Casella Waste Systems (CWST) 10-Q 8 May 20 2020 Q1 Quarterly report Financial data

COVER PAGE

COVER PAGE - shares	3 Months Ended
	Mar. 31, 2020	Apr. 30, 2020
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Transition Report	false
Entity Registrant Name	CASELLA WASTE SYSTEMS, INC.
Entity File Number	000-23211
Document Period End Date	Mar. 31, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q1
Current Fiscal Year End Date	--12-31
Entity Central Index Key	0000911177
Entity Incorporation, State or Country Code	DE
Entity Filer Category	Large Accelerated Filer
Title of 12(b) Security	Class A common stock, $0.01 par value per share
Trading Symbol	CWST
Security Exchange Name	NASDAQ
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Amendment Flag	false
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Tax Identification Number	03-0338873
Entity Address, Address Line One	25 Greens Hill Lane,
Entity Address, City or Town	Rutland,
Entity Address, State or Province	VT
Entity Address, Postal Zip Code	05701
City Area Code	802
Local Phone Number	775-0325
Class A Common Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		47,321,483
Class B Common Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		988,200

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
CURRENT ASSETS:
Cash and cash equivalents	$ 26,221	$ 3,471
Accounts receivable, net of allowance for credit losses of $2,092 and $1,468, respectively	73,509	80,205
Refundable income taxes	2,193	1,251
Prepaid expenses	8,728	8,994
Inventory	7,815	7,679
Other current assets	1,088	1,213
Total current assets	119,554	102,813
Property, plant and equipment, net of accumulated depreciation and amortization of $862,783 and $844,874, respectively	454,800	443,825
Operating lease right-of-use assets	107,133	108,025
Goodwill	186,626	185,819
Intangible assets, net	57,943	58,721
Restricted assets	1,410	1,586
Cost method investments	11,264	11,264
Deferred income taxes	7,259	8,577
Other non-current assets	11,651	11,552
Total assets	957,640	932,182
CURRENT LIABILITIES:
Current maturities of debt	5,392	4,301
Current operating lease liabilities	8,829	9,356
Accounts payable	53,822	64,396
Accrued payroll and related expenses	5,288	14,375
Accrued interest	2,094	2,041
Contract liabilities	2,860	2,299
Current accrued capping, closure and post-closure costs	9,689	10,223
Other accrued liabilities	27,179	23,598
Total current liabilities	115,153	130,589
Debt, less current portion	547,729	509,021
Operating lease liabilities, less current portion	71,729	70,709
Accrued capping, closure and post-closure costs, less current portion	63,661	61,704
Deferred income taxes	2,180	2,643
Other long-term liabilities	39,192	34,763
COMMITMENTS AND CONTINGENCIES
Casella Waste Systems, Inc. stockholders' equity
Additional paid-in capital	486,989	485,332
Accumulated deficit	(356,246)	(357,016)
Accumulated other comprehensive loss	(13,230)	(6,041)
Total stockholders' equity	117,996	122,753
Total liabilities and stockholders' equity	957,640	932,182
Class A Common Stock
Casella Waste Systems, Inc. stockholders' equity
Common stock	473	468
Class B Common Stock
Casella Waste Systems, Inc. stockholders' equity
Common stock	$ 10	$ 10

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2020USD ($)vote$ / sharesshares	Dec. 31, 2019USD ($)vote$ / sharesshares
Statement of Financial Position [Abstract]
Accounts receivable - trade, allowance for doubtful accounts | $	$ 2,092	$ 1,468
Accumulated depreciation and amortization | $	$ 862,783	$ 844,874
Class A Common Stock
Common stock, par value (in dollars per share) | $ / shares	$ 0.01	$ 0.01
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	47,320,000	46,803,000
Common stock, shares outstanding	47,320,000	46,803,000
Class B Common Stock
Common stock, par value (in dollars per share) | $ / shares	$ 0.01	$ 0.01
Common stock, shares authorized	1,000,000	1,000,000
Common stock, shares issued	988,000	988,000
Common stock, shares outstanding	988,000	988,000
Votes per share held | vote	10	10

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Income Statement [Abstract]
Revenues	$ 182,910	$ 163,664
Operating expenses:
Cost of operations	128,518	117,759
General and administration	24,352	22,742
Depreciation and amortization	21,406	17,489
Expense from acquisition activities and other items	1,009	677
Southbridge landfill closure charge	613	555
Total operating expenses	175,898	159,222
Operating income	7,012	4,442
Other expense (income):
Interest income	(51)	(117)
Interest expense	5,952	6,460
Other expense (income), net	43	(216)
Other expense, net	5,944	6,127
Income (loss) before income taxes	1,068	(1,685)
Provision for income taxes	109	29
Net income (loss)	$ 959	$ (1,714)
Basic earnings per share attributable to common stockholders:
Weighted average common shares outstanding	48,005	45,913
Basic earnings per common share (in dollars per share)	$ 0.02	$ (0.04)
Diluted earnings per share attributable to common stockholders:
Weighted average common shares outstanding	48,262	45,913
Diluted earnings per common share (in dollars per share)	$ 0.02	$ (0.04)

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 959	$ (1,714)
Hedging activity:
Interest rate swap settlements	(411)	(28)
Interest rate swap amounts reclassified into interest expense	489	25
Unrealized loss resulting from changes in fair value of derivative instruments	(7,379)	(1,554)
Other comprehensive loss	(7,301)	(1,557)
Income tax benefit related to items of other comprehensive loss	(112)	0
Other comprehensive loss, net of tax	(7,189)	(1,557)
Comprehensive loss	$ (6,230)	$ (3,271)

CONSOLIDATED STATEMENTS OF STOC

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (DEFICIT) (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Cumulative effect of new accounting principle	Additional Paid-In Capital	Accumulated Deficit	Accumulated DeficitCumulative effect of new accounting principle	Accumulated other comprehensive loss	Class A Common Stock	Class A Common StockCommon Stock	Class B Common Stock	Class B Common StockCommon Stock
Beginning balance at Dec. 31, 2018	$ (15,832)		$ 373,716	$ (388,669)		$ (1,308)		$ 419		$ 10
Beginning balance (in shares) at Dec. 31, 2018								41,944		988
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Class A common stock - equity offering	100,446		100,410					$ 36
Issuance of Class A common stock - equity offering (in shares)								3,565
Issuance of Class A common stock - acquisition	0		(1)					$ 1
Issuance of Class A common stock - acquisition (in shares)								67
Issuances of Class A common stock	260		253					$ 7
Issuance of Class A common stock (in shares)								676
Stock-based compensation	1,431		1,431
Net income (loss)	(1,714)			(1,714)
Hedging activity	(1,557)					(1,557)
Ending balance at Mar. 31, 2019	83,034		475,809	(390,383)		(2,865)		$ 463		$ 10
Ending balance (in shares) at Mar. 31, 2019							46,252	46,252	988	988
Beginning balance at Dec. 31, 2019	122,753	$ (189)	485,332	(357,016)	$ (189)	(6,041)		$ 468		$ 10
Beginning balance (in shares) at Dec. 31, 2019							46,803	46,803	988	988
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuances of Class A common stock	100		95					$ 5
Issuance of Class A common stock (in shares)								517
Stock-based compensation	1,562		1,562
Net income (loss)	959			959
Hedging activity	(7,189)					(7,189)
Ending balance at Mar. 31, 2020	$ 117,996		$ 486,989	$ (356,246)		$ (13,230)		$ 473		$ 10
Ending balance (in shares) at Mar. 31, 2020							47,320	47,320	988	988

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net income (loss)	$ 959	$ (1,714)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	21,406	17,489
Operating lease right-of-use assets expense	2,417	2,579
Interest accretion on landfill and environmental remediation liabilities	1,794	1,804
Amortization of debt issuance costs	527	575
Stock-based compensation	1,562	1,431
Loss (gain) on sale of property and equipment	137	(57)
Southbridge Landfill non-cash closure charge	51	0
Non-cash expense from acquisition activities and other items	532	14
Deferred income taxes	967	188
Changes in assets and liabilities, net of effects of acquisitions and divestitures:
Accounts receivable	6,507	2,694
Landfill operating lease contract expenditures	(50)	(50)
Accounts payable	(10,588)	(7,904)
Prepaid expenses, inventories and other assets	(171)	(3,430)
Accrued expenses, contract liabilities and other liabilities	(12,932)	(10,490)
Net cash provided by operating activities	14,791	4,777
Cash Flows from Investing Activities:
Acquisitions, net of cash acquired	(5,144)	(1,222)
Additions to property, plant and equipment	(19,851)	(18,243)
Proceeds from sale of property and equipment	51	57
Net cash used in investing activities	(24,944)	(19,408)
Cash Flows from Financing Activities:
Proceeds from debt borrowings	73,500	10,600
Principal payments on debt	(40,686)	(80,746)
Payments of debt issuance costs	(11)	0
Proceeds from the exercise of share based awards	100	260
Proceeds from the public issuance of Class A Common Stock	0	100,446
Net cash provided by financing activities	32,903	30,560
Net increase in cash and cash equivalents	22,750	15,929
Cash and cash equivalents, beginning of period	3,471	4,007
Cash and cash equivalents, end of period	26,221	19,936
Cash paid during the period for:
Interest	5,372	5,718
Income taxes, net of refunds	84	51
Supplemental Disclosure of Non-Cash Investing and Financing Activities:
Non-current assets obtained through long-term obligations	6,469	2,473
Landfill
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Operating lease right-of-use assets expense	$ 1,673	$ 1,648

BASIS OF PRESENTATION

BASIS OF PRESENTATION	3 Months Ended
	Mar. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
BASIS OF PRESENTATION	BASIS OF PRESENTATION Casella Waste Systems, Inc. (“Parent”), and its consolidated subsidiaries (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. Effective January 1, 2020, we reorganized our operations to consist of a single resource-renewal focused operation by combining our larger-scale recycling and commodity brokerage operations along with our organics services and major account and industrial services into our Resource Solutions segment. We continue to manage our solid waste operations on a geographic basis through two regional operating segments, the Eastern and Western regions, each of which provides a full range of solid waste services. Legal, tax, information technology, human resources, certain finance and accounting and other administrative functions are included in our Corporate Entities segment. Segment information reported in the three months ended March 31, 2019 and as of December 31, 2019 has been reclassified to conform with the three months ended March 31, 2020 and as of March 31, 2020 presentation. The accompanying unaudited consolidated financial statements, which include the accounts of the Parent and our wholly-owned subsidiaries, 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. Our significant accounting policies are more fully discussed in Item 8 of our Annual Report on Form 10-K for the fiscal year ended December 31, 2019, which was filed with the SEC on February 21, 2020. 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 the opinion of management, these consolidated financial statements include all adjustments, which include normal recurring and nonrecurring adjustments, necessary for a fair presentation of the financial position, results of operations and cash flows for the periods presented. The results for the three months ended March 31, 2020 may not be indicative of the results for any other interim period or the entire fiscal year. The consolidated financial statements presented herein should be read in conjunction with our audited consolidated financial statements included in our Annual Report on Form 10-K for the fiscal year ended December 31, 2019. Recent Events With the global outbreak of the novel coronavirus ("COVID-19") and the declaration of a pandemic by the World Health Organization in March 2020, the U.S. Government and all of the states in which we operate have declared the waste services industry as an essential services provider and as a result we are committed to continue to operate and provide our full breadth of services. We have prioritized the safety and well-being of our employees by strictly adhering to recommendations of the Centers for Disease Control and Prevention as well as executive orders of the states in which we operate. The COVID-19 outbreak has caused, and is likely to continue to cause, significant economic disruption across our geographic footprint and has adversely affected, and is expected to continue to adversely affect, our business. COVID-19 negatively impacted our revenues at the end of the quarter ended March 31, 2020 as many collection customers required service level changes and volumes into our landfills declined. We have experienced an increase in certain costs associated with the protection of our employees including costs for additional safety equipment, hygiene products and enhanced facility cleaning. These costs are expected to continue throughout the remainder of the year. We have also taken immediate measures to reduce costs in other areas and preserve liquidity during this period of uncertainty. As of the date of this filing, we are unable to determine or predict the nature, duration or scope of the overall impact that COVID-19 will have on our business, results of operations, liquidity and capital resources. Subsequent Events We have evaluated subsequent events or transactions that have occurred after the consolidated balance sheet date of March 31, 2020 through the date of filing of the consolidated financial statements with the SEC on this Quarterly Report on Form 10-Q. We have determined that there are no subsequent events that require disclosure in this Quarterly Report on Form 10-Q.

