loss, if estimable. We record losses related to contingencies in cost of operations or general and administration expenses, depending on the nature of the underlying transaction leading to the loss contingency.

See Note 11, Commitments and Contingencies for disclosure over loss contingencies, as applicable. Contingent liabilities accounted for under purchase accounting are recorded at their fair values. These fair values may be different from the values we would have otherwise recorded, had the contingent liability not been assumed as part of an acquisition of a business.

See Note 5, Business Combinations for disclosure over a contingent liability assumed as part of the acquisition of a business.

Revenue Recognition

We adopted ASU 2014-09, as amended, Revenue from Contracts with Customers (Topic 606) effective January 1, 2018. We adopted this guidance using the modified retrospective approach, noting that no cumulative effect adjustment to the beginning balance of Accumulated Deficit was needed. The comparative periods have not been restated and continue to be reported under Revenue Recognition (Topic 605). We applied this guidance to contracts that were not substantially completed contracts at the date of adoption. Additionally, contract modifications that occurred before the adoption date were not separately evaluated, rather the guidance was applied to the current version of the contract only. We disaggregate our revenues by applicable service line: collection, landfill, transfer, customer solutions, recycling, organics, transportation and landfill gas-to-energy.

Under the new revenue recognition guidance, revenues are measured based on the consideration specified in a contract with a customer. The circumstances that impact the timing and amount of revenue recognized for each applicable service line may vary based on the nature of the service performed. We generally recognize revenues for services over time as we satisfy the performance obligation by transferring control over the service to the customer as the service is performed and the benefit is received and consumed by the customer. Services are typically delivered in a series as a single bundled performance obligation over either a designated period of time or for specified number of services. Services may also be delivered as a single bundled service, on a period-to-period basis, or in a spot transaction. Consideration may be variable on a per ton basis and/or fixed. Fixed consideration is allocated to each distinct service and variable consideration is allocated to the increment of time that the service is performed and we have the contractual right to the fee. Fees are typically billed weekly, monthly, quarterly or in advance. Generally, the amount of consideration that we have the right to receive that is invoiced to the customer directly corresponds to the value of our performance completed to date. We elected the optional exemption, to not disclose the amount of variable consideration included in the transaction price that is allocated to outstanding performance obligations when the variable consideration is allocated entirely to unsatisfied performance obligations or to a wholly unsatisfied promise to transfer a distinct good or service that forms part of a single performance obligation. Revenues that are not satisfied over time are recognized at a point-in-time. This typically includes the sale of recycled or organic materials, as well as renewable energy credits ("RECs"). Revenues from the sale of organic or recycled materials are recognized at a point-in-time as control of the materials transfers to the customer upon shipment or pick-up by the customer. Revenues from the sale of RECs are recognized at a point-in-time as the trade is executed and control transfers to the customer.

Payments to customers that are not in exchange for a distinct good or service are recorded as a reduction of revenues. Rebates to certain customers associated with payments for recycled or organic materials that are received and subsequently processed and sold to other third-parties amounted to $6,279 in fiscal year 2018. Rebates are generally recorded as a reduction of revenues upon the sale of such materials, or upon receipt of the recycled materials at our facilities. These payments were previously recorded as a cost of operations. We did not record any revenues in fiscal year 2018 from performance obligations satisfied in previous periods.

Contract receivables, which are included in Accounts receivable - trade, net are recorded when billed or when related revenue is earned, if earlier, and represent claims against third-parties that will be settled in cash. Accounts receivable - trade, net includes gross receivables from contracts of $73,500 and $66,227 as of December 31, 2018 and December 31, 2017, respectively. Certain customers are billed in advance and, accordingly, recognition of the related revenues is deferred as a contract liability until the services are provided and control transferred to the customer. Contract liabilities of $3,074 and $1,823 as of December 31, 2018 and December 31, 2017, respectively, were reclassified out of Other accrued liabilities and presented separately on the face of the Consolidated Balance Sheets. Due to the short term nature of advanced billings, substantially all of the deferred revenue recognized as a contract liability as of December 31, 2017 was recognized as revenue during fiscal year 2018 when the services were performed.

See Note 2, Accounting Changes and Note 4, Revenue Recognition for disclosure over the new guidance.

Asset Impairments

Recovery of Long-Lived Assets. We continually assess whether events or changes in circumstances have occurred that may warrant revision of the estimated useful lives of our long-lived assets (other than goodwill) or whether the remaining balances of those assets should be evaluated for possible impairment. Long-lived assets include, for example, capitalized landfill costs, other property, plant and equipment, and identifiable intangible assets. Events or changes in circumstances that may indicate that an asset may be impaired include the following:


•	a significant decrease in the market price of an asset or asset group;


•	a significant adverse change in the extent or manner in which an asset or asset group is being used or in its physical condition;


•	a significant adverse change in legal factors or in the business climate that could affect the value of an asset or asset group, including an adverse action or assessment by a regulator;


•	an accumulation of costs significantly in excess of the amount originally expected for the acquisition or construction of a long-lived asset;


•	a current period operating or cash flow loss combined with a history of operating or cash flow losses or a projection or forecast that demonstrates continuing losses associated with the use of a long-lived asset or asset group;


•	a current expectation that, more likely than not, a long-lived asset or asset group will be sold or otherwise disposed of significantly before the end of its previously estimated useful life; or


•	an impairment of goodwill at a reporting unit.

There are certain indicators listed above that require significant judgment and understanding of the waste industry when applied to landfill development or expansion. For example, a regulator may initially deny a landfill expansion permit application although the expansion permit is ultimately granted. In addition, management may periodically divert waste from one landfill to another to conserve remaining permitted landfill airspace. Therefore, certain events could occur in the ordinary course of business and not necessarily be considered indicators of impairment due to the unique nature of the waste industry.

If an impairment indicator occurs, we perform a test of recoverability by comparing the carrying value of the asset or asset group to its undiscounted expected future cash flows. We group our long-lived assets for this purpose at the lowest level for which identifiable cash flows are primarily independent of the cash flows of other assets or asset groups. If the carrying values are in excess of undiscounted expected future cash flows, we measure any impairment by comparing the fair value of the asset or asset group to its carrying value.

To determine fair value, we use discounted cash flow analyses and estimates about the future cash flows of the asset or asset group. This analysis includes a determination of an appropriate discount rate, the amount and timing of expected future cash flows and growth rates. The cash flows employed in our discounted cash flow analyses are typically based on financial forecasts developed internally by management. The discount rate used is commensurate with the risks involved. We may also rely on third-party valuations and or information available regarding the market value for similar assets.

If the fair value of an asset or asset group is determined to be less than the carrying amount of the asset or asset group, impairment in the amount of the difference is recorded in the period that the impairment occurs. Estimating future cash flows requires significant judgment and projections may vary from the cash flows eventually realized.

See Note 16, Other Items and Charges for disclosure related to long-lived asset impairments recognized during the reporting periods.

Goodwill. We annually assess goodwill for impairment at the end of our fiscal year or more frequently if events or circumstances indicate that impairment may exist.

We may assess whether a goodwill impairment exists using either a qualitative or a quantitative assessment. If we perform a qualitative assessment, it involves determining whether events or circumstances exist that indicate it is more likely than not that the fair value of a reporting unit is less than its carrying amount, including goodwill. If based on this qualitative assessment we determine it is not more likely than not that the fair value of a reporting unit is less than its carrying amount, we will not perform a quantitative assessment. If the qualitative assessment indicates that it is more likely than not that the fair value of a reporting unit is less than its carrying amount, or if we elect not to perform a qualitative assessment, we perform a quantitative assessment, or two-step impairment test, to determine whether goodwill impairment exists at the reporting unit.

In the first step (defined as “Step 1”) of testing for goodwill impairment, we estimate the fair value of each reporting unit, which we have determined to be our geographic operating segments, our Recycling segment and our Customer Solutions business, which is included in the Other segment, and compare the fair value with the carrying value of the net assets of each reporting unit. If the fair value is less than its carrying value, then we would perform a second step (defined as “Step 2”) and determine the fair value of the goodwill. In Step 2, the fair value of goodwill is determined by deducting the fair value of a reporting unit’s identifiable assets and liabilities from the fair value of the reporting unit as a whole, as if that reporting unit had just been acquired and the purchase price were being initially allocated.

To determine the fair value of each of our reporting units as a whole we use discounted cash flow analyses, which require significant assumptions and estimates about the future operations of each reporting unit. Significant judgments inherent in this analysis include the determination of appropriate discount rates, the amount and timing of expected future cash flows and growth rates. The cash flows employed in our discounted cash flow analyses are based on financial forecasts developed internally by management. Our discount rate assumptions are based on an assessment of our risk adjusted discount rate, applicable for each reporting unit. In assessing the reasonableness of our determined fair values of our reporting units, we evaluate our results against our current market capitalization.

If the fair value of goodwill is less than its carrying value for a reporting unit, an impairment charge would be recorded to earnings. The loss recognized cannot exceed the carrying amount of goodwill. After a goodwill impairment loss is recognized, the adjusted carrying amount of goodwill becomes its new accounting basis.

In addition to an annual goodwill impairment assessment, we would evaluate a reporting unit for impairment if events or circumstances change between annual tests indicating a possible impairment. Examples of such events or circumstances include the following:


•	a significant adverse change in legal status or in the business climate;


•	an adverse action or assessment by a regulator;


•	a more likely than not expectation that a segment or a significant portion thereof will be sold; or


•	the testing for recoverability of a significant asset group within the segment.

We elected to perform a quantitative analysis as part of our annual goodwill impairment test for fiscal year 2018. As of December 31, 2018, the Step 1 testing for goodwill impairment performed for our Eastern, Western, Recycling and Customer Solutions reporting units indicated that the fair value of each reporting unit exceeded its carrying amount, including goodwill. Furthermore, the Step 1 test indicated that in each case the fair value of our Eastern, Western, Recycling and Customer Solutions reporting units exceeded its carrying value by in excess of 21.5%. We incurred no impairment of goodwill as a result of our annual goodwill impairment tests in each of fiscal years 2018, 2017 and 2016. However, there can be no assurance that goodwill will not be impaired at any time in the future.

Cost Method Investments. As of December 31, 2018, we owned 6.8% of the outstanding common stock of Recycle Rewards, Inc. (“Recycle Rewards”), a company that markets an incentive based recycling service. In fiscal year 2018, it was determined based on the operating performance of Recycle Rewards that our cost method investment in Recycle Rewards was potentially impaired. As a result, we performed a valuation analysis in fiscal year 2018, which used an income approach based on discounted cash flows to determine an equity value for Recycle Rewards in order to properly value our cost method investment in Recycle Rewards. Based on this analysis, it was determined that the fair value of our cost method investment in Recycle Rewards was less than the carrying amount and, therefore, we recorded an other-than-temporary investment impairment charge of $1,069 in fiscal year 2018. As of December 31, 2018, the carrying amount of our cost method investment in Recycle Rewards was $0.

As of December 31, 2018, we owned 5.2% of the outstanding equity value of GreenerU, Inc. (“GreenerU”), a services company focused on providing energy efficiency, sustainability and renewable energy solutions to colleges and universities. As of December 31, 2018, the carrying amount of our cost method investment in GreenerU was $309.

As of December 31, 2018, we owned 17.0% and 16.2% of the outstanding common stock of AGreen Energy LLC (“AGreen”) and BGreen Energy LLC (“BGreen”), respectively. Through AGreen and BGreen, we partner with other capital investors to build farm-based anaerobic digester's in the Northeast to generate electricity from farm and food waste streams. As of December 31, 2018, the carrying amount of our cost method investments in AGreen and BGreen was $297.

Defined Benefit Pension Plan

We make contributions to one qualified multiemployer defined benefit pension plan, the New England Teamsters and Trucking Industry Pension Fund ("Pension Plan"). The Pension Plan provides retirement benefits to participants based on their service to contributing employers. We do not administer this plan. The Pension Plan’s benefit formula is based on credited years of service and hours worked as defined in the Pension Plan document. However, the benefits accruals of all current plan participants are frozen. Our pension contributions are made in accordance with funding standards established by the Employee Retirement Income Security Act of 1974 and the Internal Revenue Code, as amended by the Pension Protection Act of 2006. The Pension Plan’s assets have been invested as determined by the Pension Plan's fiduciaries in accordance with the Pension Plan's investment policy. The Pension Plan’s asset allocation is based on the Pension Plan's investment policy and is reviewed as deemed necessary.

See Note 14, Employee Benefit Plans for disclosure over the multiemployer defined benefit pension plan.

Stock-Based Compensation

All share-based compensation cost is measured at the grant date based on the estimated fair value of the award, and is recognized as expense-in general and administration expense over the employee’s requisite service period. For purposes of calculating stock-based compensation expense, forfeitures are accounted for as they occur. Our equity awards granted generally consist of stock options, including market-based performance stock options, restricted stock, restricted stock units and performance stock units, including market-based performance stock units.

The fair value of each stock option grant is estimated using a Black-Scholes option-pricing model, with the exception of market-based performance stock option grants which are valued using a Monte Carlo option-pricing model. The fair value of restricted stock, restricted stock unit and performance stock unit grants is at a price equal to the fair market value of our Class A common stock at the date of grant. The fair value of market-based performance stock unit grants is valued using a Monte Carlo pricing model.

See Note 12, Stockholders' Equity for disclosure over stock-based compensation.

Earnings per Share

Basic earnings per share is computed by dividing the net income (loss) from continuing operations attributable to common stockholders by the weighted average number of common shares outstanding during the period. Diluted earnings per share is calculated based on the combined weighted average number of common shares and potentially dilutive shares. Dilutive shares include the assumed exercise of employee stock options, including market-based performance stock options based on the expected achievement of performance targets, unvested restricted stock awards, unvested restricted stock units and unvested performance stock units, including market-based performance units based on the expected achievement of performance targets. In computing diluted earnings per share, we utilize the treasury stock method.

See Note 17, Earnings Per Share for disclosure over the calculation of earnings per share.

Subsequent Events

Except as disclosed, no material subsequent events have occurred since December 31, 2018 through the date of this filing that would require recognition or disclosure in our consolidated financial statements.

REVENUE RECOGNITION

12 Months Ended

Dec. 31, 2018

Revenue from Contract with Customer [Abstract]

REVENUE RECOGNITION

We disaggregate our revenues by applicable service line as follows: collection, landfill, transfer, customer solutions, recycling, organics, transportation and landfill gas-to-energy.

Collection

Collection revenues are principally generated by providing waste collection and disposal services to our customers. Services may be provided as needed or as scheduled. We derive a substantial portion of our collection revenues from commercial and industrial services, which typically have a standard contract duration of three years, along with municipal services that are generally performed pursuant to contracts with municipalities with varying terms. The majority of our residential collection services are performed on a subscription basis with individual households.

Landfill

Landfill disposal services primarily consist of receiving some form of acceptable solid waste materials at one of our landfills and appropriately disposing of it. Landfill customers are typically charged a tipping fee on a per ton basis for disposing of their solid waste at our disposal facilities. In general, these fees are variable in nature.

Transfer Station

Transfer station disposal services primarily consist of receiving some form of acceptable solid waste materials at one of our transfer stations and appropriately disposing of it by transporting it to an appropriate disposal site. Transfer station customers are charged a tipping fee on a per ton basis for disposing of their solid waste at our transfer stations. In general, these fees are variable in nature.

Transportation

Transportation services consist of the transportation of large volumes of waste or recycled materials from a customer designated location to another location or disposal facility. Transportation customers are charged a fee on a per ton basis for transporting and/or disposal of the materials. In general, these fees are variable in nature.

Recycling

Recycling services primarily consist of the collection and/or receipt of recycled materials at one of our materials recovery facilities; the processing or sorting of the recycled materials; and the disposal or sale of the recycled materials. Revenues from recycling services consist of revenues derived from municipalities and customers in the form of processing fees, tipping fees and commodity sales. In brokerage arrangements, we act as an agent that facilitates the sale of recyclable materials between an inbound customer and an outbound customer. Revenues from the brokerage of recycled materials are recognized on a net basis at the time of shipment. In general, these fees are variable in nature.

Customer Solutions

Customer solutions services consist of commercial and industrial offerings. Commercial services consist of traditional collection, disposal and recycling services provided to large account multi-site customers. Industrial services consist of overall resource management services provided to large and complex organizations, such as universities, hospitals, manufacturers and municipalities, delivering a wide range of environmental services and zero waste solutions.

Organics

Organics services primarily consist of the collection and/or receipt of organic materials at one of our processing or disposal facilities; the processing of the organic materials; and the disposal or sale of the organic materials.

Landfill Gas-to-Energy

Landfill gas-to-energy services primarily consist of the generation and sale of electricity from landfill gas-to-energy facilities located at certain of our landfills; the reservation of electric generating capacity to be used by a customer on demand; and the sale of RECs.

A table of revenues disaggregated by service line and timing of revenue recognition by operating segment follows:

Fiscal Year Ended December 31, 2018



	Eastern		Western		Recycling		Other		Total Revenues
Collection	$	136,661	$	170,278	$	—	$	—	$	306,939
Landfill	28,419		66,567		—		—		94,986
Transfer	39,991		27,592		—		—		67,583
Customer solutions	—		—		—		67,464		67,464
Recycling	5		3,823		42,191		—		46,019
Organics	—		—		—		54,174		54,174
Transportation	—		14,270		—		4,096		18,366
Landfill gas-to-energy	1,397		3,732		—		—		5,129
Total Revenues	$	206,473	$	286,262	$	42,191	$	125,734	$	660,660

Transferred at a point-in-time	$	648	$	1,145	$	27,260	$	3,921	$	32,974
Transferred over time	205,825		285,117		14,931		121,813		627,686
Total revenues	$	206,473	$	286,262	$	42,191	$	125,734	$	660,660

BUSINESS COMBINATIONS

12 Months Ended

Dec. 31, 2018

Business Combinations [Abstract]

BUSINESS COMBINATIONS

In fiscal year 2018, we acquired six solid waste collection and one transfer business in our Western region and two businesses comprised of solid waste collection and transfer operations in our Eastern region. In fiscal year 2017, we acquired one solid waste collection business in our Eastern region and three solid waste collection businesses in our Western region, and in fiscal year 2016 we acquired three transfer operations. The operating results of these businesses are included in the accompanying audited consolidated statements of operations from each date of acquisition, and the purchase price has been allocated to the net assets acquired based on fair values at each date of acquisition, with the residual amounts recorded as goodwill. Acquired intangible assets other than goodwill that are subject to amortization include client lists and non-compete covenants. These are amortized over a five to ten year period from the date of acquisition. All amounts recorded to goodwill in fiscal years 2018 and 2017, except goodwill related to the acquisition of Complete Disposal Company, Inc. and its subsidiary United Material Management of Holyoke, Inc. (collectively, "Complete"), are expected to be deductible for tax purposes.

The purchase price paid for these acquisitions and the allocation of the purchase price is as follows:



	Fiscal Year Ended December 31,
	2018			2017			2016
Purchase Price:
Cash used in acquisitions, net of cash acquired	$	86,686		$	4,823		$	2,439
Notes payable	—			2,400			—
Class A common stock issued	4,258			—			—
Other non-cash considerations	—			101			—
Contingent consideration and holdbacks	8,521			736			400
Total	99,465			8,060			2,839
Current assets	3,276			93			40
Land	—			—			353
Buildings	7,889			—			1,360
Equipment	23,882			2,994			269
Other liabilities, net	(4,708		)	(49		)	(106		)
Deferred tax liability	(937		)	—			—
Intangible assets	29,934			2,334			—
Fair value of assets acquired and liabilities assumed	59,336			5,372			1,916
Excess purchase price to be allocated to goodwill	$	40,129		$	2,688		$	923

The following unaudited pro forma combined information shows our operational results as though each of the acquisitions completed had occurred as of January 1, 2016.



	Fiscal Year Ended December 31,
	2018		2017			2016
Revenues	$	699,659	$	672,898		$	642,773
Operating income (loss)	$	43,561	$	(6,601	)	$	50,970
Net income (loss) attributable to common stockholders	$	8,579	$	(18,408	)	$	(3,446	)
Basic earnings per common share attributable to common stockholders	$	0.20	$	(0.44	)	$	(0.08	)
Basic weighted average shares outstanding	42,688		41,846			41,233
Diluted earnings per common share attributable to common stockholders	$	0.19	$	(0.44	)	$	(0.08	)
Diluted weighted average shares outstanding	44,168		41,846			41,233

The pro forma results have been prepared for comparative purposes only and are not necessarily indicative of the actual results of operations had the acquisitions taken place as of January 1, 2016 or the results of our future operations. Furthermore, the pro forma results do not give effect to all cost savings or incremental costs that may occur as a result of the integration and consolidation of the completed acquisitions.

RESTRICTED ASSETS

12 Months Ended

Dec. 31, 2018

Receivables [Abstract]

RESTRICTED ASSETS

Restricted assets consist of investment securities held in trust on deposit with various banks as collateral for our obligations relative to our landfill final capping, closure and post-closure costs.

A summary of restricted assets is as follows:



	December 31,
Non Current:	2018		2017
Restricted investment securities - landfill closure	$	1,248	$	1,220

PROPERTY, PLANT AND EQUIPMENT

12 Months Ended

Dec. 31, 2018

Property, Plant and Equipment [Abstract]

PROPERTY, PLANT AND EQUIPMENT

A summary of property, plant and equipment is as follows:



	December 31,
	2018			2017
Land	$	25,490		$	24,224
Landfills	544,663			513,548
Landfill operating lease contracts	121,877			114,462
Buildings and improvements	150,885			140,155
Machinery and equipment	153,222			139,029
Rolling stock	163,758			138,102
Containers	123,383			103,501
	1,283,278			1,173,021
Less: accumulated depreciation and amortization	(878,701		)	(811,474		)
	$	404,577		$	361,547

Depreciation expense for fiscal years 2018, 2017 and 2016 was $35,351, $32,131 and $33,186, respectively. Landfill amortization expense for fiscal years 2018, 2017 and 2016 was $31,841, $27,910 and $26,529, respectively. Depletion expense on landfill operating lease contracts for fiscal years 2018, 2017 and 2016 was $9,724, $9,646 and $9,295, respectively, and was recorded in cost of operations.

GOODWILL AND INTANGIBLE ASSETS

12 Months Ended

Dec. 31, 2018

Goodwill and Intangible Assets Disclosure [Abstract]

GOODWILL AND INTANGIBLE ASSETS

A summary of the activity and balances related to goodwill by reporting segment is as follows:



	December 31, 2017		Acquisitions		December 31, 2018
Eastern	$	19,192	$	8,962	$	28,154
Western	89,369		31,167		120,536
Recycling	12,315		—		12,315
Other	1,729		—		1,729
Total	$	122,605	$	40,129	$	162,734



	December 31, 2016		Acquisitions		December 31, 2017
Eastern	$	17,429	$	1,763	$	19,192
Western	88,426		943		89,369
Recycling	12,315		—		12,315
Other	1,729		—		1,729
Total	$	119,899	$	2,706	$	122,605

A summary of intangible assets is as follows:



	Covenants Not-to-Compete			Client Lists			Total
Balance, December 31, 2018
Intangible assets	$	21,750		$	44,363		$	66,113
Less accumulated amortization	(17,584		)	(13,762		)	(31,346		)
	$	4,166		$	30,601		$	34,767



	Covenants Not-to-Compete			Client Lists			Total
Balance, December 31, 2017
Intangible assets	$	18,092		$	18,087		$	36,179
Less accumulated amortization	(16,851		)	(11,179		)	(28,030		)
	$	1,241		$	6,908		$	8,149

Intangible amortization expense for fiscal years 2018, 2017 and 2016 was $3,316, $2,061 and $2,141, respectively.

The intangible amortization expense estimated for the five fiscal years following fiscal year 2018 and thereafter is as follows:




Estimated Future Amortization Expense as of December 31, 2018
For the fiscal year ending December 31, 2019	$	5,601
For the fiscal year ending December 31, 2020	$	4,997
For the fiscal year ending December 31, 2021	$	4,094
For the fiscal year ending December 31, 2022	$	3,534
For the fiscal year ending December 31, 2023	$	3,231
Thereafter	$	13,310

- Definition

The entire disclosure for the aggregate amount of goodwill and a description of intangible assets, which may include (a) for amortizable intangible assets (also referred to as finite-lived intangible assets), the carrying amount, the amount of any significant residual value, and the weighted-average amortization period, (b) for intangible assets not subject to amortization (also referred to as indefinite-lived intangible assets), the carrying amount, and (c) the amount of research and development assets acquired and written off in the period, including the line item in the income statement in which the amounts written off are aggregated, if not readily apparent from the income statement. Also discloses (a) for amortizable intangibles assets in total and by major class, the gross carrying amount and accumulated amortization, the total amortization expense for the period, and the estimated aggregate amortization expense for each of the five succeeding fiscal years, (b) for intangible assets not subject to amortization the carrying amount in total and by major class, and (c) for goodwill, in total and for each reportable segment, the changes in the carrying amount of goodwill during the period (including the aggregate amount of goodwill acquired, the aggregate amount of impairment losses recognized, and the amount of goodwill included in the gain (loss) on disposal of a reporting unit). If any part of goodwill has not been allocated to a reportable segment, discloses the unallocated amount and the reasons for not allocating. For each impairment loss recognized related to an intangible asset (excluding goodwill), discloses: (a) a description of the impaired intangible asset and the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method for determining fair value, (c) the caption in the income statement or the statement of activities in which the impairment loss is aggregated, and (d) the segment in which the impaired intangible asset is reported. For each goodwill impairment loss recognized, discloses: (a) a description of the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method of determining the fair value of the associated reporting unit, and (c) if a recognized impairment loss is an estimate not finalized and the reasons why the estimate is not final. May also disclose the nature and amount of any significant adjustments made to a previous estimate of an impairment loss.

+ References + Details

FINAL CAPPING, CLOSURE AND POST-CLOSURE COSTS

12 Months Ended

Dec. 31, 2018

Asset Retirement Obligation Disclosure [Abstract]

FINAL CAPPING, CLOSURE AND POST-CLOSURE COSTS

Accrued final capping, closure and post-closure costs include the current and non-current portion of costs associated with obligations for final capping closure and post-closure of our landfills. We estimate our future final capping, closure and post-closure costs in order to determine the final capping, closure and post-closure expense per ton of waste placed into each landfill as further described in Note 3, Summary of Significant Accounting Policies. The anticipated time frame for paying these costs varies based on the remaining useful life of each landfill, as well as the duration of the post-closure monitoring period.

