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Document and Entity Information - USD ($) $ in Millions	12 Months Ended
Document and Entity Information - USD ($) $ in Millions	Dec. 31, 2017	Feb. 14, 2018	Jun. 30, 2017
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	Accelerated Filer
Document Type	10-K
Document Period End Date	Dec. 31, 2017
Document Period End Date	2017
Document Fiscal Period Focus	FY
Amendment Flag	false
Trading Symbol	CWST
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Public Float			$ 639.8
Class A Common Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		41,294,290
Class B Common Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		988,200

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
CURRENT ASSETS:
Cash and cash equivalents	$ 1,995	$ 2,544
Accounts receivables - trade, net of allowance for doubtful accounts of $809 and $1,069, respectively	65,953	61,196
Refundable income taxes	522	654
Prepaid expenses	8,299	7,989
Inventory	6,534	4,915
Other current assets	1,077	1,290
Total current assets	84,380	78,588
Property, plant and equipment, net of accumulated depreciation and amortization of $811,474 and $837,122, respectively	361,547	398,466
Goodwill	122,605	119,899
Intangible assets, net	8,149	7,696
Restricted assets	1,220	1,002
Cost method investments	12,333	12,333
Deferred income taxes	11,567	0
Other non-current assets	13,148	13,528
Total assets	614,949	631,512
CURRENT LIABILITIES:
Current maturities of long-term debt and capital leases	4,926	4,686
Accounts payable	47,081	44,997
Accrued payroll and related expenses	12,183	12,505
Accrued interest	2,093	4,654
Current accrued capping, closure and post-closure costs	3,035	668
Other accrued liabilities	19,251	14,916
Total current liabilities	88,569	82,426
Long-term debt and capital leases, less current portion	477,576	503,961
Accrued capping, closure and post-closure costs, less current portion	59,255	43,539
Deferred income taxes	2,305	6,178
Other long-term liabilities	25,106	19,958
COMMITMENTS AND CONTINGENCIES
Casella Waste Systems, Inc. stockholders' deficit:
Additional paid-in capital	356,638	348,434
Accumulated deficit	(395,107)	(373,308)
Accumulated other comprehensive income (loss), net of tax	184	(68)
Total Casella Waste Systems, Inc. stockholders' deficit	(37,862)	(24,526)
Noncontrolling interests	0	(24)
Total stockholders' deficit	(37,862)	(24,550)
Total liabilities and stockholders' deficit	614,949	631,512
Class A Common Stock
Casella Waste Systems, Inc. stockholders' deficit:
Common stock	413	406
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, 2017 USD ($) vote $ / shares shares	Dec. 31, 2016 USD ($) vote $ / shares shares
Accounts receivable - trade, allowance for doubtful accounts \| $	$ 809	$ 1,069
Property, plant and equipment, accumulated depreciation and amortization \| $	$ 811,474	$ 837,122
Class A Common Stock
Common stock, par value (in dollars per share) \| $ / shares	$ 0.01	$ 0.01
Common stock, authorized shares (in shares)	100,000,000	100,000,000
Common stock, issued shares (in shares)	41,298,000	40,572,000
Common stock, outstanding shares (in shares)	41,298,000	40,572,000
Common stock, votes (in votes per share) \| vote	1
Class B Common Stock
Common stock, par value (in dollars per share) \| $ / shares	$ 0.01	$ 0.01
Common stock, authorized shares (in shares)	1,000,000	1,000,000
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, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
Revenues	$ 599,309	$ 565,030	$ 546,500
Operating expenses:
Cost of operations	405,188	381,973	382,615
General and administration	79,243	75,356	72,892
Depreciation and amortization	62,102	61,856	62,704
Southbridge Landfill closure charge	65,183	0	0
Expense from divestiture, acquisition and financing costs	176	0	0
Environmental remediation charge	0	900	0
Contract settlement charge	0	0	1,940
Divestiture transactions	0	0	(5,517)
Total operating expenses	611,892	520,085	514,634
Operating (loss) income	(12,583)	44,945	31,866
Other expense (income):
Interest income	(273)	(290)	(330)
Interest expense	25,160	38,942	40,420
Loss on debt extinguishment	517	13,747	999
Loss on derivative instruments	0	0	227
Impairment of investments	0	0	2,099
Other income	(935)	(1,090)	(1,119)
Other expense, net	24,469	51,309	42,296
Loss before income taxes	(37,052)	(6,364)	(10,430)
(Benefit) provision for income taxes	(15,253)	494	1,351
Net loss	(21,799)	(6,858)	(11,781)
Less: Net (loss) income attributable to noncontrolling interests	0	(9)	1,188
Net loss attributable to common stockholders	(21,799)	(6,849)	(12,969)
Net loss attributable to common stockholders:
Net loss attributable to common stockholders	$ (21,799)	$ (6,849)	$ (12,969)
Weighted average common shares outstanding:
Basic and diluted (in shares)	41,846	41,233	40,642
Basic and diluted earnings per share:
Net loss per common share (in dollars per share)	$ (0.52)	$ (0.17)	$ (0.32)

CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net loss	$ (21,799)	$ (6,858)	$ (11,781)
Other comprehensive income (loss), net of taxes:
Interest rate swap settlements	(410)	0	0
Interest rate swap amounts reclassified into interest expense	421	0	0
Unrealized gain resulting from changes in fair value of derivative instruments	155	0	0
Unrealized gain (loss) resulting from changes in fair value of marketable securities	86	(75)	(51)
Other comprehensive income (loss), net of taxes	252	(75)	(51)
Comprehensive loss	(21,547)	(6,933)	(11,832)
Less: Net (loss) income attributable to noncontrolling interests	0	(9)	1,188
Comprehensive loss attributable to common stockholders	$ (21,547)	$ (6,924)	$ (13,020)

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, 2014	$ (12,020)	$ 340,773	$ (353,490)	$ 58	$ 233		$ 396		$ 10
Beginning balance (in shares) at Dec. 31, 2014							39,587		988
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(11,781)		(12,969)		1,188
Other comprehensive (loss) income	(51)			(51)
Issuances of Class A common stock	486	481					$ 5
Issuances of Class A common stock (in shares)							477
Stock-based compensation	3,079	3,079
Distributions to noncontrolling interest holder	(1,495)				(1,495)
Other	185	185			0
Ending balance at Dec. 31, 2015	(21,597)	344,518	(366,459)	7	(74)		$ 401		$ 10
Ending balance (in shares) at Dec. 31, 2015						40,064	40,064	988	988
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net 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
Other	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 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

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash Flows from Operating Activities:
Net loss	$ (21,799)	$ (6,858)	$ (11,781)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization	62,102	61,856	62,704
Depletion of landfill operating lease obligations	9,646	9,295	9,428
Interest accretion on landfill and environmental remediation liabilities	4,482	3,606	3,449
Amortization of debt issuance costs and discounts on long-term debt	2,692	3,881	3,977
Stock-based compensation	6,432	3,393	3,079
Environmental remediation charge	0	900
Loss (gain) on sale of property and equipment	49	(574)	0
Southbridge Landfill non-cash closure charge	63,526	0	0
Divestiture transactions	0	0	(5,517)
Loss on debt extinguishment	517	13,747	999
Loss on derivative instruments	0	0	227
Impairment of investments	0	0	2,099
Excess tax benefit on the vesting of share based awards	0	0	(185)
Deferred income taxes	(15,525)	583	795
Changes in assets and liabilities, net of effects of acquisitions and divestitures:
Accounts receivable	(4,664)	(1,029)	(4,419)
Accounts payable	2,084	76	(3,597)
Prepaid expenses, inventories and other assets	(1,404)	(2,256)	5,240
Accrued expenses and other liabilities	(600)	(6,186)	4,140
Net cash provided by operating activities	107,538	80,434	70,507
Cash Flows from Investing Activities:
Acquisitions, net of cash acquired	(5,056)	(2,839)	0
Acquisition related additions to property, plant and equipment	(469)	(38)	0
Additions to property, plant and equipment	(64,393)	(54,200)	(49,995)
Payments on landfill operating lease contracts	(7,240)	(7,249)	(5,385)
Proceeds from divestiture transactions	0	0	5,335
Proceeds from sale of property and equipment	711	1,362	715
Proceeds from property insurance settlement	0	0	546
Net cash used in investing activities	(76,447)	(62,964)	(48,784)
Cash Flows from Financing Activities:
Proceeds from long-term borrowings	185,500	604,850	355,229
Principal payments on long-term debt	(216,966)	(608,198)	(370,996)
Change in restricted cash	0	1,347	4,471
Payments of debt issuance costs	(1,452)	(8,146)	(9,025)
Payments of debt extinguishment costs	0	(7,219)	(146)
Proceeds from the exercise of share based awards	1,278	128	161
Excess tax benefit on the vesting of share based awards	0	0	185
Distribution to noncontrolling interest holders	0	0	(1,495)
Net cash used in financing activities	(31,640)	(17,238)	(21,616)
Net (decrease) increase in cash and cash equivalents	(549)	232	107
Cash and cash equivalents, beginning of period	2,544	2,312	2,205
Cash and cash equivalents, end of period	1,995	2,544	2,312
Supplemental Disclosures of Cash Flow Information:
Interest	25,029	42,712	35,232
Income taxes, net of refunds	146	274	282
Supplemental Disclosures of Non-Cash Investing and Financing Activities:
Non-current assets acquired through long-term obligations	$ 3,564	$ 2,299	$ 3,264

BASIS OF PRESENTATION	12 Months Ended
BASIS OF PRESENTATION	Dec. 31, 2017
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, major account and industrial services, discontinued operations and earnings from equity method investees, as applicable, 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, 2017

Accounting Changes and Error Corrections [Abstract]

Accounting Changes

A table providing a brief description of recent Accounting Standards Updates (“ASU”) to the Accounting Standards Codification (“ASC”) issued by the Financial Accounting Standards Board (“FASB”) deemed to have a potentially material effect on our consolidated financial statements upon adoption follows:

Accounting standards that are pending adoption at December 31, 2017



Standard	Description	Effect on the Financial Statements or Other Significant Matters

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. The amendments expand and refine hedge accounting for both financial and commodity risk components and align 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. This guidance is effective January 1, 2019 with early adoption permitted.



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. This guidance is effective January 1, 2018 with early adoption permitted.

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, 2017, 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 September 2017: 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 are currently assessing the provisions of this guidance and evaluating the impact the guidance will have on our consolidated financial statements and related disclosures. We are also in the process of aggregating lease documentation for review. The adoption of this ASU is expected to impact the balance sheet through the recognition of a right-of-use asset and a lease liability for all leases with terms in excess of 12 months. This guidance is effective January 1, 2019 using a modified retrospective transition approach with early adoption permitted.



ASU 2016-01: 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 results in a cumulative-effect adjustment to the balance sheet, the recognition of changes in fair value of certain equity investments in net income, and enhanced disclosure. This guidance is effective January 1, 2018 with a cumulative-effect adjustment, and will 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.	The adoption of this guidance requires using either a full retrospective approach for all periods presented or a modified retrospective approach with a cumulative effect adjustment to Retained Earnings as of the date of adoption. We adopted the guidance using the modified retrospective approach effective January 1, 2018 with no adjustment to Retained Earnings. We will record revenue when control is transferred to our customer, generally at the time that we provide services. 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, we concluded that we will not have a significant change to the timing of revenue recognition. We have identified certain consideration payable to customers that will be recorded as a reduction of revenues in accordance with Topic 606. These costs are currently recorded as a component of cost of operations. Additionally, 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 Retained Earnings or the accounting of these costs was deemed necessary. In assessing the impact of adopting the guidance on disclosures, we anticipate to have additional disclosures regarding the disaggregation of revenues by business segment, the presentation and roll forward of various contract asset and liability balances, changes to our accounting policy, as well as other significant judgments and disclosures regarding performance obligations and the implementation of the amended guidance.

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

12 Months Ended

Dec. 31, 2017

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 cash, accounts receivable-trade and derivative instruments. We maintain cash and cash equivalents and restricted cash 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, 2017, 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 disclosure over the amortization of landfill development costs and Note 6, 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, 2017 ("fiscal year 2017"), December 31, 2016 ("fiscal year 2016") and December 31, 2015 ("fiscal year 2015") was $295, $273 and $62, 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 (1.7% as of December 31, 2017). 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, 2017 is between approximately 9.2% and 9.9%, 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 $4,401, $3,606 and $3,370 in fiscal years 2017, 2016 and 2015, 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 8, 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 cash and investments. Surety bonds securing closure and post-closure obligations at December 31, 2017 and December 31, 2016 totaled $164,893 and $161,095, respectively. Letters of credit securing closure and post-closure obligations as of December 31, 2017 and December 31, 2016 totaled $0 and $0, respectively. See Note 5, Restricted Cash / Restricted Assets for disclosure over restricted cash securing closure and post-closure obligations.

Landfill Operating Lease Contracts

We are party to five 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 liabilities. 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 6, Property, Plant and Equipment for disclosure over depletion of landfill operating lease contracts.

Leases

We lease property and equipment in the ordinary course of our business. Our most significant lease obligations are for property and equipment specific to our industry. Our leases have varying terms. Some 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 classified as either 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 10, 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 lesser of 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 9, Long-Term Debt and Capital Leases for disclosure over our future maturities of debt, which includes capital lease payments.

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 7, 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 7, 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, 2017 and December 31, 2016, 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 cash and investments 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 9, Long-Term Debt and Capital Leases and Note 12, 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 4, 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 10, 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 2017 under the workers’ compensation plan was $1,000 per individual event. Our maximum exposure in fiscal year 2017 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 $14,480 and $13,707 as of December 31, 2017 and December 31, 2016, 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 14, 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 also 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 effective cash flow hedges, 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, 2017.

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 effective cash flow hedges, the change in fair value is recorded in our stockholders’ deficit as a component of accumulated other comprehensive income (loss) and included in interest expense at the same time as interest expense is affected by the hedged transaction. Differences paid or received over the life of the agreements are recorded as additions to or reductions of interest expense on the underlying debt.

For interest rate derivatives deemed to be ineffective cash flow hedges, the change in fair value is recorded through earnings and included in loss (gain) on derivative instruments. We were party to one interest rate swap deemed to be an ineffective cash flow hedge that matured on March 15, 2016 and were party to another interest rate swap deemed to be an ineffective cash flow hedge that was settled in fiscal year 2015 for $830 in conjunction with the refinancing of our senior revolving credit and letter of credit facility that was due March 18, 2016 (“Refinanced Revolving Credit Facility”).

See Note 12, Fair Value of Financial Instruments for fair value disclosure over derivative instruments.

In fiscal year 2017, we entered into three interest rate agreements to hedge interest rate risk associated with the variable rate portion of our long-term debt. The total notional amount of these agreements is $60,000 and requires us to receive interest based on changes in the 1-month LIBOR index with a 1.0% floor and pay interest at a weighted average rate of approximately 1.95%. Two of the agreements, with a total notional amount of $35,000, mature in February 2021, and the final agreement, with a total notional amount of $25,000, matures in February 2022. We have designated these derivative instruments as effective cash flow hedges.

In accordance with the derivatives and hedging guidance in FASB ASC 815 - Derivatives and Hedging, the effective portions of the changes in fair values of interest rate swaps have been recorded in equity as a component of accumulated other comprehensive income (loss), net of tax. As the critical terms of the interest rate swaps match the underlying debt being hedged, no ineffectiveness is recognized on these swaps and, therefore, all unrealized changes in fair value are recorded in accumulated other comprehensive income (loss), net of tax. Amounts are reclassified from accumulated other comprehensive income (loss), net of tax into earnings in the same period or periods during which the hedged transaction affects earnings.