ACCOUNTING CHANGES

ACCOUNTING CHANGES	3 Months Ended
	Mar. 31, 2020
Accounting Changes and Error Corrections [Abstract]
ACCOUNTING CHANGES	ACCOUNTING CHANGES A table providing a brief description of recent Accounting Standards Updates ("ASUs") to the Accounting Standards Codification (“ASC”) issued by the Financial Accounting Standards Board (“FASB”) that we adopted and deemed to have a material impact on our consolidated financial statements based on current account balances and activity follows: Standard Description Effect on the Financial Statements or Other Accounting standards adopted effective January 1, 2020 ASU No. 2016-13, as amended through March 2020: Financial Instrument Credit Losses (Topic 326) Requires that an entity measures all of its expected credit losses for financial assets held based on historical experience, current conditions, and reasonable and supportable forecasts. We adopted this guidance effective January 1, 2020 using the required modified-retrospective approach. We recognized a cumulative effect adjustment of $(189) to retained earnings upon implementation. This guidance replaces the incurred loss methodology with an expected loss methodology that is referred to as current expected credit loss ("CECL") methodology. CECL requires consideration of past events, current conditions, and reasonable and supportable forecasts about the future to assess credit loss estimates and will generally result in the earlier recognition of an allowance for credit losses. We have updated our business processes and systems and controls to support recognition and disclosure under the new guidance. See Note 5, Accounts Receivable, Net of Allowance for Credit Losses for additional disclosure. A table providing a brief description of recent ASUs to the ASC issued by the FASB that are pending adoption and deemed to have a possible material impact on our consolidated financial statements based on current account balances and activity follows: Standard Description Effect on the Financial Statements or Other Accounting standards issued pending adoption ASU No. 2020-04: Reference Rate Reform (Topic 848) Provides temporary optional guidance to ease the potential burden in applying GAAP to contract modifications and hedging relationships, subject to meeting certain criteria, that reference LIBOR or another reference rate expected to be discontinued. We are currently assessing the provisions of this guidance and do not expect that its adoption will have an impact on our consolidated financial statements and related disclosures. This guidance will be in effect from March 12, 2020 through December 31, 2022. ASU No. 2019-12: Income Taxes (Topic 740) Reduces the complexity over accounting for income taxes by removing certain exceptions and amending guidance to improve consistent application of accounting over income taxes. We are currently assessing the provisions of this guidance to determine whether or not its adoption will have an impact on our consolidated financial statements and related disclosures. This guidance is effective January 1, 2021 with early adoption permitted.

REVENUE RECOGNITION

REVENUE RECOGNITION	3 Months Ended
	Mar. 31, 2020
Revenue from Contract with Customer [Abstract]
REVENUE RECOGNITION	REVENUE RECOGNITION A table of revenues disaggregated by service line and timing of revenue recognition by operating segment for each of the three months ended March 31, 2020 and 2019 follows: Three Months Ended March 31, 2020 Eastern Western Resource Solutions Total Revenues Collection $ 36,829 $ 58,639 $ — $ 95,468 Landfill 3,544 16,310 — 19,854 Transfer 9,383 6,706 — 16,089 Customer solutions — — 21,663 21,663 Recycling 2 239 10,966 11,207 Organics — — 14,932 14,932 Transportation — 2,671 — 2,671 Landfill gas-to-energy 385 641 — 1,026 Total revenues $ 50,143 $ 85,206 $ 47,561 $ 182,910 Transferred at a point-in-time $ 56 $ 235 $ 4,462 $ 4,753 Transferred over time 50,087 84,971 43,099 178,157 Total revenues $ 50,143 $ 85,206 $ 47,561 $ 182,910 Three Months Ended March 31, 2019 Eastern Western Resource Solutions Total Revenues Collection $ 33,965 $ 49,597 $ — $ 83,562 Landfill 3,717 15,468 — 19,185 Transfer 8,986 5,275 — 14,261 Customer solutions — — 18,154 18,154 Recycling — 441 10,766 11,207 Organics — — 13,596 13,596 Transportation — 2,563 — 2,563 Landfill gas-to-energy 329 807 — 1,136 Total revenues $ 46,997 $ 74,151 $ 42,516 $ 163,664 Transferred at a point-in-time $ 36 $ 309 $ 6,391 $ 6,736 Transferred over time 46,961 73,842 36,125 156,928 Total revenues $ 46,997 $ 74,151 $ 42,516 $ 163,664 Payments to customers that are not in exchange for a distinct good or service are recorded as a reduction of revenues. Rebates to certain customers associated with payments for recycled or organic materials that are received and subsequently processed and sold to other third-parties amounted to $991 in the three months ended March 31, 2020 and $1,338 in the three months ended March 31, 2019. Rebates are generally recorded as a reduction of revenues upon the sale of such materials, or upon receipt of the recycled materials at our facilities. We did not record any revenues in the three months ended March 31, 2020 and March 31, 2019 from performance obligations satisfied in previous periods.

BUSINESS COMBINATIONS

BUSINESS COMBINATIONS	3 Months Ended
	Mar. 31, 2020
Business Combinations [Abstract]
BUSINESS COMBINATIONS	BUSINESS COMBINATIONS In the three months ended March 31, 2020, we acquired two businesses: one tuck-in solid waste collection business in our Western region and one recycling operation in our Resource Solutions segment. We did not acquire any business in the three months ended March 31, 2019. The operating results of the acquired businesses are included in the accompanying unaudited 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. Such assets are amortized over a five ten A summary of the purchase price paid for these acquisitions and the allocation of the purchase price for these acquisitions follows: Three Months Ended 2020 2019 Purchase Price: Cash used in acquisitions, net of cash acquired $ 4,771 $ — Holdbacks 580 — Total 5,351 — Allocated as follows: Land 325 — Buildings 678 — Equipment 2,396 — Intangible assets 1,225 — Other liabilities, net (80) — Fair value of assets acquired and liabilities assumed 4,544 — Excess purchase price allocated to goodwill $ 807 $ — Certain purchase price allocations are preliminary and are based on information existing at the acquisition dates or upon closing the transaction. Accordingly, these purchase price allocations are subject to change. Unaudited pro forma combined information that shows our operational results as though each acquisition completed since the beginning of the prior fiscal year had occurred as of January 1, 2019 is as follows: Three Months Ended 2020 2019 Revenues $ 183,262 $ 178,575 Operating income $ 7,037 $ 5,868 Net income (loss) $ 970 $ (921) Basic earnings per share attributable to common stockholders: Weighted average common shares outstanding 48,005 45,913 Basic earnings per common share $ 0.02 $ (0.02) Diluted earnings per share attributable to common stockholders: Weighted average common shares outstanding 48,262 45,913 Diluted earnings per common share $ 0.02 $ (0.02) The unaudited pro forma results set forth in the table above have been prepared for comparative purposes only and are not necessarily indicative of the actual results of operations had the acquisitions occurred as of January 1, 2019 or of the results of our future operations. Furthermore, the unaudited 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.

ACCOUNTS RECEIVABLE, NET OF ALL

ACCOUNTS RECEIVABLE, NET OF ALLOWANCE FOR CREDIT LOSSES	3 Months Ended
	Mar. 31, 2020
Credit Loss [Abstract]
ACCOUNTS RECEIVABLE, NET OF ALLOWANCE FOR CREDIT LOSSES	ACCOUNTS RECEIVABLE, NET OF ALLOWANCE FOR CREDIT LOSSES Accounts receivable represent receivables from customers for collection, transfer, recycling, disposal and other services. Our accounts receivable 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, net of allowance for credit losses represents its estimated net realizable value. Estimates are used in determining our allowance for credit losses based on, among other things, our historical loss trends, the age of outstanding accounts receivable, and current and expected economic conditions. The Additions – charged to expense in the three months ended March 31, 2020 considers the current economic conditions associated with the COVID-19 pandemic and the potential impact to our customers’ ability to pay for services that we have provided. Our reserve is evaluated and revised on a monthly basis. Past due accounts receivable are written off when deemed to be uncollectible. A summary of the changes to allowance for credit losses follows: Three Months Ended Balance at beginning of period $ 1,468 Cumulative effect of new accounting principle 189 Additions - charged to expense 880 Deductions - bad debts written off, net of recoveries (445) Balance at end of period $ 2,092

LEASES

LEASES	3 Months Ended
	Mar. 31, 2020
Leases [Abstract]
LEASES	LEASESWe lease vehicles, equipment, property and other non-core equipment in the ordinary course of our business. Leases are classified as either operating leases or finance leases, as appropriate. Our leases have varying terms and may include renewal or purchase options, escalation clauses, restrictions, lease concessions, capital project funding, penalties or other obligations that we considered historically in determining minimum rental payments. We recognize lease expense for operating leases on a straight-line basis over the lease term. We recognize depreciation expense for finance leases over either the useful life of the asset or the lease term based on the terms of the lease agreement. We are also party to three landfill operation and management agreements. These agreements are long-term landfill operating contracts with government bodies whereby we receive tipping revenue, pay normal operating expenses and assume future final capping, closure and post-closure obligations. The government body retains ownership of the landfill. There is no bargain purchase option and title to the property does not pass to us at the end of the lease term. We allocate the consideration paid to the landfill airspace rights and underlying land lease based on the relative fair values. In addition to up-front or one-time payments, the landfill operating agreements may require us to make future minimum rental payments, including success/expansion fees, other direct costs and final capping, closure and post-closure costs. The value of all future minimum rental payments is amortized and charged to cost of operations over the life of the contract. We amortize the consideration allocated to airspace rights as airspace is utilized on a units-of-consumption basis and such amortization is charged to cost of operations as airspace is consumed (e.g., as tons are placed into the landfill). The underlying value of any land lease is amortized to cost of operations on a straight-line basis over the estimated life of the operating agreement. A schedule of lease costs and other lease information follows: Three Months Ended 2020 2019 Lease cost: Amortization of right-of-use assets $ 731 $ 409 Interest expense 246 156 Fixed lease cost - vehicles, equipment and property 2,417 2,579 Fixed lease cost - landfill operating leases 1,673 1,648 Fixed lease cost 4,090 4,227 Short-term lease cost 929 658 Variable lease cost 132 7 Total lease cost $ 6,128 $ 5,457 Other information: Cash paid for amounts included in the measurement of lease liabilities: Financing cash flows for finance leases $ 961 $ 471 Operating cash flows for operating leases $ 2,442 $ 2,043 Right-of-use assets obtained in exchange for new finance lease liabilities $ 6,402 $ 2,473 Right-of-use assets obtained in exchange for new operating lease liabilities $ 2,366 $ 415 March 31, Weighted-average remaining lease term - finance leases (years) 6.2 Weighted-average remaining lease term - operating leases (years) 11.8 Weighted-average discount rate - finance leases 4.7 % Weighted-average discount rate - operating leases 5.1 % Estimated minimum future lease obligations are as follows: Operating Leases Finance Leases Fiscal year ending December 31, 2020 $ 11,086 $ 3,760 Fiscal year ending December 31, 2021 11,822 4,830 Fiscal year ending December 31, 2022 9,155 4,237 Fiscal year ending December 31, 2023 7,288 4,071 Fiscal year ending December 31, 2024 6,638 3,971 Thereafter 63,964 7,540 Total lease payments 109,953 28,409 Less: interest expense (29,395) (4,580) Lease liability balance $ 80,558 $ 23,829
LEASES	LEASESWe lease vehicles, equipment, property and other non-core equipment in the ordinary course of our business. Leases are classified as either operating leases or finance leases, as appropriate. Our leases have varying terms and may include renewal or purchase options, escalation clauses, restrictions, lease concessions, capital project funding, penalties or other obligations that we considered historically in determining minimum rental payments. We recognize lease expense for operating leases on a straight-line basis over the lease term. We recognize depreciation expense for finance leases over either the useful life of the asset or the lease term based on the terms of the lease agreement. We are also party to three landfill operation and management agreements. These agreements are long-term landfill operating contracts with government bodies whereby we receive tipping revenue, pay normal operating expenses and assume future final capping, closure and post-closure obligations. The government body retains ownership of the landfill. There is no bargain purchase option and title to the property does not pass to us at the end of the lease term. We allocate the consideration paid to the landfill airspace rights and underlying land lease based on the relative fair values. In addition to up-front or one-time payments, the landfill operating agreements may require us to make future minimum rental payments, including success/expansion fees, other direct costs and final capping, closure and post-closure costs. The value of all future minimum rental payments is amortized and charged to cost of operations over the life of the contract. We amortize the consideration allocated to airspace rights as airspace is utilized on a units-of-consumption basis and such amortization is charged to cost of operations as airspace is consumed (e.g., as tons are placed into the landfill). The underlying value of any land lease is amortized to cost of operations on a straight-line basis over the estimated life of the operating agreement. A schedule of lease costs and other lease information follows: Three Months Ended 2020 2019 Lease cost: Amortization of right-of-use assets $ 731 $ 409 Interest expense 246 156 Fixed lease cost - vehicles, equipment and property 2,417 2,579 Fixed lease cost - landfill operating leases 1,673 1,648 Fixed lease cost 4,090 4,227 Short-term lease cost 929 658 Variable lease cost 132 7 Total lease cost $ 6,128 $ 5,457 Other information: Cash paid for amounts included in the measurement of lease liabilities: Financing cash flows for finance leases $ 961 $ 471 Operating cash flows for operating leases $ 2,442 $ 2,043 Right-of-use assets obtained in exchange for new finance lease liabilities $ 6,402 $ 2,473 Right-of-use assets obtained in exchange for new operating lease liabilities $ 2,366 $ 415 March 31, Weighted-average remaining lease term - finance leases (years) 6.2 Weighted-average remaining lease term - operating leases (years) 11.8 Weighted-average discount rate - finance leases 4.7 % Weighted-average discount rate - operating leases 5.1 % Estimated minimum future lease obligations are as follows: Operating Leases Finance Leases Fiscal year ending December 31, 2020 $ 11,086 $ 3,760 Fiscal year ending December 31, 2021 11,822 4,830 Fiscal year ending December 31, 2022 9,155 4,237 Fiscal year ending December 31, 2023 7,288 4,071 Fiscal year ending December 31, 2024 6,638 3,971 Thereafter 63,964 7,540 Total lease payments 109,953 28,409 Less: interest expense (29,395) (4,580) Lease liability balance $ 80,558 $ 23,829