The changes to accrued final capping, closure and post-closure liabilities are as follows:



	Fiscal Year Ended December 31,
	2018			2017
Beginning balance	$	62,290		$	44,207
Obligations incurred	3,713			3,022
Revisions in estimates (1)	5,095			11,498
Accretion expense	5,556			4,401
Obligations settled (2)	(3,579		)	(838		)
Ending balance	$	73,075		$	62,290

(1)

Relates to changes in estimates and assumptions concerning anticipated waste flow, cost and timing of future final capping, closure and post-closure activities at certain landfills, including the Subtitle D landfill in Southbridge, Massachusetts ("Southbridge Landfill"), as well as changes to expansion airspace. See Note 11, Commitments and Contingencies and Note 16, Other Items and Charges for disclosure regarding Southbridge Landfill.


(2)	Includes amounts paid and amounts that are being processed through accounts payable as a part of our disbursement cycle.

LONG TERM DEBT AND CAPITAL LEASES

12 Months Ended

Dec. 31, 2018

Debt Disclosure [Abstract]

LONG TERM DEBT AND CAPITAL LEASES

A summary of long-term debt and capital leases is as follows:



	December 31,
	2018		2017
Senior Secured Credit Facility:
Revolving Credit Facility due May 2023; bearing interest at LIBOR plus 2.00%	$	69,600	$	—
Refinanced Revolving Credit Facility due October 2021; bore interest at LIBOR plus 2.75%	—		36,000
Term Loan Facility due May 2023; bearing interest at LIBOR plus 2.00%	350,000		—
Term Loan B Facility due October 2023; bore interest at LIBOR plus 2.50%	—		346,500
Tax-Exempt Bonds:
New York State Environmental Facilities Corporation Solid Waste Disposal Revenue Bonds Series 2014R-1 due December 2044 - fixed rate interest period through 2019; bearing interest at 3.75%	25,000		25,000
New York State Environmental Facilities Corporation Solid Waste Disposal Revenue Bonds Series 2014R-2 due December 2044 - fixed rate interest period through 2026; bearing interest at 3.125%	15,000		15,000
Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2005R-3 due January 2025 - fixed rate interest period through 2025; bearing interest at 5.25%	25,000		25,000
Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2015R-1 due August 2035 - fixed rate interest period through 2025; bearing interest at 5.125%	15,000		15,000
Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2015R-2 due August 2035 - fixed rate interest period through 2025; bearing interest at 4.375%	15,000		—
Vermont Economic Development Authority Solid Waste Disposal Long-Term Revenue Bonds Series 2013 due April 2036 - fixed rate interest period through 2028; bearing interest at 4.625%	16,000		16,000
Business Finance Authority of the State of New Hampshire Solid Waste Disposal Revenue Bonds Series 2013 due April 2029 - fixed rate interest period through 2019; bearing interest at 4.00%	11,000		11,000
Other:
Capital leases maturing through December 2107; bearing interest at a weighted average of 5.37%	11,248		5,595
Notes payable maturing through June 2027; bearing interest at a weighted average of 2.97%	2,401		2,585
Principal amount of long-term debt and capital leases	555,249		497,680
Less—unamortized discount and debt issuance costs (1)	10,950		15,178
Long-term debt and capital leases less unamortized discount and debt issuance costs	544,299		482,502
Less—current maturities of long-term debt	2,298		4,926
	$	542,001	$	477,576


(1)	A summary of unamortized discount and debt issuance costs by debt instrument follows:



	December 31,
	2018		2017
Credit Facility	$	7,118	$	—
Refinanced Revolving Credit Facility	—		3,938
Term Loan B Facility (including unamortized discount of $0 and $1,482)	—		7,392
New York State Environmental Facilities Corporation Solid Waste Disposal Revenue Bonds Series 2014R-1	847		1,034
New York State Environmental Facilities Corporation Solid Waste Disposal Revenue Bonds Series 2014R-2	450		511
Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2005R-3	517		603
Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2015R-1	622		691
Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2015R-2	493		—
Vermont Economic Development Authority Solid Waste Disposal Long-Term Revenue Bonds Series 2013	595		573
Business Finance Authority of the State of NH Solid Waste Disposal Revenue Bonds Series 2013	308		436
	$	10,950	$	15,178

Credit Facility

In fiscal year 2018, we entered into a credit agreement ("Credit Agreement"), which provides for a $350,000 aggregate principal amount term loan A facility ("Term Loan Facility") and a $200,000 revolving line of credit facility ("Revolving Credit Facility" and, together with the Term Loan Facility, the "Credit Facility"). The net proceeds from this transaction were used to repay in full the amounts outstanding of the $350,000 aggregate principal amount term loan B facility ("Term Loan B Facility") and the $160,000 revolving line of credit facility ("Refinanced Revolving Credit Facility") plus accrued and unpaid interest thereon and to pay related transaction expenses. We have the right to request, at our discretion, an increase in the amount of loans under the Credit Facility by an aggregate amount $125,000, subject to the terms and conditions set forth in the Credit Agreement.

The Credit Facility has a 5-year term and will bears interest at a rate of LIBOR plus 2.00% per annum, which will be reduced to a rate of LIBOR plus 1.25% upon us reaching a consolidated net leverage ratio of less than 2.25x. The Credit Facility is guaranteed jointly and severally, fully and unconditionally by all of our significant wholly-owned subsidiaries and secured by substantially all of our assets. As of December 31, 2018, further advances were available under the Credit Facility in the amount of $107,879. The available amount is net of outstanding irrevocable letters of credit totaling $22,521, at which date no amount had been drawn.

The Credit Agreement requires us to maintain a minimum interest coverage ratio and a maximum consolidated net leverage ratio, to be measured at the end of each fiscal quarter. As of December 31, 2018, we were in compliance with the covenants contained in the Credit Agreement. In addition to these financial covenants, the Credit Agreement also contains a number of important customary affirmative and negative covenants which restrict, among other things, our ability to sell assets, incur additional debt, create liens, make investments, and pay dividends. We do not believe that these restrictions impact our ability to meet future liquidity needs. An event of default under any of our debt agreements could permit some of our lenders, including the lenders under the Credit Facility, to declare all amounts borrowed from them to be immediately due and payable, together with accrued and unpaid interest, or, in the case of the Credit Facility, terminate the commitment to make further credit extensions thereunder, which could, in turn, trigger cross-defaults under other debt obligations. If we were unable to repay debt to our lenders, or were otherwise in default under any provision governing our outstanding debt obligations, our secured lenders could proceed against us and against the collateral securing that debt.

Tax-Exempt Financings

New York Bonds. As of December 31, 2018, we had outstanding $25,000 aggregate principal amount of Solid Waste Disposal Revenue Bonds Series 2014 ("New York Bonds 2014R-1") and $15,000 aggregate principal amount of Solid Waste Disposal Revenue Bonds Series 2014R-2 ("New York Bonds 2014R-2") issued by the New York State Environmental Facilities Corporation under the indenture dated December 1, 2014 (collectively, the “New York Bonds”). The New York Bonds 2014R-1 accrue interest at 3.75% per annum through December 1, 2019, at which time they may be converted from a fixed rate to a variable rate. The New York Bonds 2014R-2 accrue interest at 3.125% per annum through May 31, 2026, at which time they may be converted from a fixed rate to a variable rate. The New York Bonds, which are unsecured and guaranteed jointly and severally, fully and unconditionally by all of our significant wholly-owned subsidiaries, require interest payments on June 1 and December 1 of each year and mature on December 1, 2044. We borrowed the proceeds of the New York Bonds to finance or refinance certain capital projects in the state of New York and to pay certain costs of issuance of the New York Bonds.

Maine Bonds. In fiscal year 2018, we completed the issuance of $15,000 aggregate principal amount of Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2015R-2 (“FAME Bonds 2015R-2”). As of December 31, 2018, we had outstanding $25,000 aggregate principal amount of Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2005R-3 (“FAME Bonds 2005R-3”), $15,000 aggregate principal amount of Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2015 (“FAME Bonds 2015R-1”), and $15,000 aggregate principal amount of FAME Bonds 2015R-2 (collectively, the "FAME Bonds"). The FAME Bonds 2005R-3 accrue interest at 5.25% per annum, and interest is payable semiannually in arrears on February 1 and August 1 of each year until such bonds mature on January 1, 2025. The FAME Bonds 2015R-1 accrue interest at 5.125% per annum through August 1, 2025, at which time they may be converted from a fixed to a variable rate, and interest is payable semiannually in arrears on February 1 and August 1 of each year until the FAME Bonds 2015R-1 mature on August 1, 2035. The FAME Bonds 2015R-2 accrue interest at 4.375% per annum through July 31, 2025, at which time they may be converted from a fixed to a variable rate, and interest is payable semiannually each year on May 1 and November 1 until the FAME Bonds 2015R-2 mature on August 1, 2035. The FAME Bonds are unsecured and guaranteed jointly and severally, fully and unconditionally by all of our significant wholly-owned subsidiaries. We borrowed the proceeds of the offering of the FAME Bonds to finance or refinance the costs of certain of our solid waste landfill facilities and solid waste collection, organics and transfer, recycling and hauling facilities, and to pay certain costs of the issuance of the FAME Bonds.

Vermont Bonds. In fiscal year 2018, we completed the remarketing of $16,000 aggregate principal amount of 4.75% fixed rate senior unsecured Vermont Economic Development Authority Solid Waste Disposal Long-Term Revenue Bonds Series 2013 (“Vermont Bonds”). As of December 31, 2018, we had outstanding $16,000 aggregate principal amount of Vermont Bonds. The Vermont Bonds, which are guaranteed jointly and severally, fully and unconditionally by all of our significant wholly-owned subsidiaries, accrue interest at 4.625% per annum through April 2, 2028, after which time there is a mandatory tender. The Vermont Bonds mature on April 1, 2036. We borrowed the proceeds of the Vermont Bonds to finance or refinance certain qualifying property, plant and equipment assets purchased in the state of Vermont.

New Hampshire Bonds. As of December 31, 2018, we had outstanding $11,000 aggregate principal amount of senior unsecured Solid Waste Disposal Revenue Bonds Series 2013 issued by the Business Finance Authority of the State of New Hampshire (“New Hampshire Bonds”). The New Hampshire Bonds, which are guaranteed jointly and severally, fully and unconditionally by all of our significant wholly-owned subsidiaries, accrue interest at 4.00% per annum through October 1, 2019, at which time they may be converted from a fixed rate to a variable rate. During the fixed interest rate period, the New Hampshire Bonds are not be supported by a letter of credit. Interest is payable in arrears on April 1 and October 1 of each year. The New Hampshire Bonds mature on April 1, 2029. We borrowed the proceeds of the New Hampshire Bonds to finance or refinance certain qualifying property, plant and equipment assets purchased in the state of New Hampshire.

Loss on Debt Extinguishment

In order to lower our borrowing costs and reduce our market risk we completed the following transactions that resulted in a loss on debt extinguishment in fiscal years 2018, 2017 and 2016 of $7,352, $517 and $13,747, respectively:


•	the write-off of debt issuance costs and unamortized discount, in the case of our Term Loan B Facility in fiscal year 2018, associated with the refinancing of our previously outstanding senior secured credit facilities in fiscal year 2018 and fiscal year 2016 and an amendment to our previously outstanding senior secured credit facility in fiscal year 2017:

•

the write-off of debt issuance costs in connection with the remarketing of our Vermont Bonds in fiscal year 2018 and the remarketing of our Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2005R-1 (“FAME Bonds 2005R-1”) and Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2005R-2 (“FAME Bonds 2005R-2”) into the FAME Bonds 2005R-3 in fiscal year 2017; and


•	the repurchase price premium and write-off of debt issuance costs and unamortized original issue discount associated with the early redemption, repurchase and retirement of our then outstanding 7.75% senior subordinated notes due February 2019 in fiscal years 2016.

Interest Expense

The components of interest expense are as follows:



	Fiscal Year Ended December 31,
	2018			2017			2016
Interest expense on long-term debt and capital leases	$	23,816		$	22,060		$	34,741
Amortization of debt issuance costs and discount on long-term debt	2,449			2,692			3,881
Letter of credit fees	169			703			593
Less: capitalized interest	(140		)	(295		)	(273		)
Total interest expense	$	26,294		$	25,160		$	38,942

Cash Flow Hedges

The refinancing of our Credit Facility in fiscal year 2018 resulted in us dedesignating the original hedging relationship between three interest rate derivative agreements and the variable rate interest payments related to the Term Loan B Facility. We subsequently designated new hedging relationships between the three interest rate derivative agreements and the variable rate interest payments related to the Term Loan Facility based on a quantitative assessment using regression analysis, which indicated that the hedging relationships were highly effective. Because the interest rate payments associated with the variable rate portion of our long-term debt will still occur, the net gain of $1,383 associated with the interest rate derivative agreements in accumulated other comprehensive income was not reclassified into earnings. Instead, this gain will continue to be reclassified from accumulated other comprehensive income into interest expense as the interest payments affect earnings.

In fiscal year 2018, we also entered into six additional interest rate derivative agreements to further hedge interest rate risk associated with the variable rate portion of our long-term debt. The hedging relationships between these interest rate derivative agreements and the variable rate interest payments related to the Term Loan Facility were considered highly effective based on a quantitative assessment using regression analysis and, therefore, are accounted for as highly effective cash flow hedges.

The total notional amount of all of our interest rate derivative agreements is $190,000 and according to the terms of the agreements, we receive interest based on the 1-month LIBOR index and pay interest at a weighted average rate of approximately 2.54%. The agreements mature between February 2021 and May 2023. We have designated these derivative instruments as effective cash flow hedges.

A summary of the effect of cash flow hedges related to derivative instruments on the consolidated balance sheet follows:



		Fair Value
	Balance Sheet Location	December 31, 2018			December 31, 2017
Interest rate swaps	Other current assets	$	338		$	—
Interest rate swaps	Other non-current assets	482			401
Total		$	820		$	401

Interest rate swaps	Other accrued liabilities	$	387		$	123
Interest rate swaps	Other long-term liabilities	1,555			—
Total		$	1,942		$	123

Interest rate swaps	Accumulated other comprehensive (loss) income, net	$	(1,196	)	$	278
Interest rate swaps - tax provision	Accumulated other comprehensive (loss) income, net	$	(112	)	$	(112	)
		$	(1,308	)	$	166

A summary of the amount of gain or (loss) on cash flow hedging relationships related to interest rate swaps reclassified from accumulated other comprehensive (loss) income into earnings follows:



	Fiscal Year Ended December 31,
	2018			2017			2016
Statement of Operations Location	(Expense) Income
Interest expense	$	(363	)	$	(421	)	$	—

Fair Value of Debt

As of December 31, 2018, the fair value of our fixed rate debt, including the FAME Bonds, Vermont Bonds, New York Bonds and New Hampshire Bonds was approximately $121,722 and the carrying value was $122,000. The fair value of the FAME Bonds, Vermont Bonds, New York Bonds and New Hampshire Bonds is considered to be Level 2 within the fair value hierarchy as the fair value is determined using market approach pricing provided by a third-party that utilizes pricing models and pricing systems, mathematical tools and judgment to determine the evaluated price for the security based on the market information of each of the bonds or securities with similar characteristics.

As of December 31, 2018, the carrying value of our Term Loan Facility was $350,000 and the carrying value of our Revolving Credit Facility was $69,600. Their fair values are based on current borrowing rates for similar types of borrowing arrangements, or Level 2 inputs, and approximate their carrying values.

Although we have determined the estimated fair value amounts of the FAME Bonds, Vermont Bonds, New York Bonds and New Hampshire Bonds using available market information and commonly accepted valuation methodologies, a change in available market information, and/or the use of different assumptions and/or estimation methodologies could have a material effect on the estimated fair values. These amounts have not been revalued, and current estimates of fair value could differ significantly from the amounts presented.

Future Maturities of Debt

Aggregate principal maturities of long-term debt and capital leases are as follows:




Estimated Future Payments as of December 31, 2018
2019	$	2,298
2020	2,648
2021	2,175
2022	1,652
2023	421,021
Thereafter	125,455
	$	555,249

COMMITMENTS AND CONTINGENCIES

12 Months Ended

Dec. 31, 2018

Commitments and Contingencies Disclosure [Abstract]

COMMITMENTS AND CONTINGENCIES

Lease Commitments

We lease operating facilities and equipment in the ordinary course of our business under various operating leases with monthly payments varying up to approximately $23. Future minimum rental payments are recognized on a straight-line basis over the minimum lease term. Total rent expense under operating leases charged to operations was $10,571, $12,242 and $11,437 in fiscal years 2018, 2017 and 2016, respectively.

Future minimum rental payments under non-cancellable operating leases, which include landfill operating leases, are as follows:



Estimated Future Minimum Lease Payments as of December 31, 2018
2019	$	15,572
2020	12,678
2021	10,117
2022	7,953
2023	6,250
Thereafter	65,145
Total minimum lease payments	$	117,715

Legal Proceedings

In the ordinary course of our business and as a result of the extensive governmental regulation of the solid waste industry, we are subject to various judicial and administrative proceedings involving state and local agencies. In these proceedings, an agency may seek to impose fines or to revoke or deny renewal of an operating permit held by us. From time to time, we may also be subject to actions brought by special interest or other groups, adjacent landowners or residents in connection with the permitting and licensing of landfills and transfer stations, or allegations of environmental damage or violations of the permits and licenses pursuant to which we operate. In addition, we may be named defendants in various claims and suits pending for alleged damages to persons and property, alleged violations of certain laws and alleged liabilities arising out of matters occurring during the ordinary operation of a waste management business.

In accordance with FASB ASC 450 - Contingencies, we accrue for legal proceedings, inclusive of legal costs, when losses become probable and reasonably estimable. As of the end of each applicable reporting period, we review each of our legal proceedings to determine whether it is probable, reasonably possible or remote that a liability has been incurred and, if it is at least reasonably possible, whether a range of loss can be reasonably estimated under the provisions of FASB ASC 450-20. In instances where we determine that a loss is probable and we can reasonably estimate a range of loss we may incur with respect to such a matter, we record an accrual for the amount within the range that constitutes our best estimate of the possible loss. If we are able to reasonably estimate a range, but no amount within the range appears to be a better estimate than any other, we record an accrual in the amount that is the low end of such range. When a loss is reasonably possible, but not probable, we will not record an accrual, but we will disclose our estimate of the possible range of loss where such estimate can be made in accordance with FASB ASC 450-20.

Environmental Remediation Liability

We are subject to liability for environmental damage, including personal injury and property damage, that our solid waste, recycling and power generation facilities may cause to neighboring property owners, particularly as a result of the contamination of drinking water sources or soil, possibly including damage resulting from conditions that existed before we acquired the facilities. We may also be subject to liability for similar claims arising from off-site environmental contamination caused by pollutants or hazardous substances if we or our predecessors arrange or arranged to transport, treat or dispose of those materials. The following matters represent our material outstanding claims.

Southbridge Recycling & Disposal Park, Inc.

In October 2015, our Southbridge Recycling and Disposal Park, Inc. (“SRD”) subsidiary reported to the Massachusetts Department of Environmental Protection (“MADEP”) results of analysis of samples collected pursuant to our existing permit from private drinking water wells located near the Town of Southbridge, Massachusetts (“Town”) Landfill (“Southbridge Landfill”), which is operated by SRD. Those results indicated the presence of contaminants above the levels triggering notice and response obligations under MADEP regulations. In response to those results, we are carrying out an Immediate Response Action pursuant to Massachusetts General Law Chapter 21E (the "Charlton 21E Obligations") pursuant to state law. Further, we have implemented a plan to analyze and better understand the groundwater near the Southbridge Landfill and we are investigating with the objective of identifying the source or sources of the elevated levels of contamination measured in the well samples. If it is determined that some or all of the contamination originated at the Southbridge Landfill, we will work with the Town (the Southbridge Landfill owner and the former operator of an unlined portion of the Southbridge Landfill, which was used prior to our operation of a double-lined portion of the Southbridge Landfill commencing in 2004) to evaluate and allocate the liabilities related to the Charlton 21E Obligations. In July 2016, we sent correspondence to the Town pursuant to Chapter 21E of Massachusetts General Laws demanding that the Town reimburse us for the environmental response costs we had spent and that the Town be responsible for all such costs in the future, as well as any other costs or liabilities resulting from the release of contaminants from the unlined portion of the Southbridge Landfill. The Town responded in September 2016, denying that the Southbridge Landfill is the source of such contamination, and claiming that if it is, that we may owe an indemnity to the Town pursuant to the Operating Agreement between us and the Town dated May 29, 2007, as amended. We entered into a Tolling Agreement with the Town to delay any further administrative or legal actions until our work with MADEP more specifically defines the parties’ responsibilities for the Charlton 21E Obligations, if any. Please see below for further discussion of our relationship with the Town regarding the Charlton 21E Obligations.

In February 2016, we and the Town received a Notice of Intent to Sue under the Resource Conservation and Recovery Act ("RCRA") from a law firm purporting to represent residents proximate to the Southbridge Landfill (“Residents”), indicating its intent to file suit against us on behalf of the Residents alleging the groundwater contamination originated from the Southbridge Landfill. In February 2017, we received an additional Notice of Intent to Sue from the National Environmental Law Center under the Federal Clean Water Act ("CWA") and RCRA (collectively the “Acts”) on behalf of Environment America, Inc., d/b/a Environment Massachusetts, and Toxics Action Center, Inc., which have referred to themselves as the Citizen Groups. The Citizen Groups alleged that we had violated the Acts, and that they intended to seek appropriate relief in federal court for those alleged violations. On or about June 9, 2017, a lawsuit was filed against us, SRD and the Town in the United States District Court for the District of Massachusetts (the “Massachusetts Court”) by the Citizen Groups and the Residents alleging violations of the Acts (the “Litigation”), and demanding a variety of remedies under the Acts, including fines, remediation, mitigation and costs of litigation, and remedies for violations of Massachusetts civil law related to personal and property damages, including remediation, diminution of property values, compensation for lost use and enjoyment of properties, enjoinment of further operation of the Southbridge Landfill, and costs of litigation, plus interest on any damage award, on behalf of the Residents. We believe the Litigation to be factually inaccurate, and without legal merit, and we and SRD intend to vigorously defend the Litigation. Nevertheless, we believe it is reasonably possible that a loss will occur as a result of the Litigation although an estimate of loss cannot be reasonably provided at this time. We also continue to believe the Town should be responsible for costs or liabilities associated with the Litigation relative to alleged contamination originating from the unlined portion of the Southbridge Landfill, although there can be no assurance that we will not be required to incur some or all of such costs and liabilities.

In December 2017, we filed a Motion to Dismiss the Litigation, and on October 1, 2018, the Massachusetts Court granted our Motion to Dismiss, and accordingly, dismissed the Citizen Groups claims under the Acts. The Massachusetts Court has retained jurisdiction of the Residents claims. The Citizen Groups intend to appeal the Massachusetts Court’s decision to grant our Motion to Dismiss.

We entered into an Administrative Consent Order on April 26, 2017 (the “ACO”), with MADEP, the Town, and the Town of Charlton, committing us to equally share the costs with MADEP, of up to $10,000 ($5,000 each) for the Town to install a municipal waterline in the Town of Charlton ("Waterline"). Upon satisfactory completion of that Waterline, and other matters covered by the ACO, we and the Town will be released by MADEP from any future responsibilities for the Charlton 21E Obligations. We also entered into an agreement with the Town on April 28, 2017 entitled the “21E Settlement and Water System Construction Funding Agreement” (the “Waterline Agreement”), wherein we and the Town released each other from claims arising from the Charlton 21E Obligations. Pursuant to the Waterline Agreement, the Town will issue a twenty (20) year bond for our portion of the Waterline costs (up to $5,000). We have agreed to reimburse the Town for periodic payments under such bond. The Town has recently advised us that it has solicited and received proposals for the construction of the Waterline as contemplated by the ACO, and that construction of the Waterline has commenced.

We have recorded an environmental remediation liability associated with the future installation of the Waterline in other accrued liabilities and other long-term liabilities. We inflate the estimated costs in current dollars to the expected time of payment and discount the total cost to present value using a risk-free interest rate of 2.6%. Our expenditures could be significantly higher if costs exceed estimates. The changes to the environmental remediation liability associated with the Southbridge Landfill are as follows:




	Fiscal Year Ended December 31,
	2018			2017
Beginning balance	$	5,936		$	—
Accretion expense	152			82
Obligations incurred	—			6,379
Obligations settled (1)	(915		)	(525		)
Ending balance	$	5,173		$	5,936


(1)	Includes amounts that are being processed through accounts payable as a part of our disbursements cycle.

In November 2016, SRD received a cease and desist order (“Order”) from the Charlton alternate zoning enforcement officer, alleging that two storm water detention basins on SRD’s property in Charlton existed in violation of Charlton zoning requirements. SRD appealed the Order to the Charlton Zoning Board of Appeals, which upheld the Order. In June 2018, the Massachusetts Land Court approved a settlement reached between SRD and Charlton resolving all issues associated with the Order. Based on this settlement with Charlton, we paid a total of $850 in cash, and will provide ancillary services to Charlton over the next five (5) years for a total of cash and services of approximately $1,200. This matter is now resolved. We have a remaining reserve of $226 as of December 31, 2018. This settlement is recorded as part of the Southbridge Landfill closure charge, net in the fiscal year ended December 31, 2018. See Note 16, Other Items and Charges for additional disclosure.