As of December 31, 2017, we have recorded a derivative asset with a fair value of $401 in other non-current assets and a derivative liability with a fair value of $123 in other accrued liabilities associated with these cash flow hedges.

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 10, 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 4, Business Combinations for disclosure over a contingent liability assumed as part of the acquisition of a business.

Revenue Recognition

We recognize revenues for collection, transfer, recycling, disposal and other waste services as the services are provided. Certain customers are billed in advance and, accordingly, recognition of the related revenues is deferred until the services are provided.

Revenues from the sale of recycled materials are recognized upon shipment. Rebates to certain municipalities based on sales of recyclable materials are recorded upon the sale of such recyclables to third-parties and are included as a reduction of revenues. Revenues for processing of recyclable materials are recognized when the related service is provided. Revenues from the brokerage of recycled materials are recognized on a net basis at the time of shipment.

Effective January 1, 2018, we adopted ASU 2014-09, as amended, Revenue from Contracts with Customers.

See Note 2, Accounting Changes 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 15, 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 2017. As of December 31, 2017, 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 83.6%. We incurred no impairment of goodwill as a result of our annual goodwill impairment tests in each of fiscal years 2017, 2016 and 2015. 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, 2017, we owned 5.6% of the outstanding common stock of Recycle Rewards, Inc. (“Recycle Rewards”), a company that markets an incentive based recycling service. In fiscal year 2015, 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 2015, 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 $1,090 in fiscal year 2015. As of December 31, 2017, the carrying amount of our cost method investment in Recycle Rewards was $1,069.

As of December 31, 2017, 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. In fiscal year 2015, it was determined based on the operating performance and recent indications of third-party interest in GreenerU that our cost method investment in GreenerU was potentially impaired. A valuation analysis was performed by a third-party valuation specialist using a market approach based on an option pricing methodology to determine an equity value and fair market value per share for GreenerU. Based on this analysis, it was determined that the fair value of our cost method investment in GreenerU was less than the carrying amount and, therefore, we recorded an other-than-temporary investment impairment charge of $691 in fiscal year 2015. As of December 31, 2017, the carrying amount of our cost method investment in GreenerU was $309.

As of December 31, 2017, we owned 17.0% and 16.2% of the outstanding common stock of AGreen Energy LLC (“AGreen”) and BGreen Energy LLC (“BGreen”), respectively. In fiscal year 2015, AGreen and BGreen, both of which we account for as cost method investments, entered into agreements that resulted in the contribution and sale of certain assets and liabilities of AGreen and BGreen to a limited liability company in exchange for partial ownership interests in a parent of that limited liability company. As a result of the transactions, we performed an analysis to determine whether an other-than-temporary impairment in the carrying value of our cost method investments had occurred. Based on the analysis performed, which measured the fair value of our cost method investments using an in-exchange valuation premise under the market approach that utilized the estimated purchase consideration received, we recorded an other-than-temporary investment impairment charge of $318 in fiscal year 2015. As of December 31, 2017, 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 13, 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 11, 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.

Discontinued Operations

We analyze our operations that have been divested or classified as held-for-sale to determine if they qualify for discontinued operations accounting. A component of an entity, a group of components of an entity, or a business is required to be reported in discontinued operations once it meets the held for sale criteria, is disposed of by sale, or is disposed of other than by sale if the disposal represents a strategic shift that has, or will have, a major effect on an entity’s operations and financial results.

Subsequent Events

Except as disclosed, no material subsequent events have occurred since December 31, 2017 through the date of this filing that would require recognition or disclosure in our consolidated financial statements.

BUSINESS COMBINATIONS

12 Months Ended

Dec. 31, 2017

Business Combinations [Abstract]

BUSINESS COMBINATIONS

In January 2018, we acquired Complete Disposal Company, Inc. and its subsidiary United Material Management of Holyoke, Inc. (collectively, "Complete") in our Eastern region for total consideration of $16,500, subject to a purchase price adjustment.

Complete provides residential and roll-off collection services, operates a construction and demolition processing facility, and operates a solid waste transfer station with both truck and rail transfer capabilities.

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 various transfer stations. 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 2017 and 2016 are expected to be deductible for tax purposes. We did not acquire any businesses during fiscal year 2015.

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



	Fiscal Year Ended December 31,
	2017			2016			2015
Purchase Price:
Cash used in acquisitions, net of cash acquired	$	4,823		$	2,439		$	—
Notes payable	2,400			—			—
Other non-cash considerations	101			—			—
Contingent consideration and holdbacks	736			400			—
Total	8,060			2,839			—
Current assets	93			40			—
Land	—			353			—
Buildings	—			1,360			—
Equipment	2,994			269			—
Other liabilities, net	(49		)	(106		)	—
Intangible assets	2,334			—			—
Fair value of assets acquired and liabilities assumed	5,372			1,916			—
Excess purchase price to be allocated to goodwill	$	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, 2015.



	Fiscal Year Ended December 31,
	2017			2016			2015
Revenue	$	602,754		$	572,628		$	556,569
Operating (loss) income	$	(12,314	)	$	45,257		$	31,940
Net loss attributable to common stockholders	$	(21,647	)	$	(6,685	)	$	(12,947	)
Basic and diluted net loss per common share attributable to common stockholders	$	(0.52	)	$	(0.16	)	$	(0.32	)
Basic and diluted weighted average shares outstanding	41,846			41,233			40,642

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, 2015 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, 2017

Receivables [Abstract]

RESTRICTED ASSETS

Restricted assets consist of cash and investments 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,
	2017		2016
Non Current:
Restricted assets - landfill closure	$	1,220	$	1,002

PROPERTY, PLANT AND EQUIPMENT

12 Months Ended

Dec. 31, 2017

Property, Plant and Equipment [Abstract]

PROPERTY, PLANT AND EQUIPMENT

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



	December 31,
	2017			2016
Land	$	24,224		$	24,517
Landfills	513,548			570,464
Landfill operating lease contracts	114,462			133,239
Buildings and improvements	140,155			143,036
Machinery and equipment	139,029			132,748
Rolling stock	138,102			133,840
Containers	103,501			97,744
	1,173,021			1,235,588
Less: accumulated depreciation and amortization	(811,474		)	(837,122		)
	$	361,547		$	398,466

Depreciation expense for fiscal years 2017, 2016 and 2015 was $32,131, $33,186 and $33,168, respectively. Landfill amortization expense for fiscal years 2017, 2016 and 2015 was $27,910, $26,529 and $26,969, respectively. Depletion expense on landfill operating lease contracts for fiscal years 2017, 2016 and 2015 was $9,646, $9,295 and $9,428, respectively, and was recorded in cost of operations.

GOODWILL AND INTANGIBLE ASSETS

12 Months Ended

Dec. 31, 2017

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, 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



	December 31, 2015		Acquisitions		December 31, 2016
Eastern	$	17,429	$	—	$	17,429
Western	87,503		923		88,426
Recycling	12,315		—		12,315
Other	1,729		—		1,729
Total	$	118,976	$	923	$	119,899

A summary of intangible assets is as follows:



	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



	Covenants Not-to-Compete			Client Lists			Total
Balance, December 31, 2016
Intangible assets	$	17,594		$	16,071		$	33,665
Less accumulated amortization	(16,402		)	(9,567		)	(25,969		)
	$	1,192		$	6,504		$	7,696

Intangible amortization expense for fiscal years 2017, 2016 and 2015 was $2,061, $2,141 and $2,567, respectively.

The intangible amortization expense estimated for the five fiscal years following fiscal year 2017 and thereafter is as follows:




Estimated Future Amortization Expense as of December 31, 2017
For the fiscal year ending December 31, 2018	$	2,021
For the fiscal year ending December 31, 2019	$	1,637
For the fiscal year ending December 31, 2020	$	1,432
For the fiscal year ending December 31, 2021	$	1,128
For the fiscal year ending December 31, 2022	$	821
Thereafter	$	1,110

- 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, 2017

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,
	2017			2016
Beginning balance	$	44,207		$	41,041
Obligations incurred	3,022			2,441
Revisions in estimates (1)	11,498			(2,052		)
Accretion expense	4,401			3,606
Obligations settled (2)	(838		)	(829		)
Ending balance	$	62,290		$	44,207

(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 10, Commitments and Contingencies and Note 15, 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, 2017

Debt Disclosure [Abstract]

LONG TERM DEBT AND CAPITAL LEASES

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



	December 31,
	2017		2016
Senior Secured Credit Facility:
Revolving Credit Facility due October 2021; bearing interest at LIBOR plus 2.75%	$	36,000	$	62,600
Term Loan B Facility due October 2023; bearing interest at LIBOR plus 2.50%	346,500		350,000
Tax-Exempt Bonds:
New York State Environmental Facilities Corporation Solid Waste Disposal Revenue Bonds Series 2014 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		—
Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2015 due August 2035 - fixed rate interest period through 2025; bearing interest at 5.125%	15,000		15,000
Vermont Economic Development Authority Solid Waste Disposal Long-Term Revenue Bonds Series 2013 due April 2036 - fixed rate interest period through 2018; bearing interest at 4.75%	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
Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2005R-2 due January 2025 - fixed rate interest period through 2017; bore interest at 6.25%	—		21,400
Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2005R-1; letter of credit backed due January 2025 - bore interest at SIFMA Index	—		3,600
Other:
Capital leases maturing through September 2023; bearing interest at up to 7.70%	5,595		5,534
Notes payable maturing through June 2027; bearing interest at up to 7.00%	2,585		449
Principal amount of long-term debt and capital leases	497,680		525,583
Less—unamortized discount and debt issuance costs (1)	15,178		16,936
Long-term debt and capital leases less unamortized discount and debt issuance costs	482,502		508,647
Less—current maturities of long-term debt	4,926		4,686
	$	477,576	$	503,961


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



	December 31,
	2017		2016
Revolving Credit Facility	$	3,938	$	4,965
Term Loan B Facility (including unamortized discount of $1,482 and $1,712)	7,392		7,718
New York State Environmental Facilities Corporation Solid Waste Disposal Revenue Bonds Series 2014	1,034		1,221
New York State Environmental Facilities Corporation Solid Waste Disposal Revenue Bonds Series 2014R-2	511		571
Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2005R-3	603		—
Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2015	691		760
Vermont Economic Development Authority Solid Waste Disposal Long-Term Revenue Bonds Series 2013	573		605
Business Finance Authority of the State of NH Solid Waste Disposal Revenue Bonds Series 2013	436		563
Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2005R-2	—		502
Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2005R-1	—		31
	$	15,178	$	16,936

Credit Facility

In fiscal year 2016, we entered into a credit agreement ("Credit Agreement"), which provides for a $350,000 aggregate principal amount term loan B facility ("Term Loan B Facility") and a $160,000 revolving line of credit facility ("Revolving Credit Facility" and, together with the Term Loan B Facility, the "Credit Facility"). The net proceeds from this transaction were used to repay in full our senior secured asset-based revolving credit and letter of credit facility ("ABL Facility") and to redeem all of our remaining outstanding 7.75% Senior Subordinated Notes due 2019 ("2019 Notes") at a redemption price equal to 101.938% of the principal amount thereof 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 of $100,000, subject to the terms and conditions set forth in the Credit Agreement.

The Term Loan B Facility has a 7-year term and initially bore interest at a rate of LIBOR plus 3.00% per annum (with a 1.00% LIBOR floor), which would be reduced to a rate of LIBOR plus 2.75% upon us reaching a consolidated net leverage ratio of 3.75x or less. The Revolving Credit Facility has a 5-year term and initially bore interest at a rate of LIBOR plus 3.00% per annum, which is adjusted from an applicable rate of LIBOR plus 2.50% to 3.25% depending on our consolidated net leverage ratio. In fiscal year, 2017, we entered into the first amendment (“Repricing Amendment”) to the Credit Agreement. The Repricing Amendment decreased the applicable interest margin for our Term Loan B Facility by 25 basis points for both LIBOR borrowings and base rate borrowings. The applicable interest rate margin is determined based on our consolidated net leverage ratio, with the interest rate initially set at 2.75% for LIBOR borrowings (with a 1.00% LIBOR floor) and 1.75% for base rate borrowings. The applicable interest rate is reduced to 2.50% for LIBOR borrowings (with a 1.00% LIBOR floor), and 1.50% for base rate borrowings upon us reaching a consolidated net leverage ratio of 3.75x or less, which was the case at December 31, 2017.

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, 2017, further advances were available under the Revolving Credit Facility in the amount of $101,457. The available amount is net of outstanding irrevocable letters of credit totaling $22,543, 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, 2017, 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. In fiscal year 2016, we completed a financing transaction involving the issuance by the New York State Environmental Facilities Corporation of $15,000 aggregate principal amount of Solid Waste Disposal Revenue Bonds Series 2014R-2 (“New York Bonds 2016”).

As of December 31, 2017, we had outstanding $40,000 aggregate principal amount of Solid Waste Disposal Revenue Bonds Series 2014 ("New York Bonds 2014") and New York Bonds 2016 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 2014 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 2016 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 2017, we completed the remarketing of $3,600 aggregate principal amount of Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2005R-1 and $21,400 aggregate principal amount of Finance Authority of Maine Solid Waste Disposal Revenue Bonds Serires 2005R-2 as one series of bonds known as $25,000 aggregate principal amount of Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2005R-3 (“FAME Bonds 2005R-3”).

As of December 31, 2017, we had outstanding $25,000 aggregate principal amount of FAME Bonds 2005R-3. The FAME Bonds 2005R-3, which are unsecured and guaranteed jointly and severally, fully and unconditionally by all of our significant wholly-owned subsidiaries, 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.

As of December 31, 2017, we had outstanding $15,000 aggregate principal amount of senior unsecured Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2015 ("FAME Bonds 2015"). The FAME Bonds 2015, which are unsecured and guaranteed jointly and severally, fully and unconditionally by all of our significant wholly-owned subsidiaries, 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. During the fixed interest rate period, the FAME Bonds 2015 are not be supported by a letter of credit. Interest is payable semiannually in arrears on February 1 and August 1 of each year. An additional $15,000 aggregate principal amount of FAME Bonds 2015 may be offered under the same indenture in the future. The FAME Bonds 2015 mature on August 1, 2035. We borrowed the proceeds of the offering of the FAME Bonds 2015 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 2015.

Vermont Bonds. As of December 31, 2017, we had outstanding $16,000 aggregate principal amount of senior unsecured Vermont Economic Development Authority Solid Waste Disposal Long-Term Revenue Bonds Series 2013 (“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 4.75% per annum through April 1, 2018, at which time they may be converted from a fixed rate to a variable rate. During the fixed interest rate period, the Vermont Bonds are not be supported by a letter of credit. Interest is payable semiannually in arrears on April 1 and October 1 of each year. 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, 2017, 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

We recorded a loss on debt extinguishment in fiscal years 2017, 2016 and 2015 of $517, $13,747 and $999, respectively, associated with the following:


•	the write-off of debt issuance costs in connection with the Repricing Amendment in fiscal year 2017;


•	the write-off of debt issuance costs in connection with the remarketing of the FAME Bonds 2005R-1 and the FAME Bonds 2005R-2 into the FAME Bonds 2005R-3 in fiscal year 2017;


•	the write-off of debt issuance costs in connection with changes to the borrowing capacity from our ABL Facility to the Credit Facility in fiscal year 2016;


•	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 2019 Notes in fiscal years 2016 and 2015; and


•	the write-off of debt issuance costs in connection with changes to the borrowing capacity from our Refinanced Revolving Credit Facility to the ABL Facility in fiscal year 2015.