GOODWILL AND INTANGIBLE ASSETS

GOODWILL AND INTANGIBLE ASSETS	3 Months Ended
	Mar. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
GOODWILL AND INTANGIBLE ASSETS	GOODWILL AND INTANGIBLE ASSETS A summary of the activity and balances related to goodwill by reporting segment is as follows: December 31, Acquisitions March 31, Eastern region $ 30,720 $ — $ 30,720 Western region 141,055 807 141,862 Resource solutions 14,044 — 14,044 Total $ 185,819 $ 807 $ 186,626 A summary of intangible assets by intangible asset type follows: Covenants Client Lists Total Balance, March 31, 2020 Intangible assets $ 26,467 $ 72,133 $ 98,600 Less accumulated amortization (19,365) (21,292) (40,657) $ 7,102 $ 50,841 $ 57,943 Covenants Client Lists Total Balance, December 31, 2019 Intangible assets $ 26,162 $ 71,122 $ 97,284 Less accumulated amortization (18,968) (19,595) (38,563) $ 7,194 $ 51,527 $ 58,721 Intangible amortization expense was $2,093 during the three months ended March 31, 2020, as compared to $1,401 during the three months ended March 31, 2019. A summary of intangible amortization expense estimated for the five fiscal years following the fiscal year ended December 31, 2019 and thereafter follows: Estimated Future Amortization Expense as of March 31, 2020 Fiscal year ending December 31, 2020 $ 6,255 Fiscal year ending December 31, 2021 $ 6,963 Fiscal year ending December 31, 2022 $ 6,324 Fiscal year ending December 31, 2023 $ 6,131 Fiscal year ending December 31, 2024 $ 7,109 Thereafter $ 25,161

ACCRUED FINAL CAPPING, CLOSURE

ACCRUED FINAL CAPPING, CLOSURE AND POST CLOSURE	3 Months Ended
	Mar. 31, 2020
Asset Retirement Obligation Disclosure [Abstract]
ACCRUED FINAL CAPPING, CLOSURE AND POST CLOSURE	ACCRUED FINAL CAPPING, CLOSURE AND POST CLOSUREAccrued 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. 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. A summary of the changes to accrued final capping, closure and post-closure liabilities follows: Three Months Ended 2020 2019 Beginning balance $ 71,927 $ 73,075 Obligations incurred 898 543 Accretion expense 1,622 1,607 Obligations settled (1) (1,097) (1,556) Ending balance $ 73,350 $ 73,669 (1) Includes amounts that are being processed through accounts payable as a part of our disbursements cycle.

DEBT

DEBT	3 Months Ended
	Mar. 31, 2020
Debt And Derivatives Disclosure [Abstract]
DEBT	DEBT A summary of debt is as follows: March 31, December 31, Senior Secured Credit Facility: Revolving line of credit facility ("Revolving Credit Facility") due May 2023; bearing interest at LIBOR plus 1.75% $ 61,000 $ 26,900 Term loan A facility ("Term Loan Facility") due May 2023; bearing interest at LIBOR plus 1.75% 350,000 350,000 Tax-Exempt Bonds: New York State Environmental Facilities Corporation Solid Waste Disposal Revenue Bonds Series 2014 ("New York Bonds 2014") due December 2044 - fixed rate interest period through 2019; bearing interest at 2.875% 25,000 25,000 New York State Environmental Facilities Corporation Solid Waste Disposal Revenue Bonds Series 2014R-2 ("New York Bonds 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 ("FAME Bonds 2005R-3") due January 2025 - fixed rate interest period through 2025; bearing interest at 5.25% 25,000 25,000 Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2015R-1 ("FAME Bonds 2015R-1") due August 2035 - fixed rate interest period through 2025; bearing interest at 5.125% 15,000 15,000 Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2015R-2 ("FAME Bonds 2015R-2") due August 2035 - fixed rate interest period through 2025; bearing interest at 4.375% 15,000 15,000 Vermont Economic Development Authority Solid Waste Disposal Long-Term Revenue Bonds Series 2013 ("Vermont Bonds") due April 2036 - fixed rate interest period through 2028; bearing interest at 4.625% 16,000 16,000 Business Finance Authority of the State of New Hampshire Solid Waste Disposal Revenue Bonds Series 2013 ("New Hampshire Bonds") due April 2029 - fixed rate interest period through 2029; bearing interest at 2.95% 11,000 11,000 Other: Finance leases maturing through December 2107; bearing interest at a weighted average of 4.7% 23,829 18,364 Notes payable maturing through June 2027; bearing interest at a weighted average of 3.5% 5,181 5,464 Principal amount of debt 562,010 522,728 Less—unamortized debt issuance costs (1) 8,889 9,406 Debt less unamortized debt issuance costs 553,121 513,322 Less—current maturities of debt 5,392 4,301 $ 547,729 $ 509,021 (1) A summary of unamortized debt issuance costs by debt instrument follows: March 31, December 31, Revolving Credit Facility and Term Loan Facility (collectively, the "Credit Facility") $ 5,069 $ 5,478 New York Bonds 2014 1,051 1,057 New York Bonds 2014R-2 374 390 FAME Bonds 2005R-3 411 432 FAME Bonds 2015R-1 534 552 FAME Bonds 2015R-2 399 417 Vermont Bonds 527 541 New Hampshire Bonds 524 539 $ 8,889 $ 9,406 Credit Facility As of March 31, 2020, we are party to a credit agreement ("Credit Agreement"), which provides for a $350,000 Term Loan Facility and a $200,000 Revolving Credit Facility. 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 $125,000, subject to the terms and conditions set forth in the Credit Agreement. The Credit Facility has a 5-year term that matures in May 2023 and bears interest at a rate of LIBOR plus 1.75% per annum, which will be reduced to a rate of LIBOR plus as low as 1.25% upon us reaching a consolidated net leverage ratio of less than 2.25x. The Credit Facility is guaranteed jointly and severally, fully and unconditionally by all of our significant wholly-owned subsidiaries and secured by substantially all of our assets. As of March 31, 2020, further advances were available under the Credit Facility in the amount of $113,575. The available amount is net of outstanding irrevocable letters of credit totaling $25,425, 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 March 31, 2020, 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. Cash Flow Hedges Our strategy to reduce exposure to interest rate risk involves entering into interest rate derivative agreements to hedge against adverse movements in interest rates related to the variable rate portion of our long-term debt. In the three months ended March 31, 2020, we entered into three forward starting interest rate derivative agreements with a total notional amount of $60,000 that will serve to replace existing interest rate derivative agreements upon their expiration between June 2022 and May 2023. In the three months ended March 31, 2020, we also amended three interest rate derivative agreements to settle each of the 1.0% floors and replace each with a 0.0% floor in line with our Term Loan Facility, which resulted in us dedesignating the original hedging relationships. We subsequently designated new hedging relationships between the three interest rate derivative agreements and the variable rate interest payments related to the Term Loan Facility based on a quantitative assessment that was performed using regression analysis, which indicated that the hedging relationships were highly effective. Because the interest rate payments associated with the variable rate portion of our long-term debt will still occur, the net loss of $(765) associated with the dedesignated interest rate derivative agreements and the $430 cash settlement received in exchange for settling the 1.0% floors in accumulated other comprehensive loss were not reclassified into earnings. Instead, this loss and settlement amount will continue to be reclassified from accumulated other comprehensive loss into interest expense as the interest payments affect earnings. As of both March 31, 2020 and December 31, 2019, our interest rate derivative agreements have a total notional amount of $190,000. According to the terms of the agreements, we receive interest based on the 1-month LIBOR index and pay interest at a weighted average rate of approximately 2.54%. The agreements mature between February 2021 and May 2023. Additionally, we have forward starting interest rate derivative agreements with a total notional amount of $125,000 that mature between February 2026 and May 2028. We receive interest based on the 1-month LIBOR index, restricted by a 0.0% floor, and will pay interest at a weighted average rate of approximately 1.63%. We have designated these derivative instruments as highly effective cash flow hedges, and therefore the change in fair value is recorded in our stockholders’ equity as a component of accumulated other comprehensive loss and included in interest expense at the same time as interest expense is affected by the hedged transactions. Differences paid or received over the life of the agreements are recorded as additions to or reductions of interest expense on the underlying debt and included in cash flows from operating activities. A summary of the effect of cash flow hedges related to derivative instruments on the consolidated balance sheet follows: Fair Value Balance Sheet Location March 31, December 31, Interest rate swaps Other accrued liabilities $ 4,166 $ 1,824 Interest rate swaps Other long-term liabilities 8,860 3,603 $ 13,026 $ 5,427 Interest rate swaps Accumulated other comprehensive loss $ (13,230) $ (5,929) Interest rate swaps - tax provision Accumulated other comprehensive loss — (112) $ (13,230) $ (6,041) A summary of the amount of expense on cash flow hedging relationships related to interest rate swaps reclassified from accumulated other comprehensive loss into earnings follows: Three Months Ended 2020 2019 Statement of Operations Location (Expense) Income Interest expense $ (489) $ (25)