In August 2016, we filed a complaint against Steadfast Insurance Company (“Steadfast”) in the Superior Court of Suffolk County, Massachusetts (the "Court"), alleging among other things, that Steadfast breached its Pollution Liability Policy (“Policy”) purchased by us in April 2015, by refusing to acknowledge coverage under the Policy, and refusing to cover any of the costs and liabilities incurred by us as described above as well as costs and liabilities that we may incur in the future. Steadfast filed an answer and counterclaim in September 2016, denying that it has any obligations to us under the Policy, and seeking a declaratory judgment of Steadfast’s obligations under the Policy. Steadfast filed a Motion to Dismiss (the "Motion") our litigation against it, and we filed our response on July 11, 2017. On September 7, 2017, the Court denied the Motion. On July 17, 2018, we reached an agreement with Steadfast settling this litigation (the “Settlement”). Pursuant to the Settlement, Steadfast agreed to partially reimburse us for direct costs incurred or to be incurred by us under the ACO, as well as for substantial investigative costs associated with our efforts to ascertain the source of contaminants and other costs related to the Charlton 21E Obligations. Additionally, the Settlement payment is intended to reimburse us for all costs and liabilities arising out of the Litigation. Steadfast agreed to pay us $10,000, and we received the Settlement funds in the quarter ended September 30, 2018. The recovery of funds is recorded as part of the Southbridge Landfill closure charge, net in the nine months ended December 31, 2018. See Note 16, Other Items and Charges for additional disclosure.

On June 13, 2017, Town voters rejected a non-binding ballot initiative intended to provide guidance to Town officials with respect to our pursuit of other landfill development opportunities at the Southbridge Landfill. Following such rejection by the Town voters, our board of directors and senior management determined after due consideration of all facts and circumstances that it is no longer likely that further development at the existing landfill site will generate an adequate risk adjusted return at the Southbridge Landfill, and accordingly we intended to cease operations at the Southbridge Landfill when no further capacity was available. We reached this conclusion after carefully evaluating the estimated future costs associated with the permitting, engineering and construction activities for the planned expansion of the Southbridge Landfill against the possible outcomes of the permitting process and the anticipated future benefits of successful expansions. Under our May 29, 2017 Extension Agreement with the Town ("Extension Agreement"), which we accounted for as an operating lease, there are potential contractual obligations and commitments, including future cash payments and services that extend beyond the current useful life of the Southbridge Landfill, at that time expected by no later than early 2019. We delivered correspondence to the Town to this effect on August 3, 2017, citing events of Change in Law and Force Majeure pursuant to the Extension Agreement and the impacts of such events on further expansion of the Southbridge Landfill. We advised the Town that we saw no economically feasible way to operate the Southbridge Landfill beyond its current permitted life and we have filed a closure plan with MADEP. In this respect, the Town had, on or about April 11, 2018, filed a motion for a declaratory judgment and injunctive relief in the Massachusetts Court seeking a judgment from the Massachusetts Court as to the rights of the parties pursuant to the Extension Agreement, and injunctive relief to prevent us from discontinuing free collection and disposal of the Town’s municipal waste when the Southbridge Landfill ceases to accept waste (the “Town Equity Litigation”). We vigorously defended the Town Equity Litigation on its merits, and further, on the grounds that the Town Equity Litigation is not in compliance with the procedures for dispute resolution as set forth in the Extension Agreement. On June 26, 2018, the Massachusetts Court denied the Town’s request for a preliminary injunction without prejudice. Subsequently, the Town filed a successor litigation to the Town Equity Litigation (the “Current Litigation”), again seeking equitable and legal relief. We vigorously contested the Current Litigation and on November 8, 2018, the Town approved a Settlement Agreement with us which shortened the period of time we were purportedly obligated to provide the Town with free collection and disposal of the Town’s municipal waste from September, 2027 to March 31, 2024. The Town also agreed that we could close the solid waste and recycling transfer station in the Town at the end of 2018. The current litigation has been dismissed. The Southbridge Landfill was closed in November 2018 (the "Closure"). Following the Closure, we have proceeded to conduct proper closure and other activities at the Southbridge Landfill in accordance with the Extension Agreement with the Town, and Federal, state and local law. In accordance with FASB ASC 420 - Exit or Disposal Cost Obligations, a liability for costs to be incurred under a contract for its remaining term without economic benefit shall be recognized when we cease using the right conveyed by the contract. As a result of the Closure and in consideration of the Settlement Agreement with the Town, we recorded a charge amounting to $8,724 as a component of the Southbridge Landfill closure charge, net associated with the remaining future contractual obligations. See Note 16, Other Items and Charges for disclosure over the Southbridge Landfill closure charge, net.

The costs and liabilities we may be required to incur in connection with the foregoing Southbridge Landfill matters could be material to our results of operations, our cash flows and our financial condition.

Potsdam Environmental Remediation Liability

On December 20, 2000, the State of New York Department of Environmental Conservation (“DEC”) issued an Order on Consent (“Order”) which named Waste-Stream, Inc. (“WSI”), our subsidiary, General Motors Corporation (“GM”) and Niagara Mohawk Power Corporation (“NiMo”) as Respondents. The Order required that the Respondents undertake certain work on a 25-acre scrap yard and solid waste transfer station owned by WSI in Potsdam, New York, including the preparation of a Remedial Investigation and Feasibility Study (“Study”). A draft of the Study was submitted to the DEC in January 2009 (followed by a final report in May 2009). The Study estimated that the undiscounted costs associated with implementing the preferred remedies would be approximately $10,219. On February 28, 2011, the DEC issued a Proposed Remedial Action Plan for the site and accepted public comments on the proposed remedy through March 29, 2011. We submitted comments to the DEC on this matter. In April 2011, the DEC issued the final Record of Decision (“ROD”) for the site. The ROD was subsequently rescinded by the DEC for failure to respond to all submitted comments. The preliminary ROD, however, estimated that the present cost associated with implementing the preferred remedies would be approximately $12,130. The DEC issued the final ROD in June 2011 with proposed remedies consistent with its earlier ROD. An Order on Consent and Administrative Settlement naming WSI and NiMo as Respondents was executed by the Respondents and DEC with an effective date of October 25, 2013. On January 29, 2016, a Cost-Sharing Agreement was executed between WSI, NiMo, Alcoa Inc. (“Alcoa”) and Reynolds Metal Company (“Reynolds”) whereby Alcoa and Reynolds elected to voluntarily participate in the onsite remediation activities at a combined 15% participant share. It is likely that significant expenditures relating to onsite remediation will be incurred in fiscal year ending December 31, 2019. WSI is jointly and severally liable with NiMo, Alcoa and Reynolds for the total cost to remediate.

We have recorded an environmental remediation liability associated with the Potsdam site based on incurred costs to date and estimated costs to complete the remediation in other accrued liabilities and other long-term liabilities. Our expenditures could be significantly higher if costs exceed estimates. We inflate the estimated costs in current dollars to the expected time of payment and discount the total cost to present value using a risk-free interest rate of 1.5%.

A summary of the changes to the environmental remediation liability associated with the Potsdam environmental remediation liability follows:



	Fiscal Year Ended December 31,
	2018			2017
Beginning balance	$	5,758		$	5,866
Payments	(171		)	(108		)
Obligations incurred	27			—
Ending balance	$	5,614		$	5,758

North Country Environmental Services

On or about March 8, 2018, the Citizen Groups described above, delivered correspondence to our subsidiary, North Country Environmental Services, Inc. ("NCES") and us, providing notice of the Citizen Groups' intent to sue NCES and us for violations of the CWA in conjunction with NCES's operation of its landfill in Bethlehem, New Hampshire. On May 14, 2018, the Citizen Groups filed a lawsuit against NCES and us in the United States District Court for the District of New Hampshire (the “New Hampshire Court”) alleging violations of the CWA, arguing that ground water discharging into the Ammonoosuc River is a "point source" under the CWA (the "New Hampshire Litigation"). The New Hampshire Litigation seeks remediation and fines under the CWA. On June 15, 2018, we and NCES filed a Motion to Dismiss the New Hampshire Litigation. On July 13, 2018, the Citizen Groups filed objections to our Motion to Dismiss. On July 27, 2018, we filed a reply in support of our Motion to Dismiss. On September 25, 2018, the New Hampshire Court denied our Motion to Dismiss. We intend to continue to vigorously defend against the New Hampshire Litigation, which we believe is without merit.

The total expected environmental remediation payments, in today’s dollars, for each of the five succeeding fiscal years and the aggregate amount thereafter are as follows:



Estimated Future Environmental Remediation Payments as of December 31, 2018
2019	$	3,974
2020	1,289
2021	398
2022	372
2023	383
Thereafter	5,250
Total	$	11,666

A reconciliation of the expected aggregate non-inflated, undiscounted environmental remediation liability to the amount recognized in the statement of financial position is as follows:




Undiscounted liability	$	11,666
Less discount, net	(879		)
Liability balance - December 31, 2018	$	10,787

Any substantial liability incurred by us arising from environmental damage could have a material adverse effect on our business, financial condition and results of operations. We are not presently aware of any other situations that would have a material adverse impact on our business, financial condition, results of operations or cash flows.

Employment Contracts

We have entered into employment contracts with five of our executive officers. The contracts are dated June 18, 2001, March 31, 2006, July 6, 2010, September 1, 2012 and March 1, 2016. Each contract had an initial term between one and three years and a covenant not-to-compete ranging from one to two years from the date of termination. These contracts automatically extend for a one year period at the end of the initial term and any renewal period. Total annual commitments for salaries under these contracts are $1,821. In the event of a change in control of us, or in the event of involuntary termination without cause, the employment contracts provide for a payment ranging from one to three years of salary and bonuses. We also have other employment contracts or arrangements with employees who are not executive officers.

STOCKHOLDERS' EQUITY

12 Months Ended

Dec. 31, 2018

Equity [Abstract]

STOCKHOLDERS' EQUITY

Recent Developments

On January 25, 2019, we completed a public offering of 3,565 share of our Class A common stock at a public offering price of $29.50 per share. The offering resulted in net proceeds to us of $100,943, after deducting underwriting discounts and commissions and offering expenses. We intend to use the net proceeds from the offering for general corporate purposes, including potential acquisitions or development of new operations or assets with the goal of complementing or expanding our business, working capital and capital expenditures.

Common Stock

The holders of the Class A common stock are entitled to one vote for each share held. The holders of the Class B common stock are entitled to ten votes for each share held, except for the election of one director, who is elected by the holders of the Class A common stock exclusively. The Class B common stock is convertible into Class A common stock on a share-for-share basis at the option of the shareholder.

Preferred Stock

We are authorized to issue up to 944 shares of preferred stock in one or more series. As of December 31, 2018 and December 31, 2017, we had no shares issued.

Stock Based Compensation

Stock Incentive Plans

2006 Stock Incentive Plan. In the fiscal year ended April 30, 2007, we adopted the 2006 Stock Incentive Plan (“2006 Plan”). The 2006 Plan was amended in the fiscal year ended April 30, 2010. The 2006 Plan terminated as of October 9, 2016 and as a result no additional awards may be made pursuant to the 2006 Plan. Outstanding shares which are not actually issued under the 2006 Plan because such awards expire or otherwise result in shares not being issued are reserved for issuance under the 2016 Plan.

2016 Incentive Plan. In fiscal year 2016, we adopted the 2016 Incentive Plan (“2016 Plan”). Under the 2016 Plan, we may grant awards up to an aggregate amount of shares equal to the sum of: (i) 2,250 shares of Class A common stock (subject to adjustment in the event of stock splits and other similar events), plus (ii) such additional number of shares of Class A common stock as is equal to the sum of the number of shares of Class A common stock that remained available for grant under the 2006 Plan immediately prior to the expiration of the 2006 Plan and the number of shares of Class A common stock subject to awards granted under the 2006 Plan that expire or otherwise result in shares not being issued.

As of December 31, 2018, there were 1,615 Class A common stock equivalents available for future grant under the 2016 Plan, inclusive of additional Class A common stock equivalents that were previously issued under terminated plans and have become available for grant because such awards expired or otherwise resulted in shares not being issued.

Our equity awards granted consist of stock options, including market-based performance stock options, restricted stock, restricted stock units and performance stock units, including market-based performance stock units.

Stock options are granted at a price equal to the prevailing fair value of our Class A common stock at the date of grant. Generally, stock options granted have a term not to exceed ten years and vest over a one year to four year period from the date of grant.

The fair value of each stock option granted, with the exception of market-based performance stock option grants, is estimated using a Black-Scholes option-pricing model, which requires extensive use of accounting judgment and financial estimation, including estimates of the expected term stock option holders will retain their vested stock options before exercising them and the estimated volatility of our Class A common stock price over the expected term. The fair value of each market-based performance stock option granted is estimated using a Monte Carlo option-pricing model, which also requires extensive use of accounting judgment and financial estimation, including estimates of the expected term stock option holders will retain their vested stock options before exercising them and the estimated volatility of our Class A common stock price over the expected term, but also including estimates of share price appreciation of our Class A common stock as compared to the Russell 2000 Index over the requisite service period.

Restricted stock, restricted stock units and performance stock units are granted at a price equal to the fair value of our Class A common stock at the date of grant. The fair value of each market-based performance stock unit is estimated using a Monte Carlo pricing model, which requires extensive use of accounting judgment and financial estimation, including the estimated share price appreciation plus the value of dividends of our Class A common stock as compared to the Russell 2000 Index over the requisite service period.

Restricted stock granted to non-employee directors vest incrementally over a three year period beginning on the first anniversary of the date of grant. Restricted stock units granted to non-employee directors vest in full on the first anniversary of the grant date. Restricted stock units vest incrementally over an identified service period beginning on the grant date based on continued employment. Performance stock units and market-based performance stock units vest at a future date following the grant date and are based on the attainment of performance targets and market achievements.

Stock Options

A summary of stock option activity is as follows:



	Stock Options		Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (years)	Aggregate Intrinsic Value
Outstanding, December 31, 2017	727		$	5.82
Granted	—		$	—
Exercised	(98	)	$	4.80
Forfeited or expired	—		$	—
Market-based stock options vested (1)	40		$	12.48	7.9
Outstanding, December 31, 2018	669		$	6.37	5.6	$	14,788
Exercisable, December 31, 2018	669		$	6.37	5.6	$	14,788


(1)	Market-based performance stock option grants were included at 100% until they vested on December 31, 2018, at which point the actual number of options vested was adjusted based on the actual attainment of performance targets and market achievements.

During fiscal years 2018, 2017 and 2016, stock-based compensation expense for stock options was $473, $644 and $605, respectively.

During fiscal years 2018, 2017 and 2016, the aggregate intrinsic value of stock options exercised was $1,916, $4,664 and $22, respectively.

As of December 31, 2018, there was no remaining unrecognized stock-based compensation expense related to outstanding stock options.

Our calculation of stock-based compensation expense associated with stock options granted, with the exception of market-based performance stock option grants which are valued using a Monte Carlo option-pricing model, was made using the Black-Scholes valuation model. With the exception of market-based performance stock options granted in fiscal year 2016 discussed below, we did not grant any new stock options in fiscal years 2018, 2017 and 2016.

The weighted average fair value of market-based performance stock options granted during fiscal year 2016 was $6.70 per option, which was calculated using a Monte Carlo option-pricing model assuming an expected life of 7.4 years, a risk free interest rate of 2.15%, and an expected volatility of 43.10% assuming no expected dividend yield.

Expected life is calculated based on the weighted average historical life of the vested stock options, giving consideration to vesting schedules and historical exercise patterns. Risk-free interest rate is based on the U.S. Treasury yield curve for the period of the expected life of the stock option. Expected volatility is calculated using the weekly historical volatility of our Class A common stock over the expected life, except in the case of market-based performance stock option where the daily historical volatility of our Class A common stock over the expected life is used.

The Black-Scholes valuation model and the Monte Carlo option-pricing model each require extensive use of accounting judgment and financial estimation. Application of alternative assumptions could produce significantly different estimates of the fair value of stock-based compensation and consequently, the related amounts recognized in the consolidated statements of operations.

Other Stock Awards

A summary of restricted stock, restricted stock unit and performance stock unit activity is as follows:



	Restricted Stock, Restricted Stock Units, and Performance Stock Units (1)		Weighted Average Grant Price		Weighted Average Remaining Contractual Term (years)	Aggregate Intrinsic Value
Outstanding, December 31, 2017	1,091		$	9.81
Granted	230		$	24.92
Class A common stock vested	(632	)	$	9.04
Forfeited or canceled	(3	)	$	13.73
Outstanding, December 31, 2018	686		$	15.56	1.2	$	8,877
Unvested, December 31, 2018	951		$	15.95	1.3	$	11,929


(1)	Market-based performance stock unit grants are included at 100%. Attainment of maximum performance targets and market achievements would result in the issuance of an additional 265 shares of Class A common stock currently included in unvested. The market-based performance stock unit grants that vested in fiscal year 2018 resulted in the issuance of 185 additional shares of Class A common stock.

During fiscal years 2018, 2017 and 2016, stock-based compensation expense related to restricted stock, restricted stock units and performance stock units was $7,821, $5,652 and $2,673, respectively.

During fiscal years 2018, 2017 and 2016, the total fair value of other stock awards vested was $10,529, $5,706 and $3,238, respectively.

As of December 31, 2018, total unrecognized stock-based compensation expense related to restricted stock and restricted stock units was $3,024, which will be recognized over a weighted average period of 1.1 years. Total unrecognized stock-based compensation expense related to performance stock units, assuming the attainment of maximum performance targets, was $4,516, which will be recognized over a weighted average period of 1.3 years.

The weighted average fair value of market-based performance stock units granted during fiscal year 2018 was $26.02 per award, which was calculated using a Monte Carlo pricing model assuming a risk free interest rate of 2.39% and an expected volatility of 32.70% assuming no expected dividend yield. Risk-free interest rate is based on the U.S. Treasury yield curve for the expected service period of the award. Expected volatility is calculated using the daily volatility of our Class A common stock over the expected service period of the award.

The Monte Carlo pricing model requires extensive use of accounting judgment and financial estimation. Application of alternative assumptions could produce significantly different estimates of the fair value of stock-based compensation and consequently, the related amounts recognized in the consolidated statements of operations.

We also recorded $150, $136 and $115 of stock-based compensation expense related to our Amended and Restated 1997 Employee Stock Purchase Plan during fiscal years 2018, 2017 and 2016, respectively.

There was $(23) of tax benefit in the (benefit) provision for income taxes associated with stock-based compensation during fiscal year 2018. There was $117 and $0 of tax provision in the (benefit) provision for income taxes associated with stock-based compensation expense in fiscal years 2017 and 2016, respectively.

Accumulated Other Comprehensive (Loss) Income

Accumulated other comprehensive (loss) income is a component of stockholders' deficit included in the accompanying consolidated balance sheets and includes, as applicable, the effective portion of changes in the fair value of our cash flow hedges and the changes in fair value of our marketable securities.

The changes in the balances of each component of accumulated other comprehensive (loss) income are as follows:



	Marketable Securities			Interest Rate Swaps			Total
Balance as of December 31, 2015	$	7		$	—		$	7
Other comprehensive loss	(75		)	—			(75		)
Balance as of December 31, 2016	(68		)	—			(68		)
Other comprehensive income (loss) before reclassifications	59			(143		)	(84		)
Amounts reclassified from accumulated other comprehensive income (loss)	—			421			421
Income tax expense related to items in other comprehensive income (loss)	27			(112		)	(85		)
Other comprehensive income, net	86			166			252
Balance as of December 31, 2017	18			166			184
Cumulative effect of new accounting principle	(18		)	—			(18		)
Other comprehensive loss before reclassifications	—			(1,837		)	(1,837		)
Amounts reclassified from accumulated other comprehensive loss	—			363			363
Income tax expense related to items in other comprehensive income	—			—			—
Other comprehensive loss, net	—			(1,474		)	(1,474		)
Balance as of December 31, 2018	$	—		$	(1,308	)	$	(1,308	)

A summary of reclassifications out of accumulated other comprehensive (loss) income for fiscal years 2018, 2017 and 2016 is as follows:



	Fiscal Year Ended December 31,
	2018		2017		2016
Details About Accumulated Other Comprehensive Income (Loss) Components	Amounts Reclassified Out of Accumulated Other Comprehensive Income (Loss)						Affected Line Item in the Consolidated Statements of Operations
Interest rate swaps	$	363	$	421	$	—	Interest expense
	363		421		—		Income (loss) before income taxes
	—		—		—		(Benefit) provision for income taxes
	$	363	$	421	$	—	Net income (loss)

FAIR VALUE OF FINANCIAL INSTRUMENTS

12 Months Ended

Dec. 31, 2018

Fair Value Disclosures [Abstract]

FAIR VALUE OF FINANCIAL INSTRUMENTS

We use a three-tier fair value hierarchy to classify and disclose all assets and liabilities measured at fair value on a recurring basis, as well as assets and liabilities measured at fair value on a non-recurring basis, in periods subsequent to their initial measurement. These tiers include: Level 1, defined as quoted market prices in active markets for identical assets or liabilities; Level 2, defined as inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities; and Level 3, defined as unobservable inputs that are not corroborated by market data.

We use valuation techniques that maximize the use of market prices and observable inputs and minimize the use of unobservable inputs. In measuring the fair value of our financial assets and liabilities, we rely on market data or assumptions that we believe market participants would use in pricing an asset or a liability.

Assets and Liabilities Accounted for at Fair Value on a Recurring Basis

Our financial instruments include cash and cash equivalents, accounts receivable-trade, restricted investment securities held in trust on deposit with various banks as collateral for our obligations relative to our landfill final capping, closure and post-closure costs, interest rate derivatives, trade payables and long-term debt. The carrying values of cash and cash equivalents, accounts receivable - trade and trade payables approximate their respective fair values due to their short-term nature. The fair value of restricted investment securities held in trust, which are valued using quoted market prices, are included as restricted assets in the Level 1 tier below. The fair value of the interest rate derivatives included in the Level 2 tier below is calculated using discounted cash flow valuation methodologies based upon the one month LIBOR yield curves that are observable at commonly quoted intervals for the full term of the swaps. We recognize all derivatives accounted for on the balance sheet at fair value.

See Note 10, Long Term Debt and Capital Leases for disclosure over the fair value of debt.

Recurring Fair Value Measurements

Summaries of our financial assets and liabilities that are measured at fair value on a recurring basis are as follows:



	Fair Value Measurement at December 31, 2018 Using:
	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Restricted investment securities - landfill closure	$	1,248	$	—	$	—
Interest rate swaps	—		820		—
	$	1,248	$	820	$	—
Liabilities:
Interest rate swaps	$	—	$	1,942	$	—



	Fair Value Measurement at December 31, 2017 Using:
	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Restricted investment securities - landfill closure	$	1,220	$	—	$	—
Interest rate swaps	—		401		—
	$	1,220	$	401	$	—
Liabilities:
Interest rate swaps	$	—	$	123	$	—

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

EMPLOYEE BENEFIT PLANS

12 Months Ended

Dec. 31, 2018

Retirement Benefits [Abstract]

EMPLOYEE BENEFIT PLANS

Defined Contribution Plan

We offer our eligible employees the opportunity to contribute to a 401(k) plan (“401(k) Plan”). Under the provisions of the 401(k) Plan participants may direct us to defer a portion of their compensation to the 401(k) Plan, subject to Internal Revenue Code limitations. We provide an employer matching contribution equal to fifty cents for every dollar an employee invests in the 401(k) Plan up to our maximum match of one thousand dollars per employee per calendar year, subject to revision. Participants vest in employer contributions ratable over a three year period. Employer contributions for fiscal years 2018, 2017 and 2016 amounted to $1,319, $1,187 and $1,119, respectively.

Employee Stock Purchase Plan

We offer our eligible employees the opportunity to participate in an employee stock purchase plan. Under this plan, qualified employees may purchase shares of Class A common stock by payroll deduction at a 15% discount from the market price. During fiscal years 2018, 2017 and 2016, 26, 41 and 70 shares, respectively, of Class A common stock were issued under this plan. As of December 31, 2018, 117 shares of Class A common stock were available for distribution under this plan.

Multiemployer Pension Plan

We make contributions to a multiemployer defined benefit pension plan, the New England Teamsters and Trucking Industry Pension Fund, under the terms of a collective bargaining agreement that covers our union represented employees. The Pension Plan provides retirement benefits to participants based on their service to contributing employers. We do not administer this plan. The risks of participating in a multiemployer plan are different from a single-employer plan in that: (i) assets contributed to the multiemployer plan by one employer may be used to provide benefits to employees or former employees of other participating employers; (ii) if a participating employer stops contributing to the plan, the unfunded obligations of the plan may be required to be assumed by the remaining participating employers; and (iii) if we choose to stop participating in our multiemployer plan, we may be required to pay the plan a withdrawal amount based on the underfunded status of the plan.

The following table outlines our participation in the multiemployer defined benefit pension plan:



Pension Fund	EIN/Pension Plan Number	Pension Protection Act Zone Status		Funding Improvement or Rehabilitation Plan Status	Contributions to Plan						Expiration Date of CBA
		Pension Protection Act Zone Status			Fiscal Year Ended December 31,
		2018	2017		2018		2017		2016
New England Teamsters and Trucking Industry Pension Fund	04-6372430	Critical and declining	Critical and declining	Implemented	$	726	$	627	$	523	June 30, 2020

The status is based on the latest plan information for the plan year ended September 30, 2018 that we received from the pension plan and is certified by the pension plans’ actuary. Plans with a “critical and declining” status are funded at less than 65%, have a projected funding deficiency in the current or next four plan years and have a projected insolvency date which is less than the 20-year minimum statutory requirement. Our contributions to the multiemployer pension plan represent less than 5% of total contributions to such plan for the plan year ended September 30, 2017 and a rehabilitation plan has been implemented with no surcharge imposed. Under current law regarding multiemployer benefit plans, a plan’s termination, our voluntary withdrawal, or the withdrawal of all contributing employers from any under-funded multiemployer pension plan would require us to make payments to the plan for our proportionate share of the multiemployer plan’s unfunded vested liabilities. We could have adjustments to estimates for these matters in the near term that could have a material effect on its consolidated financial position, results of operations or cash flows. At the date these financial statements were issued, a Form 5500 was not available for the plan year ended September 30, 2018.