Interest Expense

The components of interest expense are as follows:



	Fiscal Year Ended December 31,
	2017			2016			2015
Interest expense on long-term debt and capital leases	$	22,060		$	34,741		$	35,868
Amortization of debt issuance costs and discount on long-term debt	2,692			3,881			3,977
Letter of credit fees	703			593			637
Less: capitalized interest	(295		)	(273		)	(62		)
Total interest expense	$	25,160		$	38,942		$	40,420

Fair Value of Debt

As of December 31, 2017, the fair value of our fixed rate debt, including the FAME Bonds 2005R-3, FAME Bonds 2015, Vermont Bonds, New York Bonds and New Hampshire Bonds was approximately $106,344 and the carrying value was $107,000. The fair value of the FAME Bonds 2005R-3, FAME Bonds 2015, 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, 2017, the fair value of our Term Loan B Facility was approximately $347,799 and the carrying value was $346,500. The fair value of the Term Loan B Facility is considered to be Level 2 within the fair value hierarchy as its fair value is based off of quoted market prices in a principal to principal market with limited public information. As of December 31, 2017, the fair value of our Revolving Credit Facility approximated its carrying value of $36,000 based on current borrowing rates for similar types of borrowing arrangements, or Level 2 inputs.

Although we have determined the estimated fair value amounts of the Term Loan B Facility, FAME Bonds 2005R-3, FAME Bonds 2015, 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, 2017
2018	$	4,926
2019	5,002
2020	5,269
2021	40,773
2022	4,279
Thereafter	437,431
	$	497,680

COMMITMENTS AND CONTINGENCIES

12 Months Ended

Dec. 31, 2017

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 $20. 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 $12,242, $11,437 and $9,392 fiscal years 2017, 2016 and 2015, 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, 2017
2018	$	18,465
2019	14,365
2020	10,511
2021	7,905
2022	5,705
Thereafter	33,760
Total minimum lease payments	$	90,711

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, 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. 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.

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 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 due to the infancy of this matter. 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.

We entered into an Administrative Consent Order on April 26, 2017 (the “ACO”), with MADEP, the Town, and the Town of Charlton ("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.

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,
	2017			2016
Beginning balance	$	—		$	—
Accretion expense	82			—
Obligations incurred	6,379			—
Obligations settled (1)	(525		)	—
Ending balance	$	5,936		$	—


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

Charlton has also demanded that we relocate retention ponds incident to the operation of the Southbridge Landfill, and that we pay damages to Charlton for the use of such retention ponds during the operation of the Southbridge Landfill. We disagree with Charlton as to the legality of the location of those retention ponds in Charlton, and are vigorously contesting claims made by Charlton. We cannot currently estimate the potential for loss associated with Charlton’s claim against us, and it is possible that we could incur a material loss in the resolution of such claim.

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. We are in the discovery phase of this litigation. Steadfast has 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 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 expect to cease operations at the Southbridge Landfill when no further capacity is available, expected by no later than December 31, 2018. We delivered correspondence to the Town to this effect on August 3, 2017, citing events of Change in Law and Force Majeure pursuant to our May 29, 2007 Extension Agreement with the Town ("Extension Agreement") and the impacts of such events on further expansion of the Southbridge Landfill. We have advised the Town that we see no economically feasible way to operate the Southbridge Landfill beyond its current permitted life and we have filed a closure plan with MADEP. Following cessation of operations, we will proceed 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. 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 the Extension Agreement, which we account for as an operating lease, there are potential contractual obligations and commitments, including future cash payments of $3,069 and services that extend beyond the current useful life of the Southbridge Landfill. 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. We may incur a loss associated with these potential contractual obligations upon cessation of operations at the Southbridge Landfill when remaining capacity is exhausted by the placement of waste at the site.

See Note 15, Other Items and Charges for disclosure over the Southbridge Landfill closure charge.

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 unlikely that any significant expenditures relating to onsite remediation will be incurred until the 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,
	2017			2016
Beginning balance	$	5,866		$	5,221
Payments	(108		)	(255		)
Obligations incurred	—			900
Ending balance	$	5,758		$	5,866

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, 2017
2018	$	865
2019	4,339
2020	755
2021	403
2022	385
Thereafter	6,621
Total	$	13,368

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	$	13,368
Less discount, net	(1,674		)
Liability balance - December 31, 2017	$	11,694

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 $1,785. 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, 2017

Equity [Abstract]

STOCKHOLDERS' EQUITY

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, 2017 and December 31, 2016 we had no shares issued.

Stock Based Compensation

Stock Incentive Plans

1997 Stock Option Plan. In the fiscal year ended April 30, 1998, we adopted the 1997 Stock Option Plan (“1997 Plan”). The 1997 Plan terminated as of July 31, 2007 and as a result no additional awards may be made pursuant to the 1997 Plan. Outstanding shares which are not actually issued under the 1997 Plan because such stock options expire or otherwise result in shares not being issued are reserved for issuance under the 2006 Plan.

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, 2017, there were 1,930 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 (1)		Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (years)	Aggregate Intrinsic Value
Outstanding, December 31, 2016	1,115		$	6.13
Granted	—		$	—
Exercised	(361	)	$	6.20
Forfeited or expired	(27	)	$	13.17
Outstanding, December 31, 2017	727		$	5.82	6.3	$	12,495
Exercisable, December 31, 2017	527		$	4.81	5.7	$	9,590
Unvested, December 31, 2017	240		$	9.16	8.3	$	3,326


(1)	Market-based performance stock option grants are included at 100%. Attainment of maximum performance targets and market achievements would result in the issuance of 40 shares of Class A common stock currently included in unvested.

During fiscal years 2017, 2016 and 2015, stock-based compensation expense for stock options was $644, $605 and $671, respectively.

During fiscal years 2017, 2016 and 2015, the aggregate intrinsic value of stock options exercised was $4,664, $22 and $52, respectively.

As of December 31, 2017, total unrecognized stock-based compensation expense related to all outstanding stock options, assuming the attainment of maximum performance targets, was $474, which will be recognized over a weighted average period of 0.7 years.

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. The weighted average fair value of stock options granted, with the exception of market-based performance stock option grants, during fiscal years 2017, 2016 and 2015 were $0.00, $0.00 and $5.35 per option, respectively, which were calculated assuming no expected dividend yield using the following weighted average assumptions:



	Fiscal Year Ended December 31,
	2017 (1)		2016 (1)		2015
Expected life	0.0 years		0.0 years		7.2 years
Risk-free interest rate	—	%	—	%	2.02	%
Expected volatility	—	%	—	%	81.31	%


(1)	In fiscal years 2017 and 2016, we only granted market-based performance stock options, which are discussed separately below.

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, 2016	1,099		$	7.03
Granted	439		$	12.32
Class A common stock vested	(420	)	$	5.21
Forfeited or canceled	(27	)	$	6.31
Outstanding, December 31, 2017	1,091		$	9.81	1.3	$	14,409
Unvested, December 31, 2017	1,453		$	10.48	1.3	$	18,216


(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 362 shares of Class A common stock currently included in unvested.

During fiscal years 2017, 2016 and 2015, stock-based compensation expense related to restricted stock, restricted stock units and performance stock units was $5,652, $2,673 and $2,314, respectively. Stock-based compensation expense related to restricted stock and restricted stock units during fiscal year 2015 included $270 of incremental compensation expense resulting from the modification of restricted stock associated with the retirement of two members of our Board of Directors.

During fiscal years 2017, 2016 and 2015, the total fair value of other stock awards vested was $5,706, $3,238 and $2,340, respectively.

As of December 31, 2017, total unrecognized stock-based compensation expense related to restricted stock and restricted stock units was $2,945, 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 $5,268, which will be recognized over a weighted average period of 1.5 years.

During fiscal years 2017, 2016 and 2015, the weighted-average grant date fair value of restricted stock, restricted stock units and performance stock units granted was $12.32, $8.97 and $4.40, respectively. The weighted average fair value of market-based performance stock units granted during fiscal year 2017 was $12.51 per award, which was calculated using a Monte Carlo pricing model assuming a risk free interest rate of 1.45% and an expected volatility of 32.80% 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 $136, $115 and $94 of stock-based compensation expense related to our Amended and Restated 1997 Employee Stock Purchase Plan during fiscal years 2017, 2016 and 2015, respectively.

There was $117 of tax provision in the (benefit) provision for income taxes associated with stock-based compensation during fiscal year 2017. There was $0 and $19 of tax benefit in the (benefit) provision for income taxes associated with stock-based compensation expense in fiscal years 2016 and 2015, respectively. We recorded a tax benefit of $0, $0 and $185 to additional paid-in-capital related to the exercise of various share based awards in fiscal years 2017, 2016 and 2015, respectively. Effective fiscal year 2016, tax savings from stock-based compensation resulting from tax deductions in excess of expense are no longer reflected as a financing cash flow in our consolidated financial statements.

Accumulated Other Comprehensive Income (Loss)

Accumulated other comprehensive income (loss) 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 income (loss) are as follows:



	Marketable Securities			Interest Rate Swaps			Total
Balance as of December 31, 2014	$	58		$	—		$	58
Other comprehensive loss	(51		)	—			(51		)
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	86			(255		)	(169		)
Amounts reclassified from accumulated other comprehensive income (loss)	—			421			421
Other comprehensive income, net	86			166			252
Balance as of December 31, 2017	$	18		$	166		$	184

A summary of reclassifications out of accumulated other comprehensive income (loss) for fiscal years 2017, 2016 and 2015 is as follows:



	Fiscal Year Ended December 31,
	2017		2016		2015
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	$	421	$	—	$	—	Interest expense
	421		—		—		Loss before income taxes
	—		—		—		(Benefit) provision for income taxes
	$	421	$	—	$	—	Net loss

FAIR VALUE OF FINANCIAL INSTRUMENTS

12 Months Ended

Dec. 31, 2017

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 cash and investments 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 cash and investments 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 9, 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, 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 assets - landfill closure	$	1,220	$	—	$	—
Interest rate swaps	—		401		—
	$	1,220	$	401	$	—
Liabilities:
Interest rate swaps	$	—	$	123	$	—



	Fair Value Measurement at December 31, 2016 Using:
	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Restricted assets - landfill closure	$	1,002	$	—	$	—

- 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, 2017

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 2017, 2016 and 2015 amounted to $1,187, $1,119 and $1,033, 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 2017, 2016 and 2015, 41, 70 and 80 shares, respectively, of Class A common stock were issued under this plan. As of December 31, 2017, 143 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,
		2017	2016		2017		2016		2015
New England Teamsters and Trucking Industry Pension Fund	04-6372430	Critical and declining	Critical	Implemented	$	627	$	523	$	413	June 30, 2020

The status is based on the latest plan information for the plan year ended September 30, 2017 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% and have a projected funding deficiency in the current or next four plan years and has 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, 2016 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, 2017.

INCOME TAXES

12 Months Ended

Dec. 31, 2017

Income Tax Disclosure [Abstract]

INCOME TAXES

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



	Fiscal Year Ended December 31,
	2017			2016			2015
Federal
Current	$	—		$	—		$	2,899
Current benefit of loss carryforwards	—			—			(2,899		)
Deferred	(15,614		)	458			395
	(15,614		)	458			395
State
Current	301			(90		)	1,112
Current benefit of loss carryforwards	(28		)	—			(557		)
Deferred	88			126			401
	361			36			956
(Benefit) provision for income taxes	$	(15,253	)	$	494		$	1,351

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 have not been adjusted.

Included in the current state tax provision for fiscal year 2015 is a $180 settlement with New York State, comprised of $168 of tax and $12 of interest. New York State had alleged that we were not permitted to file a single combined corporation franchise tax return with our subsidiaries. We believe that our position related to the filing of our New York State tax returns was correct, and, based on the prior settlement related to 2004 to 2010 tax returns and subsequent favorable litigation related to similar issues, we concluded at December 31, 2014 that no reserve would be required for our New York State filings. During fiscal year 2015, we reached the $180 settlement with the New York State for the tax years ended April 30, 2011 through April 30, 2013 on a basis similar to the prior settlement to minimize out-of-pocket costs. The settlement, which represented less than 8% of the potential cumulative liability for the years settled, was a monetary settlement without any change to our filing combined returns in New York and it closed tax years ending April 30, 2011 through April 30, 2013. Due to a change in law, we have elected to file a single combined corporation franchise tax return with our subsidiaries in New York beginning with 2015. We have not established any reserve under ASC 740 for the tax years ended April 30, 2014 and December 31, 2014, since we believe our position would more likely than not be successful.

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,
	2017			2016			2015
Federal statutory rate	35		%	35		%	35		%
Tax at statutory rate	$	(12,968	)	$	(2,228	)	$	(3,650	)
State income taxes, net of federal benefit	(1,959		)	(265		)	198
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 due to federal rate change	(18,848		)	4,370			5,272
Deductible stock awards	(1,825		)	—			—
Tax credits	(1,000		)	(1,085		)	(671		)
Non-deductible expenses	542			100			467
Non-deductible equity income in subsidiaries	—			—			(415		)
Other, net	(137		)	(398		)	150
(Benefit) provision for income taxes	$	(15,253	)	$	494		$	1,351

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,
	2017			2016
Deferred tax assets:

Net operating loss carryforwards	$	33,228		$	46,846
Accrued expenses and reserves	26,572			32,185
Book over tax depreciation of property and equipment	25,615			30,012
General business tax credit carryforwards	5,439			4,433
Alternative minimum tax credit carryforwards	3,804			3,804
Stock awards	1,958			1,720
Other	2,050			2,806
Total deferred tax assets	98,666			121,806
Less: valuation allowance	(68,355		)	(97,589		)
Total deferred tax assets after valuation allowance	30,311			24,217
Deferred tax liabilities:
Amortization of intangibles	(20,904		)	(30,296		)
Other	(145		)	(99		)
Total deferred tax liabilities	(21,049		)	(30,395		)
Net deferred tax asset (liability)	$	9,262		$	(6,178	)

The net deferred tax asset at December 31, 2017 is reflected on the balance sheet as a long-term deferred federal tax asset of $11,567 and a long-term deferred state tax liability of ($2,305).

As of December 31, 2017, we have, for federal income tax purposes, net operating loss carryforwards of approximately $101,187 that expire in the fiscal years ending December 31, 2031 through 2037 and state net operating loss carryforwards of approximately $114,362 that expire in the fiscal years ending December 31, 2018 through 2037. In addition, we have $3,804 minimum tax credit carryforwards which become refundable beginning in 2018 and will be fully refunded, if not otherwise used to offset tax liabilities, in tax year 2021. We also have $5,439 general business credit carryforwards which expire in the fiscal years ending December 31, 2023 through 2037. 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. 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 a decrease of ($29,234) for fiscal year 2017 and an increase of $4,582 for fiscal year 2016. 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, the availability of tax planning strategies, 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 asset as of December 31, 2017 and net deferred tax liability as of December 31, 2016 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 the year 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,
	2017			2016
Unrecognized tax benefits at beginning of period	$	3,107		$	3,379
Gross increases for tax positions of prior years	1			—
Gross decreases for tax positions of prior years	(1,165		)	(2		)
Reductions resulting from lapse of statute of limitations	—			(270		)
Settlements	(2		)	—
Unrecognized tax benefits at end of period	$	1,941		$	3,107

The gross decreases for tax positions of prior years for fiscal 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, 2017 and December 31, 2016 are $6 and $9, 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 $4 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 2017, 2016 and 2015, we have accrued interest of $3, $5 and $92 and penalties of $2, $4 and $8, respectively. We accrued ($3), ($91)and ($51) for interest and penalties in income tax expense related to uncertain tax positions during fiscal years 2017, 2016 and 2015, 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 2017 remain open for examination, with limited exceptions.