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	3 Months Ended
	Mar. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES Legal Proceedings In the ordinary course of our business and as a result of the extensive governmental regulation of the solid waste industry, we are subject to various judicial and administrative proceedings involving state and local agencies. In these proceedings, an agency may seek to impose fines or to revoke or deny renewal of an operating permit held by us. From time to time, we may also be subject to actions brought by special interest or other groups, adjacent landowners or residents in connection with the permitting and licensing of landfills and transfer stations, or allegations of environmental damage or violations of the permits and licenses pursuant to which we operate. In addition, we may be named defendants in various claims and suits pending for alleged damages to persons and property, alleged violations of certain laws and alleged liabilities arising out of matters occurring during the ordinary operation of a waste management business. In accordance with FASB ASC 450 - Contingencies, we accrue for legal proceedings, inclusive of legal costs, when losses become probable and reasonably estimable. As of the end of each applicable reporting period, we review each of our legal proceedings to determine whether it is probable, reasonably possible or remote that a liability has been incurred and, if it is at least reasonably possible, whether a range of loss can be reasonably estimated under the provisions of FASB ASC 450-20. In instances where we determine that a loss is probable and we can reasonably estimate a range of loss we may incur with respect to such a matter, we record an accrual for the amount within the range that constitutes our best estimate of the possible loss. If we are able to reasonably estimate a range, but no amount within the range appears to be a better estimate than any other, we record an accrual in the amount that is the low end of such range. When a loss is reasonably possible, but not probable, we will not record an accrual, but we will disclose our estimate of the possible range of loss where such estimate can be made in accordance with FASB ASC 450-20. Environmental Remediation Liability (including related litigation) 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 was operated by SRD and later closed in November 2018 when Southbridge Landfill reached its final capacity. Those results indicated the presence of contaminants above the levels triggering notice and response obligations under MADEP regulations. In response to those results, we have been carrying out an Immediate Response Action pursuant to Massachusetts General Law Chapter 21E (the "Charlton 21E Obligations") pursuant to state law. Further, we have implemented a plan to analyze and better understand the groundwater near the Southbridge Landfill and we are investigating with the objective of identifying the source or sources of the elevated levels of contamination measured in the well samples. If it is determined that some or all of the contamination originated at the Southbridge Landfill, we will work with the Town (the Southbridge Landfill owner and the former operator of an unlined portion of the Southbridge Landfill, which was used prior to our operation of a double-lined portion of the Southbridge Landfill commencing in 2004) to evaluate and allocate the liabilities related to the Charlton 21E Obligations. In July 2016, we sent correspondence to the Town pursuant to Chapter 21E of Massachusetts General Laws demanding that the Town reimburse us for the environmental response costs we had spent and that the Town be responsible for all such costs in the future, as well as any other costs or liabilities resulting from the release of contaminants from the unlined portion of the Southbridge Landfill. The Town responded in September 2016, denying that the Southbridge Landfill is the source of such contamination, and claiming that if it is, that we may owe an indemnity to the Town pursuant to the Operating Agreement between us and the Town dated May 29, 2007, as amended. We entered into a Tolling Agreement with the Town to delay any further administrative or legal actions until our work with MADEP more specifically defines the parties’ responsibilities for the Charlton 21E Obligations, if any. Please see below for further discussion of our relationship with the Town regarding the Charlton 21E Obligations. In February 2016, we and the Town received a Notice of Intent to Sue under the Resource Conservation and Recovery Act ("RCRA") from a law firm purporting to represent residents proximate to the Southbridge Landfill (“Residents”), indicating its intent to file suit against us on behalf of the Residents alleging the groundwater contamination originated from the Southbridge Landfill. In February 2017, we received an additional Notice of Intent to Sue from the National Environmental Law Center under the Federal Clean Water Act ("CWA") and RCRA (collectively the “Acts”) on behalf of Environment America, Inc., d/b/a Environment Massachusetts, and Toxics Action Center, Inc., which have referred to themselves as the Citizen Groups. The Citizen Groups alleged that we had violated the Acts, and that they intended to seek appropriate relief in federal court for those alleged violations. On or about June 9, 2017, a lawsuit was filed against us, SRD and the Town in the United States District Court for the District of Massachusetts (the “Massachusetts Court”) by the Citizen Groups and the Residents alleging violations of the Acts (the “Litigation”), and demanding a variety of remedies under the Acts, including fines, remediation, mitigation and costs of litigation, and remedies for violations of Massachusetts civil law related to personal and property damages, including remediation, diminution of property values, compensation for lost use and enjoyment of properties, enjoinment of further operation of the Southbridge Landfill, and costs of litigation, plus interest on any damage award, on behalf of the Residents. We believe the Litigation to be factually inaccurate, and without legal merit, and we and SRD are vigorously defending the Litigation. Nevertheless, we believe it is reasonably possible that a loss will occur as a result of the Litigation although an estimate of loss cannot be reasonably provided at this time. We also continue to believe the Town should be responsible for costs or liabilities associated with the Litigation relative to alleged contamination originating from the unlined portion of the Southbridge Landfill, although there can be no assurance that we will not be required to incur some or all of such costs and liabilities. In December 2017, we filed a Motion to Dismiss the Litigation, and on October 1, 2018, the Massachusetts Court granted our Motion to Dismiss, and accordingly, dismissed the Citizen Groups claims under the Acts. The Massachusetts Court has retained jurisdiction of the Residents claims. The Citizen Groups intend to appeal the Massachusetts Court’s decision to grant our Motion to Dismiss. The Residents moved for a stay of their case until the Citizen Groups appealed. We opposed the stay and in March 2019, the Massachusetts Court denied the Residents motion for a stay. We are in active discovery in the Residents case. We entered into an Administrative Consent Order on April 26, 2017 (the “ACO”), with MADEP, the Town, and the Town of Charlton, committing us to equally share the costs with MADEP, of up to $10,000 ($5,000 each) for the Town to install a municipal waterline in the Town of Charlton ("Waterline"). Upon satisfactory completion of that Waterline, and other matters covered by the ACO, we and the Town will be released by MADEP from any future responsibilities for the Charlton 21E Obligations. We also entered into an agreement with the Town on April 28, 2017 entitled the “21E Settlement and Water System Construction Funding Agreement” (the “Waterline Agreement”), wherein we and the Town released each other from claims arising from the Charlton 21E Obligations. Pursuant to the Waterline Agreement, the Town will issue a twenty (20) year bond for our portion of the Waterline costs (up to $5,000). We have agreed to reimburse the Town for periodic payments under such bond. Construction of the waterline is complete and homeowners are relying on municipal water supply. Remaining aspects of the project are minor and are expected to be completed in 2020. Bond reimbursement to the Town will commence in the fiscal year ending December 31, 2020. We have recorded an environmental remediation liability related to our obligation associated with the 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 1.9%. Our expenditures could be significantly higher if costs exceed estimates. A summary of the changes to the environmental remediation liability associated with the Southbridge Landfill follows: Three Months Ended 2020 2019 Beginning balance $ 4,596 $ 5,173 Accretion expense 30 34 Obligations incurred 27 — Obligations settled (1) (12) (141) Ending balance $ 4,641 $ 5,066 (1) Includes amounts that are being processed through accounts payable as a part of our disbursements cycle. We completed the first phase of landfill capping and closure in fiscal year 2019 at the Southbridge Landfill and are actively seeking approval from MADEP to close and cap the remainder of the landfill. 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. The majority of the remediation work has been completed as of March 31, 2020. 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%. The environmental remediation liability associated with the Potsdam site was $1,151 as of both March 31, 2020 and December 31, 2019. Legal Proceedings North Country Environmental Services On or about March 8, 2018, the Citizen Groups described above delivered correspondence to our subsidiary, North Country Environmental Services, Inc. ("NCES") and us, providing notice of the Citizen Groups' intent to sue NCES and us for violations of the CWA in conjunction with NCES's operation of its landfill in Bethlehem, New Hampshire ("NCES Landfill"). On May 14, 2018, the Citizen Groups filed a lawsuit against NCES and us in the United States District Court for the District of New Hampshire (the “New Hampshire Court”) alleging violations of the CWA, arguing that ground water discharging into the Ammonoosuc River is a "point source" under the CWA (the "New Hampshire Litigation"). The New Hampshire Litigation seeks remediation and fines under the CWA. On June 15, 2018, we and NCES filed a Motion to Dismiss the New Hampshire Litigation. On July 13, 2018, the Citizen Groups filed objections to our Motion to Dismiss. On July 27, 2018, we filed a reply in support of our Motion to Dismiss. On September 25, 2018, the New Hampshire Court denied our Motion to Dismiss. In March of 2019, we filed a motion in the New Hampshire Litigation asking for a stay of this litigation until certain appeals from discordant federal circuit courts were heard by the Supreme Court of the United States (“SCOTUS”), in the case identified as “County of Maui the. Hawaii Wildlife Fund (“MAUI”)”. Our motion for a stay was granted in the New Hampshire Litigation, and SCOTUS heard the case in 2019 and issued a ruling on April 23, 2020. SCOTUS remanded the case to the U.S. Court of Appeals for the Ninth Circuit in San Francisco (the “Circuit Court”) ruling that the Circuit Court’s standard as to whether ground water impacts navigable waters is too broad. SCOTUS ruled 6-3 that the question should be whether “…the addition of the pollutants through ground water is the functional equivalent of a direct discharge from the point source into navigable waters”. We do not believe that the MAUI decision resolves the issues presented in the New Hampshire Litigation, and until the Circuit Court rules in the remanded MAUI case, we intend to continue to vigorously defend against the New Hampshire Litigation, which we believe is without merit. Ontario County, New York Class Action Litigation On or about September 17, 2019, Richard Vandemortel and Deb Vandemortel filed a class action complaint against us on behalf of similarly situated citizens in Ontario County, New York. The lawsuit has been filed in Ontario County (the “New York Litigation”). It alleges that over one thousand (1,000) citizens constitute the putative class in the New York Litigation, and it seeks damages for diminution of property values and infringement of the putative class’ rights to live without interference to their daily lives due to odors emanating from the Ontario County Landfill, which is operated by us pursuant to a long-term Operation, Maintenance and Lease Agreement with Ontario County. The New York Litigation was served on us on October 14, 2019. We are reviewing the New York Litigation and intend to present a vigorous defense. Hakes Landfill Litigation On or about December 19, 2019, the New York State Department of Environmental Conservation (“Department”) issued certain permits to us to expand the landfill owned and operated by Hakes C&D Disposal Inc. (“Hakes”) in the Town of Campbell, Steuben County, New York. The permits authorize approximately five years of expansion capacity at the Hakes Landfill. The authorizations issued by the Department followed approvals issued by the Town of Campbell Planning Board (“Planning Board”) in January 2019, and the Town Board of the Town of Campbell (“Town Board”) in March 2019, granting site plan review and a zoning change for the project. Through litigation commenced by the Sierra Club, several other non-governmental organizations, and several individuals, the Petitioners have challenged the approvals issued by the Department, the Planning Board and the Town Board in New York State Supreme Court, Steuben County. The challenge is based upon allegations that the agencies issuing these approvals did not follow the requirements of Article 8 of the Environmental Conservation Law of the State of New York, the State Environmental Quality Review Act (“SEQRA”), by failing to address certain radioactivity issues alleged by Petitioners to be associated with certain wastes drilling wastes authorized for disposal at the Hakes Landfill. The petitioners have also made a motion for a preliminary injunction to restrain construction and operation of the expansion cell. We, as well as all of the involved agencies, are vigorously defending against the litigation. The parties to the litigation have entered into a stipulation to facilitate progress in the litigation and the motion for a preliminary injunction has been adjourned until the end of August, which should give the court time to address the merits of the petition before addressing the motion for a preliminary injunction. There is no restriction on construction and we anticipate completing the construction at the Hakes Landfill by the end of August, 2020. Loss Contingency On January 9, 2019, NCES filed an application for a 1.2 million (cy) expansion of the capacity of the NCES Landfill with the New Hampshire Department of Environmental Services (“NHDES”) (“Stage VI Expansion”). The Stage VI Expansion would provide NCES with over five (5) years of additional capacity beyond the capacity of Stage V. On January 9, 2019, NCES filed an application for a 1.2 million (cy) expansion of the capacity of the NCES Landfill with the New Hampshire Department of Environmental Services (“NHDES”) (“Stage VI Expansion”). The Stage VI Expansion would provide NCES with over five (5) years of additional capacity beyond the capacity of Stage V. In January 2020, NHDES informed NCES and us that NHDES had concerns regarding the short-term public benefit need for the Stage VI expansion, and also in respect of certain technical concerns regarding the Stage VI expansion. Given the fact the NHDES decided to review our permit application for the Stage VI Expansion with respect to public benefit determination using a different regulatory framework than used in any of our previous permitting activities at NCES, we informed the NHDES on February 11, 2020, that while we vigorously disagreed with NHDES’ review of our application and the context for the NHDES’ concerns, we would withdraw our application with the expectation of refiling the application with the NHDES as soon as possible. We refiled our application on March 17, 2020. While the refiling of the application for the Stage VI Expansion could be rejected by the NHDES, and while delay of the Stage VI Expansion will surely occur, we remain confident that we will receive a permit for the Stage VI Expansion. We believe that a loss of $1,415 is reasonably possible, but not probable.

STOCKHOLDERS' EQUITY

STOCKHOLDERS' EQUITY	3 Months Ended
	Mar. 31, 2020
Equity [Abstract]
STOCKHOLDERS' EQUITY	STOCKHOLDERS' EQUITY Stock Based Compensation Shares Available For Issuance In the fiscal year ended December 31, 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 (up to 2,723 shares) as is equal to the sum of the number of shares of Class A common stock that remained available for grant under the 2006 Stock Incentive Plan (“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, terminate or are otherwise surrendered, canceled, forfeited or repurchased by us. As of March 31, 2020, there were 1,121 Class A common stock equivalents available for future grant under the 2016 Plan. Stock Options 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 The fair value of each stock option granted 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. A summary of stock option activity follows: Stock Options (1) Weighted Average Exercise Price Weighted Average Remaining Contractual Term (years) Aggregate Intrinsic Value Outstanding, December 31, 2019 98 $ 9.20 Granted — $ — Exercised (8) $ 12.48 Forfeited — $ — Outstanding, March 31, 2020 90 $ 8.91 5.5 $ 2,717 Exercisable, March 31, 2020 90 $ 8.91 5.5 $ 2,717 We did not record any stock-based compensation expense for stock options during both the three months ended March 31, 2020 and March 31, 2019. During the three months ended March 31, 2020, the aggregate intrinsic value of stock options exercised was $296. Other Stock Awards Restricted stock awards, restricted stock units and performance stock units, with the exception of market-based 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. Generally, restricted stock awards granted to non-employee directors vest incrementally over a three A summary of restricted stock, restricted stock unit and performance stock unit activity follows: Restricted Stock, Restricted Stock Units, and Performance Stock Units (1) Weighted Weighted Average Remaining Contractual Term (years) Aggregate Intrinsic Value Outstanding, December 31, 2019 393 $ 28.23 Granted 138 $ 47.00 Class A Common Stock Vested (108) $ 19.44 Forfeited (2) $ 25.41 Outstanding, March 31, 2020 421 $ 36.63 2.2 $ 16,455 Unvested, March 31, 2020 710 $ 37.60 2.0 $ 27,755 (1) Market-based performance stock unit grants are included at the 100% attainment level. Attainment of the maximum performance targets and market achievements would result in the issuance of an additional 289 shares of Class A common stock currently included in unvested. Stock-based compensation expense related to restricted stock, restricted stock units and performance stock units was $1,515 during the three months ended March 31, 2020, as compared to $1,390 during the three months ended March 31, 2019. During the three months ended March 31, 2020, the total fair value of other stock awards vested was $4,979. As of March 31, 2020, total unrecognized stock-based compensation expense related to outstanding restricted stock was $45, which will be recognized over a weighted average period of 2.7 years. As of March 31, 2020, total unrecognized stock-based compensation expense related to outstanding restricted stock units was $5,148, which will be recognized over a weighted average period of 2.3 years. As of March 31, 2020, total unrecognized stock-based compensation expense related to outstanding performance stock units was $7,356 to be recognized over a weighted average period of 2.1 years. We also recorded $47 of stock-based compensation expense related to our Amended and Restated 1997 Employee Stock Purchase Plan during the three months ended March 31, 2020, as compared to $41 during the three months ended March 31, 2019. Accumulated Other Comprehensive Loss A summary of the changes in the balances of each component of accumulated other comprehensive loss, net of tax follows: Interest Rate Swaps Balance, December 31, 2019 $ (6,041) Other comprehensive loss before reclassifications (7,790) Amounts reclassified from accumulated other comprehensive loss 489 Income tax benefit related to items of other comprehensive loss 112 Net current-period other comprehensive loss (7,189) Balance, March 31, 2020 $ (13,230) A summary of reclassifications out of accumulated other comprehensive loss, net of tax follows: Three Months Ended 2020 2019 Details About Accumulated Other Comprehensive Loss Components Amounts Reclassified Out of Accumulated Other Comprehensive Loss Affected Line Item in the Consolidated Interest rate swaps $ 489 $ 25 Interest expense 489 25 Income before income taxes (112) — Provision (benefit) for income taxes $ 601 $ 25 Net income

EARNINGS PER SHARE

EARNINGS PER SHARE	3 Months Ended
	Mar. 31, 2020
Earnings Per Share [Abstract]
EARNINGS PER SHARE	EARNINGS PER SHAREBasic earnings per share is computed by dividing the net income (loss) 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, which include the assumed exercise of employee stock options, 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. A summary of the numerator and denominators used in the computation of earnings per share follows: Three Months Ended 2020 2019 Numerator: Net income (loss) $ 959 $ (1,714) Denominators: Number of shares outstanding, end of period: Class A common stock 47,320 46,252 Class B common stock 988 988 Shares to be issued - acquisition 36 36 Unvested restricted stock (1) (9) Effect of weighted average shares outstanding (338) (1,354) Basic weighted average common shares outstanding 48,005 45,913 Impact of potentially dilutive securities: Dilutive effect of stock options and other stock awards 257 — Diluted weighted average common shares outstanding 48,262 45,913 Anti-dilutive potentially issuable shares — 1,422

OTHER ITEMS AND CHARGES

OTHER ITEMS AND CHARGES	3 Months Ended
	Mar. 31, 2020
Unusual or Infrequent Items, or Both [Abstract]
OTHER ITEMS AND CHARGES	OTHER ITEMS AND CHARGES Expense from Acquisition Activities and Other Items In the three months ended March 31, 2020 and 2019, we recorded charges of $1,009 and $677, respectively, associated primarily with acquisition activities. Southbridge Landfill Closure Charge In 2017, we initiated the plan to cease operations of the Southbridge Landfill and later closed it in November 2018 when Southbridge Landfill reached its final capacity .