INCOME TAXES

12 Months Ended

Dec. 31, 2018

Income Tax Disclosure [Abstract]

INCOME TAXES

A summary of the (benefit) provision for income taxes is as follows:



	Fiscal Year Ended December 31,
	2018			2017			2016
Federal
Current	$	(1,902	)	$	—		$	—
Deferred	1,255			(15,614		)	458
	(647		)	(15,614		)	458
State
Current	2,575			301			(90		)
Current benefit of loss carryforwards	(2,307		)	(28		)	—
Deferred	(5		)	88			126
	263			361			36
(Benefit) provision for income taxes	$	(384	)	$	(15,253	)	$	494

During fiscal year 2018, we recognized a $(937) deferred tax benefit related to the Complete acquisition due to a reduction of the valuation allowance. In determining the need for a valuation allowance, we have assessed the available means of recovering deferred tax assets, including the existence of reversing temporary differences. The valuation allowance decreased due to the recognition of additional reversing temporary differences from the $937 deferred tax liability recorded through goodwill on the acquisition. The $937 deferred tax liability related to the Complete acquisition was based on the impact of temporary differences between the amounts of assets and liabilities recognized for financial reporting purposes and such amounts recognized for income tax purposes. The valuation allowance was reduced by $(1,635) in the quarter ended March 31, 2018, with the offsetting increase in the Complete goodwill, based on initial estimates of the Complete temporary differences. The valuation allowance was increased by $406 in quarter ended September 30, 2018 and $292 in quarter ended December 31, 2018, with an offsetting decrease in the Complete goodwill, based on the availability of better estimates of the Complete temporary differences upon the filing of the prior year returns by Complete’s sellers in the quarter and anticipated net operating loss carryforwards.

On December 22, 2017, the Act was enacted. The Act, which is also commonly referred to as “U.S. tax reform,” significantly changes United States corporate income tax laws by, among other things, reducing the US corporate income tax rate from 35% to 21% starting in 2018. Under the Act, federal net operating loss carryforwards generated as of the end of 2017 continue to be carried forward for 20 years and are generally available to fully offset taxable income earned in a tax year. Federal net operating losses generated after 2017 will be carried forward indefinitely, but generally may only offset up to 80% of taxable income earned in future tax years. In fiscal year 2017, we revalued our deferred taxes due to these changes, including (a) revaluing our federal net deferred taxes before valuation allowance using the 21% tax rate resulting in an increased net federal deferred tax provision of $33,700; (b) revaluing our federal valuation allowance using the 21% tax rate, including the impact of tax planning strategies, resulting in a federal deferred tax benefit to continuing operations of $(36,556); and (c) recognizing a federal deferred tax benefit of $(12,758) for 80% of indefinite lived deferred tax liabilities, which are anticipated to be available as a source of taxable income upon reversal of deferred tax assets that would also have indefinite lives.

In fiscal year 2016, we elected early adoption of ASU 2016-09 using the prospective transition method related to stock compensation which contains several amendments that simplify the accounting for employee share-based payment transactions. Related to the accounting for income taxes, the new standard eliminates the accounting for excess tax benefits to be recognized in additional paid-in capital and tax deficiencies recognized either in the income tax provision or in additional paid-in capital. Under the new standard, all excess tax benefits and tax deficiencies are recorded in the income tax provision. We recognized no net tax impact upon adoption due to the valuation allowance position and prior periods were not adjusted.

The differences in the (benefit) provision for income taxes and the amounts determined by applying the Federal statutory rate to income before provision for income taxes are as follows:



	Fiscal Year Ended December 31,
	2018			2017			2016
Federal statutory rate	21		%	35		%	35		%
Tax at statutory rate	$	1,268		$	(12,968	)	$	(2,228	)
State income taxes, net of federal benefit	(89		)	(1,959		)	(265		)
Decrease in net federal deferred tax assets before valuation allowance change due to federal rate change	—			33,700			—
Decrease in valuation allowance by 80% of indefinite lived deferred liabilities due to US tax reform	—			(12,758		)	—
Other changes in valuation allowance, including the federal rate change in fiscal year 2017	(1,613		)	(18,848		)	4,370
Non-deductible officer compensation	2,214			—			—
Deductible stock awards	(2,048		)	(1,825		)	—
Tax credits	(686		)	(1,000		)	(1,085		)
Non-deductible expenses	633			542			100
Other, net	(63		)	(137		)	(398		)
(Benefit) provision for income taxes	$	(384	)	$	(15,253	)	$	494

Deferred income taxes reflect the impact of temporary differences between the amounts of assets and liabilities recognized for financial reporting purposes and such amounts recognized for income tax purposes. A summary of deferred tax assets and liabilities is as follows:



	December 31,
	2018			2017
Deferred tax assets:
Accrued expenses and reserves	$	34,647		$	26,572
Net operating loss carryforwards	31,241			33,228
Book over tax depreciation of property and equipment	19,048			25,615
General business tax credit carryforwards	6,192			5,439
Stock awards	2,310			1,958
Alternative minimum tax credit carryforwards	1,902			3,804
Other	3,023			2,050
Total deferred tax assets	98,363			98,666
Less: valuation allowance	(69,189		)	(68,355		)
Total deferred tax assets after valuation allowance	29,174			30,311
Deferred tax liabilities:
Amortization of intangibles	(22,026		)	(20,904		)
Other	(73		)	(145		)
Total deferred tax liabilities	(22,099		)	(21,049		)
Net deferred tax asset	$	7,075		$	9,262

The net deferred tax asset at December 31, 2018 is reflected on the balance sheet as a long-term deferred federal tax asset of $9,594 and a long-term deferred state tax liability of $(2,519).

As of December 31, 2018, we have, for federal income tax purposes, net operating loss carryforwards of approximately $110,586 that expire in the fiscal years ending December 31, 2031 through 2037 and $3,209, which do not expire. We have state net operating loss carryforwards of approximately $86,312 that expire in the fiscal years ending December 31, 2019 through 2038. In addition, we have $1,902 minimum tax credit carryforwards which are fully refundable for tax years 2019 through 2021, if not otherwise used to offset tax liabilities. We also have $6,192 general business credit carryforwards which expire in the fiscal years ending December 31, 2022 through 2038. Sections 382 and 383 of the Internal Revenue Code can limit the amount of net operating loss and credit carryforwards which may be used in a tax year in the event of certain stock ownership changes. With the exception of $1,320 federal net operating losses we acquired with the Complete acquisition, we are not currently subject to these limitations but could become subject to them if there were significant changes in the ownership of our stock.

In assessing the realizability of carryforwards and other deferred tax assets, management considers whether it is more likely than not that some portion or all of the deferred tax assets will not be realized. We adjust the valuation allowance in the period management determines it is more likely than not that deferred tax assets will or will not be realized. The change in the valuation allowance was an increase of $834 for fiscal year 2018 and a decrease of $(29,234) for fiscal year 2017. In determining the need for a valuation allowance, we have assessed the available means of recovering deferred tax assets, including the ability to carryback net operating losses, the existence of reversing temporary differences, and available sources of future taxable income. We have also considered the ability to implement certain strategies, such as a potential sale of assets that would, if necessary, be implemented to accelerate taxable income and use expiring deferred tax assets.

The net deferred tax assets include deferred tax liabilities related to amortizable goodwill, which are anticipated to reverse in an indefinite future period and to generate future taxable income upon reversal. Prior to the Act, federal net operating losses, including potential losses from the reversal of deferred tax assets, could only be carried forward for 20 years. The reversal of the indefinite lived goodwill was not available as a source of future taxable income since it was uncertain whether the income generated would be available in the same tax periods in which losses from the reversal of deferred tax assets could be utilized. As such, prior to the Act we did not treat the reversal of amortizable goodwill as an available source of taxable income in determining the valuation allowance.

Beginning in 2018 under the Act, future federal net operating losses generated may be carried forward indefinitely and generally may offset up to 80% of taxable income earned in a tax year. Because potential losses from the reversal of deferred tax assets in future years may be carried forward indefinitely, we consider it more likely than not that 80% of the reversal of deferred tax liabilities for amortizable goodwill will be available as a source of taxable income.

In the fourth quarter of 2017, we revalued our net federal deferred tax assets using the 21% tax rate as enacted under the Act. The valuation allowance was also adjusted in this quarter due to the federal tax rate change and to recognize a $(12,758) federal deferred tax benefit for 80% of deferred tax liabilities for amortizable goodwill. Due to the Act, we recognized a $(15,614) federal deferred tax benefit in 2017 and decreased our total valuation allowance by $(29,234). We believe we are able to support the deferred tax assets recognized as of the end of fiscal years 2018 and 2017 based on all of the available evidence.

The provisions of FASB ASC 740-10-25-5 prescribe the minimum recognition threshold that a tax position is required to meet before being recognized in the financial statements. Additionally, FASB ASC 740-10-25-5 provides guidance on de-recognition, measurement, classification, interest and penalties, accounting in interim periods, disclosure and transition. Under FASB ASC 740-10-25-5, an entity may only recognize or continue to recognize tax positions that meet a “more likely than not” threshold.

A reconciliation of the beginning and ending amount of gross unrecognized tax benefits is as follows:



	Fiscal Year Ended December 31,
	2018			2017
Unrecognized tax benefits at beginning of period	$	1,941		$	3,107
Gross increases for tax positions of prior years	—			1
Gross decreases for tax positions of prior years	—			(1,165		)
Reductions resulting from lapse of statute of limitations	(1,939		)	—
Settlements	—			(2		)
Unrecognized tax benefits at end of period	$	2		$	1,941

The fiscal year 2018 reductions resulting from a lapse of the statute of limitations primarily related to unrecognized benefits which had reduced net operating loss carryforwards. The tax positions primarily related to fiscal years 2007 and prior and based on administrative practice of the tax authorities, we have reduced the unrecognized tax benefits. The gross decreases for tax positions of prior years for fiscal year 2017 are due to the reduction in the federal corporate tax rate to 21%. Since the majority of our unrecognized benefits reduce net operating loss carryforwards, the amounts were reduced consistent with the overall rate reduction related to the net operating loss deferred asset.

Included in the balances at December 31, 2018 and December 31, 2017 are $2 and $6, respectively, of unrecognized tax benefits (net of the federal benefit on state issues) that, if recognized, would favorably affect the effective income tax rate in future periods. We anticipate $2 of unrecognized tax benefits to reverse within the next 12 months due to the expiration of the applicable statute of limitations.

Our continuing practice is to recognize interest and penalties related to income tax matters in income tax expense. Related to uncertain tax positions during fiscal years 2018, 2017 and 2016, we have accrued interest of $2, $3 and $5 and penalties of $1, $2 and $4, respectively. We accrued $(2), $(3)and $(91) for interest and penalties in income tax expense related to uncertain tax positions during fiscal years 2018, 2017 and 2016, respectively.

To the extent interest and penalties are not assessed with respect to uncertain tax positions, amounts accrued will be reduced and reflected as a reduction of the overall income tax provision.

We are subject to U.S. federal income tax, as well as income tax of multiple state jurisdictions. Due to Federal and state net operating loss carryforwards, income tax returns from years ending in 1998 through 2018 remain open for examination, with limited exceptions.

EARNINGS PER SHARE

12 Months Ended

Dec. 31, 2018

Earnings Per Share [Abstract]

EARNINGS PER SHARE

A summary of the numerator and denominators used in the computation of earnings per share is as follows:



	Fiscal Year Ended December 31,
	2018			2017			2016
Numerator:
Net income (loss) attributable to common stockholders	$	6,420		$	(21,799	)	$	(6,849	)
Denominator:
Class A common stock	41,944			41,298			40,572
Class B common stock	988			988			988
Shares to be issued - acquisition	103			—			—
Unvested restricted stock	(9		)	(38		)	(88		)
Effect of weighted average shares outstanding	(338		)	(402		)	(239		)
Basic weighted average common shares outstanding	42,688			41,846			41,233
Impact of potentially dilutive securities:
Dilutive effect of stock options and stock awards	1,480			—			—
Diluted weighted average common shares outstanding	44,168			41,846			41,233
Antidilutive potentially issuable shares	2			2,219			2,442

OTHER ITEMS AND CHARGES

12 Months Ended

Dec. 31, 2018

Unusual or Infrequent Items, or Both [Abstract]

OTHER ITEMS AND CHARGES

Southbridge Landfill Closure Charge, Net

In June 2017, we initiated the plan to cease operations of our Southbridge Landfill as disclosed in Note 11, Commitments and Contingencies. Accordingly, in fiscal years 2018 and 2017, we recorded charges associated with the closure of our Southbridge Landfill as follows:



	Fiscal Year Ended December 31,
	2018			2017
Asset impairment charge (1)	$	—		$	47,999
Project development charge (2)	—			9,149
Environmental remediation charge (3)	—			6,379
Contract settlement charge (4)	8,724			—
Landfill closure project charge (5)	6,012			—
Charlton settlement charge (6)	1,216			—
Legal and transaction costs (7)	2,102			1,656
Recovery on insurance settlement (8)	(10,000		)	—
Southbridge Landfill closure charge, net	$	8,054		$	65,183


(1)	We performed a test of recoverability under FASB ASC 360, which indicated that the carrying value of our asset group that includes the Southbridge Landfill was no longer recoverable and, as a result, the asset group was assessed for impairment with an impairment charge allocated to the long-lived assets of the Southbridge Landfill in accordance with FASB ASC 360.


(2)	We wrote-off deferred costs associated with Southbridge Landfill permitting activities no longer deemed viable.


(3)	We recorded an environmental remediation charge associated with the installation of a municipal waterline. See Note 11, Commitments and Contingencies for additional disclosure.


(4)	We recorded a contract settlement charge associated with the closure of Southbridge Landfill and the remaining future obligations due to the Town of Southbridge under the landfill operating agreement with the Town of Southbridge. See Note 11, Commitments and Contingencies for additional disclosure.


(5)	We recorded a landfill closure project charge associated with increased costs under the revised closure plan at our Southbridge Landfill.


(6)	We established a reserve associated with settlement of the Town of Charlton's claim against us. See Note 11, Commitments and Contingencies for additional disclosure.


(7)	We incurred legal and other transaction costs associated with various matters as part of the Southbridge Landfill closure. See Note 11, Commitments and Contingencies for additional disclosure.


(8)	We recorded a recovery on an environmental insurance settlement associated with the Southbridge Landfill closure. See Note 11, Commitments and Contingencies for additional disclosure.

Contract Settlement Charge

In fiscal year 2018, we recorded contract settlement charges of $2,100 associated with the termination and discounted buy-out of a commodities marketing and brokerage agreement.

Expense from Acquisition Activities and Other Items

In fiscal year 2018, we recorded a charge of $1,872 associated with acquisition activities and the write-off of deferred costs related to the expiration of our shelf registration statement, and in fiscal year 2017, we recorded a charge of $176 related to acquisition activities. See Note 5, Business Combinations for disclosure over acquisition activity.

Development Project Charge

In fiscal year 2018, we recorded development project charges of $311 associated with previously deferred costs that were written off as a result of the negative vote in a public referendum relating to the NCES Landfill.

Environmental Remediation Charge

We recorded an environmental remediation charge of $900 in fiscal year 2016 due to changes in cost estimates associated with the Potsdam environmental remediation liability. See Note 11, Commitments and Contingencies for further disclosure.

RELATED PARTY TRANSACTIONS	12 Months Ended
RELATED PARTY TRANSACTIONS	Dec. 31, 2018
Related Party Transactions [Abstract]
RELATED PARTY TRANSACTIONS	RELATED PARTY TRANSACTIONS Services During fiscal years 2018, 2017 and 2016, we retained the services of Casella Construction, Inc. ("CCI"), a company substantially owned by sons of John Casella, our Chairman and Chief Executive Officer, and Douglas Casella, a member of our Board of Directors, as a contractor in developing or closing certain landfills owned by us as well as providing transportation services. Total purchased services charged to operations or capitalized to landfills for fiscal years 2018, 2017 and 2016 were $3,421, $3,377 and $4,024, respectively, of which $32 and $30 were outstanding and included in either accounts payable or other current liabilities as of December 31, 2018 and December 31, 2017, respectively. In addition to the total purchased services, we provided various waste collection and disposal services to CCI. Total revenues recorded for fiscal years 2018, 2017 and 2016 were $156, $237 and $307, respectively. Leases In the fiscal year ended April 30, 1994, we entered into two leases for operating facilities with a partnership of which John Casella, our Chairman and Chief Executive Officer, and Douglas Casella, a member of our Board of Directors, are the general partners. The leases have since been extended through August 2023. The terms of the lease agreements require monthly payments of approximately $28. Total expense charged to operations for fiscal years 2018, 2017 and 2016 under these agreements was $349, $360 and $371, respectively. Landfill Post-closure We have agreed to pay the cost of post-closure on a landfill owned by John Casella, our Chairman and Chief Executive Officer, and Douglas Casella, a member of our Board of Directors. We paid the cost of closing this landfill in 1992, and the post-closure maintenance obligations are expected to last until the fiscal year ending December 31, 2024. In fiscal years 2018, 2017 and 2016, we paid $14, $27 and $10, respectively, pursuant to this agreement. As of December 31, 2018 and December 31, 2017, we have accrued $48 and $60, respectively, for costs associated with its post-closure obligations.

SEGMENT REPORTING

12 Months Ended

Dec. 31, 2018

Segment Reporting [Abstract]

SEGMENT REPORTING

We report selected information about operating segments in a manner consistent with that used for internal management reporting. We classify our solid waste operations on a geographic basis through regional operating segments, our Western and Eastern regions. Revenues associated with our solid waste operations are derived mainly from solid waste collection and disposal, landfill, landfill gas-to-energy, transfer and recycling services in the northeastern United States. Our revenues in the Recycling segment are derived from municipalities and customers in the form of processing fees, tipping fees and commodity sales. Organics services, ancillary operations, along with major account and industrial services, are included in our Other segment.

Fiscal Year Ended December 31, 2018



Segment	Outside revenues		Inter-company revenue			Depreciation and amortization		Operating income (loss)			Interest expense, net			Capital expenditures		Goodwill		Total assets
Eastern	$	206,473	$	52,866		$	26,538	$	4,684		$	12		$	23,393	$	28,154	$	184,679
Western	286,262		81,515			35,843		41,529			(148		)	41,850		120,536		428,934
Recycling	42,191		6,426			4,345		(7,805		)	140			4,476		12,315		48,629
Other	125,734		1,982			3,782		1,325			26,017			3,513		1,729		70,168
Eliminations	—		(142,789		)	—		—			—			—		—		—
Total	$	660,660	$	—		$	70,508	$	39,733		$	26,021		$	73,232	$	162,734	$	732,410

Fiscal Year Ended December 31, 2017



Segment	Outside revenues		Inter-company revenue			Depreciation and amortization		Operating income (loss)			Interest expense, net			Capital expenditures		Goodwill		Total assets
Eastern	$	181,170	$	50,335		$	23,815	$	(51,867	)	$	3		$	17,153	$	19,192	$	157,248
Western	250,771		71,510			30,766		35,035			(220		)	42,082		89,369		344,324
Recycling	62,307		246			4,125		2,805			143			2,006		12,315		48,612
Other	105,061		1,881			3,396		1,444			24,961			3,621		1,729		64,765
Eliminations	—		(123,972		)	—		—			—			—		—		—
Total	$	599,309	$	—		$	62,102	$	(12,583	)	$	24,887		$	64,862	$	122,605	$	614,949

Fiscal Year Ended December 31, 2016



Segment	Outside revenues		Inter-company revenue			Depreciation and amortization		Operating income (loss)		Interest expense, net			Capital expenditures		Goodwill		Total assets
Eastern	$	176,539	$	45,728		$	27,036	$	9,697	$	(16	)	$	18,363	$	17,429	$	202,420
Western	233,168		67,985			27,511		30,576		(248		)	31,637		88,426		327,628
Recycling	52,911		1,003			4,212		2,542		156			2,218		12,315		49,931
Other	102,412		1,615			3,097		2,130		38,760			2,020		1,729		51,533
Eliminations	—		(116,331		)	—		—		—			—		—		—
Total	$	565,030	$	—		$	61,856	$	44,945	$	38,652		$	54,238	$	119,899	$	631,512

Amount of our total revenue attributable to services provided are as follows:



	Fiscal Year Ended December 31,
	2018				2017				2016
Collection	$	303,418	45.9	%	$	263,688	44.0	%	$	249,640	44.2	%
Disposal	181,110		27.4	%	160,073		26.7	%	154,211		27.3	%
Power generation	5,129		0.8	%	5,375		0.9	%	5,921		1.0	%
Processing	7,174		1.1	%	7,994		1.3	%	6,282		1.1	%
Solid waste operations	496,831		75.2	%	437,130		72.9	%	416,054		73.6	%
Organics	54,174		8.2	%	39,815		6.6	%	41,587		7.4	%
Customer solutions	67,464		10.2	%	60,057		10.1	%	54,478		9.6	%
Recycling	42,191		6.4	%	62,307		10.4	%	52,911		9.4	%
Total revenues	$	660,660	100.0	%	$	599,309	100.0	%	$	565,030	100.0	%

QUARTERLY FINANCIAL INFORMATION (UNAUDITED)

12 Months Ended

Dec. 31, 2018

Quarterly Financial Information Disclosure [Abstract]

QUARTERLY FINANCIAL INFORMATION (UNAUDITED)

The following is a summary of certain items in the consolidated statements of operations by quarter:



Fiscal Year 2018	First Quarter			Second Quarter		Third Quarter		Fourth Quarter
Revenues	$	147,455		$	165,649	$	172,832	$	174,724
Operating income (loss)	$	838		$	15,149	$	28,884	$	(5,138	)
Net (loss) income	$	(3,910	)	$	1,704	$	22,302	$	(13,676	)
Earnings per common share:								—
Basic weighted average common shares outstanding	42,370			42,661		42,779		42,936
Basic earnings per share	$	(0.09	)	$	0.04	$	0.52	$	(0.32	)
Diluted weighted average common shares outstanding	42,370			43,916		44,175		42,936
Diluted earnings per share	$	(0.09	)	$	0.04	$	0.50	$	(0.32	)



Fiscal Year 2017	First Quarter			Second Quarter			Third Quarter		Fourth Quarter
Revenues	$	133,802		$	154,016		$	160,269	$	151,222
Operating income (loss)	$	6,564		$	(47,279	)	$	18,277	$	9,855
Net (loss) income	$	(224	)	$	(53,675	)	$	12,080	$	20,020
Earnings per common share:
Basic weighted average common shares outstanding	41,584			41,811			41,951		42,033
Basic earnings per share	$	(0.01	)	$	(1.28	)	$	0.29	$	0.48
Diluted weighted average common shares outstanding	41,584			41,811			43,295		43,394
Diluted earnings per share	$	(0.01	)	$	(1.28	)	$	0.28	$	0.46

Our transfer and disposal revenues historically have been lower from the months of November through March. This seasonality reflects the lower volume of waste during the late fall, winter and early spring months. Since certain of our operating and fixed costs remain constant throughout fiscal year, operating income is impacted by a similar seasonality. In addition, particularly harsh weather conditions typically result in increased operating costs.

Our recycling business experiences increased volumes of newspaper in November and December due to increased newspaper advertising and retail activity during the holiday season.

Schedule II - Valuation Accounts

12 Months Ended

Dec. 31, 2018

Valuation and Qualifying Accounts [Abstract]

Schedule II - Valuation Accounts

Schedule II

Valuation Accounts

Allowance for Doubtful Accounts

(in thousands)



	Fiscal Year Ended December 31,
	2018			2017			2016
Balance at beginning of period	$	809		$	1,069		$	988
Additions—charged to expense	1,620			290			1,107
Deductions—bad debts written off, net of recoveries	(1,498		)	(550		)	(1,026		)
Balance at end of period	$	931		$	809		$	1,069

ACCOUNTING CHANGES (Policies)

12 Months Ended

Dec. 31, 2018

Accounting Changes and Error Corrections [Abstract]

Basis of Accounting

Casella Waste Systems, Inc. (“Parent”), its consolidated subsidiaries and any partially owned entities over which it has a controlling financial interest (collectively, “we”, “us” or “our”), is a regional, vertically integrated solid waste services company that provides collection, transfer, disposal, landfill, landfill gas-to-energy, recycling and organics services in the northeastern United States. We market recyclable metals, aluminum, plastics, paper and corrugated cardboard, which have been processed at our recycling facilities, as well as recyclables purchased from third-parties. We manage our solid waste operations on a geographic basis through two regional operating segments, our Eastern and Western regions, each of which provides a full range of solid waste services, and our larger-scale recycling and commodity brokerage operations through our Recycling segment. Organics services, ancillary operations, along with major account and industrial services are included in our Other segment.

The accompanying consolidated financial statements, which include the accounts of the Parent, our wholly-owned subsidiaries and any partially owned entities over which we have a controlling financial interest, have been prepared in accordance with generally accepted accounting principles in the United States (“GAAP”) pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”). All significant intercompany accounts and transactions are eliminated in consolidation. Investments in entities in which we do not have a controlling financial interest are accounted for under either the equity method or the cost method of accounting, as appropriate.

Accounting Standards that are Adopted and Pending Adoption



Standard	Description	Effect on the Financial Statements or Other Significant Matters
Accounting standards updates ("ASU") that were adopted effective January 1, 2018
ASU 2017-12: Derivatives and Hedging (Topic 815)	Requires that an entity align its risk management activities and financial reporting for hedging relationships through changes to both the designation and measurement guidance for qualifying hedging relationships and the presentation of hedge results. This guidance expands and refines hedge accounting for both financial and commodity risk components and aligns the recognition and presentation of the effects of the hedging instrument and the hedged item in the financial statements.	The adoption of this guidance affects the designation and measurement guidance for qualifying hedging relationships and the method of presenting hedge results, including the addition of a tabular disclosure related to the effect on the income statement of fair value and cash flow hedges and no longer measuring and reporting hedge ineffectiveness. We early adopted this guidance using a modified retrospective approach effective April 1, 2018 with an initial application date of January 1, 2018 with no adjustment to Accumulated Deficit. See Note 10, Long-Term Debt and Capital Leases for additional disclosure.

ASU 2017-09: Compensation - Stock Compensation (Topic 718)	Requires that an entity should account for the effects of a modification to an award unless all of the following conditions are met: the fair value of the modified award is the same as the fair value of the original award immediately before the original award is modified; the vesting conditions of the modified award are the same as the vesting conditions immediately before the original award is modified; and the classification of modified award as an equity instrument or a liability instrument is the same as the classification of the original award immediately before the original award is modified.	The adoption of this guidance could affect equity compensation expense and net income if there is a modification of an award.