OTHER ITEMS AND CHARGES

12 Months Ended

Dec. 31, 2017

Unusual or Infrequent Items, or Both [Abstract]

OTHER ITEMS AND CHARGES

Southbridge Landfill Closure Charge

In June 2017, we initiated the plan to cease operations of our Southbridge Landfill. Accordingly, in fiscal year 2017, we recorded charges associated with the closure of our Southbridge Landfill as follows:



	Fiscal Year Ended December 31,
	2017		2016		2015
Asset impairment charge (1)	$	47,999	$	—	$	—
Project development charge (2)	9,149		—		—
Environmental remediation charge (3)	6,379		—		—
Legal and transaction costs (4)	1,656		—		—
Southbridge Landfill closure charge	$	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 future installation of a municipal waterline. See Note 10, Commitments and Contingencies for additional disclosure.


(4)	We incurred legal and other transaction costs associated with various matters as part of the Southbridge Landfill closure. See Note 10, Commitments and Contingencies for additional disclosure.

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 Item 3, “Legal Proceedings” and Note 10, Commitments and Contingencies for further disclosure.

Expense from Divestiture, Acquisition and Financing Costs

In fiscal year 2017, we incurred $176 of expenses primarily associated with legal costs for the acquisition of Complete in January 2018.

See Note 4, Business Combinations for disclosure over the acquisition.

Contract Settlement Charge

In fiscal year 2015, we recorded a contract settlement charge of $1,940 associated with settlement of the Expera Old Town, LLC v. Casella Waste Systems, Inc. legal matter.

DIVESTITURE TRANSACTIONS

12 Months Ended

Dec. 31, 2017

Discontinued Operations and Disposal Groups [Abstract]

DIVESTITURE TRANSACTIONS

Sale of Business. In fiscal year 2015, we divested of a business, which included the sale of certain assets associated with various waste collection routes in our Western region, for total consideration of $872, resulting in a gain of $590.

Maine Energy. In the fiscal year ended April 30, 2013, we executed a purchase and sale agreement with the City of Biddeford, Maine, pursuant to which we agreed to sell the real property of Maine Energy Recovery Company, LP (“Maine Energy”) to the City of Biddeford. We agreed to sell Maine Energy for an undiscounted purchase consideration of $6,650, which was to be paid to us in installments over twenty-one years. The transaction closed in November 2012. In December 2012, we ceased operations of the Maine Energy facility and initiated the decommissioning, demolition and site remediation process in accordance with the provisions of the agreement. We have completed the demolition process and site remediation under the auspices and in accordance with work plans approved by the Maine Department of Environmental Protection and the U.S. Environmental Protection Agency. In consideration of the fact that the project was substantially completed and based on incurred costs to date and estimates at that time regarding the remaining costs to fulfill our obligation under the purchase and sale agreement, we reversed a reserve of $1,149 of excess costs to complete the divestiture in fiscal year 2015. As of December 31, 2017, we had no remaining costs to complete the divestiture accrued as we had fulfilled our obligation under the agreement.

CARES and Related Transaction. Casella-Altela Regional Environmental Services, LLC (“CARES”) is a joint venture that owned and operated a water and leachate treatment facility for the natural gas drilling industry in Pennsylvania. Our joint venture partner in CARES is Altela, Inc. (“Altela”). We held an ownership interest in CARES of 51% and, in accordance with FASB ASC 810-10-15, we consolidated the assets, liabilities and results of operations of CARES into our consolidated financial statements due to our controlling financial interest in the joint venture. In the fiscal year ended April 30, 2014 ("fiscal year 2014"), we determined that assets of the CARES water treatment facility were no longer operational or were not operating within product performance parameters. As a result, we initiated a plan to abandon and shut down the operations of CARES. It was determined that the carrying value of the assets of CARES was no longer recoverable and, as a result, the carrying value of the asset group was assessed for impairment. As a result, we recorded an impairment charge of $7,455 in fiscal year 2014 to the asset group of CARES in our Western region.

We executed a purchase and sale agreement in fiscal year 2015 pursuant to which we and Altela agreed to sell certain assets of the CARES water treatment facility to an unrelated third-party. We sold these assets of CARES for purchase consideration of $3,500, resulting in a gain of $2,850 in fiscal year 2015, 49% of which was attributable to Altela, the noncontrolling interest holder. In connection with this transaction, we also sold certain of our equipment and real estate to the same unrelated third-party for total consideration of $1,050, resulting in a gain of $928 in fiscal year 2015.

In fiscal year 2016, we dissolved CARES in accordance with the CARES Limited Liability Company Agreement, and in fiscal year 2017, we dissolved CARES McKean, LLC in accordance with Pennsylvania dissolution proceedings. Upon dissolution we deconsolidated the assets, liabilities and equity components, including the noncontrolling interest.

EARNINGS PER SHARE

12 Months Ended

Dec. 31, 2017

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,
	2017			2016			2015
Numerator:
Loss before income taxes	$	(21,799	)	$	(6,849	)	$	(12,969	)
Denominator:
Class A common stock	41,298			40,572			40,064
Class B common stock	988			988			988
Unvested restricted stock	(38		)	(88		)	(115		)
Effect of weighted average shares outstanding	(402		)	(239		)	(295		)
Weighted average common shares outstanding	41,846			41,233			40,642
Antidilutive potentially issuable shares	2,219			2,442			2,259

RELATED PARTY TRANSACTIONS	12 Months Ended
RELATED PARTY TRANSACTIONS	Dec. 31, 2017
Related Party Transactions [Abstract]
RELATED PARTY TRANSACTIONS	RELATED PARTY TRANSACTIONS Services During fiscal years 2017, 2016 and 2015, we retained the services of Casella Construction, Inc. ("CCI"), a company wholly 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. Total purchased services charged to operations or capitalized to landfills for fiscal years 2017, 2016 and 2015 were $3,377, $4,024 and $1,341, respectively, of which $30 and $18 were outstanding and included in either accounts payable or other current liabilities as of December 31, 2017 and December 31, 2016, respectively. In addition to the total purchased services, we provided various waste collection and disposal services to CCI. Total revenues recorded for fiscal years 2017, 2016 and 2015 were $237, $307 and $415, 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 April 2018 with a five year option to extend the terms. The terms of the lease agreements require monthly payments of approximately $28. Total expense charged to operations for fiscal years 2017, 2016 and 2015 under these agreements was $360, $371 and $384, 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 2017, 2016 and 2015, we paid $27, $10 and $9, respectively, pursuant to this agreement. As of December 31, 2017 and December 31, 2016, we have accrued $60 and $70, respectively, for costs associated with its post-closure obligations.

SEGMENT REPORTING

12 Months Ended

Dec. 31, 2017

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, major account and industrial services, discontinued operations, and earnings from equity method investees, as applicable, are included in our Other segment.

Fiscal Year Ended December 31, 2017



Segment	Outside revenues		Inter-company revenue			Depreciation and amortization		Operating (loss) income			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 (loss) income		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

Fiscal Year Ended December 31, 2015



Segment	Outside revenues		Inter-company revenue			Depreciation and amortization		Operating (loss) income			Interest expense, net			Capital expenditures		Goodwill		Total assets
Eastern	$	167,467	$	43,560		$	25,977	$	7,338		$	(200	)	$	24,840	$	17,429	$	212,922
Western	231,951		68,284			29,488		26,035			165			20,282		87,503		318,730
Recycling	46,338		995			4,480		(2,406		)	25			1,770		12,315		49,355
Other	100,744		1,014			2,759		899			40,100			3,103		1,729		52,662
Eliminations	—		(113,853		)	—		—			—			—		—		—
Total	$	546,500	$	—		$	62,704	$	31,866		$	40,090		$	49,995	$	118,976	$	633,669

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



	Fiscal Year Ended December 31,
	2017				2016				2015
Collection	$	263,688	44.0	%	$	249,640	44.2	%	$	238,301	43.6	%
Disposal	160,073		26.7	%	154,211		27.3	%	156,536		28.6	%
Power generation	5,375		0.9	%	5,921		1.0	%	6,796		1.2	%
Processing	7,994		1.3	%	6,282		1.1	%	6,061		1.1	%
Solid waste operations	437,130		72.9	%	416,054		73.6	%	407,694		74.5	%
Organics	39,815		6.6	%	41,587		7.4	%	39,134		7.2	%
Customer solutions	60,057		10.1	%	54,478		9.6	%	53,334		9.8	%
Recycling	62,307		10.4	%	52,911		9.4	%	46,338		8.5	%
Total revenues	$	599,309	100.0	%	$	565,030	100.0	%	$	546,500	100.0	%

QUARTERLY FINANCIAL INFORMATION (UNAUDITED)

12 Months Ended

Dec. 31, 2017

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 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



Fiscal Year 2016	First Quarter			Second Quarter		Third Quarter		Fourth Quarter
Revenues	$	125,432		$	144,670	$	151,133	$	143,795
Operating income	$	1,974		$	15,596	$	17,378	$	9,997
Net (loss) income	$	(7,614	)	$	5,192	$	7,537	$	(11,973	)
Net (loss) income attributable to common stockholders	$	(7,608	)	$	5,195	$	7,537	$	(11,973	)
Earnings per common share:
Basic weighted average common shares outstanding	40,996			41,132		41,377		41,422
Basic earnings per share	$	(0.19	)	$	0.13	$	0.18	$	(0.29	)
Diluted weighted average common shares outstanding	40,996			41,598		42,287		41,422
Diluted earnings per share	$	(0.19	)	$	0.12	$	0.18	$	(0.29	)

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, 2017

Valuation and Qualifying Accounts [Abstract]

Schedule II - Valuation Accounts

Schedule II

Valuation Accounts

Allowance for Doubtful Accounts

(in thousands)



	Fiscal Year Ended December 31,
	2017			2016			2015
Balance at beginning of period	$	1,069		$	988		$	2,153
Additions—charged to expense	290			1,107			1,344
Deductions—bad debts written off, net of recoveries	(550		)	(1,026		)	(2,509		)
Balance at end of period	$	809		$	1,069		$	988

ACCOUNTING CHANGES (Policies)

12 Months Ended

Dec. 31, 2017

Accounting Changes and Error Corrections [Abstract]

Accounting Changes

Accounting standards that are pending adoption at December 31, 2017



Standard	Description	Effect on the Financial Statements or Other Significant Matters

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. The amendments expand and refine hedge accounting for both financial and commodity risk components and align 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. This guidance is effective January 1, 2019 with early adoption permitted.



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. This guidance is effective January 1, 2018 with early adoption permitted.

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, 2017, 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 September 2017: 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 are currently assessing the provisions of this guidance and evaluating the impact the guidance will have on our consolidated financial statements and related disclosures. We are also in the process of aggregating lease documentation for review. The adoption of this ASU is expected to impact the balance sheet through the recognition of a right-of-use asset and a lease liability for all leases with terms in excess of 12 months. This guidance is effective January 1, 2019 using a modified retrospective transition approach with early adoption permitted.



ASU 2016-01: 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 results in a cumulative-effect adjustment to the balance sheet, the recognition of changes in fair value of certain equity investments in net income, and enhanced disclosure. This guidance is effective January 1, 2018 with a cumulative-effect adjustment, and will 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.	The adoption of this guidance requires using either a full retrospective approach for all periods presented or a modified retrospective approach with a cumulative effect adjustment to Retained Earnings as of the date of adoption. We adopted the guidance using the modified retrospective approach effective January 1, 2018 with no adjustment to Retained Earnings. We will record revenue when control is transferred to our customer, generally at the time that we provide services. 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, we concluded that we will not have a significant change to the timing of revenue recognition. We have identified certain consideration payable to customers that will be recorded as a reduction of revenues in accordance with Topic 606. These costs are currently recorded as a component of cost of operations. Additionally, 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 Retained Earnings or the accounting of these costs was deemed necessary. In assessing the impact of adopting the guidance on disclosures, we anticipate to have additional disclosures regarding the disaggregation of revenues by business segment, the presentation and roll forward of various contract asset and liability balances, changes to our accounting policy, as well as other significant judgments and disclosures regarding performance obligations and the implementation of the amended guidance.

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 8, 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 9, 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

For interest rate derivatives deemed to be ineffective cash flow hedges, the change in fair value is recorded through earnings and included in loss (gain) on derivative instruments.

Contingent Liabilities and Legal Proceedings

Contingent Liabilities

Legal Proceedings

Revenue Recognition

Effective January 1, 2018, we adopted ASU 2014-09, as amended, Revenue from Contracts with Customers.

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 15, 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

Earnings per Share

Discontinued Operations

Subsequent Events

Restricted Assets

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

Segment Reporting

ACCOUNTING CHANGES (Tables)

12 Months Ended

Dec. 31, 2017

Accounting Changes and Error Corrections [Abstract]

Schedule of Recent Accounting Pronouncements Not Yet Adopted

Accounting standards that are pending adoption at December 31, 2017



Standard	Description	Effect on the Financial Statements or Other Significant Matters

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. The amendments expand and refine hedge accounting for both financial and commodity risk components and align 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. This guidance is effective January 1, 2019 with early adoption permitted.



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. This guidance is effective January 1, 2018 with early adoption permitted.

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, 2017, 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 September 2017: 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 are currently assessing the provisions of this guidance and evaluating the impact the guidance will have on our consolidated financial statements and related disclosures. We are also in the process of aggregating lease documentation for review. The adoption of this ASU is expected to impact the balance sheet through the recognition of a right-of-use asset and a lease liability for all leases with terms in excess of 12 months. This guidance is effective January 1, 2019 using a modified retrospective transition approach with early adoption permitted.



ASU 2016-01: 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 results in a cumulative-effect adjustment to the balance sheet, the recognition of changes in fair value of certain equity investments in net income, and enhanced disclosure. This guidance is effective January 1, 2018 with a cumulative-effect adjustment, and will 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.	The adoption of this guidance requires using either a full retrospective approach for all periods presented or a modified retrospective approach with a cumulative effect adjustment to Retained Earnings as of the date of adoption. We adopted the guidance using the modified retrospective approach effective January 1, 2018 with no adjustment to Retained Earnings. We will record revenue when control is transferred to our customer, generally at the time that we provide services. 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, we concluded that we will not have a significant change to the timing of revenue recognition. We have identified certain consideration payable to customers that will be recorded as a reduction of revenues in accordance with Topic 606. These costs are currently recorded as a component of cost of operations. Additionally, 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 Retained Earnings or the accounting of these costs was deemed necessary. In assessing the impact of adopting the guidance on disclosures, we anticipate to have additional disclosures regarding the disaggregation of revenues by business segment, the presentation and roll forward of various contract asset and liability balances, changes to our accounting policy, as well as other significant judgments and disclosures regarding performance obligations and the implementation of the amended guidance.

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)

12 Months Ended

Dec. 31, 2017

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,
	2017			2016
Land	$	24,224		$	24,517
Landfills	513,548			570,464
Landfill operating lease contracts	114,462			133,239
Buildings and improvements	140,155			143,036
Machinery and equipment	139,029			132,748
Rolling stock	138,102			133,840
Containers	103,501			97,744
	1,173,021			1,235,588
Less: accumulated depreciation and amortization	(811,474		)	(837,122		)
	$	361,547		$	398,466

BUSINESS COMBINATIONS (Tables)

12 Months Ended

Dec. 31, 2017

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,
	2017			2016			2015
Purchase Price:
Cash used in acquisitions, net of cash acquired	$	4,823		$	2,439		$	—
Notes payable	2,400			—			—
Other non-cash considerations	101			—			—
Contingent consideration and holdbacks	736			400			—
Total	8,060			2,839			—
Current assets	93			40			—
Land	—			353			—
Buildings	—			1,360			—
Equipment	2,994			269			—
Other liabilities, net	(49		)	(106		)	—
Intangible assets	2,334			—			—
Fair value of assets acquired and liabilities assumed	5,372			1,916			—
Excess purchase price to be allocated to goodwill	$	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, 2015.