FAIR VALUE OF FINANCIAL INSTRUM

FAIR VALUE OF FINANCIAL INSTRUMENTS	3 Months Ended
	Mar. 31, 2020
Fair Value Disclosures [Abstract]
FAIR VALUE OF FINANCIAL INSTRUMENTS	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 Our financial instruments include cash and cash equivalents, accounts receivable, restricted investment securities held in trust on deposit with various banks as collateral for our obligations relative to our landfill final capping, closure and post-closure costs, interest rate swaps, trade payables and long-term debt. The carrying values of cash and cash equivalents, accounts receivable and trade payables approximate their respective fair values due to their short-term nature. The fair value of restricted investment securities held in trust, which are valued using quoted market prices, are included as restricted assets in the Level 1 tier below. The fair value of the interest rate swaps 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. Recurring Fair Value Measurements Summaries of our financial assets and liabilities that are measured at fair value on a recurring basis follow: Fair Value Measurement at March 31, 2020 Using: Quoted Prices in Significant Other Significant Assets: Restricted investment securities - landfill closure $ 1,410 $ — $ — Liabilities: Interest rate swaps $ — $ 13,026 $ — Fair Value Measurement at December 31, 2019 Using: Quoted Prices in Significant Other Significant Assets: Restricted investment securities - landfill closure $ 1,586 $ — $ — Liabilities: Interest rate swaps $ — $ 5,427 $ — Fair Value of Debt As of March 31, 2020, the fair value of our fixed rate debt, including our FAME Bonds 2005R-3, FAME Bonds 2015R-1, FAME Bonds 2015R-2, Vermont Bonds, New York Bonds 2014, New York Bonds 2014R-2 and New Hampshire Bonds was approximately $120,327 and the carrying value was $122,000. The fair value of the FAME Bonds 2005R-3, the FAME Bonds 2015R-1, the FAME Bonds 2015R-2, the Vermont Bonds, the New York Bonds 2014, the New York Bonds 2014R-2 and the 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 March 31, 2020, the carrying value of our Term Loan Facility was $350,000 and the carrying value of our Revolving Credit Facility was $61,000. Their fair values are based on current borrowing rates for similar types of borrowing arrangements, or Level 2 inputs, and approximate their carrying values.

SEGMENT REPORTING

SEGMENT REPORTING	3 Months Ended
	Mar. 31, 2020
Segment Reporting [Abstract]
SEGMENT REPORTING	SEGMENT REPORTINGWe report selected information about our reportable 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. We classify our resource-renewal services in our Resource Solutions segment. Revenues associated with our resource renewal operations are derived from organics services, major account and industrial services, as well as recycling services generated from both municipalities and customers in the form of processing fees, tipping fees and commodity sales. Legal, tax, information technology, human resources, certain finance and accounting and other administrative functions are included in our Corporate Entities segment. Three Months Ended March 31, 2020 Segment Outside Inter-company Depreciation and Operating Total Eastern $ 50,143 $ 11,839 $ 5,958 $ 975 $ 206,334 Western 85,206 25,546 13,232 5,642 599,815 Resource solutions 47,561 2,894 1,610 1,003 93,199 Corporate entities — — 606 (608) 58,292 Eliminations — (40,279) — — — $ 182,910 $ — $ 21,406 $ 7,012 $ 957,640 Three Months Ended March 31, 2019 Segment Outside Inter-company Depreciation and Operating Total Eastern $ 46,997 $ 10,771 $ 5,260 $ (626) $ 195,851 Western 74,151 20,218 10,234 5,378 494,066 Resource solutions 42,516 2,387 1,294 401 86,222 Corporate entities — — 701 (711) 52,174 Eliminations — (33,376) — — — $ 163,664 $ — $ 17,489 $ 4,442 $ 828,313 A summary of our revenues attributable to services provided follows: Three Months Ended 2020 2019 Collection $ 94,577 $ 83,080 Disposal 38,625 36,054 Power generation 1,026 1,136 Processing 1,121 878 Solid waste operations 135,349 121,148 Organics 14,932 13,596 Customer solutions 21,663 18,154 Recycling 10,966 10,766 Resource solutions operations 47,561 42,516 Total revenues $ 182,910 $ 163,664

ACCOUNTING CHANGES (Policies)

ACCOUNTING CHANGES (Policies)	3 Months Ended
	Mar. 31, 2020
Accounting Changes and Error Corrections [Abstract]
Basis of Accounting	Casella Waste Systems, Inc. (“Parent”), and its consolidated subsidiaries (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. Effective January 1, 2020, we reorganized our operations to consist of a single resource-renewal focused operation by combining our larger-scale recycling and commodity brokerage operations along with our organics services and major account and industrial services into our Resource Solutions segment. We continue to manage our solid waste operations on a geographic basis through two regional operating segments, the Eastern and Western regions, each of which provides a full range of solid waste services. Legal, tax, information technology, human resources, certain finance and accounting and other administrative functions are included in our Corporate Entities segment. Segment information reported in the three months ended March 31, 2019 and as of December 31, 2019 has been reclassified to conform with the three months ended March 31, 2020 and as of March 31, 2020 presentation. The accompanying unaudited consolidated financial statements, which include the accounts of the Parent and our wholly-owned subsidiaries, 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. Our significant accounting policies are more fully discussed in Item 8 of our Annual Report on Form 10-K for the fiscal year ended December 31, 2019, which was filed with the SEC on February 21, 2020.
Use of Estimates	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 the opinion of management, these consolidated financial statements include all adjustments, which include normal recurring and nonrecurring adjustments, necessary for a fair presentation of the financial position, results of operations and cash flows for the periods presented. The results for the three months ended March 31, 2020 may not be indicative of the results for any other interim period or the entire fiscal year.
Subsequent Events	We have evaluated subsequent events or transactions that have occurred after the consolidated balance sheet date of March 31, 2020 through the date of filing of the consolidated financial statements with the SEC on this Quarterly Report on Form 10-Q. We have determined that there are no subsequent events that require disclosure in this Quarterly Report on Form 10-Q.
Accounting Standards that are Adopted and Pending Adoption	Standard Description Effect on the Financial Statements or Other Accounting standards adopted effective January 1, 2020 ASU No. 2016-13, as amended through March 2020: Financial Instrument Credit Losses (Topic 326) Requires that an entity measures all of its expected credit losses for financial assets held based on historical experience, current conditions, and reasonable and supportable forecasts. We adopted this guidance effective January 1, 2020 using the required modified-retrospective approach. We recognized a cumulative effect adjustment of $(189) to retained earnings upon implementation. This guidance replaces the incurred loss methodology with an expected loss methodology that is referred to as current expected credit loss ("CECL") methodology. CECL requires consideration of past events, current conditions, and reasonable and supportable forecasts about the future to assess credit loss estimates and will generally result in the earlier recognition of an allowance for credit losses. We have updated our business processes and systems and controls to support recognition and disclosure under the new guidance. See Note 5, Accounts Receivable, Net of Allowance for Credit Losses for additional disclosure. A table providing a brief description of recent ASUs to the ASC issued by the FASB that are pending adoption and deemed to have a possible material impact on our consolidated financial statements based on current account balances and activity follows: Standard Description Effect on the Financial Statements or Other Accounting standards issued pending adoption ASU No. 2020-04: Reference Rate Reform (Topic 848) Provides temporary optional guidance to ease the potential burden in applying GAAP to contract modifications and hedging relationships, subject to meeting certain criteria, that reference LIBOR or another reference rate expected to be discontinued. We are currently assessing the provisions of this guidance and do not expect that its adoption will have an impact on our consolidated financial statements and related disclosures. This guidance will be in effect from March 12, 2020 through December 31, 2022. ASU No. 2019-12: Income Taxes (Topic 740) Reduces the complexity over accounting for income taxes by removing certain exceptions and amending guidance to improve consistent application of accounting over income taxes. We are currently assessing the provisions of this guidance to determine whether or not its adoption will have an impact on our consolidated financial statements and related disclosures. This guidance is effective January 1, 2021 with early adoption permitted.
Leases	We lease vehicles, equipment, property and other non-core equipment in the ordinary course of our business. Leases are classified as either operating leases or finance leases, as appropriate. Our leases have varying terms and may include renewal or purchase options, escalation clauses, restrictions, lease concessions, capital project funding, penalties or other obligations that we considered historically in determining minimum rental payments. We recognize lease expense for operating leases on a straight-line basis over the lease term. We recognize depreciation expense for finance leases over either the useful life of the asset or the lease term based on the terms of the lease agreement.We are also party to three landfill operation and management agreements. These agreements are long-term landfill operating contracts with government bodies whereby we receive tipping revenue, pay normal operating expenses and assume future final capping, closure and post-closure obligations. The government body retains ownership of the landfill. There is no bargain purchase option and title to the property does not pass to us at the end of the lease term. We allocate the consideration paid to the landfill airspace rights and underlying land lease based on the relative fair values. In addition to up-front or one-time payments, the landfill operating agreements may require us to make future minimum rental payments, including success/expansion fees, other direct costs and final capping, closure and post-closure costs. The value of all future minimum rental payments is amortized and charged to cost of operations over the life of the contract. We amortize the consideration allocated to airspace rights as airspace is utilized on a units-of-consumption basis and such amortization is charged to cost of operations as airspace is consumed (e.g., as tons are placed into the landfill). The underlying value of any land lease is amortized to cost of operations on a straight-line basis over the estimated life of the operating agreement.
Accrued Final Capping, Closure and Post Closure	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. 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.
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
Segment Reporting	We report selected information about our reportable 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. We classify our resource-renewal services in our Resource Solutions segment. Revenues associated with our resource renewal operations are derived from organics services, major account and industrial services, as well as recycling services generated from both municipalities and customers in the form of processing fees, tipping fees and commodity sales. Legal, tax, information technology, human resources, certain finance and accounting and other administrative functions are included in our Corporate Entities segment.

ACCOUNTING CHANGES (Tables)

ACCOUNTING CHANGES (Tables)	3 Months Ended
	Mar. 31, 2020
Accounting Changes and Error Corrections [Abstract]
Schedule of New Accounting Pronouncements and Changes in Accounting Principles	A table providing a brief description of recent Accounting Standards Updates ("ASUs") to the Accounting Standards Codification (“ASC”) issued by the Financial Accounting Standards Board (“FASB”) that we adopted and deemed to have a material impact on our consolidated financial statements based on current account balances and activity follows: Standard Description Effect on the Financial Statements or Other Accounting standards adopted effective January 1, 2020 ASU No. 2016-13, as amended through March 2020: Financial Instrument Credit Losses (Topic 326) Requires that an entity measures all of its expected credit losses for financial assets held based on historical experience, current conditions, and reasonable and supportable forecasts. We adopted this guidance effective January 1, 2020 using the required modified-retrospective approach. We recognized a cumulative effect adjustment of $(189) to retained earnings upon implementation. This guidance replaces the incurred loss methodology with an expected loss methodology that is referred to as current expected credit loss ("CECL") methodology. CECL requires consideration of past events, current conditions, and reasonable and supportable forecasts about the future to assess credit loss estimates and will generally result in the earlier recognition of an allowance for credit losses. We have updated our business processes and systems and controls to support recognition and disclosure under the new guidance. See Note 5, Accounts Receivable, Net of Allowance for Credit Losses for additional disclosure. A table providing a brief description of recent ASUs to the ASC issued by the FASB that are pending adoption and deemed to have a possible material impact on our consolidated financial statements based on current account balances and activity follows: Standard Description Effect on the Financial Statements or Other Accounting standards issued pending adoption ASU No. 2020-04: Reference Rate Reform (Topic 848) Provides temporary optional guidance to ease the potential burden in applying GAAP to contract modifications and hedging relationships, subject to meeting certain criteria, that reference LIBOR or another reference rate expected to be discontinued. We are currently assessing the provisions of this guidance and do not expect that its adoption will have an impact on our consolidated financial statements and related disclosures. This guidance will be in effect from March 12, 2020 through December 31, 2022. ASU No. 2019-12: Income Taxes (Topic 740) Reduces the complexity over accounting for income taxes by removing certain exceptions and amending guidance to improve consistent application of accounting over income taxes. We are currently assessing the provisions of this guidance to determine whether or not its adoption will have an impact on our consolidated financial statements and related disclosures. This guidance is effective January 1, 2021 with early adoption permitted.