ASU 2016-18: Statement of Cash Flows (Topic 230)	Requires that an entity should explain the change during the period of cash, cash equivalents, and amounts generally described as restricted cash or restricted cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows.	The adoption of this guidance is retrospective to each period presented. As a result of this adoption, we reclassified $1,347 of restricted cash from net cash used in investing activities in fiscal year 2016.

ASU 2016-01, as amended through March 2018: Financial Instruments - Overall (Topic 825-10)	Requires the following: (1) equity investments (except those accounted for under the equity method of accounting, or those that result in consolidation of the investee) to be measured at fair value with changes in fair value recognized in net income; (2) entities to use the exit price notion when measuring the fair value of financial instruments for disclosure purposes; (3) separate presentation of financial assets and financial liabilities by measurement category and form of financial asset; and (4) the elimination of the disclosure requirement to disclose the method(s) and significant assumptions used to estimate the fair value that is required to be disclosed for financial instruments measured at amortized cost.	The adoption of this guidance resulted in a cumulative-effect adjustment to Accumulated Deficit, recognition of the change in fair value of certain equity investments in net income, and enhanced disclosure. The adoption of this guidance did not have a material impact on our consolidated financial statements.

ASU 2014-09, as amended through November 2017: Revenue from Contracts with Customers (Topic 606)	The core principle of the guidance is that using a five step methodology an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. The standard also requires enhanced qualitative and quantitative disclosure regarding revenue recognition from customer contracts.	We adopted the guidance using the modified retrospective approach effective January 1, 2018 with no adjustment to Accumulated Deficit. We adopted the standard through the application of the portfolio approach. We selected a sample of customer contracts to assess under the guidance of the new standard that were characteristically representative of each portfolio. Upon completion of our review, the guidance did not result in a significant change to the timing of revenue recognition. We identified certain immaterial sales commissions, which represent costs of obtaining a contract, that should be capitalized as contract acquisition costs under the guidance and amortized to general and administration expense over the expected life of the customer contract. Based on the immateriality of these sales commissions, no adjustment to Accumulated Deficit nor the accounting of these costs was deemed necessary. See Note 4, Revenue Recognition for additional disclosure.



Standard	Description	Effect on the Financial Statements or Other Significant Matters
Accounting standards that are pending adoption at December 31, 2018



ASU 2018-16: Derivatives and Hedging (Topic 815)	Allows an entity to use the overnight index swap ("OIS") rate as a benchmark interest rate for hedge accounting purposes in conjunction with ASU 2017-12: Derivatives and Hedging.	The adoption of this guidance is not expected to have a material impact on our consolidated financial statements as we do not have any hedges that use the OIS as a benchmark interest rate. This guidance is effective January 1, 2019 because we early adopted ASU 2017-12: Derivatives and Hedging, with an initial application date of January 1, 2018.

ASU 2017-04: Intangibles - Goodwill and Other (Topic 350)	Requires that when an entity is performing its annual, or interim, goodwill impairment test, it should compare the fair value of the reporting unit with its carrying amount when calculating its impairment charge, noting that the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. Additionally, if applicable, an entity should consider income tax effects from any tax deductible goodwill on the carrying amount of the reporting unit when calculating its impairment charge.	As of December 31, 2018, we did not record a goodwill impairment charge related to our annual goodwill impairment test because at that time the fair value of each reporting unit exceeded its respective carrying value. Upon adoption, if the carrying value of any of these reporting units exceeds the fair value when we perform a goodwill impairment test, we would record an impairment charge equal to the amount by which the carrying value exceeds its fair value. This guidance is effective January 1, 2020 with early adoption permitted for interim or annual goodwill impairment tests performed after January 1, 2017.



ASU 2016-02, as amended through December 2018: Leases (Topic 842)	Requires that a lessee recognize at the commencement date: a lease liability, which is the obligation of the lessee to make lease payments arising from a lease, measured on a discounted basis; and a right-of-use asset, which is an asset that represents the lessee’s right to use, or control the use of, a specified asset for the lease term.	We adopted the guidance using the prospective optional transition method effective January 1, 2019, which allows us to elect not to restate comparative periods and recognize the effects of applying this guidance as a cumulative-effect adjustment to retained earnings as of January 1, 2019. Upon adopting this guidance, we will recognize a right-of-use asset and a lease liability for leases classified as operating leases with a term in excess of 12 months in our consolidated balance sheet. As a part of the implementation, we have applied the practical expedient package. The practical expedient package allowed us to: 1) not reassess lease classification for existing leases; 2) not reassess whether a contract contains a lease for existing contracts; and 3) not reassess initial direct costs for existing leases. With the assistance of third-party resources, we designed internal controls over the adoption of this guidance and implemented a third-party enterprise lease management software solution. In conjunction with this, we have modified our lease policy and internal business process to effectively manage and account for leases as well as support recognition and disclosure under the new standard. As of January 1, 2019, we expect to recognize a right-of-use asset for operating leases of between approximately $106,000 and $121,000 and a corresponding lease liability of between approximately $76,000 and $91,000 with the difference primarily associated with prepaid amounts for certain landfill operating leases that will be reclassified from property, plant and equipment. We do not expect to recognize a material cumulative effect adjustment to retained earnings and we do not expect the adoption of this guidance to have a material impact on our consolidated statements of operations or our consolidated statements of cash flows. We also do not expect that the adoption of this guidance will have a material impact on the accounting for our finance leases. This guidance will require additional disclosures over leases in order to comply with the standard.

Management's Estimates and Assumptions

Management’s Estimates and Assumptions

Cash and Cash Equivalents

We consider all highly liquid investments purchased with original maturities of three months or less to be cash equivalents.

Concentrations of Credit Risk

Accounts Receivable - Trade, Net of Allowance for Doubtful Accounts

Accounts Receivable – Trade, Net of Allowance for Doubtful Accounts

Inventory

Inventory includes secondary fibers, recyclables ready for sale, and parts and supplies. Inventory is stated at the lower of cost (first-in, first-out) or market.

Property, Plant and Equipment



Asset Classification		Estimated Useful Life
Buildings and improvements		10-30 years
Machinery and equipment		5-10 years
Rolling stock		5-10 years
Containers		5-12 years
Furniture and Fixtures		3-8 years

The cost of maintenance and repairs is charged to operations as incurred.

Landfill Accounting and Final Capping, Closure and Post-Closure Costs

Landfill Accounting

Life Cycle Accounting

Landfill Development Costs

Landfill Airspace

We apply the following guidelines in determining a landfill’s remaining permitted and expansion airspace:


•	we control the land on which the expansion is sought;


•	all technical siting criteria have been met or a variance has been obtained or is reasonably expected to be obtained;


•	we have not identified any legal or political impediments which we believe will not be resolved in our favor;


•	we are actively working on obtaining any necessary permits and we expect that all required permits will be received; and


•	senior management has approved the project.

Final Capping, Closure and Post-Closure Costs

The following is a description of our landfill asset retirement activities and related accounting:

See Note 9, Final Capping, Closure and Post-Closure Costs for disclosure over asset retirement obligations related to final capping, closure and post-closure costs.

Landfill Operating Lease Contracts

Leases

Goodwill and Intangible Assets

Investments in Unconsolidated Entities

Fair Value of Financial Instruments

Assets and Liabilities Accounted for at Fair Value on a Recurring Basis

See Note 10, Long Term Debt and Capital Leases for disclosure over the fair value of debt.

Business Combinations

Environmental Remediation Liabilities

Self-Insurance Liabilities and Related Costs

Income Taxes

Derivatives and Hedging

Contingent Liabilities

Legal Proceedings

Revenue Recognition

Payments to customers that are not in exchange for a distinct good or service are recorded as a reduction of revenues.

Asset Impairments


•	a significant decrease in the market price of an asset or asset group;


•	a significant adverse change in the extent or manner in which an asset or asset group is being used or in its physical condition;


•	a significant adverse change in legal factors or in the business climate that could affect the value of an asset or asset group, including an adverse action or assessment by a regulator;


•	an accumulation of costs significantly in excess of the amount originally expected for the acquisition or construction of a long-lived asset;


•	a current period operating or cash flow loss combined with a history of operating or cash flow losses or a projection or forecast that demonstrates continuing losses associated with the use of a long-lived asset or asset group;


•	a current expectation that, more likely than not, a long-lived asset or asset group will be sold or otherwise disposed of significantly before the end of its previously estimated useful life; or


•	an impairment of goodwill at a reporting unit.

See Note 16, Other Items and Charges for disclosure related to long-lived asset impairments recognized during the reporting periods.

Goodwill. We annually assess goodwill for impairment at the end of our fiscal year or more frequently if events or circumstances indicate that impairment may exist.


•	a significant adverse change in legal status or in the business climate;


•	an adverse action or assessment by a regulator;


•	a more likely than not expectation that a segment or a significant portion thereof will be sold; or


•	the testing for recoverability of a significant asset group within the segment.

Defined Benefit Pension Plan

Stock-Based Compensation

ACCOUNTING CHANGES (Tables)

12 Months Ended

Dec. 31, 2018

Accounting Changes and Error Corrections [Abstract]

Schedule of Recent Accounting Pronouncements Not Yet Adopted



Standard	Description	Effect on the Financial Statements or Other Significant Matters
Accounting standards updates ("ASU") that were adopted effective January 1, 2018
ASU 2017-12: Derivatives and Hedging (Topic 815)	Requires that an entity align its risk management activities and financial reporting for hedging relationships through changes to both the designation and measurement guidance for qualifying hedging relationships and the presentation of hedge results. This guidance expands and refines hedge accounting for both financial and commodity risk components and aligns the recognition and presentation of the effects of the hedging instrument and the hedged item in the financial statements.	The adoption of this guidance affects the designation and measurement guidance for qualifying hedging relationships and the method of presenting hedge results, including the addition of a tabular disclosure related to the effect on the income statement of fair value and cash flow hedges and no longer measuring and reporting hedge ineffectiveness. We early adopted this guidance using a modified retrospective approach effective April 1, 2018 with an initial application date of January 1, 2018 with no adjustment to Accumulated Deficit. See Note 10, Long-Term Debt and Capital Leases for additional disclosure.

ASU 2017-09: Compensation - Stock Compensation (Topic 718)	Requires that an entity should account for the effects of a modification to an award unless all of the following conditions are met: the fair value of the modified award is the same as the fair value of the original award immediately before the original award is modified; the vesting conditions of the modified award are the same as the vesting conditions immediately before the original award is modified; and the classification of modified award as an equity instrument or a liability instrument is the same as the classification of the original award immediately before the original award is modified.	The adoption of this guidance could affect equity compensation expense and net income if there is a modification of an award.



ASU 2016-18: Statement of Cash Flows (Topic 230)	Requires that an entity should explain the change during the period of cash, cash equivalents, and amounts generally described as restricted cash or restricted cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows.	The adoption of this guidance is retrospective to each period presented. As a result of this adoption, we reclassified $1,347 of restricted cash from net cash used in investing activities in fiscal year 2016.

ASU 2016-01, as amended through March 2018: Financial Instruments - Overall (Topic 825-10)	Requires the following: (1) equity investments (except those accounted for under the equity method of accounting, or those that result in consolidation of the investee) to be measured at fair value with changes in fair value recognized in net income; (2) entities to use the exit price notion when measuring the fair value of financial instruments for disclosure purposes; (3) separate presentation of financial assets and financial liabilities by measurement category and form of financial asset; and (4) the elimination of the disclosure requirement to disclose the method(s) and significant assumptions used to estimate the fair value that is required to be disclosed for financial instruments measured at amortized cost.	The adoption of this guidance resulted in a cumulative-effect adjustment to Accumulated Deficit, recognition of the change in fair value of certain equity investments in net income, and enhanced disclosure. The adoption of this guidance did not have a material impact on our consolidated financial statements.

ASU 2014-09, as amended through November 2017: Revenue from Contracts with Customers (Topic 606)	The core principle of the guidance is that using a five step methodology an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. The standard also requires enhanced qualitative and quantitative disclosure regarding revenue recognition from customer contracts.	We adopted the guidance using the modified retrospective approach effective January 1, 2018 with no adjustment to Accumulated Deficit. We adopted the standard through the application of the portfolio approach. We selected a sample of customer contracts to assess under the guidance of the new standard that were characteristically representative of each portfolio. Upon completion of our review, the guidance did not result in a significant change to the timing of revenue recognition. We identified certain immaterial sales commissions, which represent costs of obtaining a contract, that should be capitalized as contract acquisition costs under the guidance and amortized to general and administration expense over the expected life of the customer contract. Based on the immateriality of these sales commissions, no adjustment to Accumulated Deficit nor the accounting of these costs was deemed necessary. See Note 4, Revenue Recognition for additional disclosure.



Standard	Description	Effect on the Financial Statements or Other Significant Matters
Accounting standards that are pending adoption at December 31, 2018



ASU 2018-16: Derivatives and Hedging (Topic 815)	Allows an entity to use the overnight index swap ("OIS") rate as a benchmark interest rate for hedge accounting purposes in conjunction with ASU 2017-12: Derivatives and Hedging.	The adoption of this guidance is not expected to have a material impact on our consolidated financial statements as we do not have any hedges that use the OIS as a benchmark interest rate. This guidance is effective January 1, 2019 because we early adopted ASU 2017-12: Derivatives and Hedging, with an initial application date of January 1, 2018.

ASU 2017-04: Intangibles - Goodwill and Other (Topic 350)	Requires that when an entity is performing its annual, or interim, goodwill impairment test, it should compare the fair value of the reporting unit with its carrying amount when calculating its impairment charge, noting that the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. Additionally, if applicable, an entity should consider income tax effects from any tax deductible goodwill on the carrying amount of the reporting unit when calculating its impairment charge.	As of December 31, 2018, we did not record a goodwill impairment charge related to our annual goodwill impairment test because at that time the fair value of each reporting unit exceeded its respective carrying value. Upon adoption, if the carrying value of any of these reporting units exceeds the fair value when we perform a goodwill impairment test, we would record an impairment charge equal to the amount by which the carrying value exceeds its fair value. This guidance is effective January 1, 2020 with early adoption permitted for interim or annual goodwill impairment tests performed after January 1, 2017.



ASU 2016-02, as amended through December 2018: Leases (Topic 842)	Requires that a lessee recognize at the commencement date: a lease liability, which is the obligation of the lessee to make lease payments arising from a lease, measured on a discounted basis; and a right-of-use asset, which is an asset that represents the lessee’s right to use, or control the use of, a specified asset for the lease term.	We adopted the guidance using the prospective optional transition method effective January 1, 2019, which allows us to elect not to restate comparative periods and recognize the effects of applying this guidance as a cumulative-effect adjustment to retained earnings as of January 1, 2019. Upon adopting this guidance, we will recognize a right-of-use asset and a lease liability for leases classified as operating leases with a term in excess of 12 months in our consolidated balance sheet. As a part of the implementation, we have applied the practical expedient package. The practical expedient package allowed us to: 1) not reassess lease classification for existing leases; 2) not reassess whether a contract contains a lease for existing contracts; and 3) not reassess initial direct costs for existing leases. With the assistance of third-party resources, we designed internal controls over the adoption of this guidance and implemented a third-party enterprise lease management software solution. In conjunction with this, we have modified our lease policy and internal business process to effectively manage and account for leases as well as support recognition and disclosure under the new standard. As of January 1, 2019, we expect to recognize a right-of-use asset for operating leases of between approximately $106,000 and $121,000 and a corresponding lease liability of between approximately $76,000 and $91,000 with the difference primarily associated with prepaid amounts for certain landfill operating leases that will be reclassified from property, plant and equipment. We do not expect to recognize a material cumulative effect adjustment to retained earnings and we do not expect the adoption of this guidance to have a material impact on our consolidated statements of operations or our consolidated statements of cash flows. We also do not expect that the adoption of this guidance will have a material impact on the accounting for our finance leases. This guidance will require additional disclosures over leases in order to comply with the standard.

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

Estimated Useful Lives of Assets

We provide for depreciation and amortization using the straight-line method by charges to operations in amounts that allocate the cost of the assets over their estimated useful lives as follows:



Asset Classification		Estimated Useful Life
Buildings and improvements		10-30 years
Machinery and equipment		5-10 years
Rolling stock		5-10 years
Containers		5-12 years
Furniture and Fixtures		3-8 years

A summary of property, plant and equipment is as follows:



	December 31,
	2018			2017
Land	$	25,490		$	24,224
Landfills	544,663			513,548
Landfill operating lease contracts	121,877			114,462
Buildings and improvements	150,885			140,155
Machinery and equipment	153,222			139,029
Rolling stock	163,758			138,102
Containers	123,383			103,501
	1,283,278			1,173,021
Less: accumulated depreciation and amortization	(878,701		)	(811,474		)
	$	404,577		$	361,547

REVENUE RECOGNITION (Tables)

12 Months Ended

Dec. 31, 2018

Revenue from Contract with Customer [Abstract]

Disaggregation of Revenue

A table of revenues disaggregated by service line and timing of revenue recognition by operating segment follows:

Fiscal Year Ended December 31, 2018



	Eastern		Western		Recycling		Other		Total Revenues
Collection	$	136,661	$	170,278	$	—	$	—	$	306,939
Landfill	28,419		66,567		—		—		94,986
Transfer	39,991		27,592		—		—		67,583
Customer solutions	—		—		—		67,464		67,464
Recycling	5		3,823		42,191		—		46,019
Organics	—		—		—		54,174		54,174
Transportation	—		14,270		—		4,096		18,366
Landfill gas-to-energy	1,397		3,732		—		—		5,129
Total Revenues	$	206,473	$	286,262	$	42,191	$	125,734	$	660,660

Transferred at a point-in-time	$	648	$	1,145	$	27,260	$	3,921	$	32,974
Transferred over time	205,825		285,117		14,931		121,813		627,686
Total revenues	$	206,473	$	286,262	$	42,191	$	125,734	$	660,660

BUSINESS COMBINATIONS (Tables)

12 Months Ended

Dec. 31, 2018

Business Combinations [Abstract]

Schedule of Purchase Price Paid for Acquisitions

The purchase price paid for these acquisitions and the allocation of the purchase price is as follows:



	Fiscal Year Ended December 31,
	2018			2017			2016
Purchase Price:
Cash used in acquisitions, net of cash acquired	$	86,686		$	4,823		$	2,439
Notes payable	—			2,400			—
Class A common stock issued	4,258			—			—
Other non-cash considerations	—			101			—
Contingent consideration and holdbacks	8,521			736			400
Total	99,465			8,060			2,839
Current assets	3,276			93			40
Land	—			—			353
Buildings	7,889			—			1,360
Equipment	23,882			2,994			269
Other liabilities, net	(4,708		)	(49		)	(106		)
Deferred tax liability	(937		)	—			—
Intangible assets	29,934			2,334			—
Fair value of assets acquired and liabilities assumed	59,336			5,372			1,916
Excess purchase price to be allocated to goodwill	$	40,129		$	2,688		$	923

Schedule of Unaudited Pro forma Combined Information

The following unaudited pro forma combined information shows our operational results as though each of the acquisitions completed had occurred as of January 1, 2016.



	Fiscal Year Ended December 31,
	2018		2017			2016
Revenues	$	699,659	$	672,898		$	642,773
Operating income (loss)	$	43,561	$	(6,601	)	$	50,970
Net income (loss) attributable to common stockholders	$	8,579	$	(18,408	)	$	(3,446	)
Basic earnings per common share attributable to common stockholders	$	0.20	$	(0.44	)	$	(0.08	)
Basic weighted average shares outstanding	42,688		41,846			41,233
Diluted earnings per common share attributable to common stockholders	$	0.19	$	(0.44	)	$	(0.08	)
Diluted weighted average shares outstanding	44,168		41,846			41,233

RESTRICTED ASSETS (Tables)

12 Months Ended

Dec. 31, 2018

Receivables [Abstract]

Summary of Restricted Assets

A summary of restricted assets is as follows:



	December 31,
Non Current:	2018		2017
Restricted investment securities - landfill closure	$	1,248	$	1,220

PROPERTY, PLANT AND EQUIPMENT (Tables)

12 Months Ended

Dec. 31, 2018

Property, Plant and Equipment [Abstract]

Components of Property, Plant and Equipment

We provide for depreciation and amortization using the straight-line method by charges to operations in amounts that allocate the cost of the assets over their estimated useful lives as follows:



Asset Classification		Estimated Useful Life
Buildings and improvements		10-30 years
Machinery and equipment		5-10 years
Rolling stock		5-10 years
Containers		5-12 years
Furniture and Fixtures		3-8 years

A summary of property, plant and equipment is as follows:



	December 31,
	2018			2017
Land	$	25,490		$	24,224
Landfills	544,663			513,548
Landfill operating lease contracts	121,877			114,462
Buildings and improvements	150,885			140,155
Machinery and equipment	153,222			139,029
Rolling stock	163,758			138,102
Containers	123,383			103,501
	1,283,278			1,173,021
Less: accumulated depreciation and amortization	(878,701		)	(811,474		)
	$	404,577		$	361,547

GOODWILL AND INTANGIBLE ASSETS (Tables)

12 Months Ended

Dec. 31, 2018

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Activity and Balances Related to Goodwill by Reporting Segment

A summary of the activity and balances related to goodwill by reporting segment is as follows:



	December 31, 2017		Acquisitions		December 31, 2018
Eastern	$	19,192	$	8,962	$	28,154
Western	89,369		31,167		120,536
Recycling	12,315		—		12,315
Other	1,729		—		1,729
Total	$	122,605	$	40,129	$	162,734



	December 31, 2016		Acquisitions		December 31, 2017
Eastern	$	17,429	$	1,763	$	19,192
Western	88,426		943		89,369
Recycling	12,315		—		12,315
Other	1,729		—		1,729
Total	$	119,899	$	2,706	$	122,605

Components of Intangible Assets

A summary of intangible assets is as follows:



	Covenants Not-to-Compete			Client Lists			Total
Balance, December 31, 2018
Intangible assets	$	21,750		$	44,363		$	66,113
Less accumulated amortization	(17,584		)	(13,762		)	(31,346		)
	$	4,166		$	30,601		$	34,767



	Covenants Not-to-Compete			Client Lists			Total
Balance, December 31, 2017
Intangible assets	$	18,092		$	18,087		$	36,179
Less accumulated amortization	(16,851		)	(11,179		)	(28,030		)
	$	1,241		$	6,908		$	8,149

Estimated Future Amortization Expense

The intangible amortization expense estimated for the five fiscal years following fiscal year 2018 and thereafter is as follows:




Estimated Future Amortization Expense as of December 31, 2018
For the fiscal year ending December 31, 2019	$	5,601
For the fiscal year ending December 31, 2020	$	4,997
For the fiscal year ending December 31, 2021	$	4,094
For the fiscal year ending December 31, 2022	$	3,534
For the fiscal year ending December 31, 2023	$	3,231
Thereafter	$	13,310

FINAL CAPPING, CLOSURE AND POST-CLOSURE COSTS (Tables)

12 Months Ended

Dec. 31, 2018

Asset Retirement Obligation Disclosure [Abstract]

Changes to Accrued Capping, Closure and Post-Closure Liabilities

The changes to accrued final capping, closure and post-closure liabilities are as follows:



	Fiscal Year Ended December 31,
	2018			2017
Beginning balance	$	62,290		$	44,207
Obligations incurred	3,713			3,022
Revisions in estimates (1)	5,095			11,498
Accretion expense	5,556			4,401
Obligations settled (2)	(3,579		)	(838		)
Ending balance	$	73,075		$	62,290

(1)


(2)	Includes amounts paid and amounts that are being processed through accounts payable as a part of our disbursement cycle.