	Fiscal Year Ended December 31,
	2017			2016			2015
Revenue	$	602,754		$	572,628		$	556,569
Operating (loss) income	$	(12,314	)	$	45,257		$	31,940
Net loss attributable to common stockholders	$	(21,647	)	$	(6,685	)	$	(12,947	)
Basic and diluted net loss per common share attributable to common stockholders	$	(0.52	)	$	(0.16	)	$	(0.32	)
Basic and diluted weighted average shares outstanding	41,846			41,233			40,642

RESTRICTED ASSETS (Tables)

12 Months Ended

Dec. 31, 2017

Receivables [Abstract]

Summary of Restricted Assets

A summary of restricted assets is as follows:



	December 31,
	2017		2016
Non Current:
Restricted assets - landfill closure	$	1,220	$	1,002

PROPERTY, PLANT AND EQUIPMENT (Tables)

12 Months Ended

Dec. 31, 2017

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,
	2017			2016
Land	$	24,224		$	24,517
Landfills	513,548			570,464
Landfill operating lease contracts	114,462			133,239
Buildings and improvements	140,155			143,036
Machinery and equipment	139,029			132,748
Rolling stock	138,102			133,840
Containers	103,501			97,744
	1,173,021			1,235,588
Less: accumulated depreciation and amortization	(811,474		)	(837,122		)
	$	361,547		$	398,466

GOODWILL AND INTANGIBLE ASSETS (Tables)

12 Months Ended

Dec. 31, 2017

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, 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



	December 31, 2015		Acquisitions		December 31, 2016
Eastern	$	17,429	$	—	$	17,429
Western	87,503		923		88,426
Recycling	12,315		—		12,315
Other	1,729		—		1,729
Total	$	118,976	$	923	$	119,899

Components of Intangible Assets

A summary of intangible assets is as follows:



	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



	Covenants Not-to-Compete			Client Lists			Total
Balance, December 31, 2016
Intangible assets	$	17,594		$	16,071		$	33,665
Less accumulated amortization	(16,402		)	(9,567		)	(25,969		)
	$	1,192		$	6,504		$	7,696

Estimated Future Amortization Expense

The intangible amortization expense estimated for the five fiscal years following fiscal year 2017 and thereafter is as follows:




Estimated Future Amortization Expense as of December 31, 2017
For the fiscal year ending December 31, 2018	$	2,021
For the fiscal year ending December 31, 2019	$	1,637
For the fiscal year ending December 31, 2020	$	1,432
For the fiscal year ending December 31, 2021	$	1,128
For the fiscal year ending December 31, 2022	$	821
Thereafter	$	1,110

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

12 Months Ended

Dec. 31, 2017

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,
	2017			2016
Beginning balance	$	44,207		$	41,041
Obligations incurred	3,022			2,441
Revisions in estimates (1)	11,498			(2,052		)
Accretion expense	4,401			3,606
Obligations settled (2)	(838		)	(829		)
Ending balance	$	62,290		$	44,207

(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, 2017

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,
	2017		2016
Senior Secured Credit Facility:
Revolving Credit Facility due October 2021; bearing interest at LIBOR plus 2.75%	$	36,000	$	62,600
Term Loan B Facility due October 2023; bearing interest at LIBOR plus 2.50%	346,500		350,000
Tax-Exempt Bonds:
New York State Environmental Facilities Corporation Solid Waste Disposal Revenue Bonds Series 2014 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		—
Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2015 due August 2035 - fixed rate interest period through 2025; bearing interest at 5.125%	15,000		15,000
Vermont Economic Development Authority Solid Waste Disposal Long-Term Revenue Bonds Series 2013 due April 2036 - fixed rate interest period through 2018; bearing interest at 4.75%	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
Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2005R-2 due January 2025 - fixed rate interest period through 2017; bore interest at 6.25%	—		21,400
Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2005R-1; letter of credit backed due January 2025 - bore interest at SIFMA Index	—		3,600
Other:
Capital leases maturing through September 2023; bearing interest at up to 7.70%	5,595		5,534
Notes payable maturing through June 2027; bearing interest at up to 7.00%	2,585		449
Principal amount of long-term debt and capital leases	497,680		525,583
Less—unamortized discount and debt issuance costs (1)	15,178		16,936
Long-term debt and capital leases less unamortized discount and debt issuance costs	482,502		508,647
Less—current maturities of long-term debt	4,926		4,686
	$	477,576	$	503,961


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



	December 31,
	2017		2016
Revolving Credit Facility	$	3,938	$	4,965
Term Loan B Facility (including unamortized discount of $1,482 and $1,712)	7,392		7,718
New York State Environmental Facilities Corporation Solid Waste Disposal Revenue Bonds Series 2014	1,034		1,221
New York State Environmental Facilities Corporation Solid Waste Disposal Revenue Bonds Series 2014R-2	511		571
Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2005R-3	603		—
Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2015	691		760
Vermont Economic Development Authority Solid Waste Disposal Long-Term Revenue Bonds Series 2013	573		605
Business Finance Authority of the State of NH Solid Waste Disposal Revenue Bonds Series 2013	436		563
Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2005R-2	—		502
Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2005R-1	—		31
	$	15,178	$	16,936

Components of Interest Expense

The components of interest expense are as follows:



	Fiscal Year Ended December 31,
	2017			2016			2015
Interest expense on long-term debt and capital leases	$	22,060		$	34,741		$	35,868
Amortization of debt issuance costs and discount on long-term debt	2,692			3,881			3,977
Letter of credit fees	703			593			637
Less: capitalized interest	(295		)	(273		)	(62		)
Total interest expense	$	25,160		$	38,942		$	40,420

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, 2017
2018	$	4,926
2019	5,002
2020	5,269
2021	40,773
2022	4,279
Thereafter	437,431
	$	497,680

COMMITMENTS AND CONTINGENCIES (Tables)

12 Months Ended

Dec. 31, 2017

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, 2017
2018	$	18,465
2019	14,365
2020	10,511
2021	7,905
2022	5,705
Thereafter	33,760
Total minimum lease payments	$	90,711

Schedule of Environmental Liability Associated with Potsdam

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



	Fiscal Year Ended December 31,
	2017			2016
Beginning balance	$	5,866		$	5,221
Payments	(108		)	(255		)
Obligations incurred	—			900
Ending balance	$	5,758		$	5,866

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




	Fiscal Year Ended December 31,
	2017			2016
Beginning balance	$	—		$	—
Accretion expense	82			—
Obligations incurred	6,379			—
Obligations settled (1)	(525		)	—
Ending balance	$	5,936		$	—


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

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, 2017
2018	$	865
2019	4,339
2020	755
2021	403
2022	385
Thereafter	6,621
Total	$	13,368

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	$	13,368
Less discount, net	(1,674		)
Liability balance - December 31, 2017	$	11,694

STOCKHOLDERS' EQUITY (Tables)

12 Months Ended

Dec. 31, 2017

Equity [Abstract]

Summary of Stock Option Activity

A summary of stock option activity is as follows:



	Stock Options (1)		Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (years)	Aggregate Intrinsic Value
Outstanding, December 31, 2016	1,115		$	6.13
Granted	—		$	—
Exercised	(361	)	$	6.20
Forfeited or expired	(27	)	$	13.17
Outstanding, December 31, 2017	727		$	5.82	6.3	$	12,495
Exercisable, December 31, 2017	527		$	4.81	5.7	$	9,590
Unvested, December 31, 2017	240		$	9.16	8.3	$	3,326


(1)	Market-based performance stock option grants are included at 100%. Attainment of maximum performance targets and market achievements would result in the issuance of 40 shares of Class A common stock currently included in unvested.

Schedule of Fair Value of Stock Options Weighted Average Assumptions

The weighted average fair value of stock options granted, with the exception of market-based performance stock option grants, during fiscal years 2017, 2016 and 2015 were $0.00, $0.00 and $5.35 per option, respectively, which were calculated assuming no expected dividend yield using the following weighted average assumptions:



	Fiscal Year Ended December 31,
	2017 (1)		2016 (1)		2015
Expected life	0.0 years		0.0 years		7.2 years
Risk-free interest rate	—	%	—	%	2.02	%
Expected volatility	—	%	—	%	81.31	%


(1)	In fiscal years 2017 and 2016, we only granted market-based performance stock options, which are discussed separately below.

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, 2016	1,099		$	7.03
Granted	439		$	12.32
Class A common stock vested	(420	)	$	5.21
Forfeited or canceled	(27	)	$	6.31
Outstanding, December 31, 2017	1,091		$	9.81	1.3	$	14,409
Unvested, December 31, 2017	1,453		$	10.48	1.3	$	18,216


(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 362 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 income (loss) are as follows:



	Marketable Securities			Interest Rate Swaps			Total
Balance as of December 31, 2014	$	58		$	—		$	58
Other comprehensive loss	(51		)	—			(51		)
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	86			(255		)	(169		)
Amounts reclassified from accumulated other comprehensive income (loss)	—			421			421
Other comprehensive income, net	86			166			252
Balance as of December 31, 2017	$	18		$	166		$	184

Reclassification Out of Accumulated Other Comprehensive Income (Loss)

A summary of reclassifications out of accumulated other comprehensive income (loss) for fiscal years 2017, 2016 and 2015 is as follows:



	Fiscal Year Ended December 31,
	2017		2016		2015
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	$	421	$	—	$	—	Interest expense
	421		—		—		Loss before income taxes
	—		—		—		(Benefit) provision for income taxes
	$	421	$	—	$	—	Net loss

FAIR VALUE OF FINANCIAL INSTRUMENTS (Tables)

12 Months Ended

Dec. 31, 2017

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, 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 assets - landfill closure	$	1,220	$	—	$	—
Interest rate swaps	—		401		—
	$	1,220	$	401	$	—
Liabilities:
Interest rate swaps	$	—	$	123	$	—



	Fair Value Measurement at December 31, 2016 Using:
	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets:
Restricted assets - landfill closure	$	1,002	$	—	$	—

EMPLOYEE BENEFIT PLANS EMPLOYEE BENEFIT PLANS (Tables)

12 Months Ended

Dec. 31, 2017

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,
		2017	2016		2017		2016		2015
New England Teamsters and Trucking Industry Pension Fund	04-6372430	Critical and declining	Critical	Implemented	$	627	$	523	$	413	June 30, 2020

INCOME TAXES (Tables)

12 Months Ended

Dec. 31, 2017

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,
	2017			2016			2015
Federal
Current	$	—		$	—		$	2,899
Current benefit of loss carryforwards	—			—			(2,899		)
Deferred	(15,614		)	458			395
	(15,614		)	458			395
State
Current	301			(90		)	1,112
Current benefit of loss carryforwards	(28		)	—			(557		)
Deferred	88			126			401
	361			36			956
(Benefit) provision for income taxes	$	(15,253	)	$	494		$	1,351

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,
	2017			2016			2015
Federal statutory rate	35		%	35		%	35		%
Tax at statutory rate	$	(12,968	)	$	(2,228	)	$	(3,650	)
State income taxes, net of federal benefit	(1,959		)	(265		)	198
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 due to federal rate change	(18,848		)	4,370			5,272
Deductible stock awards	(1,825		)	—			—
Tax credits	(1,000		)	(1,085		)	(671		)
Non-deductible expenses	542			100			467
Non-deductible equity income in subsidiaries	—			—			(415		)
Other, net	(137		)	(398		)	150
(Benefit) provision for income taxes	$	(15,253	)	$	494		$	1,351

Schedule of Deferred Tax Assets and Liabilities



	December 31,
	2017			2016
Deferred tax assets:

Net operating loss carryforwards	$	33,228		$	46,846
Accrued expenses and reserves	26,572			32,185
Book over tax depreciation of property and equipment	25,615			30,012
General business tax credit carryforwards	5,439			4,433
Alternative minimum tax credit carryforwards	3,804			3,804
Stock awards	1,958			1,720
Other	2,050			2,806
Total deferred tax assets	98,666			121,806
Less: valuation allowance	(68,355		)	(97,589		)
Total deferred tax assets after valuation allowance	30,311			24,217
Deferred tax liabilities:
Amortization of intangibles	(20,904		)	(30,296		)
Other	(145		)	(99		)
Total deferred tax liabilities	(21,049		)	(30,395		)
Net deferred tax asset (liability)	$	9,262		$	(6,178	)

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,
	2017			2016
Unrecognized tax benefits at beginning of period	$	3,107		$	3,379
Gross increases for tax positions of prior years	1			—
Gross decreases for tax positions of prior years	(1,165		)	(2		)
Reductions resulting from lapse of statute of limitations	—			(270		)
Settlements	(2		)	—
Unrecognized tax benefits at end of period	$	1,941		$	3,107

OTHER ITEMS AND CHARGES OTHER ITEMS AND CHARGES (Tables)

12 Months Ended

Dec. 31, 2017

Unusual or Infrequent Items, or Both [Abstract]

Charges Associated with Closure of Southbridge Landfill

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



	Fiscal Year Ended December 31,
	2017		2016		2015
Asset impairment charge (1)	$	47,999	$	—	$	—
Project development charge (2)	9,149		—		—
Environmental remediation charge (3)	6,379		—		—
Legal and transaction costs (4)	1,656		—		—
Southbridge Landfill closure charge	$	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 future installation of a municipal waterline. See Note 10, Commitments and Contingencies for additional disclosure.


(4)	We incurred legal and other transaction costs associated with various matters as part of the Southbridge Landfill closure. See Note 10, Commitments and Contingencies for additional disclosure.