REVENUE RECOGNITION (Tables)

REVENUE RECOGNITION (Tables)	3 Months Ended
	Mar. 31, 2020
Revenue from Contract with Customer [Abstract]
Schedule of Disaggregation of Revenue	A table of revenues disaggregated by service line and timing of revenue recognition by operating segment for each of the three months ended March 31, 2020 and 2019 follows: Three Months Ended March 31, 2020 Eastern Western Resource Solutions Total Revenues Collection $ 36,829 $ 58,639 $ — $ 95,468 Landfill 3,544 16,310 — 19,854 Transfer 9,383 6,706 — 16,089 Customer solutions — — 21,663 21,663 Recycling 2 239 10,966 11,207 Organics — — 14,932 14,932 Transportation — 2,671 — 2,671 Landfill gas-to-energy 385 641 — 1,026 Total revenues $ 50,143 $ 85,206 $ 47,561 $ 182,910 Transferred at a point-in-time $ 56 $ 235 $ 4,462 $ 4,753 Transferred over time 50,087 84,971 43,099 178,157 Total revenues $ 50,143 $ 85,206 $ 47,561 $ 182,910 Three Months Ended March 31, 2019 Eastern Western Resource Solutions Total Revenues Collection $ 33,965 $ 49,597 $ — $ 83,562 Landfill 3,717 15,468 — 19,185 Transfer 8,986 5,275 — 14,261 Customer solutions — — 18,154 18,154 Recycling — 441 10,766 11,207 Organics — — 13,596 13,596 Transportation — 2,563 — 2,563 Landfill gas-to-energy 329 807 — 1,136 Total revenues $ 46,997 $ 74,151 $ 42,516 $ 163,664 Transferred at a point-in-time $ 36 $ 309 $ 6,391 $ 6,736 Transferred over time 46,961 73,842 36,125 156,928 Total revenues $ 46,997 $ 74,151 $ 42,516 $ 163,664

BUSINESS COMBINATIONS (Tables)

BUSINESS COMBINATIONS (Tables)	3 Months Ended
	Mar. 31, 2020
Business Combinations [Abstract]
Summary of Purchase Price Paid for Acquisitions	A summary of the purchase price paid for these acquisitions and the allocation of the purchase price for these acquisitions follows: Three Months Ended 2020 2019 Purchase Price: Cash used in acquisitions, net of cash acquired $ 4,771 $ — Holdbacks 580 — Total 5,351 — Allocated as follows: Land 325 — Buildings 678 — Equipment 2,396 — Intangible assets 1,225 — Other liabilities, net (80) — Fair value of assets acquired and liabilities assumed 4,544 — Excess purchase price allocated to goodwill $ 807 $ —
Schedule of Unaudited Pro forma Combined Information	Unaudited pro forma combined information that shows our operational results as though each acquisition completed since the beginning of the prior fiscal year had occurred as of January 1, 2019 is as follows: Three Months Ended 2020 2019 Revenues $ 183,262 $ 178,575 Operating income $ 7,037 $ 5,868 Net income (loss) $ 970 $ (921) Basic earnings per share attributable to common stockholders: Weighted average common shares outstanding 48,005 45,913 Basic earnings per common share $ 0.02 $ (0.02) Diluted earnings per share attributable to common stockholders: Weighted average common shares outstanding 48,262 45,913 Diluted earnings per common share $ 0.02 $ (0.02)

ACCOUNTS RECEIVABLE, NET OF A_2

ACCOUNTS RECEIVABLE, NET OF ALLOWANCE FOR CREDIT LOSSES (Tables)	3 Months Ended
	Mar. 31, 2020
Credit Loss [Abstract]
Summary of Changes to Allowance for Credit Losses	A summary of the changes to allowance for credit losses follows: Three Months Ended Balance at beginning of period $ 1,468 Cumulative effect of new accounting principle 189 Additions - charged to expense 880 Deductions - bad debts written off, net of recoveries (445) Balance at end of period $ 2,092

LEASES (Tables)

LEASES (Tables)	3 Months Ended
	Mar. 31, 2020
Leases [Abstract]
Schedule of Lease Costs and Other Lease Information	A schedule of lease costs and other lease information follows: Three Months Ended 2020 2019 Lease cost: Amortization of right-of-use assets $ 731 $ 409 Interest expense 246 156 Fixed lease cost - vehicles, equipment and property 2,417 2,579 Fixed lease cost - landfill operating leases 1,673 1,648 Fixed lease cost 4,090 4,227 Short-term lease cost 929 658 Variable lease cost 132 7 Total lease cost $ 6,128 $ 5,457 Other information: Cash paid for amounts included in the measurement of lease liabilities: Financing cash flows for finance leases $ 961 $ 471 Operating cash flows for operating leases $ 2,442 $ 2,043 Right-of-use assets obtained in exchange for new finance lease liabilities $ 6,402 $ 2,473 Right-of-use assets obtained in exchange for new operating lease liabilities $ 2,366 $ 415 March 31, Weighted-average remaining lease term - finance leases (years) 6.2 Weighted-average remaining lease term - operating leases (years) 11.8 Weighted-average discount rate - finance leases 4.7 % Weighted-average discount rate - operating leases 5.1 %
Schedule of Estimated Minimum Future Finance Lease Obligations	Estimated minimum future lease obligations are as follows: Operating Leases Finance Leases Fiscal year ending December 31, 2020 $ 11,086 $ 3,760 Fiscal year ending December 31, 2021 11,822 4,830 Fiscal year ending December 31, 2022 9,155 4,237 Fiscal year ending December 31, 2023 7,288 4,071 Fiscal year ending December 31, 2024 6,638 3,971 Thereafter 63,964 7,540 Total lease payments 109,953 28,409 Less: interest expense (29,395) (4,580) Lease liability balance $ 80,558 $ 23,829
Schedule of Estimated Minimum Future Operating Lease Obligations	Estimated minimum future lease obligations are as follows: Operating Leases Finance Leases Fiscal year ending December 31, 2020 $ 11,086 $ 3,760 Fiscal year ending December 31, 2021 11,822 4,830 Fiscal year ending December 31, 2022 9,155 4,237 Fiscal year ending December 31, 2023 7,288 4,071 Fiscal year ending December 31, 2024 6,638 3,971 Thereafter 63,964 7,540 Total lease payments 109,953 28,409 Less: interest expense (29,395) (4,580) Lease liability balance $ 80,558 $ 23,829

GOODWILL AND INTANGIBLE ASSETS

GOODWILL AND INTANGIBLE ASSETS (Tables)	3 Months Ended
	Mar. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Summary of Goodwill Activity	A summary of the activity and balances related to goodwill by reporting segment is as follows: December 31, Acquisitions March 31, Eastern region $ 30,720 $ — $ 30,720 Western region 141,055 807 141,862 Resource solutions 14,044 — 14,044 Total $ 185,819 $ 807 $ 186,626
Summary of Intangible Assets by Intangible Asset Type	A summary of intangible assets by intangible asset type follows: Covenants Client Lists Total Balance, March 31, 2020 Intangible assets $ 26,467 $ 72,133 $ 98,600 Less accumulated amortization (19,365) (21,292) (40,657) $ 7,102 $ 50,841 $ 57,943 Covenants Client Lists Total Balance, December 31, 2019 Intangible assets $ 26,162 $ 71,122 $ 97,284 Less accumulated amortization (18,968) (19,595) (38,563) $ 7,194 $ 51,527 $ 58,721
Summary of Intangible Amortization Expense Estimated	A summary of intangible amortization expense estimated for the five fiscal years following the fiscal year ended December 31, 2019 and thereafter follows: Estimated Future Amortization Expense as of March 31, 2020 Fiscal year ending December 31, 2020 $ 6,255 Fiscal year ending December 31, 2021 $ 6,963 Fiscal year ending December 31, 2022 $ 6,324 Fiscal year ending December 31, 2023 $ 6,131 Fiscal year ending December 31, 2024 $ 7,109 Thereafter $ 25,161

ACCRUED FINAL CAPPING, CLOSUR_2

ACCRUED FINAL CAPPING, CLOSURE AND POST CLOSURE (Tables)	3 Months Ended
	Mar. 31, 2020
Asset Retirement Obligation Disclosure [Abstract]
Summary of Changes to Accrued Capping, Closure and Post-Closure Liabilities	A summary of the changes to accrued final capping, closure and post-closure liabilities follows: Three Months Ended 2020 2019 Beginning balance $ 71,927 $ 73,075 Obligations incurred 898 543 Accretion expense 1,622 1,607 Obligations settled (1) (1,097) (1,556) Ending balance $ 73,350 $ 73,669 (1) Includes amounts that are being processed through accounts payable as a part of our disbursements cycle.

DEBT (Tables)

DEBT (Tables)	3 Months Ended
	Mar. 31, 2020
Debt And Derivatives Disclosure [Abstract]
Summary of Long-term Debt and Finance Leases by Debt Instrument	A summary of debt is as follows: March 31, December 31, Senior Secured Credit Facility: Revolving line of credit facility ("Revolving Credit Facility") due May 2023; bearing interest at LIBOR plus 1.75% $ 61,000 $ 26,900 Term loan A facility ("Term Loan Facility") due May 2023; bearing interest at LIBOR plus 1.75% 350,000 350,000 Tax-Exempt Bonds: New York State Environmental Facilities Corporation Solid Waste Disposal Revenue Bonds Series 2014 ("New York Bonds 2014") due December 2044 - fixed rate interest period through 2019; bearing interest at 2.875% 25,000 25,000 New York State Environmental Facilities Corporation Solid Waste Disposal Revenue Bonds Series 2014R-2 ("New York Bonds 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 ("FAME Bonds 2005R-3") due January 2025 - fixed rate interest period through 2025; bearing interest at 5.25% 25,000 25,000 Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2015R-1 ("FAME Bonds 2015R-1") due August 2035 - fixed rate interest period through 2025; bearing interest at 5.125% 15,000 15,000 Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2015R-2 ("FAME Bonds 2015R-2") due August 2035 - fixed rate interest period through 2025; bearing interest at 4.375% 15,000 15,000 Vermont Economic Development Authority Solid Waste Disposal Long-Term Revenue Bonds Series 2013 ("Vermont Bonds") due April 2036 - fixed rate interest period through 2028; bearing interest at 4.625% 16,000 16,000 Business Finance Authority of the State of New Hampshire Solid Waste Disposal Revenue Bonds Series 2013 ("New Hampshire Bonds") due April 2029 - fixed rate interest period through 2029; bearing interest at 2.95% 11,000 11,000 Other: Finance leases maturing through December 2107; bearing interest at a weighted average of 4.7% 23,829 18,364 Notes payable maturing through June 2027; bearing interest at a weighted average of 3.5% 5,181 5,464 Principal amount of debt 562,010 522,728 Less—unamortized debt issuance costs (1) 8,889 9,406 Debt less unamortized debt issuance costs 553,121 513,322 Less—current maturities of debt 5,392 4,301 $ 547,729 $ 509,021 (1) A summary of unamortized debt issuance costs by debt instrument follows: March 31, December 31, Revolving Credit Facility and Term Loan Facility (collectively, the "Credit Facility") $ 5,069 $ 5,478 New York Bonds 2014 1,051 1,057 New York Bonds 2014R-2 374 390 FAME Bonds 2005R-3 411 432 FAME Bonds 2015R-1 534 552 FAME Bonds 2015R-2 399 417 Vermont Bonds 527 541 New Hampshire Bonds 524 539 $ 8,889 $ 9,406
Summary of Cash Flow Hedges	A summary of the effect of cash flow hedges related to derivative instruments on the consolidated balance sheet follows: Fair Value Balance Sheet Location March 31, December 31, Interest rate swaps Other accrued liabilities $ 4,166 $ 1,824 Interest rate swaps Other long-term liabilities 8,860 3,603 $ 13,026 $ 5,427 Interest rate swaps Accumulated other comprehensive loss $ (13,230) $ (5,929) Interest rate swaps - tax provision Accumulated other comprehensive loss — (112) $ (13,230) $ (6,041) A summary of the amount of expense on cash flow hedging relationships related to interest rate swaps reclassified from accumulated other comprehensive loss into earnings follows: Three Months Ended 2020 2019 Statement of Operations Location (Expense) Income Interest expense $ (489) $ (25)

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Tables)	3 Months Ended
	Mar. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Summary of Environmental Liability	A summary of the changes to the environmental remediation liability associated with the Southbridge Landfill follows: Three Months Ended 2020 2019 Beginning balance $ 4,596 $ 5,173 Accretion expense 30 34 Obligations incurred 27 — Obligations settled (1) (12) (141) Ending balance $ 4,641 $ 5,066 (1) Includes amounts that are being processed through accounts payable as a part of our disbursements cycle.