LONG TERM DEBT AND CAPITAL LEASES (Tables)

12 Months Ended

Dec. 31, 2018

Debt Disclosure [Abstract]

Components of Long-Term Debt and Capital Leases

A summary of long-term debt and capital leases is as follows:



	December 31,
	2018		2017
Senior Secured Credit Facility:
Revolving Credit Facility due May 2023; bearing interest at LIBOR plus 2.00%	$	69,600	$	—
Refinanced Revolving Credit Facility due October 2021; bore interest at LIBOR plus 2.75%	—		36,000
Term Loan Facility due May 2023; bearing interest at LIBOR plus 2.00%	350,000		—
Term Loan B Facility due October 2023; bore interest at LIBOR plus 2.50%	—		346,500
Tax-Exempt Bonds:
New York State Environmental Facilities Corporation Solid Waste Disposal Revenue Bonds Series 2014R-1 due December 2044 - fixed rate interest period through 2019; bearing interest at 3.75%	25,000		25,000
New York State Environmental Facilities Corporation Solid Waste Disposal Revenue Bonds Series 2014R-2 due December 2044 - fixed rate interest period through 2026; bearing interest at 3.125%	15,000		15,000
Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2005R-3 due January 2025 - fixed rate interest period through 2025; bearing interest at 5.25%	25,000		25,000
Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2015R-1 due August 2035 - fixed rate interest period through 2025; bearing interest at 5.125%	15,000		15,000
Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2015R-2 due August 2035 - fixed rate interest period through 2025; bearing interest at 4.375%	15,000		—
Vermont Economic Development Authority Solid Waste Disposal Long-Term Revenue Bonds Series 2013 due April 2036 - fixed rate interest period through 2028; bearing interest at 4.625%	16,000		16,000
Business Finance Authority of the State of New Hampshire Solid Waste Disposal Revenue Bonds Series 2013 due April 2029 - fixed rate interest period through 2019; bearing interest at 4.00%	11,000		11,000
Other:
Capital leases maturing through December 2107; bearing interest at a weighted average of 5.37%	11,248		5,595
Notes payable maturing through June 2027; bearing interest at a weighted average of 2.97%	2,401		2,585
Principal amount of long-term debt and capital leases	555,249		497,680
Less—unamortized discount and debt issuance costs (1)	10,950		15,178
Long-term debt and capital leases less unamortized discount and debt issuance costs	544,299		482,502
Less—current maturities of long-term debt	2,298		4,926
	$	542,001	$	477,576


(1)	A summary of unamortized discount and debt issuance costs by debt instrument follows:



	December 31,
	2018		2017
Credit Facility	$	7,118	$	—
Refinanced Revolving Credit Facility	—		3,938
Term Loan B Facility (including unamortized discount of $0 and $1,482)	—		7,392
New York State Environmental Facilities Corporation Solid Waste Disposal Revenue Bonds Series 2014R-1	847		1,034
New York State Environmental Facilities Corporation Solid Waste Disposal Revenue Bonds Series 2014R-2	450		511
Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2005R-3	517		603
Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2015R-1	622		691
Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2015R-2	493		—
Vermont Economic Development Authority Solid Waste Disposal Long-Term Revenue Bonds Series 2013	595		573
Business Finance Authority of the State of NH Solid Waste Disposal Revenue Bonds Series 2013	308		436
	$	10,950	$	15,178

Components of Interest Expense

The components of interest expense are as follows:



	Fiscal Year Ended December 31,
	2018			2017			2016
Interest expense on long-term debt and capital leases	$	23,816		$	22,060		$	34,741
Amortization of debt issuance costs and discount on long-term debt	2,449			2,692			3,881
Letter of credit fees	169			703			593
Less: capitalized interest	(140		)	(295		)	(273		)
Total interest expense	$	26,294		$	25,160		$	38,942

Schedule of Cash Flow Hedges Related to Derivative Instruments

A summary of the effect of cash flow hedges related to derivative instruments on the consolidated balance sheet follows:



		Fair Value
	Balance Sheet Location	December 31, 2018			December 31, 2017
Interest rate swaps	Other current assets	$	338		$	—
Interest rate swaps	Other non-current assets	482			401
Total		$	820		$	401

Interest rate swaps	Other accrued liabilities	$	387		$	123
Interest rate swaps	Other long-term liabilities	1,555			—
Total		$	1,942		$	123

Interest rate swaps	Accumulated other comprehensive (loss) income, net	$	(1,196	)	$	278
Interest rate swaps - tax provision	Accumulated other comprehensive (loss) income, net	$	(112	)	$	(112	)
		$	(1,308	)	$	166

Schedule of Gain (Loss) On Cash Flow Hedges

A summary of the amount of gain or (loss) on cash flow hedging relationships related to interest rate swaps reclassified from accumulated other comprehensive (loss) income into earnings follows:



	Fiscal Year Ended December 31,
	2018			2017			2016
Statement of Operations Location	(Expense) Income
Interest expense	$	(363	)	$	(421	)	$	—

Schedule of Future Maturities of Debt

Aggregate principal maturities of long-term debt and capital leases are as follows:




Estimated Future Payments as of December 31, 2018
2019	$	2,298
2020	2,648
2021	2,175
2022	1,652
2023	421,021
Thereafter	125,455
	$	555,249

COMMITMENTS AND CONTINGENCIES (Tables)

12 Months Ended

Dec. 31, 2018

Commitments and Contingencies Disclosure [Abstract]

Schedule of Future Minimum Rental Payments under Non-Cancellable Operating Leases

Future minimum rental payments under non-cancellable operating leases, which include landfill operating leases, are as follows:



Estimated Future Minimum Lease Payments as of December 31, 2018
2019	$	15,572
2020	12,678
2021	10,117
2022	7,953
2023	6,250
Thereafter	65,145
Total minimum lease payments	$	117,715

Schedule of Environmental Remedial Liability

The changes to the environmental remediation liability associated with the Southbridge Landfill are as follows:




	Fiscal Year Ended December 31,
	2018			2017
Beginning balance	$	5,936		$	—
Accretion expense	152			82
Obligations incurred	—			6,379
Obligations settled (1)	(915		)	(525		)
Ending balance	$	5,173		$	5,936


(1)	Includes amounts that are being processed through accounts payable as a part of our disbursements cycle.

A summary of the changes to the environmental remediation liability associated with the Potsdam environmental remediation liability follows:



	Fiscal Year Ended December 31,
	2018			2017
Beginning balance	$	5,758		$	5,866
Payments	(171		)	(108		)
Obligations incurred	27			—
Ending balance	$	5,614		$	5,758

Schedule of Total Expected Environmental Remediation Payments for Succeeding Year

The total expected environmental remediation payments, in today’s dollars, for each of the five succeeding fiscal years and the aggregate amount thereafter are as follows:



Estimated Future Environmental Remediation Payments as of December 31, 2018
2019	$	3,974
2020	1,289
2021	398
2022	372
2023	383
Thereafter	5,250
Total	$	11,666

Reconciliation of Expected Aggregate Non-inflated, Undiscounted Environmental Remediation Liability to Amount Recognized in Statement of Financial Position

A reconciliation of the expected aggregate non-inflated, undiscounted environmental remediation liability to the amount recognized in the statement of financial position is as follows:




Undiscounted liability	$	11,666
Less discount, net	(879		)
Liability balance - December 31, 2018	$	10,787

STOCKHOLDERS' EQUITY (Tables)

12 Months Ended

Dec. 31, 2018

Equity [Abstract]

Summary of Stock Option Activity

A summary of stock option activity is as follows:



	Stock Options		Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (years)	Aggregate Intrinsic Value
Outstanding, December 31, 2017	727		$	5.82
Granted	—		$	—
Exercised	(98	)	$	4.80
Forfeited or expired	—		$	—
Market-based stock options vested (1)	40		$	12.48	7.9
Outstanding, December 31, 2018	669		$	6.37	5.6	$	14,788
Exercisable, December 31, 2018	669		$	6.37	5.6	$	14,788


(1)	Market-based performance stock option grants were included at 100% until they vested on December 31, 2018, at which point the actual number of options vested was adjusted based on the actual attainment of performance targets and market achievements.

Summary of Restricted Stock, Restricted Stock Unit and Performance Stock Unit Activity

A summary of restricted stock, restricted stock unit and performance stock unit activity is as follows:



	Restricted Stock, Restricted Stock Units, and Performance Stock Units (1)		Weighted Average Grant Price		Weighted Average Remaining Contractual Term (years)	Aggregate Intrinsic Value
Outstanding, December 31, 2017	1,091		$	9.81
Granted	230		$	24.92
Class A common stock vested	(632	)	$	9.04
Forfeited or canceled	(3	)	$	13.73
Outstanding, December 31, 2018	686		$	15.56	1.2	$	8,877
Unvested, December 31, 2018	951		$	15.95	1.3	$	11,929


(1)	Market-based performance stock unit grants are included at 100%. Attainment of maximum performance targets and market achievements would result in the issuance of an additional 265 shares of Class A common stock currently included in unvested.

Accumulated Other Comprehensive Income (Loss)

The changes in the balances of each component of accumulated other comprehensive (loss) income are as follows:



	Marketable Securities			Interest Rate Swaps			Total
Balance as of December 31, 2015	$	7		$	—		$	7
Other comprehensive loss	(75		)	—			(75		)
Balance as of December 31, 2016	(68		)	—			(68		)
Other comprehensive income (loss) before reclassifications	59			(143		)	(84		)
Amounts reclassified from accumulated other comprehensive income (loss)	—			421			421
Income tax expense related to items in other comprehensive income (loss)	27			(112		)	(85		)
Other comprehensive income, net	86			166			252
Balance as of December 31, 2017	18			166			184
Cumulative effect of new accounting principle	(18		)	—			(18		)
Other comprehensive loss before reclassifications	—			(1,837		)	(1,837		)
Amounts reclassified from accumulated other comprehensive loss	—			363			363
Income tax expense related to items in other comprehensive income	—			—			—
Other comprehensive loss, net	—			(1,474		)	(1,474		)
Balance as of December 31, 2018	$	—		$	(1,308	)	$	(1,308	)

Reclassification Out of Accumulated Other Comprehensive Income (Loss)

A summary of reclassifications out of accumulated other comprehensive (loss) income for fiscal years 2018, 2017 and 2016 is as follows:



	Fiscal Year Ended December 31,
	2018		2017		2016
Details About Accumulated Other Comprehensive Income (Loss) Components	Amounts Reclassified Out of Accumulated Other Comprehensive Income (Loss)						Affected Line Item in the Consolidated Statements of Operations
Interest rate swaps	$	363	$	421	$	—	Interest expense
	363		421		—		Income (loss) before income taxes
	—		—		—		(Benefit) provision for income taxes
	$	363	$	421	$	—	Net income (loss)

FAIR VALUE OF FINANCIAL INSTRUMENTS (Tables)

12 Months Ended

Dec. 31, 2018

Fair Value Disclosures [Abstract]

Assets and Liabilities Measured at Fair Value on Recurring Basis

Summaries of our financial assets and liabilities that are measured at fair value on a recurring basis are as follows:



	Fair Value Measurement at December 31, 2018 Using:
	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Restricted investment securities - landfill closure	$	1,248	$	—	$	—
Interest rate swaps	—		820		—
	$	1,248	$	820	$	—
Liabilities:
Interest rate swaps	$	—	$	1,942	$	—



	Fair Value Measurement at December 31, 2017 Using:
	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Restricted investment securities - landfill closure	$	1,220	$	—	$	—
Interest rate swaps	—		401		—
	$	1,220	$	401	$	—
Liabilities:
Interest rate swaps	$	—	$	123	$	—

EMPLOYEE BENEFIT PLANS EMPLOYEE BENEFIT PLANS (Tables)

12 Months Ended

Dec. 31, 2018

Retirement Benefits [Abstract]

Schedule of Multiemployer Defined Benefit Pension Plans

The following table outlines our participation in the multiemployer defined benefit pension plan:



Pension Fund	EIN/Pension Plan Number	Pension Protection Act Zone Status		Funding Improvement or Rehabilitation Plan Status	Contributions to Plan						Expiration Date of CBA
		Pension Protection Act Zone Status			Fiscal Year Ended December 31,
		2018	2017		2018		2017		2016
New England Teamsters and Trucking Industry Pension Fund	04-6372430	Critical and declining	Critical and declining	Implemented	$	726	$	627	$	523	June 30, 2020

INCOME TAXES (Tables)

12 Months Ended

Dec. 31, 2018

Income Tax Disclosure [Abstract]

Schedule of Provision (Benefit) for Income Taxes Continuing Operations

A summary of the (benefit) provision for income taxes is as follows:



	Fiscal Year Ended December 31,
	2018			2017			2016
Federal
Current	$	(1,902	)	$	—		$	—
Deferred	1,255			(15,614		)	458
	(647		)	(15,614		)	458
State
Current	2,575			301			(90		)
Current benefit of loss carryforwards	(2,307		)	(28		)	—
Deferred	(5		)	88			126
	263			361			36
(Benefit) provision for income taxes	$	(384	)	$	(15,253	)	$	494

Schedule of Difference in Provision (Benefit) for Income Taxes

The differences in the (benefit) provision for income taxes and the amounts determined by applying the Federal statutory rate to income before provision for income taxes are as follows:



	Fiscal Year Ended December 31,
	2018			2017			2016
Federal statutory rate	21		%	35		%	35		%
Tax at statutory rate	$	1,268		$	(12,968	)	$	(2,228	)
State income taxes, net of federal benefit	(89		)	(1,959		)	(265		)
Decrease in net federal deferred tax assets before valuation allowance change due to federal rate change	—			33,700			—
Decrease in valuation allowance by 80% of indefinite lived deferred liabilities due to US tax reform	—			(12,758		)	—
Other changes in valuation allowance, including the federal rate change in fiscal year 2017	(1,613		)	(18,848		)	4,370
Non-deductible officer compensation	2,214			—			—
Deductible stock awards	(2,048		)	(1,825		)	—
Tax credits	(686		)	(1,000		)	(1,085		)
Non-deductible expenses	633			542			100
Other, net	(63		)	(137		)	(398		)
(Benefit) provision for income taxes	$	(384	)	$	(15,253	)	$	494

Schedule of Deferred Tax Assets and Liabilities



	December 31,
	2018			2017
Deferred tax assets:
Accrued expenses and reserves	$	34,647		$	26,572
Net operating loss carryforwards	31,241			33,228
Book over tax depreciation of property and equipment	19,048			25,615
General business tax credit carryforwards	6,192			5,439
Stock awards	2,310			1,958
Alternative minimum tax credit carryforwards	1,902			3,804
Other	3,023			2,050
Total deferred tax assets	98,363			98,666
Less: valuation allowance	(69,189		)	(68,355		)
Total deferred tax assets after valuation allowance	29,174			30,311
Deferred tax liabilities:
Amortization of intangibles	(22,026		)	(20,904		)
Other	(73		)	(145		)
Total deferred tax liabilities	(22,099		)	(21,049		)
Net deferred tax asset	$	7,075		$	9,262

Schedule of Reconciliation of Gross Unrecognized Tax Benefits

A reconciliation of the beginning and ending amount of gross unrecognized tax benefits is as follows:



	Fiscal Year Ended December 31,
	2018			2017
Unrecognized tax benefits at beginning of period	$	1,941		$	3,107
Gross increases for tax positions of prior years	—			1
Gross decreases for tax positions of prior years	—			(1,165		)
Reductions resulting from lapse of statute of limitations	(1,939		)	—
Settlements	—			(2		)
Unrecognized tax benefits at end of period	$	2		$	1,941

EARNINGS PER SHARE (Tables)

12 Months Ended

Dec. 31, 2018

Earnings Per Share [Abstract]

Schedule of Numerator and Denominator Used in Computation of Earnings Per Share

A summary of the numerator and denominators used in the computation of earnings per share is as follows:



	Fiscal Year Ended December 31,
	2018			2017			2016
Numerator:
Net income (loss) attributable to common stockholders	$	6,420		$	(21,799	)	$	(6,849	)
Denominator:
Class A common stock	41,944			41,298			40,572
Class B common stock	988			988			988
Shares to be issued - acquisition	103			—			—
Unvested restricted stock	(9		)	(38		)	(88		)
Effect of weighted average shares outstanding	(338		)	(402		)	(239		)
Basic weighted average common shares outstanding	42,688			41,846			41,233
Impact of potentially dilutive securities:
Dilutive effect of stock options and stock awards	1,480			—			—
Diluted weighted average common shares outstanding	44,168			41,846			41,233
Antidilutive potentially issuable shares	2			2,219			2,442

OTHER ITEMS AND CHARGES OTHER ITEMS AND CHARGES (Tables)

12 Months Ended

Dec. 31, 2018

Unusual or Infrequent Items, or Both [Abstract]

Charges Associated with Closure of Southbridge Landfill

Accordingly, in fiscal years 2018 and 2017, we recorded charges associated with the closure of our Southbridge Landfill as follows:



	Fiscal Year Ended December 31,
	2018			2017
Asset impairment charge (1)	$	—		$	47,999
Project development charge (2)	—			9,149
Environmental remediation charge (3)	—			6,379
Contract settlement charge (4)	8,724			—
Landfill closure project charge (5)	6,012			—
Charlton settlement charge (6)	1,216			—
Legal and transaction costs (7)	2,102			1,656
Recovery on insurance settlement (8)	(10,000		)	—
Southbridge Landfill closure charge, net	$	8,054		$	65,183


(1)	We performed a test of recoverability under FASB ASC 360, which indicated that the carrying value of our asset group that includes the Southbridge Landfill was no longer recoverable and, as a result, the asset group was assessed for impairment with an impairment charge allocated to the long-lived assets of the Southbridge Landfill in accordance with FASB ASC 360.


(2)	We wrote-off deferred costs associated with Southbridge Landfill permitting activities no longer deemed viable.


(3)	We recorded an environmental remediation charge associated with the installation of a municipal waterline. See Note 11, Commitments and Contingencies for additional disclosure.


(4)	We recorded a contract settlement charge associated with the closure of Southbridge Landfill and the remaining future obligations due to the Town of Southbridge under the landfill operating agreement with the Town of Southbridge. See Note 11, Commitments and Contingencies for additional disclosure.


(5)	We recorded a landfill closure project charge associated with increased costs under the revised closure plan at our Southbridge Landfill.


(6)	We established a reserve associated with settlement of the Town of Charlton's claim against us. See Note 11, Commitments and Contingencies for additional disclosure.


(7)	We incurred legal and other transaction costs associated with various matters as part of the Southbridge Landfill closure. See Note 11, Commitments and Contingencies for additional disclosure.


(8)	We recorded a recovery on an environmental insurance settlement associated with the Southbridge Landfill closure. See Note 11, Commitments and Contingencies for additional disclosure.

SEGMENT REPORTING (Tables)

12 Months Ended

Dec. 31, 2018

Segment Reporting [Abstract]

Summary of Financial Information by Reportable Segment

Fiscal Year Ended December 31, 2018



Segment	Outside revenues		Inter-company revenue			Depreciation and amortization		Operating income (loss)			Interest expense, net			Capital expenditures		Goodwill		Total assets
Eastern	$	206,473	$	52,866		$	26,538	$	4,684		$	12		$	23,393	$	28,154	$	184,679
Western	286,262		81,515			35,843		41,529			(148		)	41,850		120,536		428,934
Recycling	42,191		6,426			4,345		(7,805		)	140			4,476		12,315		48,629
Other	125,734		1,982			3,782		1,325			26,017			3,513		1,729		70,168
Eliminations	—		(142,789		)	—		—			—			—		—		—
Total	$	660,660	$	—		$	70,508	$	39,733		$	26,021		$	73,232	$	162,734	$	732,410

Fiscal Year Ended December 31, 2017



Segment	Outside revenues		Inter-company revenue			Depreciation and amortization		Operating income (loss)			Interest expense, net			Capital expenditures		Goodwill		Total assets
Eastern	$	181,170	$	50,335		$	23,815	$	(51,867	)	$	3		$	17,153	$	19,192	$	157,248
Western	250,771		71,510			30,766		35,035			(220		)	42,082		89,369		344,324
Recycling	62,307		246			4,125		2,805			143			2,006		12,315		48,612
Other	105,061		1,881			3,396		1,444			24,961			3,621		1,729		64,765
Eliminations	—		(123,972		)	—		—			—			—		—		—
Total	$	599,309	$	—		$	62,102	$	(12,583	)	$	24,887		$	64,862	$	122,605	$	614,949

Fiscal Year Ended December 31, 2016



Segment	Outside revenues		Inter-company revenue			Depreciation and amortization		Operating income (loss)		Interest expense, net			Capital expenditures		Goodwill		Total assets
Eastern	$	176,539	$	45,728		$	27,036	$	9,697	$	(16	)	$	18,363	$	17,429	$	202,420
Western	233,168		67,985			27,511		30,576		(248		)	31,637		88,426		327,628
Recycling	52,911		1,003			4,212		2,542		156			2,218		12,315		49,931
Other	102,412		1,615			3,097		2,130		38,760			2,020		1,729		51,533
Eliminations	—		(116,331		)	—		—		—			—		—		—
Total	$	565,030	$	—		$	61,856	$	44,945	$	38,652		$	54,238	$	119,899	$	631,512

Summary of Revenue Attributable to Services Provided by Company

Amount of our total revenue attributable to services provided are as follows:



	Fiscal Year Ended December 31,
	2018				2017				2016
Collection	$	303,418	45.9	%	$	263,688	44.0	%	$	249,640	44.2	%
Disposal	181,110		27.4	%	160,073		26.7	%	154,211		27.3	%
Power generation	5,129		0.8	%	5,375		0.9	%	5,921		1.0	%
Processing	7,174		1.1	%	7,994		1.3	%	6,282		1.1	%
Solid waste operations	496,831		75.2	%	437,130		72.9	%	416,054		73.6	%
Organics	54,174		8.2	%	39,815		6.6	%	41,587		7.4	%
Customer solutions	67,464		10.2	%	60,057		10.1	%	54,478		9.6	%
Recycling	42,191		6.4	%	62,307		10.4	%	52,911		9.4	%
Total revenues	$	660,660	100.0	%	$	599,309	100.0	%	$	565,030	100.0	%

QUARTERLY FINANCIAL INFORMATION (UNAUDITED) (Tables)

12 Months Ended

Dec. 31, 2018

Quarterly Financial Information Disclosure [Abstract]

Summary of Quarterly Financial Information

The following is a summary of certain items in the consolidated statements of operations by quarter:



Fiscal Year 2018	First Quarter			Second Quarter		Third Quarter		Fourth Quarter
Revenues	$	147,455		$	165,649	$	172,832	$	174,724
Operating income (loss)	$	838		$	15,149	$	28,884	$	(5,138	)
Net (loss) income	$	(3,910	)	$	1,704	$	22,302	$	(13,676	)
Earnings per common share:								—
Basic weighted average common shares outstanding	42,370			42,661		42,779		42,936
Basic earnings per share	$	(0.09	)	$	0.04	$	0.52	$	(0.32	)
Diluted weighted average common shares outstanding	42,370			43,916		44,175		42,936
Diluted earnings per share	$	(0.09	)	$	0.04	$	0.50	$	(0.32	)



Fiscal Year 2017	First Quarter			Second Quarter			Third Quarter		Fourth Quarter
Revenues	$	133,802		$	154,016		$	160,269	$	151,222
Operating income (loss)	$	6,564		$	(47,279	)	$	18,277	$	9,855
Net (loss) income	$	(224	)	$	(53,675	)	$	12,080	$	20,020
Earnings per common share:
Basic weighted average common shares outstanding	41,584			41,811			41,951		42,033
Basic earnings per share	$	(0.01	)	$	(1.28	)	$	0.29	$	0.48
Diluted weighted average common shares outstanding	41,584			41,811			43,295		43,394
Diluted earnings per share	$	(0.01	)	$	(1.28	)	$	0.28	$	0.46

BASIS OF PRESENTATION (Detail)	12 Months Ended
BASIS OF PRESENTATION (Detail)	Dec. 31, 2018 Segment
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Operating segments	2

ACCOUNTING CHANGES (Details) - USD ($) $ in Thousands	12 Months Ended
ACCOUNTING CHANGES (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reclassification of restricted cash	$ (164,197)	$ (76,447)	$ (62,964)
Restatement adjustment \| Accounting Standards Update 2016-18
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reclassification of restricted cash			$ (1,347)
Scenario, forecast \| Minimum \| Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Right-of-use asset				$ 106
Lease liability				76
Scenario, forecast \| Maximum \| Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Right-of-use asset				121
Lease liability				$ 91

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Estimated Useful Lives of Assets (Detail)	12 Months Ended
	Dec. 31, 2018
Minimum \| Building and Improvements
Property, Plant and Equipment [Line Items]
Property plant and equipment, estimated useful life	10 years
Minimum \| Machinery and Equipment
Property, Plant and Equipment [Line Items]
Property plant and equipment, estimated useful life	5 years
Minimum \| Rolling Stock
Property, Plant and Equipment [Line Items]
Property plant and equipment, estimated useful life	5 years
Minimum \| Containers
Property, Plant and Equipment [Line Items]
Property plant and equipment, estimated useful life	5 years
Minimum \| Furniture and Fixtures
Property, Plant and Equipment [Line Items]
Property plant and equipment, estimated useful life	3 years
Maximum \| Building and Improvements
Property, Plant and Equipment [Line Items]
Property plant and equipment, estimated useful life	30 years
Maximum \| Machinery and Equipment
Property, Plant and Equipment [Line Items]
Property plant and equipment, estimated useful life	10 years
Maximum \| Rolling Stock
Property, Plant and Equipment [Line Items]
Property plant and equipment, estimated useful life	10 years
Maximum \| Containers
Property, Plant and Equipment [Line Items]
Property plant and equipment, estimated useful life	12 years
Maximum \| Furniture and Fixtures
Property, Plant and Equipment [Line Items]
Property plant and equipment, estimated useful life	8 years

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Landfill Accounting (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) Agreement	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Property, Plant and Equipment [Line Items]
Capitalized interest	$ 140	$ 295	$ 273
Closure and post-closure costs incurrence period	30 years
Estimate of inflation rate (as a percent)	1.50%
Accretion expense	$ 5,556	4,401
Number of operation and management agreements entered into \| Agreement	4
Closure And Post Closure Costs
Property, Plant and Equipment [Line Items]
Accretion expense	$ 5,556	4,401	$ 3,606
Surety bond	201,177	164,893
Letters of credit	$ 0	$ 0
Minimum
Property, Plant and Equipment [Line Items]
Rate of asset retirement obligation (as a percent)	8.70%
Maximum
Property, Plant and Equipment [Line Items]
Rate of asset retirement obligation (as a percent)	9.80%

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Goodwill and Intangible Assets (Detail)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Intangible assets, useful life (no more than)	10 years

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Investments in Unconsolidated Entities (Detail) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Accounting Policies [Abstract]
Investments under equity method of accounting	$ 0	$ 0

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Self-Insurance Liabilities and Related Costs (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Capital Leased Assets [Line Items]
Maximum exposure automobile plan per individual event	$ 1,000,000
Self insurance reserves	15,040,000	$ 14,480,000
Automobile Plan
Capital Leased Assets [Line Items]
Maximum exposure automobile plan per individual event	$ 1,200,000

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES -Revenue Recognition (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenues	$ (174,724)	$ (172,832)	$ (165,649)	$ (147,455)	$ (151,222)	$ (160,269)	$ (154,016)	$ (133,802)	$ (660,660)	$ (599,309)	$ (565,030)
Gross receivables from contracts	73,500				66,227				73,500	66,227
Contract liabilities	$ 3,074				$ 1,823				3,074	$ 1,823
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] \| Accounting Standards Update 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenues									$ 6,279

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Asset Impairments (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Goodwill impairment incurred	$ 0	$ 0	$ 0
Impairment of investments	1,069,000	0	$ 0
Carrying amount of cost method investment	$ 11,264,000	$ 12,333,000
Recycle Rewards Inc
Segment Reporting Information [Line Items]
Outstanding common stock percentage	6.80%
Impairment of investments	$ 1,069,000
Carrying amount of cost method investment	$ 0
GreenerU Inc
Segment Reporting Information [Line Items]
Outstanding common stock percentage	5.20%
Carrying amount of cost method investment	$ 309,000
Agreen Energy LLC
Segment Reporting Information [Line Items]
Outstanding common stock percentage	17.00%
Bgreen Energy LLC
Segment Reporting Information [Line Items]
Outstanding common stock percentage	16.20%
Agreen And Bgreen
Segment Reporting Information [Line Items]
Carrying amount of cost method investment	$ 297,000
Eastern
Segment Reporting Information [Line Items]
Reporting units exceeded their carrying values (as a percent)	21.50%
Western
Segment Reporting Information [Line Items]
Reporting units exceeded their carrying values (as a percent)	21.50%
Recycling
Segment Reporting Information [Line Items]
Reporting units exceeded their carrying values (as a percent)	21.50%
Other
Segment Reporting Information [Line Items]
Reporting units exceeded their carrying values (as a percent)	21.50%