EARNINGS PER SHARE (Tables)

12 Months Ended

Dec. 31, 2017

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,
	2017			2016			2015
Numerator:
Loss before income taxes	$	(21,799	)	$	(6,849	)	$	(12,969	)
Denominator:
Class A common stock	41,298			40,572			40,064
Class B common stock	988			988			988
Unvested restricted stock	(38		)	(88		)	(115		)
Effect of weighted average shares outstanding	(402		)	(239		)	(295		)
Weighted average common shares outstanding	41,846			41,233			40,642
Antidilutive potentially issuable shares	2,219			2,442			2,259

SEGMENT REPORTING (Tables)

12 Months Ended

Dec. 31, 2017

Segment Reporting [Abstract]

Summary of Financial Information by Reportable Segment

Fiscal Year Ended December 31, 2017



Segment	Outside revenues		Inter-company revenue			Depreciation and amortization		Operating (loss) income			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 (loss) income		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

Fiscal Year Ended December 31, 2015



Segment	Outside revenues		Inter-company revenue			Depreciation and amortization		Operating (loss) income			Interest expense, net			Capital expenditures		Goodwill		Total assets
Eastern	$	167,467	$	43,560		$	25,977	$	7,338		$	(200	)	$	24,840	$	17,429	$	212,922
Western	231,951		68,284			29,488		26,035			165			20,282		87,503		318,730
Recycling	46,338		995			4,480		(2,406		)	25			1,770		12,315		49,355
Other	100,744		1,014			2,759		899			40,100			3,103		1,729		52,662
Eliminations	—		(113,853		)	—		—			—			—		—		—
Total	$	546,500	$	—		$	62,704	$	31,866		$	40,090		$	49,995	$	118,976	$	633,669

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,
	2017				2016				2015
Collection	$	263,688	44.0	%	$	249,640	44.2	%	$	238,301	43.6	%
Disposal	160,073		26.7	%	154,211		27.3	%	156,536		28.6	%
Power generation	5,375		0.9	%	5,921		1.0	%	6,796		1.2	%
Processing	7,994		1.3	%	6,282		1.1	%	6,061		1.1	%
Solid waste operations	437,130		72.9	%	416,054		73.6	%	407,694		74.5	%
Organics	39,815		6.6	%	41,587		7.4	%	39,134		7.2	%
Customer solutions	60,057		10.1	%	54,478		9.6	%	53,334		9.8	%
Recycling	62,307		10.4	%	52,911		9.4	%	46,338		8.5	%
Total revenues	$	599,309	100.0	%	$	565,030	100.0	%	$	546,500	100.0	%

QUARTERLY FINANCIAL INFORMATION (UNAUDITED) (Tables)

12 Months Ended

Dec. 31, 2017

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 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



Fiscal Year 2016	First Quarter			Second Quarter		Third Quarter		Fourth Quarter
Revenues	$	125,432		$	144,670	$	151,133	$	143,795
Operating income	$	1,974		$	15,596	$	17,378	$	9,997
Net (loss) income	$	(7,614	)	$	5,192	$	7,537	$	(11,973	)
Net (loss) income attributable to common stockholders	$	(7,608	)	$	5,195	$	7,537	$	(11,973	)
Earnings per common share:
Basic weighted average common shares outstanding	40,996			41,132		41,377		41,422
Basic earnings per share	$	(0.19	)	$	0.13	$	0.18	$	(0.29	)
Diluted weighted average common shares outstanding	40,996			41,598		42,287		41,422
Diluted earnings per share	$	(0.19	)	$	0.12	$	0.18	$	(0.29	)

BASIS OF PRESENTATION (Detail)	12 Months Ended
BASIS OF PRESENTATION (Detail)	Dec. 31, 2017 Segment
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Operating segments	2

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Estimated Useful Lives of Assets (Detail)	12 Months Ended
	Dec. 31, 2017
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, 2017 USD ($) Agreement	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Property, Plant and Equipment [Line Items]
Capitalized interest	$ 295	$ 273	$ 62
Closure and post-closure costs incurrence period	30 years
Estimate of inflation rate	1.70%
Accretion expense	$ 4,401	3,606
Number of operation and management agreements entered into \| Agreement	5
Closure And Post Closure Costs
Property, Plant and Equipment [Line Items]
Accretion expense	$ 4,401	3,606	$ 3,370
Surety bond	164,893	161,095
Letters of credit	$ 0	$ 0
Minimum
Property, Plant and Equipment [Line Items]
Rate of asset retirement obligation	9.20%
Maximum
Property, Plant and Equipment [Line Items]
Rate of asset retirement obligation	9.90%

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Goodwill and Intangible Assets (Detail)	12 Months Ended
	Dec. 31, 2017
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, 2017	Dec. 31, 2016
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, 2017	Dec. 31, 2016
Capital Leased Assets [Line Items]
Maximum exposure automobile plan per individual event	$ 1,000
Self insurance reserves	14,480,000	$ 13,707,000
Automobile Plan
Capital Leased Assets [Line Items]
Maximum exposure automobile plan per individual event	$ 1,200

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Derivatives and Hedging (Detail)	12 Months Ended
	Dec. 31, 2015 USD ($)	Dec. 31, 2017 USD ($) Agreement	Mar. 15, 2016 Agreement
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Number of interest rate swaps (agreement) \| Agreement			1
Settlement of forward starting interest rate derivative agreements	$ 830,000
Derivative asset in other non-current assets		$ 401,000
Derivative liability in other accrued liabilities		$ 123,000
Interest Rate Contracts
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Number of interest rate swaps (agreement) \| Agreement		3
Total notional amount		$ 60,000,000.0
Weighted average rate paid		1.95%
Interest Rate Contracts \| LIBOR
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Floor rate received		1.00%
Interest Rate Contracts - February 2021
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total notional amount		$ 35,000,000
Interest Rate Contracts - February 2022
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total notional amount		$ 25,000,000

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Asset Impairments (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Goodwill impairment incurred	$ 0	$ 0	$ 0
Investment impairment charge	0	0	2,099,000
Carrying amount of cost method investment	$ 12,333,000	$ 12,333,000
Recycle Rewards Inc
Segment Reporting Information [Line Items]
Outstanding common stock percentage	5.60%
Investment impairment charge			1,090,000
Carrying amount of cost method investment	$ 1,069,000
GreenerU Inc
Segment Reporting Information [Line Items]
Outstanding common stock percentage	5.20%
Investment impairment charge			691,000
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]
Investment impairment charge			$ 318,000
Carrying amount of cost method investment	$ 297,000
Eastern
Segment Reporting Information [Line Items]
Reporting units exceeded their carrying values	83.60%
Western
Segment Reporting Information [Line Items]
Reporting units exceeded their carrying values	74.60%
Recycling
Segment Reporting Information [Line Items]
Reporting units exceeded their carrying values	74.60%
Other
Segment Reporting Information [Line Items]
Reporting units exceeded their carrying values	74.60%

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Defined Benefit Pension Plan (Details)	12 Months Ended
	Dec. 31, 2017 plan
Multiemployer Pension Plans \| New England Teamsters and Trucking Industry Pension Fund
Multiemployer Plans [Line Items]
Number of plans	1

BUSINESS COMBINATIONS - Narrative (Detail) $ in Thousands	1 Months Ended	12 Months Ended
BUSINESS COMBINATIONS - Narrative (Detail) $ in Thousands	Jan. 31, 2018 USD ($)	Dec. 31, 2017 transfer_station	Dec. 31, 2015 transfer_station
Business Acquisition [Line Items]
Number of businesses acquired			0
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
Subsequent Event
Business Acquisition [Line Items]
Total consideration from Complete Disposal acquisition \| $	$ 16,500
Eastern \| Collection Business
Business Acquisition [Line Items]
Number of businesses acquired		1
Western \| Solid Waste Collection Business
Business Acquisition [Line Items]
Number of businesses acquired		3

BUSINESS COMBINATIONS - Schedule of Purchase Price Paid for Acquisitions (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Purchase Price:
Cash used in acquisitions, net of cash acquired	$ 5,056	$ 2,839	$ 0
Total
Excess purchase price to be allocated to goodwill	122,605	119,899	118,976
Transfer Stations Acquisition
Purchase Price:
Cash used in acquisitions, net of cash acquired	4,823	2,439	0
Notes payable	2,400	0	0
Other non-cash considerations	101	0	0
Contingent consideration and holdbacks	736	400	0
Total
Total	8,060	2,839	0
Current assets	93	40	0
Land	0	353	0
Buildings	0	1,360	0
Equipment	2,994	269	0
Other liabilities, net	(49)	(106)	0
Intangible assets	2,334	0	0
Fair value of assets acquired and liabilities assumed	5,372	1,916	0
Excess purchase price to be allocated to goodwill	$ 2,688	$ 923	$ 0

BUSINESS COMBINATIONS - Schedule of Unaudited Pro forma Combined Information (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Business Combinations [Abstract]
Revenue	$ 602,754	$ 572,628	$ 556,569
Operating (loss) income	(12,314)	45,257	31,940
Net loss attributable to common stockholders	$ (21,647)	$ (6,685)	$ (12,947)
Basic net loss per common share attributable to common stockholders (in dollars per share)	$ (0.52)	$ (0.16)	$ (0.32)
Diluted net loss per common share attributable to common stockholders (in dollars per share)	$ (0.52)	$ (0.16)	$ (0.32)
Basic and diluted weighted average shares outstanding (in shares)	41,846	41,233	40,642

RESTRICTED ASSETS (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Receivables [Abstract]
Restricted assets - landfill closure	$ 1,220	$ 1,002

PROPERTY, PLANT AND EQUIPMENT - Components of Property, Plant and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 1,173,021	$ 1,235,588
Less: accumulated depreciation and amortization	(811,474)	(837,122)
Property, plant and equipment, net	361,547	398,466
Land
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	24,224	24,517
Landfills
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	513,548	570,464
Landfill operating lease contracts
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	114,462	133,239
Building and Improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	140,155	143,036
Machinery and Equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	139,029	132,748
Rolling Stock
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	138,102	133,840
Containers
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 103,501	$ 97,744

PROPERTY, PLANT AND EQUIPMENT - Narrative (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Depreciation expense	$ 32,131	$ 33,186	$ 33,168
Depletion expense on operating lease contracts	9,646	9,295	9,428
Landfills
Property, Plant and Equipment [Line Items]
Amortization expense	$ 27,910	$ 26,529	$ 26,969

GOODWILL AND INTANGIBLE ASSETS - Schedule of Activity and Balances Related to Goodwill by Reporting Segment (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Goodwill [Roll Forward]
Goodwill, beginning balance	$ 119,899	$ 118,976
Acquisitions	2,706	923
Goodwill, ending balance	122,605	119,899
Eastern
Goodwill [Roll Forward]
Goodwill, beginning balance	17,429	17,429
Acquisitions	1,763	0
Goodwill, ending balance	19,192	17,429
Western
Goodwill [Roll Forward]
Goodwill, beginning balance	88,426	87,503
Acquisitions	943	923
Goodwill, ending balance	89,369	88,426
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, 2017	Dec. 31, 2016	Dec. 31, 2015
Finite-Lived Intangible Assets [Line Items]
Intangible assets	$ 36,179	$ 33,665
Less accumulated amortization	(28,030)	(25,969)
Intangible assets, net	8,149	7,696
Intangible amortization expenses	2,061	2,141	$ 2,567
Covenants Not-to-Compete
Finite-Lived Intangible Assets [Line Items]
Intangible assets	18,092	17,594
Less accumulated amortization	(16,851)	(16,402)
Intangible assets, net	1,241	1,192
Client Lists
Finite-Lived Intangible Assets [Line Items]
Intangible assets	18,087	16,071
Less accumulated amortization	(11,179)	(9,567)
Intangible assets, net	$ 6,908	$ 6,504

GOODWILL AND INTANGIBLE ASSETS - Estimated Future Amortization Expense (Detail) $ in Thousands	Dec. 31, 2017 USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
For the fiscal year ending December 31, 2018	$ 2,021
For the fiscal year ending December 31, 2019	1,637
For the fiscal year ending December 31, 2020	1,432
For the fiscal year ending December 31, 2021	1,128
For the fiscal year ending December 31, 2022	821
Thereafter	$ 1,110

FINAL CAPPING, CLOSURE AND POST-CLOSURE COSTS (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning balance	$ 44,207	$ 41,041
Obligations incurred	3,022	2,441
Revisions in estimates	11,498	(2,052)
Accretion expense	4,401	3,606
Obligations settled	(838)	(829)
Ending balance	$ 62,290	$ 44,207

LONG TERM DEBT AND CAPITAL LEASES - Components of Long-Term Debt and Capital Leases (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Long-term debt and capital lease	$ 497,680	$ 525,583
Less—unamortized discount and debt issuance costs	15,178	16,936
Long-term debt and capital leases less unamortized discount and debt issuance costs	482,502	508,647
Less—current maturities of long-term debt	4,926	4,686
Long-term debt and capital leases, less current maturities	$ 477,576	503,961
Revolving Credit Facility
Debt Instrument [Line Items]
Interest rate	2.75%
Long-term debt and capital lease	$ 36,000	62,600
Less—unamortized discount and debt issuance costs	3,938	4,965
New York State Environmental Facilities Corporation Solid Waste Disposal Revenue Bonds Series 2014 due December 2044 - fixed rate interest period through 2019; bearing interest at 3.75%
Debt Instrument [Line Items]
Long-term debt and capital lease	25,000	25,000
Less—unamortized discount and debt issuance costs	$ 1,034	1,221
Debt instrument 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]
Long-term debt and capital lease	$ 15,000	15,000
Less—unamortized discount and debt issuance costs	$ 511	571
Debt instrument 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]
Long-term debt and capital lease	$ 25,000	0
Less—unamortized discount and debt issuance costs	$ 603	0
Debt instrument interest rate	5.25%
Vermont Economic Development Authority Solid Waste Disposal Long-Term Revenue Bonds Series 2013 due April 2036 - fixed rate interest period through 2018; bearing interest at 4.75%
Debt Instrument [Line Items]
Long-term debt and capital lease	$ 15,000	15,000
Less—unamortized discount and debt issuance costs	$ 691	760
Debt instrument interest rate	5.125%
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]
Long-term debt and capital lease	$ 16,000	16,000
Less—unamortized discount and debt issuance costs	$ 573	605
Debt instrument interest rate	4.75%
Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2005R-2 due January 2025 - fixed rate interest period through 2017; bore interest at 6.25%
Debt Instrument [Line Items]
Long-term debt and capital lease	$ 11,000	11,000
Less—unamortized discount and debt issuance costs	$ 436	563
Debt instrument interest rate	4.00%
Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2005R-2 due January 2025 - fixed rate interest period through 2017; bore interest at 6.25%
Debt Instrument [Line Items]
Long-term debt and capital lease	$ 0	21,400
Less—unamortized discount and debt issuance costs	0	$ 502
Debt instrument interest rate		6.25%
Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2005R-1; letter of credit backed due January 2025 - bore interest at SIFMA Index
Debt Instrument [Line Items]
Long-term debt and capital lease	0	$ 3,600
Less—unamortized discount and debt issuance costs	0	31
Capital leases maturing through September 2023; bearing interest at up to 7.70%
Debt Instrument [Line Items]
Long-term debt and capital lease	$ 5,595	5,534
Debt instrument interest rate	7.70%
Notes payable maturing through June 2027; bearing interest at up to 7.00%
Debt Instrument [Line Items]
Long-term debt and capital lease	$ 2,585	449
Debt instrument interest rate	7.00%
Term Loan B Facility due October 2023; bearing interest at LIBOR plus 2.50% \| Secured Debt
Debt Instrument [Line Items]
Interest rate	2.50%
Long-term debt and capital lease	$ 346,500	350,000
Less—unamortized discount and debt issuance costs	7,392	7,718
Unamortized discount	$ 1,482	$ 1,712

LONG TERM DEBT AND CAPITAL LEASES - Credit Facility (Details)	12 Months Ended
	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Line of Credit Facility [Line Items]
Debt redemption price		101.938%
Revolving Credit Facility due October 2021; bearing interest at LIBOR plus 3.00%
Line of Credit Facility [Line Items]
Basis spread on variable rate		3.00%
Secured Debt \| Term Loan B Facility
Line of Credit Facility [Line Items]
Principal amount		$ 350,000,000
Facility term		7 years
Net leverage ratio		3.75
Interest rate	2.50%
Secured Debt \| Term Loan B Facility \| LIBOR
Line of Credit Facility [Line Items]
Basis spread on variable rate		2.75%
Secured Debt \| Term Loan B Facility \| LIBOR \| Maximum
Line of Credit Facility [Line Items]
Basis spread on variable rate		3.00%
Secured Debt \| Term Loan B Facility \| LIBOR Floor \| Minimum
Line of Credit Facility [Line Items]
Basis spread on variable rate		1.00%
Secured Debt \| Term Loan Facility B, Repricing Amendment
Line of Credit Facility [Line Items]
Net leverage ratio	3.75
Secured Debt \| Term Loan Facility B, Repricing Amendment \| LIBOR
Line of Credit Facility [Line Items]
Interest rate	2.75%
Secured Debt \| Term Loan Facility B, Repricing Amendment \| LIBOR \| Debt Instrument, Covenant Compliance, Consolidated Net Leverage Ratio
Line of Credit Facility [Line Items]
Interest rate	2.50%
Secured Debt \| Term Loan Facility B, Repricing Amendment \| LIBOR Floor
Line of Credit Facility [Line Items]
Interest rate	1.00%
Secured Debt \| Term Loan Facility B, Repricing Amendment \| LIBOR Floor \| Debt Instrument, Covenant Compliance, Consolidated Net Leverage Ratio
Line of Credit Facility [Line Items]
Interest rate	1.00%
Secured Debt \| Term Loan Facility B, Repricing Amendment \| Base Rate
Line of Credit Facility [Line Items]
Decrease in basis points	0.25%
Interest rate	1.75%
Secured Debt \| Term Loan Facility B, Repricing Amendment \| Base Rate \| Debt Instrument, Covenant Compliance, Consolidated Net Leverage Ratio
Line of Credit Facility [Line Items]
Interest rate	1.50%
Line of Credit \| Revolving Credit Facility due October 2021; bearing interest at LIBOR plus 3.00% \| Revolving Credit Facility
Line of Credit Facility [Line Items]
Credit facility maximum		$ 160,000,000
Facility term		5 years
Remaining capacity	$ 101,457,000
Line of Credit \| Revolving Credit Facility due October 2021; bearing interest at LIBOR plus 3.00% \| Revolving Credit Facility \| Minimum
Line of Credit Facility [Line Items]
Debt instrument interest rate		2.50%
Line of Credit \| Revolving Credit Facility due October 2021; bearing interest at LIBOR plus 3.00% \| Revolving Credit Facility \| Maximum
Line of Credit Facility [Line Items]
Debt instrument interest rate		3.25%
Line of Credit \| Revolving Credit Facility due October 2021; bearing interest at LIBOR plus 3.00% \| Letter of Credit
Line of Credit Facility [Line Items]
Outstanding irrevocable letters of credit totaling	$ 22,543,000
Senior Subordinated Notes, Due February 2019; bore interest at 7.75%
Line of Credit Facility [Line Items]
Debt instrument interest rate		7.75%
Revolving Credit Facility
Line of Credit Facility [Line Items]
Additional revolver capacity		$ 100,000,000
Interest rate	2.75%