STOCKHOLDERS' EQUITY (Tables)

STOCKHOLDERS' EQUITY (Tables)	3 Months Ended
	Mar. 31, 2020
Equity [Abstract]
Summary of Stock Option Activity	A summary of stock option activity follows: Stock Options (1) Weighted Average Exercise Price Weighted Average Remaining Contractual Term (years) Aggregate Intrinsic Value Outstanding, December 31, 2019 98 $ 9.20 Granted — $ — Exercised (8) $ 12.48 Forfeited — $ — Outstanding, March 31, 2020 90 $ 8.91 5.5 $ 2,717 Exercisable, March 31, 2020 90 $ 8.91 5.5 $ 2,717
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 follows: Restricted Stock, Restricted Stock Units, and Performance Stock Units (1) Weighted Weighted Average Remaining Contractual Term (years) Aggregate Intrinsic Value Outstanding, December 31, 2019 393 $ 28.23 Granted 138 $ 47.00 Class A Common Stock Vested (108) $ 19.44 Forfeited (2) $ 25.41 Outstanding, March 31, 2020 421 $ 36.63 2.2 $ 16,455 Unvested, March 31, 2020 710 $ 37.60 2.0 $ 27,755 (1) Market-based performance stock unit grants are included at the 100% attainment level. Attainment of the maximum performance targets and market achievements would result in the issuance of an additional 289 shares of Class A common stock currently included in unvested.
Summary of Changes in Balances of Each Component of Accumulated Other Comprehensive Loss	A summary of the changes in the balances of each component of accumulated other comprehensive loss, net of tax follows: Interest Rate Swaps Balance, December 31, 2019 $ (6,041) Other comprehensive loss before reclassifications (7,790) Amounts reclassified from accumulated other comprehensive loss 489 Income tax benefit related to items of other comprehensive loss 112 Net current-period other comprehensive loss (7,189) Balance, March 31, 2020 $ (13,230)
Summary of Reclassifications Out of Accumulated Other Comprehensive Loss	A summary of reclassifications out of accumulated other comprehensive loss, net of tax follows: Three Months Ended 2020 2019 Details About Accumulated Other Comprehensive Loss Components Amounts Reclassified Out of Accumulated Other Comprehensive Loss Affected Line Item in the Consolidated Interest rate swaps $ 489 $ 25 Interest expense 489 25 Income before income taxes (112) — Provision (benefit) for income taxes $ 601 $ 25 Net income

EARNINGS PER SHARE (Tables)

EARNINGS PER SHARE (Tables)	3 Months Ended
	Mar. 31, 2020
Earnings Per Share [Abstract]
Summary of Earnings per Share Computation	A summary of the numerator and denominators used in the computation of earnings per share follows: Three Months Ended 2020 2019 Numerator: Net income (loss) $ 959 $ (1,714) Denominators: Number of shares outstanding, end of period: Class A common stock 47,320 46,252 Class B common stock 988 988 Shares to be issued - acquisition 36 36 Unvested restricted stock (1) (9) Effect of weighted average shares outstanding (338) (1,354) Basic weighted average common shares outstanding 48,005 45,913 Impact of potentially dilutive securities: Dilutive effect of stock options and other stock awards 257 — Diluted weighted average common shares outstanding 48,262 45,913 Anti-dilutive potentially issuable shares — 1,422

FAIR VALUE OF FINANCIAL INSTR_2

FAIR VALUE OF FINANCIAL INSTRUMENTS (Tables)	3 Months Ended
	Mar. 31, 2020
Fair Value Disclosures [Abstract]
Summary of Financial Assets and Liabilities Measured at Fair Value	Summaries of our financial assets and liabilities that are measured at fair value on a recurring basis follow: Fair Value Measurement at March 31, 2020 Using: Quoted Prices in Significant Other Significant Assets: Restricted investment securities - landfill closure $ 1,410 $ — $ — Liabilities: Interest rate swaps $ — $ 13,026 $ — Fair Value Measurement at December 31, 2019 Using: Quoted Prices in Significant Other Significant Assets: Restricted investment securities - landfill closure $ 1,586 $ — $ — Liabilities: Interest rate swaps $ — $ 5,427 $ —

SEGMENT REPORTING (Tables)

SEGMENT REPORTING (Tables)	3 Months Ended
	Mar. 31, 2020
Segment Reporting [Abstract]
Summary of Segment Reporting Information by Segment	Three Months Ended March 31, 2020 Segment Outside Inter-company Depreciation and Operating Total Eastern $ 50,143 $ 11,839 $ 5,958 $ 975 $ 206,334 Western 85,206 25,546 13,232 5,642 599,815 Resource solutions 47,561 2,894 1,610 1,003 93,199 Corporate entities — — 606 (608) 58,292 Eliminations — (40,279) — — — $ 182,910 $ — $ 21,406 $ 7,012 $ 957,640 Three Months Ended March 31, 2019 Segment Outside Inter-company Depreciation and Operating Total Eastern $ 46,997 $ 10,771 $ 5,260 $ (626) $ 195,851 Western 74,151 20,218 10,234 5,378 494,066 Resource solutions 42,516 2,387 1,294 401 86,222 Corporate entities — — 701 (711) 52,174 Eliminations — (33,376) — — — $ 163,664 $ — $ 17,489 $ 4,442 $ 828,313
Summary of Revenue Attributable to Services	A summary of our revenues attributable to services provided follows: Three Months Ended 2020 2019 Collection $ 94,577 $ 83,080 Disposal 38,625 36,054 Power generation 1,026 1,136 Processing 1,121 878 Solid waste operations 135,349 121,148 Organics 14,932 13,596 Customer solutions 21,663 18,154 Recycling 10,966 10,766 Resource solutions operations 47,561 42,516 Total revenues $ 182,910 $ 163,664

BASIS OF PRESENTATION (Details)

BASIS OF PRESENTATION (Details)	3 Months Ended
	Mar. 31, 2020regional_operating_segment
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of regional operating segments	2

ACCOUNTING CHANGES (Details)

ACCOUNTING CHANGES (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Jan. 01, 2020	Dec. 31, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adjustment to retained earnings	$ (356,246)		$ (357,016)
Cumulative effect of new accounting principle
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adjustment to retained earnings		$ (189)

REVENUE RECOGNITION - Disaggreg

REVENUE RECOGNITION - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Disaggregation of Revenue [Line Items]
Total revenues	$ 182,910	$ 163,664
Transferred at a point-in-time
Disaggregation of Revenue [Line Items]
Total revenues	4,753	6,736
Transferred over time
Disaggregation of Revenue [Line Items]
Total revenues	178,157	156,928
Collection
Disaggregation of Revenue [Line Items]
Total revenues	95,468	83,562
Landfill
Disaggregation of Revenue [Line Items]
Total revenues	19,854	19,185
Transfer
Disaggregation of Revenue [Line Items]
Total revenues	16,089	14,261
Customer solutions
Disaggregation of Revenue [Line Items]
Total revenues	21,663	18,154
Recycling
Disaggregation of Revenue [Line Items]
Total revenues	11,207	11,207
Organics
Disaggregation of Revenue [Line Items]
Total revenues	14,932	13,596
Transportation
Disaggregation of Revenue [Line Items]
Total revenues	2,671	2,563
Landfill gas-to-energy
Disaggregation of Revenue [Line Items]
Total revenues	1,026	1,136
Eastern
Disaggregation of Revenue [Line Items]
Total revenues	50,143	46,997
Eastern | Transferred at a point-in-time
Disaggregation of Revenue [Line Items]
Total revenues	56	36
Eastern | Transferred over time
Disaggregation of Revenue [Line Items]
Total revenues	50,087	46,961
Eastern | Collection
Disaggregation of Revenue [Line Items]
Total revenues	36,829	33,965
Eastern | Landfill
Disaggregation of Revenue [Line Items]
Total revenues	3,544	3,717
Eastern | Transfer
Disaggregation of Revenue [Line Items]
Total revenues	9,383	8,986
Eastern | Customer solutions
Disaggregation of Revenue [Line Items]
Total revenues	0	0
Eastern | Recycling
Disaggregation of Revenue [Line Items]
Total revenues	2	0
Eastern | Organics
Disaggregation of Revenue [Line Items]
Total revenues	0	0
Eastern | Transportation
Disaggregation of Revenue [Line Items]
Total revenues	0	0
Eastern | Landfill gas-to-energy
Disaggregation of Revenue [Line Items]
Total revenues	385	329
Western
Disaggregation of Revenue [Line Items]
Total revenues	85,206	74,151
Western | Transferred at a point-in-time
Disaggregation of Revenue [Line Items]
Total revenues	235	309
Western | Transferred over time
Disaggregation of Revenue [Line Items]
Total revenues	84,971	73,842
Western | Collection
Disaggregation of Revenue [Line Items]
Total revenues	58,639	49,597
Western | Landfill
Disaggregation of Revenue [Line Items]
Total revenues	16,310	15,468
Western | Transfer
Disaggregation of Revenue [Line Items]
Total revenues	6,706	5,275
Western | Customer solutions
Disaggregation of Revenue [Line Items]
Total revenues	0	0
Western | Recycling
Disaggregation of Revenue [Line Items]
Total revenues	239	441
Western | Organics
Disaggregation of Revenue [Line Items]
Total revenues	0	0
Western | Transportation
Disaggregation of Revenue [Line Items]
Total revenues	2,671	2,563
Western | Landfill gas-to-energy
Disaggregation of Revenue [Line Items]
Total revenues	641	807
Resource Solutions
Disaggregation of Revenue [Line Items]
Total revenues	47,561	42,516
Resource Solutions | Transferred at a point-in-time
Disaggregation of Revenue [Line Items]
Total revenues	4,462	6,391
Resource Solutions | Transferred over time
Disaggregation of Revenue [Line Items]
Total revenues	43,099	36,125
Resource Solutions | Collection
Disaggregation of Revenue [Line Items]
Total revenues	0	0
Resource Solutions | Landfill
Disaggregation of Revenue [Line Items]
Total revenues	0	0
Resource Solutions | Transfer
Disaggregation of Revenue [Line Items]
Total revenues	0	0
Resource Solutions | Customer solutions
Disaggregation of Revenue [Line Items]
Total revenues	21,663	18,154
Resource Solutions | Recycling
Disaggregation of Revenue [Line Items]
Total revenues	10,966	10,766
Resource Solutions | Organics
Disaggregation of Revenue [Line Items]
Total revenues	14,932	13,596
Resource Solutions | Transportation
Disaggregation of Revenue [Line Items]
Total revenues	0	0
Resource Solutions | Landfill gas-to-energy
Disaggregation of Revenue [Line Items]
Total revenues	$ 0	$ 0

REVENUE RECOGNITION - Narrative

REVENUE RECOGNITION - Narrative (Details) - USD ($)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Rebates	$ (182,910,000)	$ (163,664,000)
Revenue recognized fro performance obligation satisfied in previous period	0	0
Gross receivables from contracts	74,161,000		$ 80,191,000
Contract liabilities	2,860,000		$ 2,299,000
Adjustments | Accounting Standards Update 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Rebates	$ 991,000	$ 1,338,000

BUSINESS COMBINATIONS - Narrati

BUSINESS COMBINATIONS - Narrative (Details) - business	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Business Acquisition [Line Items]
Number of businesses acquired	2	0
Minimum
Business Acquisition [Line Items]
Useful life of finite lived intangible assets	5 years
Maximum
Business Acquisition [Line Items]
Useful life of finite lived intangible assets	10 years
Western | Tuck-in Solid Waste Collection Business
Business Acquisition [Line Items]
Number of businesses acquired	1
Resource Solutions | Recycling Operation
Business Acquisition [Line Items]
Number of businesses acquired	1

BUSINESS COMBINATIONS - Summary

BUSINESS COMBINATIONS - Summary of Purchase Price Paid for Acquisitions (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Purchase Price:
Cash used in acquisitions, net of cash acquired	$ 5,144	$ 1,222
Allocated as follows:
Excess purchase price allocated to goodwill	186,626		$ 185,819
Waste Collection Acquisitions
Purchase Price:
Cash used in acquisitions, net of cash acquired	4,771	0
Holdbacks	580	0
Total	5,351	0
Allocated as follows:
Land	325	0
Buildings	678	0
Equipment	2,396	0
Intangible assets	1,225	0
Other liabilities, net	(80)	0
Fair value of assets acquired and liabilities assumed	4,544	0
Excess purchase price allocated to goodwill	$ 807	$ 0

BUSINESS COMBINATIONS - Schedul

BUSINESS COMBINATIONS - Schedule of Unaudited Pro forma Combined Information (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Business Combinations [Abstract]
Revenues	$ 183,262	$ 178,575
Operating income	7,037	5,868
Net income (loss)	$ 970	$ (921)
Weighted average common shares outstanding, basic	48,005	45,913
Basic earnings per common share (in dollars per share)	$ 0.02	$ (0.02)
Weighted average common shares outstanding, diluted	48,262	45,913
Diluted earnings per common share (in dollars per share)	$ 0.02	$ (0.02)

ACCOUNTS RECEIVABLE, NET OF A_3

ACCOUNTS RECEIVABLE, NET OF ALLOWANCE FOR CREDIT LOSSES (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2020USD ($)
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	$ 1,468
Additions - charged to expense	880
Deductions - bad debts written off, net of recoveries	(445)
Balance at end of period	2,092
Cumulative effect of new accounting principle
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	$ 189

LEASES - Narrative (Details)

LEASES - Narrative (Details)	3 Months Ended
	Mar. 31, 2020Agreement
Leases [Abstract]
Number of landfill operation and management agreements	3