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Defined Benefit Pension Plan (Details)	12 Months Ended
	Dec. 31, 2018 plan
Multiemployer Pension Plans \| New England Teamsters and Trucking Industry Pension Fund
Multiemployer Plans [Line Items]
Number of plans	1

BUSINESS COMBINATIONS - Narrative (Detail) - transfer_station	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Intangible assets, useful life	10 years
Minimum
Business Acquisition [Line Items]
Intangible assets, useful life	5 years
Maximum
Business Acquisition [Line Items]
Intangible assets, useful life	10 years
Western \| Solid Waste Collection Business
Business Acquisition [Line Items]
Number of businesses acquired	6	3
Western \| Transfer Business
Business Acquisition [Line Items]
Number of businesses acquired	1
Eastern \| Solid Waste Collection Business
Business Acquisition [Line Items]
Number of businesses acquired		1
Eastern \| Collection Business
Business Acquisition [Line Items]
Number of businesses acquired	2

BUSINESS COMBINATIONS - Schedule of Purchase Price Paid for Acquisitions (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Purchase Price:
Cash used in acquisitions, net of cash acquired	$ 88,918	$ 5,056	$ 2,839
Excess purchase price to be allocated to goodwill	162,734	122,605	119,899
Transfer Stations Acquisition
Purchase Price:
Cash used in acquisitions, net of cash acquired	86,686	4,823	2,439
Notes payable	0	2,400	0
Class A common stock issued	4,258	0	0
Other non-cash considerations	0	101	0
Contingent consideration and holdbacks	8,521	736	400
Total	99,465	8,060	2,839
Current assets	3,276	93	40
Land	0	0	353
Buildings	7,889	0	1,360
Equipment	23,882	2,994	269
Other liabilities, net	(4,708)	(49)	(106)
Deferred tax liability	(937)	0	0
Intangible assets	29,934	2,334	0
Fair value of assets acquired and liabilities assumed	59,336	5,372	1,916
Excess purchase price to be allocated to goodwill	$ 40,129	$ 2,688	$ 923

BUSINESS COMBINATIONS - Schedule of Unaudited Pro forma Combined Information (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Business Combinations [Abstract]
Revenues									$ 699,659	$ 672,898	$ 642,773
Operating income (loss)									43,561	(6,601)	50,970
Net income (loss) attributable to common stockholders									$ 8,579	$ (18,408)	$ (3,446)
Basic earnings per common share attributable to common stockholders (in dollars per share)									$ 0.20	$ (0.44)	$ (0.08)
Basic weighted average shares outstanding (in shares)	42,936	42,779	42,661	42,370	42,033	41,951	41,811	41,584	42,688	41,846	41,233
Diluted earnings per common share attributable to common stockholders (in dollars per share)									$ 0.19	$ (0.44)	$ (0.08)
Diluted weighted average shares outstanding (in shares)	42,936	44,175	43,916	42,370	43,394	43,295	41,811	41,584	44,168	41,846	41,233

RESTRICTED ASSETS (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Receivables [Abstract]
Restricted investment securities - landfill closure	$ 1,248	$ 1,220

PROPERTY, PLANT AND EQUIPMENT - Components of Property, Plant and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 1,283,278	$ 1,173,021
Less: accumulated depreciation and amortization	(878,701)	(811,474)
Property, plant and equipment, net	404,577	361,547
Land
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	25,490	24,224
Landfills
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	544,663	513,548
Landfill operating lease contracts
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	121,877	114,462
Building and Improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	150,885	140,155
Machinery and Equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	153,222	139,029
Rolling Stock
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	163,758	138,102
Containers
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 123,383	$ 103,501

PROPERTY, PLANT AND EQUIPMENT - Narrative (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Depreciation expense	$ 35,351	$ 32,131	$ 33,186
Depletion expense on operating lease contracts	9,724	9,646	9,295
Landfills
Property, Plant and Equipment [Line Items]
Amortization expense	$ 31,841	$ 27,910	$ 26,529

GOODWILL AND INTANGIBLE ASSETS - Schedule of Activity and Balances Related to Goodwill by Reporting Segment (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Goodwill [Roll Forward]
Goodwill, beginning balance	$ 122,605	$ 119,899
Acquisitions	40,129	2,706
Goodwill, ending balance	162,734	122,605
Eastern
Goodwill [Roll Forward]
Goodwill, beginning balance	19,192	17,429
Acquisitions	8,962	1,763
Goodwill, ending balance	28,154	19,192
Western
Goodwill [Roll Forward]
Goodwill, beginning balance	89,369	88,426
Acquisitions	31,167	943
Goodwill, ending balance	120,536	89,369
Recycling
Goodwill [Roll Forward]
Goodwill, beginning balance	12,315	12,315
Acquisitions	0	0
Goodwill, ending balance	12,315	12,315
Other
Goodwill [Roll Forward]
Goodwill, beginning balance	1,729	1,729
Acquisitions	0	0
Goodwill, ending balance	$ 1,729	$ 1,729

GOODWILL AND INTANGIBLE ASSETS - Components of Intangible Assets (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Intangible assets	$ 66,113	$ 36,179
Less accumulated amortization	(31,346)	(28,030)
Intangible assets, net	34,767	8,149
Intangible amortization expenses	3,316	2,061	$ 2,141
Covenants Not-to-Compete
Finite-Lived Intangible Assets [Line Items]
Intangible assets	21,750	18,092
Less accumulated amortization	(17,584)	(16,851)
Intangible assets, net	4,166	1,241
Client Lists
Finite-Lived Intangible Assets [Line Items]
Intangible assets	44,363	18,087
Less accumulated amortization	(13,762)	(11,179)
Intangible assets, net	$ 30,601	$ 6,908

GOODWILL AND INTANGIBLE ASSETS - Estimated Future Amortization Expense (Detail) $ in Thousands	Dec. 31, 2018 USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
For the fiscal year ending December 31, 2019	$ 5,601
For the fiscal year ending December 31, 2020	4,997
For the fiscal year ending December 31, 2021	4,094
For the fiscal year ending December 31, 2022	3,534
For the fiscal year ending December 31, 2023	3,231
Thereafter	$ 13,310

FINAL CAPPING, CLOSURE AND POST-CLOSURE COSTS (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning balance	$ 62,290	$ 44,207
Obligations incurred	3,713	3,022
Revisions in estimates	5,095	11,498
Accretion expense	5,556	4,401
Obligations settled	(3,579)	(838)
Ending balance	$ 73,075	$ 62,290

LONG TERM DEBT AND CAPITAL LEASES - Components of Long-Term Debt and Capital Leases (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Principal amount of long-term debt and capital leases	$ 555,249	$ 497,680
Less—unamortized discount and debt issuance costs	10,950	15,178
Long-term debt and capital leases less unamortized discount and debt issuance costs	544,299	482,502
Less—current maturities of long-term debt	2,298	4,926
Long-term debt and capital leases, less current maturities	542,001	477,576
Revolving Credit Facility due May 2023; bearing interest at LIBOR plus 2.00%
Debt Instrument [Line Items]
Principal amount of long-term debt and capital leases	69,600	0
Refinanced Revolving Credit Facility due October 2021; bore interest at LIBOR plus 2.75%
Debt Instrument [Line Items]
Principal amount of long-term debt and capital leases	0	36,000
Less—unamortized discount and debt issuance costs	0	3,938
New York State Environmental Facilities Corporation Solid Waste Disposal Revenue Bonds Series 2014R-1 due December 2044 - fixed rate interest period through 2019; bearing interest at 3.75%
Debt Instrument [Line Items]
Principal amount of long-term debt and capital leases	25,000	25,000
Less—unamortized discount and debt issuance costs	$ 847	1,034
Stated interest rate	3.75%
New York State Environmental Facilities Corporation Solid Waste Disposal Revenue Bonds Series 2014R-2 due December 2044 - fixed rate interest period through 2026; bearing interest at 3.125%
Debt Instrument [Line Items]
Principal amount of long-term debt and capital leases	$ 15,000	15,000
Less—unamortized discount and debt issuance costs	$ 450	511
Stated interest rate	3.125%
Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2005R-3 due January 2025 - fixed rate interest period through 2025; bearing interest at 5.25%
Debt Instrument [Line Items]
Principal amount of long-term debt and capital leases	$ 25,000	25,000
Less—unamortized discount and debt issuance costs	$ 517	603
Stated interest rate	5.25%
Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2015R-1 due August 2035 - fixed rate interest period through 2025; bearing interest at 5.125%
Debt Instrument [Line Items]
Principal amount of long-term debt and capital leases	$ 15,000	15,000
Less—unamortized discount and debt issuance costs	$ 622	691
Stated interest rate	5.125%
Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2015R-2 due August 2035 - fixed rate interest period through 2025; bearing interest at 4.375%
Debt Instrument [Line Items]
Principal amount of long-term debt and capital leases	$ 15,000	0
Less—unamortized discount and debt issuance costs	$ 493	0
Stated interest rate	4.375%
Vermont Economic Development Authority Solid Waste Disposal Long-Term Revenue Bonds Series 2013 due April 2036 - fixed rate interest period through 2028; bearing interest at 4.625%
Debt Instrument [Line Items]
Principal amount of long-term debt and capital leases	$ 16,000	16,000
Less—unamortized discount and debt issuance costs	$ 595	573
Stated interest rate	4.625%
Business Finance Authority of the State of New Hampshire Solid Waste Disposal Revenue Bonds Series 2013 due April 2029 - fixed rate interest period through 2019; bearing interest at 4.00%
Debt Instrument [Line Items]
Principal amount of long-term debt and capital leases	$ 11,000	11,000
Less—unamortized discount and debt issuance costs	$ 308	436
Stated interest rate	4.00%
Capital leases maturing through December 2107; bearing interest at a weighted average of 5.37%
Debt Instrument [Line Items]
Principal amount of long-term debt and capital leases	$ 11,248	5,595
Weighted average interest rate	5.37%
Notes payable maturing through June 2027; bearing interest at a weighted average of 2.97%
Debt Instrument [Line Items]
Principal amount of long-term debt and capital leases	$ 2,401	2,585
Weighted average interest rate	2.97%
Credit Facility
Debt Instrument [Line Items]
Less—unamortized discount and debt issuance costs	$ 7,118	0
Term Loan Facility due May 2023; bearing interest at LIBOR plus 2.00% \| Secured Debt
Debt Instrument [Line Items]
Principal amount of long-term debt and capital leases	350,000	0
Term Loan B Facility due October 2023; bore interest at LIBOR plus 2.50% \| Secured Debt
Debt Instrument [Line Items]
Principal amount of long-term debt and capital leases	0	346,500
Less—unamortized discount and debt issuance costs	0	7,392
Unamortized discount	$ 0	$ 1,482
LIBOR \| Revolving Credit Facility due May 2023; bearing interest at LIBOR plus 2.00%
Debt Instrument [Line Items]
Basis spread on variable rate	2.00%
LIBOR \| Refinanced Revolving Credit Facility due October 2021; bore interest at LIBOR plus 2.75%
Debt Instrument [Line Items]
Basis spread on variable rate	2.75%
LIBOR \| Term Loan Facility due May 2023; bearing interest at LIBOR plus 2.00% \| Secured Debt
Debt Instrument [Line Items]
Basis spread on variable rate	2.00%
LIBOR \| Term Loan B Facility due October 2023; bore interest at LIBOR plus 2.50% \| Secured Debt
Debt Instrument [Line Items]
Basis spread on variable rate	2.50%

LONG TERM DEBT AND CAPITAL LEASES - Credit Facility (Details)	12 Months Ended
	Dec. 31, 2018 USD ($)
Secured Debt \| Term Facility due 2023 (Term Loan A Facility) [Member] \| Line of Credit
Line of Credit Facility [Line Items]
Aggregate principal amount issued	$ 350,000,000
Secured Debt \| Term Loan B Facility
Line of Credit Facility [Line Items]
Aggregate principal amount issued	$ 350,000,000
Facility term	5 years
Net leverage ratio	2.25
Secured Debt \| Term Loan B Facility \| LIBOR
Line of Credit Facility [Line Items]
Basis spread on variable rate (as a percent)	1.25%
Basis spread on variable rate	2.50%
Secured Debt \| Term Loan B Facility \| LIBOR \| Maximum
Line of Credit Facility [Line Items]
Basis spread on variable rate (as a percent)	2.00%
Revolving Credit Facility \| Revolving Credit Facility Due 2023 [Member] \| Line of Credit
Line of Credit Facility [Line Items]
Credit facility maximum	$ 200,000,000
Line of Credit \| Refinanced Revolving Credit Facility due October 2021; bore interest at LIBOR plus 2.75% \| Revolving Credit Facility
Line of Credit Facility [Line Items]
Credit facility maximum	160,000,000
Remaining capacity	107,879,000
Line of Credit \| Refinanced Revolving Credit Facility due October 2021; bore interest at LIBOR plus 2.75% \| Letter of Credit
Line of Credit Facility [Line Items]
Outstanding irrevocable letters of credit totaling	22,521,000
Revolving Credit Facility
Line of Credit Facility [Line Items]
Additional revolver capacity	$ 125,000,000

LONG TERM DEBT AND CAPITAL LEASES - Tax-Exempt Financings (Details)	12 Months Ended
	Dec. 31, 2018 USD ($)
Unsecured Debt \| New York State Environmental Facilities Corporation Solid Waste Disposal Revenue Bonds Series 2014R-1 due December 2044 - fixed rate interest period through 2019; bearing interest at 3.75%
Debt Instrument [Line Items]
Aggregate principal amount outstanding	$ 25,000,000
Unsecured Debt \| New York State Environmental Facilities Corporation Solid Waste Disposal Revenue Bonds Series 2014R-2 due December 2044 - fixed rate interest period through 2026; bearing interest at 3.125%
Debt Instrument [Line Items]
Aggregate principal amount outstanding	15,000,000
Unsecured Debt \| Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2005R-3 due January 2025 - fixed rate interest period through 2025; bearing interest at 5.25%
Debt Instrument [Line Items]
Aggregate principal amount outstanding	$ 25,000,000
Stated interest rate	5.25%
Unsecured Debt \| Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2015R-2 due August 2035 - fixed rate interest period through 2025; bearing interest at 4.375%
Debt Instrument [Line Items]
Aggregate principal amount outstanding	$ 15,000,000
Stated interest rate	4.375%
Aggregate principal amount issued	$ 15,000,000
Unsecured Debt \| Vermont Economic Development Authority Solid Waste Disposal Revenue Bonds [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate during period	4.625%
New York Bonds, 2014R-1
Debt Instrument [Line Items]
Stated interest rate	3.75%
New York State Environmental Facilities Corporation Solid Waste Disposal Revenue Bonds Series 2014R-2 due December 2044 - fixed rate interest period through 2026; bearing interest at 3.125%
Debt Instrument [Line Items]
Stated interest rate	3.125%
Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2015R-2 due August 2035 - fixed rate interest period through 2025
Debt Instrument [Line Items]
Aggregate principal amount outstanding	$ 15,000,000
Stated interest rate	5.125%
Fixed Rate Bonds \| Vermont Bonds
Debt Instrument [Line Items]
Aggregate principal amount outstanding	$ 16,000,000
Stated interest rate	4.75%
Aggregate principal amount issued	$ 16,000,000
New Hampshire Bonds
Debt Instrument [Line Items]
Aggregate principal amount outstanding	$ 11,000,000
Stated interest rate	4.00%

LONG TERM DEBT AND CAPITAL LEASES - Loss on Debt Extinguishment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Loss on debt extinguishment	$ 7,352	$ 517	$ 13,747
Senior Subordinated Notes, Due February 2019; bore interest at 7.75%tes Due Two Thousand Nineteen [Member]
Debt Instrument [Line Items]
Stated interest rate			7.75%

LONG TERM DEBT AND CAPITAL LEASES - Components of Interest Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Debt Disclosure [Abstract]
Interest expense on long-term debt and capital leases	$ 23,816	$ 22,060	$ 34,741
Amortization of debt issuance costs and discounts on long-term debt	2,449	2,692	3,881
Letter of credit fees	169	703	593
Less: capitalized interest	(140)	(295)	(273)
Total interest expense	$ 26,294	$ 25,160	$ 38,942

LONG TERM DEBT AND CAPITAL LEASES - Cash Flow Hedges (Details)	12 Months Ended
	Dec. 31, 2018 USD ($) interest_rate_derviative
Debt Instrument [Line Items]
Net gain on interest rat derivative agreements in accumulated other comprehensive income \| $	$ 1,383,000
Interest Rate Contract \| Cash Flow Hedging
Debt Instrument [Line Items]
Number of interest rate derivatives held \| interest_rate_derviative	6
Notional amount \| $	$ 190,000,000
Weighted average percentage rate paid	2.54%
Term Loan B Facility \| Interest Rate Contract \| Cash Flow Hedging
Debt Instrument [Line Items]
Number of interest rate derivatives held \| interest_rate_derviative	3

LONG TERM DEBT AND CAPITAL LEASES - Schedule of Cash Flow Hedges Related to Derivative Instruments on the Balance Sheet (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Cash flow hedge derivatives, assets	$ 820	$ 401
Cash flow hedge derivatives, liabilities	1,942	123
Accumulated other comprehensive (loss) income, net - interest rate swaps	(1,476)	267	$ 0
Other current assets \| Designated as hedging instrument \| Interest rate swaps
Debt Instrument [Line Items]
Cash flow hedge derivatives, assets	338	0
Other non-current assets \| Designated as hedging instrument \| Interest rate swaps
Debt Instrument [Line Items]
Cash flow hedge derivatives, assets	482	401
Other accrued liabilities \| Designated as hedging instrument \| Interest rate swaps
Debt Instrument [Line Items]
Cash flow hedge derivatives, liabilities	387	123
Other long-term liabilities \| Designated as hedging instrument \| Interest rate swaps
Debt Instrument [Line Items]
Cash flow hedge derivatives, liabilities	1,555	0
Accumulated other comprehensive (loss) income, net \| Designated as hedging instrument \| Interest rate swaps
Debt Instrument [Line Items]
Accumulated other comprehensive (loss) income, net - interest rate swaps	(1,196)	278
Accumulated other comprehensive (loss) income, net - interest rate swaps - tax provision	(112)	(112)
Accumulated other comprehensive (loss) income, net	$ (1,308)	$ 166

LONG TERM DEBT AND CAPITAL LEASES - Schedule of Gain (Loss) On Cash Flow Hedges (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on cash flow hedging	$ (363)	$ (421)	$ 0
Designated as hedging instrument \| Interest rate swaps \| Interest expense
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on cash flow hedging	$ (363)	$ (421)	$ 0

LONG TERM DEBT AND CAPITAL LEASES - Fair Value of Debt (Details) $ in Thousands	Dec. 31, 2018 USD ($)
Carrying Value \| Revolving Credit Facility due May 2023; bearing interest at LIBOR plus 2.00%
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of line of credit	$ 69,600
Carrying Value \| Fixed Rate Bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of debt	121,722
Carrying Value \| Secured Debt \| Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2015R-2 due August 2035 - fixed rate interest period through 2025; bearing interest at 4.375%
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of debt	350,000
Fair Value \| Significant Other Observable Inputs (Level 2) \| Fixed Rate Bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of debt	$ 122,000

LONG TERM DEBT AND CAPITAL LEASES - Schedule of Future Maturities of Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Debt Disclosure [Abstract]
2019	$ 2,298
2020	2,648
2021	2,175
2022	1,652
2023	421,021
Thereafter	125,455
Long-term debt and capital lease	$ 555,249	$ 497,680

COMMITMENTS AND CONTINGENCIES - Narrative (Detail)		1 Months Ended	3 Months Ended	12 Months Ended
COMMITMENTS AND CONTINGENCIES - Narrative (Detail)	Apr. 28, 2017 USD ($)	Nov. 30, 2016 basin	Sep. 30, 2018 USD ($)	Dec. 31, 2018 USD ($) executive_officer	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Apr. 26, 2017 USD ($)	Jan. 29, 2016	Apr. 30, 2011 USD ($)	May 31, 2009 USD ($)	Dec. 20, 2000 a
Other Commitments [Line Items]
Monthly payments (up to)				$ 23,000
Total rent expense under operating leases charged to operations				10,571,000	$ 12,242,000	$ 11,437,000
Number of storm water basins \| basin		2
Payments for litigation settlement				$ 850,000
Ancillary services period				5 years
Litigation settlement, total cash and services				$ 1,200,000
Number of executive officers \| executive_officer				5
Intangible assets, useful life				10 years
Contract extension period				1 year
Total annual commitments for salaries				$ 1,821,000
Notice of Intent to Sue under the Resource Conservation and Recovery Act
Other Commitments [Line Items]
Agreement in principle amount (up to)							$ 5,000,000
Steadfast Insurance Company
Other Commitments [Line Items]
Litigation settlement, amount awarded form other party			$ 10,000,000
Minimum
Other Commitments [Line Items]
Initial term of employment contract				1 year
Intangible assets, useful life				5 years
Salary and bonuses payment range				1 year
Minimum \| Employment Contracts
Other Commitments [Line Items]
Intangible assets, useful life				1 year
Maximum
Other Commitments [Line Items]
Initial term of employment contract				3 years
Intangible assets, useful life				10 years
Salary and bonuses payment range				3 years
Maximum \| Employment Contracts
Other Commitments [Line Items]
Intangible assets, useful life				2 years
Southbridge Landfill
Other Commitments [Line Items]
Risk free interest rate (as a percent)				2.60%
Litigation settlement, total cash and services				$ 1,216,000	0
Reserve for probable loss				226,000
Litigation settlement, amount awarded form other party				10,000,000	$ 0
Loss on contract termination				$ 8,724,000
Potsdam Environmental Remediation Liability
Other Commitments [Line Items]
Risk free interest rate (as a percent)				1.50%
Number of acres composing solid waste transfer station (in acres) \| a											25
Estimate of total undiscounted costs associated with implementing the preferred remedies									$ 12,130,000	$ 10,219,000
Remediation activities, participant share percentage								15.00%
MADEP \| Notice of Intent to Sue under the Resource Conservation and Recovery Act
Other Commitments [Line Items]
Agreement in principle amount (up to)							$ 10,000,000
21E Settlement and Water System Construction Funding Agreement \| Bonds
Other Commitments [Line Items]
Facility term	20 years
21E Settlement and Water System Construction Funding Agreement \| Bonds \| Maximum
Other Commitments [Line Items]
Anticipated costs	$ 5,000,000

COMMITMENTS AND CONTINGENCIES - Schedule of Future Minimum Rental Payments under Non-Cancellable Operating Leases (Detail) $ in Thousands	Dec. 31, 2018 USD ($)
Commitments and Contingencies Disclosure [Abstract]
2019	$ 15,572
2020	12,678
2021	10,117
2022	7,953
2023	6,250
Thereafter	65,145
Total minimum lease payments	$ 117,715

COMMITMENTS AND CONTINGENCIES - Schedule of Environmental Liability Associated with Southbridge Landfill (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Accrual for Environmental Loss Contingencies [Roll Forward]
Ending balance	$ 10,787
Southbridge Landfill
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	5,936	$ 0
Accretion expense	152	82
Obligations incurred	0	6,379
Obligations settled	(915)	(525)
Ending balance	$ 5,173	$ 5,936

COMMITMENTS AND CONTINGENCIES - Schedule of Environmental Liability Associated with Potsdam (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Accrual for Environmental Loss Contingencies [Roll Forward]
Ending balance	$ 10,787
Potsdam Environmental Remediation Liability
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	5,758	$ 5,866
Payments	(171)	(108)
Obligations incurred	27	0
Ending balance	$ 5,614	$ 5,758

COMMITMENTS AND CONTINGENCIES - Schedule of Future Minimum Rental (Detail) $ in Thousands	Dec. 31, 2018 USD ($)
Commitments and Contingencies Disclosure [Abstract]
2019	$ 3,974
2020	1,289
2021	398
2022	372
2023	383
Thereafter	5,250
Total	$ 11,666

COMMITMENTS AND CONTINGENCIES - Reconciliation of Expected Aggregate Non-inflated, Undiscounted Amount to Amount Recognized in Statements of Financial Position (Detail) $ in Thousands	Dec. 31, 2018 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Undiscounted liability	$ 11,666
Less discount, net	(879)
Liability balance - December 31, 2018	$ 10,787