LONG TERM DEBT AND CAPITAL LEASES - Tax-Exempt Financings (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Aggregate principal amount	$ 497,680,000	$ 525,583,000
New York Bonds, 2016
Debt Instrument [Line Items]
Principal amount		15,000,000
New York Bonds, 2014
Debt Instrument [Line Items]
Aggregate principal amount	$ 40,000,000
Debt instrument 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]
Debt instrument interest rate	3.125%
Aggregate principal amount	$ 15,000,000	15,000,000
Unsecured Debt \| Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2005R-1; letter of credit backed due January 2025 - bore interest at SIFMA Index
Debt Instrument [Line Items]
Principal amount	3,600,000
Unsecured Debt \| Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2005R-2 due January 2025 - fixed rate interest period through 2017; bore interest at 6.25%
Debt Instrument [Line Items]
Principal amount	21,400,000
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]
Principal amount	$ 25,000,000
Debt instrument interest rate	5.25%
Vermont Economic Development Authority Solid Waste Disposal Long-Term Revenue Bonds Series 2013 due April 2036 - fixed rate interest period through 2018; bearing interest at 4.75%
Debt Instrument [Line Items]
Debt instrument interest rate	5.125%
Aggregate principal amount	$ 15,000,000	$ 15,000,000
Additional bond issued	15,000,000
Fixed Rate Bonds \| Vermont Bonds
Debt Instrument [Line Items]
Aggregate principal amount	$ 16,000,000
Debt instrument interest rate	4.75%
New Hampshire Bonds
Debt Instrument [Line Items]
Aggregate principal amount	$ 11,000,000
Debt instrument interest rate	4.00%

LONG TERM DEBT AND CAPITAL LEASES - Loss on Debt Extinguishment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Debt Disclosure [Abstract]
Loss on debt extinguishment	$ 517	$ 13,747	$ 999

LONG TERM DEBT AND CAPITAL LEASES - Components of Interest Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Debt Disclosure [Abstract]
Interest expense on long-term debt and capital leases	$ 22,060	$ 34,741	$ 35,868
Amortization of debt issuance costs and discounts on long-term debt	2,692	3,881	3,977
Letter of credit fees	703	593	637
Less: capitalized interest	(295)	(273)	(62)
Total interest expense	$ 25,160	$ 38,942	$ 40,420

LONG TERM DEBT AND CAPITAL LEASES - Fair Value of Debt (Details) $ in Thousands	Dec. 31, 2017 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of line of credit	$ 36,000
Carrying Value \| Fixed Rate Bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of debt	106,344
Carrying Value \| Secured Debt \| Term Loan B Facility
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of debt	347,799
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	107,000
Fair Value \| Significant Other Observable Inputs (Level 2) \| Secured Debt \| Term Loan B Facility
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of debt	$ 346,500

LONG TERM DEBT AND CAPITAL LEASES - Schedule of Future Maturities of Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Debt Disclosure [Abstract]
2018	$ 4,926
2019	5,002
2020	5,269
2021	40,773
2022	4,279
Thereafter	437,431
Long-term debt and capital lease	$ 497,680	$ 525,583

COMMITMENTS AND CONTINGENCIES - Narrative (Detail) $ in Thousands		12 Months Ended
	Apr. 28, 2017 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($) executive_officer	Dec. 31, 2016 USD ($)	Dec. 31, 2015 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)			$ 20
Total rent expense under operating leases charged to operations			$ 12,242	$ 11,437	$ 9,392
Number of executive officers \| executive_officer			5
Intangible assets, useful life			10 years
Contract extension period			1 year
Total annual commitments for salaries			$ 1,785
Notice of Intent to Sue under the Resource Conservation and Recovery Act
Other Commitments [Line Items]
Agreement in principle amount (up to)						$ 5,000
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
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
Southbridge Landfill
Other Commitments [Line Items]
Risk free interest rate			2.60%
Potsdam Environmental Remediation Liability
Other Commitments [Line Items]
Risk free interest rate			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	$ 10,219
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
Scenario, Forecast \| Southbridge Landfill \| Maximum
Other Commitments [Line Items]
Future cash payments		$ 3,069
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

COMMITMENTS AND CONTINGENCIES - Schedule of Future Minimum Rental Payments under Non-Cancellable Operating Leases (Detail) $ in Thousands	Dec. 31, 2017 USD ($)
Commitments and Contingencies Disclosure [Abstract]
2018	$ 18,465
2019	14,365
2020	10,511
2021	7,905
2022	5,705
Thereafter	33,760
Total minimum lease payments	$ 90,711

COMMITMENTS AND CONTINGENCIES - Schedule of Environmental Liability Associated with Southbridge Landfill (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Accrual for Environmental Loss Contingencies [Roll Forward]
Ending balance	$ 11,694
Southbridge Landfill
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	0	$ 0
Accretion expense	82	0
Obligations incurred	6,379	0
Obligations settled	(525)	0
Ending balance	$ 5,936	$ 0

COMMITMENTS AND CONTINGENCIES - Schedule of Environmental Liability Associated with Potsdam (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Accrual for Environmental Loss Contingencies [Roll Forward]
Ending balance	$ 11,694
Potsdam Environmental Remediation Liability
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	5,866	$ 5,221
Payments	(108)	(255)
Obligations incurred	0	900
Ending balance	$ 5,758	$ 5,866

COMMITMENTS AND CONTINGENCIES - Schedule of Future Minimum Rental (Detail) $ in Thousands	Dec. 31, 2017 USD ($)
Commitments and Contingencies Disclosure [Abstract]
2018	$ 865
2019	4,339
2020	755
2021	403
2022	385
Thereafter	6,621
Total	$ 13,368

COMMITMENTS AND CONTINGENCIES - Reconciliation of Expected Aggregate Non-inflated, Undiscounted Amount to Amount Recognized in Statements of Financial Position (Detail) $ in Thousands	Dec. 31, 2017 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Undiscounted liability	$ 13,368
Less discount, net	(1,674)
Liability Balance - December 31, 2017	$ 11,694

STOCKHOLDERS' EQUITY - Narrative (Detail) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($) vote $ / shares shares	Dec. 31, 2016 USD ($) vote $ / shares shares	Dec. 31, 2015 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
Options granted (in dollars per share) \| $ / shares	$ 0.00	$ 0.00	$ 5.35
Expected dividend yield	0.00%	0.00%	0.00%
Expected life	1 day	1 day	7 years 2 months 27 days
Risk-free interest rate	0.00%	0.00%	2.02%
Expected volatility	0.00%	0.00%	81.31%
Total fair value of other stock awards vested	$ 5,706	$ 3,238	$ 2,340
Tax benefits from additional paid-in-capital adjustments	0	0	185
Stock Options
Limited Partners' Capital Account [Line Items]
Stock-based compensation expense	644	605	671
Aggregate intrinsic value of stock options exercised	4,664	$ 22	52
Total unrecognized stock-based compensation expense related to all outstanding stock options (in shares)	474
Market-based Performance Stock Options
Limited Partners' Capital Account [Line Items]
Expected dividend yield		0.00%
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		43.10%
Restricted Stock, Restricted Stock Units and Performance Stock Units
Limited Partners' Capital Account [Line Items]
Stock-based compensation expense	$ 5,652	$ 2,673	2,314
Granted (in dollars per share) \| $ / shares	$ 12.32
Restricted Stock and Restricted Stock Unit
Limited Partners' Capital Account [Line Items]
Incremental compensation expense			$ 270
Unrecognized stock-based compensation expense	$ 2,945
Restricted Stock, Restricted Stock Units and Performance Stock Units
Limited Partners' Capital Account [Line Items]
Employee Service Share-based Compensation, Tax Benefit from Exercise of Stock Options	$ 117
Granted (in dollars per share) \| $ / shares	$ 12.32	$ 8.97	$ 4.40
Income taxes associated with stock-based compensation expense		$ 0	$ 19
Market-based Performance Stock Units
Limited Partners' Capital Account [Line Items]
Expected dividend yield	0.00%
Weighted average fair value of market-based performance (in dollars per share) \| $ / shares	$ 12.51
Risk-free interest rate	1.45%
Expected volatility	32.80%
Amended and Restated 1997 Employee Stock Purchase Plan
Limited Partners' Capital Account [Line Items]
Stock-based compensation expense	$ 136	$ 115	$ 94
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	$ 5,268
Weighted Average \| Stock Options
Limited Partners' Capital Account [Line Items]
Unrecognized stock-based compensation expense, weighted average period	8 months
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 6 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	143,000
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	1,930,000
Class B Common Stock
Limited Partners' Capital Account [Line Items]
Vote for each share held (in votes per share) \| vote	10	10

STOCKHOLDERS' EQUITY - Summary of Stock Option Activity (Detail) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($) $ / shares shares
Stock Options
Outstanding, beginning balance (in shares)	1,115
Granted (in shares)	0
Exercised (in shares)	(361)
Forfeited (in shares)	(27)
Outstanding, ending balance (in shares)	727
Exercisable (in shares)	527
Unvested (in shares)	240
Weighted Average Exercise Price
Outstanding, beginning balance (in dollars per share) \| $ / shares	$ 6.13
Granted (in dollars per share) \| $ / shares	0.00
Exercised (in dollars per share) \| $ / shares	6.20
Forfeited (in dollars per share) \| $ / shares	13.17
Outstanding, ending balance (in dollars per share) \| $ / shares	5.82
Exercisable (in dollars per share) \| $ / shares	4.81
Unvested (in dollars per share) \| $ / shares	$ 9.16
Weighted average remaining contractual term, outstanding	6 years 4 months 1 day
Weighted average remaining contractual term, exercisable	5 years 7 months 25 days
Weighted average remaining contractual term, unvested	8 years 4 months 6 days
Aggregate intrinsic value, outstanding \| $	$ 12,495
Aggregate intrinsic value, exercisable \| $	9,590
Aggregate intrinsic value, unvested \| $	$ 3,326
Market-based Performance Stock Options
Weighted Average Exercise Price
Attainment level percentage	100.00%
Additional issuance if performance targets met (in shares)	40

STOCKHOLDERS' EQUITY - Schedule of Fair Value of Stock Options Weighted Average Assumptions (Detail)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Equity [Abstract]
Expected life	1 day	1 day	7 years 2 months 27 days
Risk-free interest rate	0.00%	0.00%	2.02%
Expected volatility	0.00%	0.00%	81.31%

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, 2017 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)	1,099
Granted (in shares)	439
Forfeited (in shares)	(27)
Outstanding, ending balance (in shares)	1,091
Unvested (in shares)	1,453
Weighted Average Grant Price
Outstanding, beginning balance (in dollars per share) \| $ / shares	$ 7.03
Granted (in dollars per share) \| $ / shares	12.32
Forfeited (in dollars per share) \| $ / shares	6.31
Outstanding, ending balance (in dollars per share) \| $ / shares	9.81
Weighted average grant price, unvested, ending balance (in dollars per share) \| $ / shares	$ 10.48
Weighted average remaining contractual term, outstanding	1 year 3 months 6 days
Weighted average remaining contractual term, unvested	1 year 3 months 12 days
Aggregate intrinsic value, outstanding \| $	$ 14,409
Aggregate intrinsic value, unvested \| $	$ 18,216
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)	(420)
Weighted Average Grant Price
Vested (in dollars per share) \| $ / shares	$ 5.21
Class A Common Stock \| Performance Stock Units
Weighted Average Grant Price
Additional issuance if performance targets met (in shares)	362

STOCKHOLDERS' EQUITY - Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ (24,550)	$ (21,597)	$ (12,020)
Other comprehensive income (loss) before reclassifications	(169)
Amounts reclassified from accumulated other comprehensive income (loss)	421
Other comprehensive income (loss), net of taxes	252	(75)	(51)
Ending balance	(37,862)	(24,550)	(21,597)
Marketable Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(68)	7	58
Other comprehensive income (loss) before reclassifications	86
Amounts reclassified from accumulated other comprehensive income (loss)	0
Other comprehensive income (loss), net of taxes	86	(75)	(51)
Ending balance	18	(68)	7
Interest rate swaps
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	0	0	0
Other comprehensive income (loss) before reclassifications	(255)
Amounts reclassified from accumulated other comprehensive income (loss)	421
Other comprehensive income (loss), net of taxes	166	0	0
Ending balance	166	0	0
Accumulated Other Comprehensive Income (Loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(68)	7	58
Other comprehensive income (loss), net of taxes	252	(75)	(51)
Ending balance	$ 184	$ (68)	$ 7

STOCKHOLDERS' EQUITY - Reclassification Out of Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense									$ 25,160	$ 38,942	$ 40,420
Loss before income taxes									37,052	6,364	10,430
(Benefit) provision for income taxes									(15,253)	494	1,351
Net loss	$ (20,020)	$ (12,080)	$ 53,675	$ 224	$ 11,973	$ (7,537)	$ (5,192)	$ 7,614	21,799	6,858	11,781
Derivative instruments \| Interest rate swaps \| Reclassification Out of Accumulated Other Comprehensive Income (Loss)
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense									421	0	0
Loss before income taxes									421	0	0
(Benefit) provision for income taxes									0	0	0
Net loss									$ 421	$ 0	$ 0

FAIR VALUE OF FINANCIAL INSTRUMENTS (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Assets:
Restricted assets - landfill closure	$ 1,220	$ 1,002
Quoted Prices in Active Markets for Identical Assets (Level 1) \| Fair Value, Measurements, Recurring
Assets:
Restricted assets - landfill closure		1,002
Interest rate swaps	0
Total asset fair value	1,220
Liabilities:
Interest rate swaps	0
Quoted Prices in Active Markets for Identical Assets (Level 1) \| Fair Value, Measurements, Recurring \| Restricted assets - landfill closure
Assets:
Restricted assets - landfill closure	1,220
Significant Other Observable Inputs (Level 2) \| Fair Value, Measurements, Recurring
Assets:
Restricted assets - landfill closure		0
Interest rate swaps	401
Total asset fair value	401
Liabilities:
Interest rate swaps	123
Significant Other Observable Inputs (Level 2) \| Fair Value, Measurements, Recurring \| Restricted assets - landfill closure
Assets:
Restricted assets - landfill closure	0
Significant Unobservable Inputs (Level 3) \| Fair Value, Measurements, Recurring
Assets:
Restricted assets - landfill closure		$ 0
Interest rate swaps	0
Total asset fair value	0
Liabilities:
Interest rate swaps	0
Significant Unobservable Inputs (Level 3) \| Fair Value, Measurements, Recurring \| Restricted assets - landfill closure
Assets:
Restricted assets - landfill closure	$ 0

EMPLOYEE BENEFIT PLANS - Narrative (Detail) - USD ($) shares in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
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	$ 1,187,000	$ 1,119,000	$ 1,033,000
Class A Common Stock
Employee Stock Purchase Plan [Line Items]
Discount rate	15.00%
Stock issued under stock purchase plan (in shares)	41	70	80
Stock available for distribution under stock purchase plan (in shares)	143

EMPLOYEE BENEFIT PLANS - Multiemployer Defined Benefit Pension Plan (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Multiemployer Pension Plans \| New England Teamsters and Trucking Industry Pension Fund
Multiemployer Plans [Line Items]
Contributions to Plan	$ 627	$ 523	$ 413

INCOME TAXES - Schedule of Provision (Benefit) for Income Taxes Continuing Operations (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Federal
Current	$ 0	$ 0	$ 2,899
Current benefit of loss carryforwards	0	0	(2,899)
Deferred	(15,614)	458	395
Total	(15,614)	458	395
State
Current	301	(90)	1,112
Current benefit of loss carryforwards	(28)	0	(557)
Deferred	88	126	401
Total	361	36	956
(Benefit) provision for income taxes	$ (15,253)	$ 494	$ 1,351

INCOME TAXES - Narrative (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
INCOME TAXES - Narrative (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Increase in tax provision due to Tax Act		$ 33,700
Deferred tax benefit related to continuing operations	$ (29,234)	36,556
Deferred tax benefit of indefinite lived deferred tax liabilities	12,758	12,758	$ 0	$ 0
Income tax settlement amount				180
Tax paid for income tax settlement				168
Interest paid for income tax settlement				$ 12
Potential cumulative liability (less than)				8.00%
Deferred federal taxes asset	11,567	11,567	0
Long-term deferred state tax liability	2,305	2,305	6,178
Net operating loss carryforwards	101,187	101,187
State net operating loss carryforwards expiry period	114,362	114,362
Alternative minimum tax credit carryforwards	3,804	3,804	3,804
General business tax credit carryforwards	5,439	5,439	4,433
Increase (decrease) in valuation allowance		(29,234)	4,582
Deferred tax expense (benefit) due to Tax Cuts and Jobs Act	(15,614)
Unrecognized tax benefit net of federal benefit on state issue	6	6	9
Unrecognized tax benefits	4	4
Uncertain tax positions, accrued interest	3	3	5	$ 92
Uncertain tax positions, penalties	2	2	4	8
Accrued income tax expense	$ (3)	$ (3)	$ (91)	$ (51)

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, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Federal statutory rate		35.00%	35.00%	35.00%
Tax at statutory rate		$ (12,968)	$ (2,228)	$ (3,650)
State income taxes, net of federal benefit		(1,959)	(265)	198
Decrease in net federal deferred tax assets before valuation allowance change due to federal rate change		33,700	0	0
Decrease in valuation allowance by 80% of indefinite lived deferred liabilities due to US tax reform	$ (12,758)	(12,758)	0	0
Other changes in valuation allowance, including due to federal rate change		(18,848)	4,370	5,272
Deductible stock awards		(1,825)	0	0
Tax credits		(1,000)	(1,085)	(671)
Non-deductible expenses		542	100	467
Non-deductible equity income in subsidiaries		0	0	(415)
Other, net		(137)	(398)	150
(Benefit) provision for income taxes		$ (15,253)	$ 494	$ 1,351

INCOME TAXES - Schedule of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets:
Net operating loss carryforwards	$ 33,228	$ 46,846
Accrued expenses and reserves	26,572	32,185
Book over tax depreciation of property and equipment	25,615	30,012
General business tax credit carryforwards	5,439	4,433
Alternative minimum tax credit carryforwards	3,804	3,804
Stock awards	1,958	1,720
Other	2,050	2,806
Total deferred tax assets	98,666	121,806
Less: valuation allowance	(68,355)	(97,589)
Total deferred tax assets after valuation allowance	30,311	24,217
Deferred tax liabilities:
Amortization of intangibles	(20,904)	(30,296)
Other	(145)	(99)
Total deferred tax liabilities	(21,049)	(30,395)
Net deferred tax asset	$ 9,262
Net deferred tax liability		$ (6,178)

INCOME TAXES - Schedule of Reconciliation of Gross Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits at beginning of period	$ 3,107	$ 3,379
Gross increases for tax positions of prior years	1	0
Gross decreases for tax positions of prior years	(1,165)	(2)
Reductions resulting from lapse of statute of limitations	0	(270)
Settlements	(2)	0
Unrecognized tax benefits at end of period	$ 1,941	$ 3,107

OTHER ITEMS AND CHARGES (Detail) - USD ($) $ in Thousands	12 Months Ended
OTHER ITEMS AND CHARGES (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Site Contingency [Line Items]
Asset impairment charge	$ 47,999	$ 0	$ 0
Project development charge	9,149	0	0
Environmental remediation charge	0	900	0
Legal and transaction costs	1,656	0	0
Landfill Closure Charge	65,183	0	0
Legal costs for the acquisition	176	0	0
Contract settlement charge	0	0	1,940
Southbridge Landfill
Site Contingency [Line Items]
Environmental remediation charge	$ 6,379	$ 0	$ 0

DIVESTITURE TRANSACTIONS DIVESTITURE TRANSACTIONS (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Apr. 30, 2013
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Divestiture transactions	$ 0	$ 0	$ (5,517,000)
Remaining divestiture costs	19,251,000	14,916,000
Proceeds from sale of assets	0	$ 0	5,335,000
Disposal Group, Not Discontinued Operations \| Casella-Altela Regional Environmental Services, LLC
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Membership interest				51.00%
Disposal Group, Not Discontinued Operations \| Maine Energy Facility
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Undiscounted purchase consideration					$ 6,650,000
Undiscounted purchase consideration paid in installments					21 years
Divestiture transactions			1,149,000
Remaining divestiture costs	$ 0
Disposal Group, Not Discontinued Operations \| Western
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration received from sale of assets			872,000
Gain (loss) on disposal			590,000
Disposal Group, Not Discontinued Operations \| Western \| Cares
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Impairment charge				$ 7,455,000
Disposal Group, Disposed of by Sale, Not Discontinued Operations \| Casella-Altela Regional Environmental Services, LLC
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (loss) on disposal			2,850,000
Proceeds from sale of assets			3,500,000
Disposal Group, Disposed of by Sale, Not Discontinued Operations \| Casella-Altela Regional Environmental Services, LLC \| Equipment and Real Estate
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (loss) on disposal			928,000
Proceeds from sale of assets			$ 1,050,000
Disposal Group, Disposed of by Sale, Not Discontinued Operations \| Altela, Inc.
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Membership interest			49.00%

EARNINGS PER SHARE (Detail) - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Numerator:
Loss before income taxes	$ (21,799)	$ (6,849)	$ (12,969)
Denominator:
Unvested restricted stock (in shares)	(38)	(88)	(115)
Effect of weighted average shares outstanding (in shares)	(402)	(239)	(295)
Weighted average common shares outstanding (in shares)	41,846	41,233	40,642
Antidilutive potentially issuable shares (in shares)	2,219	2,442	2,259
Class A Common Stock
Denominator:
Common stock, outstanding shares (in shares)	41,298	40,572	40,064
Class B Common Stock
Denominator:
Common stock, outstanding shares (in shares)	988	988	988

RELATED PARTY TRANSACTIONS (Detail) $ in Thousands	12 Months Ended
RELATED PARTY TRANSACTIONS (Detail) $ in Thousands	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Apr. 30, 1994 Lease
Related Party Transaction [Line Items]
Total services purchased	$ 3,377	$ 4,024	$ 1,341
Outstanding accounts payable	30	18
Number of leases \| Lease				2
Total expense charged to operations under lease agreement	360	371	384
Accrued costs associated with post-closure obligations	62,290	44,207	41,041
Restricted assets - landfill closure
Related Party Transaction [Line Items]
Landfill post-closure cost	27	10	9
Accrued costs associated with post-closure obligations	$ 60	70
Capital Lease Obligations
Related Party Transaction [Line Items]
Lease extended period	5 years
CCI
Related Party Transaction [Line Items]
Revenue from related party	$ 237	$ 307	$ 415
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, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Revenues	$ 151,222	$ 160,269	$ 154,016	$ 133,802	$ 143,795	$ 151,133	$ 144,670	$ 125,432	$ 599,309	$ 565,030	$ 546,500
Depreciation and amortization									62,102	61,856	62,704
Operating (loss) income	9,855	$ 18,277	$ (47,279)	$ 6,564	9,997	$ 17,378	$ 15,596	$ 1,974	(12,583)	44,945	31,866
Interest expense, net									24,887	38,652	40,090
Capital expenditures									64,862	54,238	49,995
Goodwill	122,605				119,899				122,605	119,899	118,976
Total assets	614,949				631,512				614,949	631,512	633,669
Eastern
Segment Reporting Information [Line Items]
Goodwill	19,192				17,429				19,192	17,429	17,429
Western
Segment Reporting Information [Line Items]
Goodwill	89,369				88,426				89,369	88,426	87,503
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 \| Eastern
Segment Reporting Information [Line Items]
Revenues									181,170	176,539	167,467
Depreciation and amortization									23,815	27,036	25,977
Operating (loss) income									(51,867)	9,697	7,338
Interest expense, net									3	(16)	(200)
Capital expenditures									17,153	18,363	24,840
Goodwill	19,192				17,429				19,192	17,429	17,429
Total assets	157,248				202,420				157,248	202,420	212,922
Operating Segments \| Western
Segment Reporting Information [Line Items]
Revenues									250,771	233,168	231,951
Depreciation and amortization									30,766	27,511	29,488
Operating (loss) income									35,035	30,576	26,035
Interest expense, net									(220)	(248)	165
Capital expenditures									42,082	31,637	20,282
Goodwill	89,369				88,426				89,369	88,426	87,503
Total assets	344,324				327,628				344,324	327,628	318,730
Operating Segments \| Recycling
Segment Reporting Information [Line Items]
Revenues									62,307	52,911	46,338
Depreciation and amortization									4,125	4,212	4,480
Operating (loss) income									2,805	2,542	(2,406)
Interest expense, net									143	156	25
Capital expenditures									2,006	2,218	1,770
Goodwill	12,315				12,315				12,315	12,315	12,315
Total assets	48,612				49,931				48,612	49,931	49,355
Operating Segments \| Other
Segment Reporting Information [Line Items]
Revenues									105,061	102,412	100,744
Depreciation and amortization									3,396	3,097	2,759
Operating (loss) income									1,444	2,130	899
Interest expense, net									24,961	38,760	40,100
Capital expenditures									3,621	2,020	3,103
Goodwill	1,729				1,729				1,729	1,729	1,729
Total assets	64,765				51,533				64,765	51,533	52,662
Eliminations
Segment Reporting Information [Line Items]
Revenues									(123,972)	(116,331)	(113,853)
Depreciation and amortization									0	0	0
Operating (loss) income									0	0	0
Interest expense, net									0	0	0
Capital expenditures									0	0	0
Goodwill	0				0				0	0	0
Total assets	$ 0				$ 0				0	0	0
Eliminations \| Eastern
Segment Reporting Information [Line Items]
Revenues									50,335	45,728	43,560
Eliminations \| Western
Segment Reporting Information [Line Items]
Revenues									71,510	67,985	68,284
Eliminations \| Recycling
Segment Reporting Information [Line Items]
Revenues									246	1,003	995
Eliminations \| Other
Segment Reporting Information [Line Items]
Revenues									$ 1,881	$ 1,615	$ 1,014

SEGMENT REPORTING - Summary of Revenue Attributable to Services Provided by Company (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenue from External Customer [Line Items]
Revenues	$ 151,222	$ 160,269	$ 154,016	$ 133,802	$ 143,795	$ 151,133	$ 144,670	$ 125,432	$ 599,309	$ 565,030	$ 546,500
Revenues percentage									100.00%	100.00%	100.00%
Collection
Revenue from External Customer [Line Items]
Revenues									$ 263,688	$ 249,640	$ 238,301
Revenues percentage									44.00%	44.20%	43.60%
Disposal
Revenue from External Customer [Line Items]
Revenues									$ 160,073	$ 154,211	$ 156,536
Revenues percentage									26.70%	27.30%	28.60%
Power generation
Revenue from External Customer [Line Items]
Revenues									$ 5,375	$ 5,921	$ 6,796
Revenues percentage									0.90%	1.00%	1.20%
Processing
Revenue from External Customer [Line Items]
Revenues									$ 7,994	$ 6,282	$ 6,061
Revenues percentage									1.30%	1.10%	1.10%
Solid waste operations
Revenue from External Customer [Line Items]
Revenues									$ 437,130	$ 416,054	$ 407,694
Revenues percentage									72.90%	73.60%	74.50%
Organics
Revenue from External Customer [Line Items]
Revenues									$ 39,815	$ 41,587	$ 39,134
Revenues percentage									6.60%	7.40%	7.20%
Customer solutions
Revenue from External Customer [Line Items]
Revenues									$ 60,057	$ 54,478	$ 53,334
Revenues percentage									10.10%	9.60%	9.80%
Recycling
Revenue from External Customer [Line Items]
Revenues									$ 62,307	$ 52,911	$ 46,338
Revenues percentage									10.40%	9.40%	8.50%

QUARTERLY FINANCIAL INFORMATION (UNAUDITED) (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Revenues	$ 151,222	$ 160,269	$ 154,016	$ 133,802	$ 143,795	$ 151,133	$ 144,670	$ 125,432	$ 599,309	$ 565,030	$ 546,500
Operating income (loss)	9,855	18,277	(47,279)	6,564	9,997	17,378	15,596	1,974	(12,583)	44,945	31,866
Net (loss) income	$ 20,020	$ 12,080	$ (53,675)	$ (224)	(11,973)	7,537	5,192	(7,614)	(21,799)	(6,858)	(11,781)
Net (loss) income attributable to common stockholders					$ (11,973)	$ 7,537	$ 5,195	$ (7,608)	$ (21,799)	$ (6,849)	$ (12,969)
Earnings per common share:
Basic weighted average common shares outstanding (in shares)	42,033	41,951	41,811	41,584	41,422	41,377	41,132	40,996
Basic earnings per share (in dollars per share)	$ 0.48	$ 0.29	$ (1.28)	$ (0.01)	$ (0.29)	$ 0.18	$ 0.13	$ (0.19)
Diluted weighted average common shares outstanding (in shares)	43,394	43,295	41,811	41,584	41,422	42,287	41,598	40,996
Diluted earnings per share (in dollars per share)	$ 0.46	$ 0.28	$ (1.28)	$ (0.01)	$ (0.29)	$ 0.18	$ 0.12	$ (0.19)

Schedule II - Valuation Accounts (Detail) - Allowance for Doubtful Accounts - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	$ 1,069	$ 988	$ 2,153
Additions—charged to expense	290	1,107	1,344
Deductions—bad debts written off, net of recoveries	(550)	(1,026)	(2,509)
Balance at end of period	$ 809	$ 1,069	$ 988