STOCKHOLDERS' EQUITY - Narrative (Detail) $ / shares in Units, $ in Thousands		12 Months Ended
	Jan. 25, 2019 USD ($) $ / shares shares	Dec. 31, 2018 USD ($) vote $ / shares shares	Dec. 31, 2017 USD ($) vote shares	Dec. 31, 2016 USD ($) $ / shares
Limited Partners' Capital Account [Line Items]
Preferred stock authorized to issue (up to) (in shares) \| shares		944,000
Shares issued (in shares) \| shares		0	0
Expected dividend yield			0.00%	0.00%
Total fair value of other stock awards vested		$ 10,529	$ 5,706	$ 3,238
Stock Options
Limited Partners' Capital Account [Line Items]
Stock-based compensation expense		473	644	605
Aggregate intrinsic value of stock options exercised		1,916	4,664	$ 22
Market-based Performance Stock Options
Limited Partners' Capital Account [Line Items]
Weighted average fair value of market-based performance (in dollars per share) \| $ / shares				$ 6.70
Expected life				7 years 4 months 24 days
Risk-free interest rate				2.15%
Expected volatility (as a percent)				43.10%
Expected dividend yield				0.00%
Restricted Stock, Restricted Stock Units and Performance Stock Units
Limited Partners' Capital Account [Line Items]
Stock-based compensation expense		7,821	5,652	$ 2,673
Restricted Stock and Restricted Stock Unit
Limited Partners' Capital Account [Line Items]
Unrecognized stock-based compensation expense		3,024
Restricted Stock, Restricted Stock Units and Performance Stock Units
Limited Partners' Capital Account [Line Items]
Tax provision (benefit)		$ (23)
Income taxes associated with stock-based compensation expense			117	0
Market-based Performance Stock Units
Limited Partners' Capital Account [Line Items]
Weighted average fair value of market-based performance (in dollars per share) \| $ / shares		$ 26.02
Risk-free interest rate		2.39%
Expected volatility (as a percent)		32.70%
Expected dividend yield		0.00%
Amended and Restated 1997 Employee Stock Purchase Plan
Limited Partners' Capital Account [Line Items]
Stock-based compensation expense		$ 150	$ 136	$ 115
Non-Employee Director \| Restricted Stock Awards
Limited Partners' Capital Account [Line Items]
Options vesting period		3 years
Maximum \| Performance Stock Units
Limited Partners' Capital Account [Line Items]
Unrecognized stock-based compensation expense		$ 4,516
Weighted Average \| Restricted Stock and Restricted Stock Unit
Limited Partners' Capital Account [Line Items]
Unrecognized stock-based compensation expense, weighted average period		1 year 1 month 6 days
Weighted Average \| Performance Stock Units
Limited Partners' Capital Account [Line Items]
Unrecognized stock-based compensation expense, weighted average period		1 year 3 months
2016 Incentive Plan
Limited Partners' Capital Account [Line Items]
Options granted period		10 years
2016 Incentive Plan \| Minimum
Limited Partners' Capital Account [Line Items]
Options vesting period		1 year
2016 Incentive Plan \| Maximum
Limited Partners' Capital Account [Line Items]
Options vesting period		4 years
Class A Common Stock
Limited Partners' Capital Account [Line Items]
Vote for each share held (in votes per share) \| vote		1
Number of shares available for future grant (in shares) \| shares		117,000
Class A Common Stock \| 2016 Incentive Plan
Limited Partners' Capital Account [Line Items]
Common stock, authorized shares (in shares) \| shares			2,250,000
Number of shares available for future grant (in shares) \| shares		1,615,000
Class B Common Stock
Limited Partners' Capital Account [Line Items]
Vote for each share held (in votes per share) \| vote		10	10
Subsequent Event \| Class A Common Stock \| Public Stock Offering
Limited Partners' Capital Account [Line Items]
Sale of stock, number of shares issued (in shares) \| shares	3,565,000
Sale of stock, price per share (in dollars per share) \| $ / shares	$ 29.50
Sale of stock, net proceeds	$ 100,943

STOCKHOLDERS' EQUITY - Summary of Stock Option Activity (Detail) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) $ / shares shares
Stock Options
Outstanding, beginning balance (in shares) \| shares	727
Granted (in shares) \| shares	0
Exercised (in shares) \| shares	(98)
Forfeited (in shares) \| shares	0
Outstanding, ending balance (in shares) \| shares	669
Exercisable (in shares) \| shares	669
Weighted Average Exercise Price
Outstanding, beginning balance (in dollars per share) \| $ / shares	$ 5.82
Granted (in dollars per share) \| $ / shares	0.00
Exercised (in dollars per share) \| $ / shares	4.80
Forfeited (in dollars per share) \| $ / shares	0.00
Outstanding, ending balance (in dollars per share) \| $ / shares	6.37
Exercisable (in dollars per share) \| $ / shares	$ 6.37
Weighted average remaining contractual term, outstanding	5 years 6 months 23 days
Weighted average remaining contractual term, exercisable	5 years 6 months 23 days
Aggregate intrinsic value, outstanding \| $	$ 14,788
Aggregate intrinsic value, exercisable \| $	$ 14,788
Market-based Performance Stock Options
Stock Options
Market-based stock options vested (in shares) \| shares	40
Weighted Average Exercise Price
Market-based stock options vested (in dollars per share) \| $ / shares	$ 12.48
Weighted average remaining contractual term, vested	7 years 10 months 23 days
Attainment level percentage	100.00%

STOCKHOLDERS' EQUITY - Summary of Restricted Stock, Restricted Stock Unit and Performance Stock Unit Activity (Detail) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) $ / shares shares
Restricted Stock, Restricted Stock Units and Performance Stock Units
Restricted Stock, Restricted Stock Units, and Performance Stock Units
Outstanding, beginning balance (in shares)	1,091
Granted (in shares)	230
Forfeited (in shares)	(3)
Outstanding, ending balance (in shares)	686
Unvested, ending balance (in shares)	951
Weighted Average Grant Price
Outstanding, beginning balance (in dollars per share) \| $ / shares	$ 9.81
Granted (in dollars per share) \| $ / shares	24.92
Forfeited (in dollars per share) \| $ / shares	13.73
Outstanding, ending balance (in dollars per share) \| $ / shares	15.56
Weighted average grant price, unvested, ending balance (in dollars per share) \| $ / shares	$ 15.95
Weighted average remaining contractual term, outstanding	1 year 2 months 3 days
Weighted average remaining contractual term, unvested	1 year 3 months
Aggregate intrinsic value, outstanding \| $	$ 8,877
Aggregate intrinsic value, unvested \| $	$ 11,929
Performance Stock Units
Weighted Average Grant Price
Attainment level percentage	100.00%
Class A Common Stock \| Restricted Stock, Restricted Stock Units and Performance Stock Units
Restricted Stock, Restricted Stock Units, and Performance Stock Units
Vested (in shares)	(632)
Weighted Average Grant Price
Vested (in dollars per share) \| $ / shares	$ 9.04
Class A Common Stock \| Performance Stock Units
Weighted Average Grant Price
Additional issuance if performance targets met (in shares)	265
Additional shares issued (in shares)	185

STOCKHOLDERS' EQUITY - Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2018
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ (37,862)	$ (24,550)	$ (21,597)
Cumulative effect of new accounting principle				$ (18)
Other comprehensive income (loss) before reclassifications	(1,837)	(84)
Amounts reclassified from accumulated other comprehensive income (loss)	363	421
Income tax expense related to items in other comprehensive income (loss)	0	(85)	0
Other comprehensive (loss) income, net of tax	(1,474)	252	(75)
Ending balance	(15,832)	(37,862)	(24,550)
Marketable Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	18	(68)	7
Cumulative effect of new accounting principle				(18)
Other comprehensive income (loss) before reclassifications	0	59
Amounts reclassified from accumulated other comprehensive income (loss)		0
Income tax expense related to items in other comprehensive income (loss)	0	27
Other comprehensive (loss) income, net of tax	0	86	(75)
Ending balance	0	18	(68)
Interest rate swaps
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	166	0	0
Cumulative effect of new accounting principle				0
Other comprehensive income (loss) before reclassifications	(1,837)	(143)
Amounts reclassified from accumulated other comprehensive income (loss)	363	421
Income tax expense related to items in other comprehensive income (loss)	0	(112)
Other comprehensive (loss) income, net of tax	(1,474)	166	0
Ending balance	(1,308)	166	0
Accumulated Other Comprehensive Income (Loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	184	(68)	7
Cumulative effect of new accounting principle				$ (18)
Other comprehensive (loss) income, net of tax	(1,474)	252	(75)
Ending balance	$ (1,308)	$ 184	$ (68)

STOCKHOLDERS' EQUITY - Reclassification Out of Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense	$ 26,294	$ 25,160	$ 38,942
Income (loss) before income taxes	(6,036)	37,052	6,364
(Benefit) provision for income taxes	(384)	(15,253)	494
Net (loss) income attributable to common stockholders	(6,420)	21,799	6,849
Interest rate swaps \| Interest rate swaps \| Reclassification Out of Accumulated Other Comprehensive Income (Loss)
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense	363	421	0
Income (loss) before income taxes	363	421	0
(Benefit) provision for income taxes	0	0	0
Net (loss) income attributable to common stockholders	$ 363	$ 421	$ 0

FAIR VALUE OF FINANCIAL INSTRUMENTS (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Assets:
Restricted investment securities - landfill closure	$ 1,248	$ 1,220
Quoted Prices in Active Markets for Identical Assets (Level 1) \| Fair Value, Measurements, Recurring
Assets:
Interest rate swaps	0	0
Total asset fair value	1,248	1,220
Liabilities:
Interest rate swaps	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) \| Fair Value, Measurements, Recurring \| Landfills
Assets:
Restricted investment securities - landfill closure	1,248	1,220
Significant Other Observable Inputs (Level 2) \| Fair Value, Measurements, Recurring
Assets:
Interest rate swaps	820	401
Total asset fair value	820	401
Liabilities:
Interest rate swaps	1,942	123
Significant Other Observable Inputs (Level 2) \| Fair Value, Measurements, Recurring \| Landfills
Assets:
Restricted investment securities - landfill closure	0	0
Significant Unobservable Inputs (Level 3) \| Fair Value, Measurements, Recurring
Assets:
Interest rate swaps	0	0
Total asset fair value	0	0
Liabilities:
Interest rate swaps	0	0
Significant Unobservable Inputs (Level 3) \| Fair Value, Measurements, Recurring \| Landfills
Assets:
Restricted investment securities - landfill closure	$ 0	$ 0

EMPLOYEE BENEFIT PLANS - Narrative (Detail) - USD ($) shares in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Employee Stock Purchase Plan [Line Items]
Maximum matching contribution per dollar per employee contribution	$ 0.50
Maximum match per employee per calendar year	$ 1,000
Employer contributions vesting period	3 years
Employer contributions	$ 1,319,000	$ 1,187,000	$ 1,119,000
Class A Common Stock
Employee Stock Purchase Plan [Line Items]
Discount rate	15.00%
Stock issued under stock purchase plan (in shares)	26	41	70
Stock available for distribution under stock purchase plan (in shares)	117

EMPLOYEE BENEFIT PLANS - Multiemployer Defined Benefit Pension Plan (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Multiemployer Pension Plans \| New England Teamsters and Trucking Industry Pension Fund
Multiemployer Plans [Line Items]
Contributions to Plan	$ 726	$ 627	$ 523

INCOME TAXES - Schedule of Provision (Benefit) for Income Taxes Continuing Operations (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Federal
Current	$ (1,902)	$ 0	$ 0
Deferred	1,255	(15,614)	458
Total	(647)	(15,614)	458
State
Current	2,575	301	(90)
Current benefit of loss carryforwards	(2,307)	(28)	0
Deferred	(5)	88	126
Total	263	361	36
(Benefit) provision for income taxes	$ (384)	$ (15,253)	$ 494

INCOME TAXES - Narrative (Detail) - USD ($) $ in Thousands	3 Months Ended				12 Months Ended
INCOME TAXES - Narrative (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Sep. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating Loss Carryforwards [Line Items]
Deferred income taxes adjustment					$ 1,250	$ (15,525)	$ 583
Deferred tax liabilities, goodwill	$ 937				937
Increase in tax provision due to Tax Act						33,700
Increase (decrease) deferred tax benefit related to continuing operations				$ (29,234)		(36,556)
Deferred tax benefit of indefinite lived deferred tax liabilities				12,758	0	12,758	0
Deferred federal taxes asset	9,594			11,567	9,594	11,567
Long-term deferred state tax liability	(2,519)			(2,305)	(2,519)	(2,305)
Net operating loss carryforwards subject to expiration	110,586				110,586
Net operating loss carryforwards not subject to expiration	3,209				3,209
State net operating loss carryforwards expiry period	86,312				86,312
Alternative minimum tax credit carryforwards	1,902			3,804	1,902	3,804
General business tax credit carryforwards	6,192			5,439	6,192	5,439
Increase (decrease) in valuation allowance					834	(29,234)
Deferred tax expense (benefit) due to Tax Cuts and Jobs Act				(15,614)
Unrecognized tax benefit net of federal benefit on state issue	2			6	2	6
Unrecognized tax benefits	2				2
Uncertain tax positions, accrued interest	2			3	2	3	5
Uncertain tax positions, penalties	1			2	1	2	4
Accrued income tax expense	(2)			$ (3)	(2)	$ (3)	$ (91)
Goodwill
Operating Loss Carryforwards [Line Items]
Deferred income taxes adjustment	292	$ 406	$ (1,635)		(937)
Complete Disposal Company, Inc
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	$ 1,320				$ 1,320

INCOME TAXES - Schedule of Difference in Provision (Benefit) for Income Taxes (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Federal statutory rate		21.00%	35.00%	35.00%
Tax at statutory rate		$ 1,268	$ (12,968)	$ (2,228)
State income taxes, net of federal benefit		(89)	(1,959)	(265)
Decrease in net federal deferred tax assets before valuation allowance change due to federal rate change		0	33,700	0
Decrease in valuation allowance by 80% of indefinite lived deferred liabilities due to US tax reform	$ (12,758)	0	(12,758)	0
Other changes in valuation allowance, including the federal rate change in fiscal year 2017		(1,613)	(18,848)	4,370
Non-deductible officer compensation		2,214	0	0
Deductible stock awards		(2,048)	(1,825)	0
Tax credits		(686)	(1,000)	(1,085)
Non-deductible expenses		633	542	100
Other, net		(63)	(137)	(398)
(Benefit) provision for income taxes		$ (384)	$ (15,253)	$ 494

INCOME TAXES - Schedule of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets:
Accrued expenses and reserves	$ 34,647	$ 26,572
Net operating loss carryforwards	31,241	33,228
Book over tax depreciation of property and equipment	19,048	25,615
General business tax credit carryforwards	6,192	5,439
Stock awards	2,310	1,958
Alternative minimum tax credit carryforwards	1,902	3,804
Other	3,023	2,050
Total deferred tax assets	98,363	98,666
Less: valuation allowance	(69,189)	(68,355)
Total deferred tax assets after valuation allowance	29,174	30,311
Deferred tax liabilities:
Amortization of intangibles	(22,026)	(20,904)
Other	(73)	(145)
Total deferred tax liabilities	(22,099)	(21,049)
Net deferred tax asset	$ 7,075	$ 9,262

INCOME TAXES - Schedule of Reconciliation of Gross Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits at beginning of period	$ 1,941	$ 3,107
Gross increases for tax positions of prior years	0	1
Gross decreases for tax positions of prior years	0	(1,165)
Reductions resulting from lapse of statute of limitations	(1,939)	0
Settlements	0	(2)
Unrecognized tax benefits at end of period	$ 2	$ 1,941

EARNINGS PER SHARE (Detail) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Numerator:
Net income (loss) attributable to common stockholders									$ 6,420	$ (21,799)	$ (6,849)
Denominator:
Shares to be issued - acquisition (in shares)									103	0	0
Unvested restricted stock (in shares)									(9)	(38)	(88)
Effect of weighted average shares outstanding (in shares)									(338)	(402)	(239)
Weighted average common shares outstanding (in shares)									42,688	41,846	41,233
Dilutive effect of stock options and stock awards (in shares)									1,480	0	0
Diluted weighted average shares outstanding (in shares)	42,936	44,175	43,916	42,370	43,394	43,295	41,811	41,584	44,168	41,846	41,233
Antidilutive potentially issuable shares (in shares)									2	2,219	2,442
Class A Common Stock
Denominator:
Common stock, outstanding shares (in shares)	41,944				41,298				41,944	41,298	40,572
Class B Common Stock
Denominator:
Common stock, outstanding shares (in shares)	988				988				988	988	988

OTHER ITEMS AND CHARGES - Charges Associated with Closure of Southbridge Landfill (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Site Contingency [Line Items]
Project development charge	$ 311	$ 0	$ 0
Environmental remediation charge	0	0	900
Contract settlement charge	2,100	0	0
Landfill closure project charge	16,179	63,526	0
Charlton settlement charge	1,200
Southbridge Landfill closure charge, net	8,054	65,183	$ 0
Southbridge Landfill
Site Contingency [Line Items]
Asset impairment charge	0	47,999
Project development charge	0	9,149
Environmental remediation charge	0	6,379
Contract settlement charge	8,724	0
Landfill closure project charge	6,012	0
Charlton settlement charge	1,216	0
Legal and transaction costs	2,102	1,656
Recovery on insurance settlement	(10,000)	0
Southbridge Landfill closure charge, net	$ 8,054	$ 65,183

OTHER ITEMS AND CHARGES OTHER ITEMS AND CHARGES - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Unusual or Infrequent Items, or Both [Abstract]
Contract settlement charge	$ 2,100	$ 0	$ 0
Write-off deferral costs	1,872
Expense from acquisition activities and other items		176
Development project charge	311	0	0
Environmental remediation charge	$ 0	$ 0	$ 900

RELATED PARTY TRANSACTIONS (Detail) $ in Thousands	12 Months Ended
RELATED PARTY TRANSACTIONS (Detail) $ in Thousands	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Apr. 30, 1994 Lease
Related Party Transaction [Line Items]
Total services purchased	$ 3,421	$ 3,377	$ 4,024
Outstanding accounts payable	32	30
Number of leases \| Lease				2
Total expense charged to operations under lease agreement	349	360	371
Accrued costs associated with post-closure obligations	73,075	62,290	44,207
Landfills
Related Party Transaction [Line Items]
Landfill post-closure cost	14	27	10
Accrued costs associated with post-closure obligations	48	60
CCI
Related Party Transaction [Line Items]
Revenue from related party	156	$ 237	$ 307
Related Party
Related Party Transaction [Line Items]
Leases monthly payments	$ 28

SEGMENT REPORTING - Summary of Financial Information by Reportable Segment (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Revenues	$ 174,724	$ 172,832	$ 165,649	$ 147,455	$ 151,222	$ 160,269	$ 154,016	$ 133,802	$ 660,660	$ 599,309	$ 565,030
Depreciation and amortization									70,508	62,102	61,856
Operating income (loss)	(5,138)	$ 28,884	$ 15,149	$ 838	9,855	$ 18,277	$ (47,279)	$ 6,564	39,733	(12,583)	44,945
Goodwill	162,734				122,605				162,734	122,605	119,899
Total assets	732,410				614,949				732,410	614,949
Eastern
Segment Reporting Information [Line Items]
Goodwill	28,154				19,192				28,154	19,192	17,429
Western
Segment Reporting Information [Line Items]
Goodwill	120,536				89,369				120,536	89,369	88,426
Recycling
Segment Reporting Information [Line Items]
Goodwill	12,315				12,315				12,315	12,315	12,315
Other
Segment Reporting Information [Line Items]
Goodwill	1,729				1,729				1,729	1,729	1,729
Operating Segments
Segment Reporting Information [Line Items]
Revenues									660,660	599,309	565,030
Depreciation and amortization									70,508	62,102	61,856
Operating income (loss)									39,733	(12,583)	44,945
Interest expense, net									26,021	24,887	38,652
Capital expenditures									73,232	64,862	54,238
Goodwill	162,734				122,605				162,734	122,605	119,899
Total assets	732,410				614,949				732,410	614,949	631,512
Operating Segments \| Eastern
Segment Reporting Information [Line Items]
Revenues									206,473	181,170	176,539
Depreciation and amortization									26,538	23,815	27,036
Operating income (loss)									4,684	(51,867)	9,697
Interest expense, net									12	3	(16)
Capital expenditures									23,393	17,153	18,363
Goodwill	28,154				19,192				28,154	19,192	17,429
Total assets	184,679				157,248				184,679	157,248	202,420
Operating Segments \| Western
Segment Reporting Information [Line Items]
Revenues									286,262	250,771	233,168
Depreciation and amortization									35,843	30,766	27,511
Operating income (loss)									41,529	35,035	30,576
Interest expense, net									(148)	(220)	(248)
Capital expenditures									41,850	42,082	31,637
Goodwill	120,536				89,369				120,536	89,369	88,426
Total assets	428,934				344,324				428,934	344,324	327,628
Operating Segments \| Recycling
Segment Reporting Information [Line Items]
Revenues									42,191	62,307	52,911
Depreciation and amortization									4,345	4,125	4,212
Operating income (loss)									(7,805)	2,805	2,542
Interest expense, net									140	143	156
Capital expenditures									4,476	2,006	2,218
Goodwill	12,315				12,315				12,315	12,315	12,315
Total assets	48,629				48,612				48,629	48,612	49,931
Operating Segments \| Other
Segment Reporting Information [Line Items]
Revenues									125,734	105,061	102,412
Depreciation and amortization									3,782	3,396	3,097
Operating income (loss)									1,325	1,444	2,130
Interest expense, net									26,017	24,961	38,760
Capital expenditures									3,513	3,621	2,020
Goodwill	1,729				1,729				1,729	1,729	1,729
Total assets	$ 70,168				$ 64,765				70,168	64,765	51,533
Eliminations
Segment Reporting Information [Line Items]
Revenues									(142,789)	(123,972)	(116,331)
Eliminations \| Eastern
Segment Reporting Information [Line Items]
Revenues									52,866	50,335	45,728
Eliminations \| Western
Segment Reporting Information [Line Items]
Revenues									81,515	71,510	67,985
Eliminations \| Recycling
Segment Reporting Information [Line Items]
Revenues									6,426	246	1,003
Eliminations \| Other
Segment Reporting Information [Line Items]
Revenues									$ 1,982	$ 1,881	$ 1,615

SEGMENT REPORTING - Summary of Revenue Attributable to Services Provided by Company (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue from External Customer [Line Items]
Revenues	$ 174,724	$ 172,832	$ 165,649	$ 147,455	$ 151,222	$ 160,269	$ 154,016	$ 133,802	$ 660,660	$ 599,309	$ 565,030
Revenues percentage									100.00%	100.00%	100.00%
Collection
Revenue from External Customer [Line Items]
Revenues									$ 303,418	$ 263,688	$ 249,640
Revenues percentage									45.90%	44.00%	44.20%
Disposal
Revenue from External Customer [Line Items]
Revenues									$ 181,110	$ 160,073	$ 154,211
Revenues percentage									27.40%	26.70%	27.30%
Power generation
Revenue from External Customer [Line Items]
Revenues									$ 5,129	$ 5,375	$ 5,921
Revenues percentage									0.80%	0.90%	1.00%
Processing
Revenue from External Customer [Line Items]
Revenues									$ 7,174	$ 7,994	$ 6,282
Revenues percentage									1.10%	1.30%	1.10%
Solid waste operations
Revenue from External Customer [Line Items]
Revenues									$ 496,831	$ 437,130	$ 416,054
Revenues percentage									75.20%	72.90%	73.60%
Organics
Revenue from External Customer [Line Items]
Revenues									$ 54,174	$ 39,815	$ 41,587
Revenues percentage									8.20%	6.60%	7.40%
Customer solutions
Revenue from External Customer [Line Items]
Revenues									$ 67,464	$ 60,057	$ 54,478
Revenues percentage									10.20%	10.10%	9.60%
Recycling
Revenue from External Customer [Line Items]
Revenues									$ 42,191	$ 62,307	$ 52,911
Revenues percentage									6.40%	10.40%	9.40%

QUARTERLY FINANCIAL INFORMATION (UNAUDITED) (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Revenues	$ 174,724	$ 172,832	$ 165,649	$ 147,455	$ 151,222	$ 160,269	$ 154,016	$ 133,802	$ 660,660	$ 599,309	$ 565,030
Operating income (loss)	(5,138)	28,884	15,149	838	9,855	18,277	(47,279)	6,564	39,733	(12,583)	44,945
Net (loss) income	$ (13,676)	$ 22,302	$ 1,704	$ (3,910)	$ 20,020	$ 12,080	$ (53,675)	$ (224)	$ 6,420	$ (21,799)	$ (6,858)
Earnings per common share:
Basic weighted average shares outstanding (in shares)	42,936	42,779	42,661	42,370	42,033	41,951	41,811	41,584	42,688	41,846	41,233
Basic earnings per common share (in dollars per share)	$ (0.32)	$ 0.52	$ 0.04	$ (0.09)	$ 0.48	$ 0.29	$ (1.28)	$ (0.01)	$ 0.15	$ (0.52)	$ (0.17)
Diluted weighted average shares outstanding (in shares)	42,936	44,175	43,916	42,370	43,394	43,295	41,811	41,584	44,168	41,846	41,233
Diluted earnings per common share (in dollars per share)	$ (0.32)	$ 0.50	$ 0.04	$ (0.09)	$ 0.46	$ 0.28	$ (1.28)	$ (0.01)	$ 0.15	$ (0.52)	$ (0.17)

Schedule II - Valuation Accounts (Detail) - Allowance for Credit Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	$ 809	$ 1,069	$ 988
Additions—charged to expense	1,620	290	1,107
Deductions—bad debts written off, net of recoveries	(1,498)	(550)	(1,026)
Balance at end of period	$ 931	$ 809	$ 1,069

Label	Element	Value
Retained Earnings [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 18,000

REVENUE RECOGNITION (Details) - USD ($) $ in Thousands	12 Months Ended
REVENUE RECOGNITION (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	$ 660,660	$ 599,309	$ 565,030
Eastern
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	206,473
Western
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	286,262
Recycling
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	42,191
Other
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	125,734
Collection
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	306,939
Collection \| Eastern
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	136,661
Collection \| Western
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	170,278
Collection \| Recycling
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	0
Collection \| Other
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	0
Landfill
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	94,986
Landfill \| Eastern
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	28,419
Landfill \| Western
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	66,567
Landfill \| Recycling
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	0
Landfill \| Other
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	0
Transfer
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	67,583
Transfer \| Eastern
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	39,991
Transfer \| Western
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	27,592
Transfer \| Recycling
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	0
Transfer \| Other
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	0
Customer solutions
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	67,464
Customer solutions \| Eastern
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	0
Customer solutions \| Western
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	0
Customer solutions \| Recycling
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	0
Customer solutions \| Other
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	67,464
Recycling
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	46,019
Recycling \| Eastern
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	5
Recycling \| Western
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	3,823
Recycling \| Recycling
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	42,191
Recycling \| Other
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	0
Organics
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	54,174
Organics \| Eastern
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	0
Organics \| Western
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	0
Organics \| Recycling
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	0
Organics \| Other
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	54,174
Transportation
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	18,366
Transportation \| Eastern
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	0
Transportation \| Western
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	14,270
Transportation \| Recycling
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	0
Transportation \| Other
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	4,096
Landfill gas-to-energy
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	5,129
Landfill gas-to-energy \| Eastern
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	1,397
Landfill gas-to-energy \| Western
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	3,732
Landfill gas-to-energy \| Recycling
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	0
Landfill gas-to-energy \| Other
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	0
Transferred at a point-in-time
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	32,974
Transferred at a point-in-time \| Eastern
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	648
Transferred at a point-in-time \| Western
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	1,145
Transferred at a point-in-time \| Recycling
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	27,260
Transferred at a point-in-time \| Other
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	3,921
Transferred over time
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	627,686
Transferred over time \| Eastern
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	205,825
Transferred over time \| Western
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	285,117
Transferred over time \| Recycling
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	14,931
Transferred over time \| Other
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total revenues	$ 121,813