LEASES - Schedule of Lease Cost

LEASES - Schedule of Lease Costs and Other Lease Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Lease cost:
Amortization of right-of-use assets	$ 731	$ 409
Interest expense	246	156
Fixed lease cost	4,090	4,227
Short-term lease cost	929	658
Variable lease cost	132	7
Total lease cost	6,128	5,457
Cash paid for amounts included in the measurement of lease liabilities:
Financing cash flows for finance leases	961	471
Operating cash flows for operating leases	2,442	2,043
Right-of-use assets obtained in exchange for new finance lease liabilities	6,402	2,473
Right-of-use assets obtained in exchange for new operating lease liabilities	$ 2,366	415
Weighted-average remaining lease term - finance leases (years)	6 years 2 months 12 days
Weighted-average remaining lease term - operating leases (years)	11 years 9 months 18 days
Weighted-average discount rate - finance leases	4.70%		4.70%
Weighted-average discount rate - operating leases	5.10%
Vehicles, equipment and property
Lease cost:
Fixed lease cost	$ 2,417	2,579
Landfill
Lease cost:
Fixed lease cost	$ 1,673	$ 1,648

LEASES - Schedule of Estimated

LEASES - Schedule of Estimated Minimum Future Lease Obligations (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Operating Leases
Fiscal year ending December 31, 2020	$ 11,086
Fiscal year ending December 31, 2021	11,822
Fiscal year ending December 31, 2022	9,155
Fiscal year ending December 31, 2023	7,288
Fiscal year ending December 31, 2024	6,638
Thereafter	63,964
Total lease payments	109,953
Less: interest expense	(29,395)
Lease liability balance	80,558
Finance Leases
Fiscal year ending December 31, 2020	3,760
Fiscal year ending December 31, 2021	4,830
Fiscal year ending December 31, 2022	4,237
Fiscal year ending December 31, 2023	4,071
Fiscal year ending December 31, 2024	3,971
Thereafter	7,540
Total lease payments	28,409
Less: interest expense	(4,580)
Lease liability balance	$ 23,829	$ 18,364

GOODWILL AND INTANGIBLE ASSET_2

GOODWILL AND INTANGIBLE ASSETS - Summary of Goodwill Activity (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2020USD ($)
Goodwill [Roll Forward]
Goodwill, beginning balance	$ 185,819
Acquisitions	807
Goodwill, ending balance	186,626
Eastern
Goodwill [Roll Forward]
Goodwill, beginning balance	30,720
Acquisitions	0
Goodwill, ending balance	30,720
Western
Goodwill [Roll Forward]
Goodwill, beginning balance	141,055
Acquisitions	807
Goodwill, ending balance	141,862
Resource Solutions
Goodwill [Roll Forward]
Goodwill, beginning balance	14,044
Acquisitions	0
Goodwill, ending balance	$ 14,044

GOODWILL AND INTANGIBLE ASSET_3

GOODWILL AND INTANGIBLE ASSETS - Summary of Intangible Assets by Intangible Asset Type (Detail) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Intangible assets	$ 98,600	$ 97,284
Less accumulated amortization	(40,657)	(38,563)
Intangible assets, net	57,943	58,721
Covenants Not-to-Compete
Finite-Lived Intangible Assets [Line Items]
Intangible assets	26,467	26,162
Less accumulated amortization	(19,365)	(18,968)
Intangible assets, net	7,102	7,194
Client Lists
Finite-Lived Intangible Assets [Line Items]
Intangible assets	72,133	71,122
Less accumulated amortization	(21,292)	(19,595)
Intangible assets, net	$ 50,841	$ 51,527

GOODWILL AND INTANGIBLE ASSET_4

GOODWILL AND INTANGIBLE ASSETS - Narrative (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible amortization expense	$ 2,093	$ 1,401

GOODWILL AND INTANGIBLE ASSET_5

GOODWILL AND INTANGIBLE ASSETS - Summary of Intangible Amortization Expense Estimated (Detail) $ in Thousands	Dec. 31, 2019USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
Fiscal year ending December 31, 2020	$ 6,255
Fiscal year ending December 31, 2021	6,963
Fiscal year ending December 31, 2022	6,324
Fiscal year ending December 31, 2023	6,131
Fiscal year ending December 31, 2024	7,109
Thereafter	$ 25,161

ACCRUED FINAL CAPPING, CLOSUR_3

ACCRUED FINAL CAPPING, CLOSURE AND POST CLOSURE - Summary of Changes to Accrued Capping, Closure and Post-Closure Liabilities (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning balance	$ 71,927	$ 73,075
Obligations incurred	898	543
Accretion expense	1,622	1,607
Obligations settled	(1,097)	(1,556)
Ending balance	$ 73,350	$ 73,669

DEBT - Summary of Components of

DEBT - Summary of Components of Long-Term Debt and Capital Leases by Debt Instrument (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Principal amount of debt	$ 562,010	$ 522,728
Finance leases maturing through December 2107; bearing interest at a weighted average of 4.7%	23,829	18,364
Less - unamortized debt issuance costs	8,889	9,406
Debt less unamortized debt issuance costs	553,121	513,322
Less—current maturities of debt	5,392	4,301
Debt, less current portion	$ 547,729	$ 509,021
Weighted-average discount rate - finance leases	4.70%	4.70%
Revolving line of credit facility ("Revolving Credit Facility") due May 2023; bearing interest at LIBOR plus 1.75%
Debt Instrument [Line Items]
Principal amount of debt	$ 61,000	$ 26,900
Revolving line of credit facility ("Revolving Credit Facility") due May 2023; bearing interest at LIBOR plus 1.75% | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate	1.75%	1.75%
Secured Debt | Term loan A facility ("Term Loan Facility") due May 2023; bearing interest at LIBOR plus 1.75%
Debt Instrument [Line Items]
Principal amount of debt	$ 350,000	$ 350,000
Secured Debt | Term loan A facility ("Term Loan Facility") due May 2023; bearing interest at LIBOR plus 1.75% | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate	1.75%	1.75%
Credit Facility
Debt Instrument [Line Items]
Less - unamortized debt issuance costs	$ 5,069	$ 5,478
New York State Environmental Facilities Corporation Solid Waste Disposal Revenue Bonds Series 2014 ("New York Bonds 2014") due December 2044 - fixed rate interest period through 2019; bearing interest at 2.875%
Debt Instrument [Line Items]
Principal amount of debt	25,000	25,000
Less - unamortized debt issuance costs	$ 1,051	$ 1,057
Stated interest rate	2.875%	2.875%
New York State Environmental Facilities Corporation Solid Waste Disposal Revenue Bonds Series 2014R-2 ("New York Bonds 2014R-2") due December 2044 - fixed rate interest period through 2026; bearing interest at 3.125%
Debt Instrument [Line Items]
Principal amount of debt	$ 15,000	$ 15,000
Less - unamortized debt issuance costs	$ 374	$ 390
Stated interest rate	3.125%	3.125%
Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2005R-3 ("FAME Bonds 2005R-3") due January 2025 - fixed rate interest period through 2025; bearing interest at 5.25%
Debt Instrument [Line Items]
Principal amount of debt	$ 25,000	$ 25,000
Less - unamortized debt issuance costs	$ 411	$ 432
Stated interest rate	5.25%	5.25%
Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2015R-1 ("FAME Bonds 2015R-1") due August 2035 - fixed rate interest period through 2025; bearing interest at 5.125%
Debt Instrument [Line Items]
Principal amount of debt	$ 15,000	$ 15,000
Less - unamortized debt issuance costs	$ 534	$ 552
Stated interest rate	5.125%	5.125%
Finance Authority of Maine Solid Waste Disposal Revenue Bonds Series 2015R-2 ("FAME Bonds 2015R-2") due August 2035 - fixed rate interest period through 2025; bearing interest at 4.375%
Debt Instrument [Line Items]
Principal amount of debt	$ 15,000	$ 15,000
Less - unamortized debt issuance costs	$ 399	$ 417
Stated interest rate	4.375%	4.375%
Vermont Economic Development Authority Solid Waste Disposal Long-Term Revenue Bonds Series 2013 ("Vermont Bonds") due April 2036 - fixed rate interest period through 2028; bearing interest at 4.625%
Debt Instrument [Line Items]
Principal amount of debt	$ 16,000	$ 16,000
Less - unamortized debt issuance costs	$ 527	$ 541
Stated interest rate	4.625%	4.625%
Business Finance Authority of the State of New Hampshire Solid Waste Disposal Revenue Bonds Series 2013 ("New Hampshire Bonds") due April 2029 - fixed rate interest period through 2029; bearing interest at 2.95%
Debt Instrument [Line Items]
Principal amount of debt	$ 11,000	$ 11,000
Less - unamortized debt issuance costs	$ 524	$ 539
Stated interest rate	2.95%	2.95%
Notes payable maturing through June 2027; bearing interest at a weighted average of 3.5%
Debt Instrument [Line Items]
Principal amount of debt	$ 5,181	$ 5,464
Weighted average interest rate	3.50%	3.50%

DEBT - Credit Facility (Details

DEBT - Credit Facility (Details)	3 Months Ended
	Mar. 31, 2020USD ($)
Line of Credit
Debt Instrument [Line Items]
Debt instrument, term	5 years
Net leverage ratio	2.25
Line of credit facility, remaining borrowing capacity	$ 113,575,000
Line of Credit | LIBOR
Debt Instrument [Line Items]
Floor interest rate received	1.25%
Line of Credit | Maximum | LIBOR
Debt Instrument [Line Items]
Floor interest rate received	1.75%
Secured Debt | Term Loan Facility | Line of Credit
Debt Instrument [Line Items]
Aggregate principal amount	$ 350,000,000
Revolving Credit Facility | Revolving Credit Facility Due 2023 | Line of Credit
Debt Instrument [Line Items]
Credit facility maximum	200,000,000
Letters of credit outstanding	25,425,000
Credit Facility
Debt Instrument [Line Items]
Additional revolver capacity	$ 125,000,000

DEBT - Cash Flow Hedges (Detail

DEBT - Cash Flow Hedges (Details) - Cash Flow Hedging	3 Months Ended
	Mar. 31, 2020USD ($)numberOfPlantiffs	Jun. 30, 2022USD ($)numberOfPlantiffs	Dec. 31, 2019USD ($)
Interest Rate Derivative
Debt Instrument [Line Items]
Number of interest rate derivative agreements | numberOfPlantiffs	3
Notional amount	$ 190,000,000		$ 190,000,000
Floor interest rate	0.00%		1.00%
Loss from derivative instrument	$ 765,000
Proceeds from Hedge, Investing Activities	$ 430,000
Weighted average percentage rate paid	2.54%		2.54%
Interest Rate Derivative | Forecast
Debt Instrument [Line Items]
Number of interest rate derivative agreements | numberOfPlantiffs		3
Notional amount		$ 60,000,000
Forward Starting Interest Rate Derivative
Debt Instrument [Line Items]
Notional amount	$ 125,000,000
Floor interest rate	0.00%
Weighted average percentage rate paid	1.63%

DEBT - Schedule Of Cash Flow He

DEBT - Schedule Of Cash Flow Hedges Related to Derivative Instruments On the Balance Sheet (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Derivatives, Fair Value [Line Items]
Unrealized loss resulting from changes in fair value of derivative instruments	$ (7,379)	$ (1,554)
Designated as Hedging Instrument | Interest rate swaps
Derivatives, Fair Value [Line Items]
Cash flow hedge derivatives, liabilities	13,026		$ 5,427
Other accrued liabilities | Designated as Hedging Instrument | Interest rate swaps
Derivatives, Fair Value [Line Items]
Cash flow hedge derivatives, liabilities	4,166		1,824
Other long-term liabilities | Designated as Hedging Instrument | Interest rate swaps
Derivatives, Fair Value [Line Items]
Cash flow hedge derivatives, liabilities	8,860		3,603
Accumulated other comprehensive loss | Designated as Hedging Instrument | Interest rate swaps
Derivatives, Fair Value [Line Items]
Unrealized loss resulting from changes in fair value of derivative instruments	(13,230)		(5,929)
Accumulated other comprehensive loss, interest rate swaps, tax provision	0		(112)
Accumulated other comprehensive loss	$ (13,230)		$ (6,041)

DEBT - Schedule of Loss On Cash

DEBT - Schedule of Loss On Cash Flow Hedges (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Derivative Instruments, Gain (Loss) [Line Items]
Other comprehensive loss, reclassification adjustment from AOCI	$ (489)	$ (25)
Designated as Hedging Instrument | Interest rate swaps | Interest expense
Derivative Instruments, Gain (Loss) [Line Items]
Other comprehensive loss, reclassification adjustment from AOCI	$ (489)	$ (25)

COMMITMENTS AND CONTINGENCIES -

COMMITMENTS AND CONTINGENCIES - Narrative (Detail) numberOfPlantiffs in Thousands	Sep. 17, 2019numberOfPlantiffs	Apr. 28, 2017USD ($)	Mar. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Mar. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Apr. 26, 2017USD ($)	Jan. 29, 2016	Apr. 30, 2011USD ($)	May 31, 2009USD ($)	Dec. 20, 2000a
Southbridge Landfill
Loss Contingencies [Line Items]
Risk free interest percentage rate			1.90%
Environmental remediation liability			$ 4,641,000	$ 4,596,000	$ 5,066,000	$ 5,173,000
Potsdam Environmental Remediation
Loss Contingencies [Line Items]
Risk free interest percentage rate			1.50%
Scrap yard and solid waste transfer station (in acres) | a											25
Undiscounted costs preferred remedies									$ 12,130,000	$ 10,219,000
Remediation activities, participant share percentage								15.00%
Environmental remediation liability			$ 1,151,000	$ 1,151,000
21E Settlement and Water System Construction Funding Agreement | Bonds
Loss Contingencies [Line Items]
Bond period		20 years
21E Settlement and Water System Construction Funding Agreement | Bonds | Maximum
Loss Contingencies [Line Items]
Anticipated cost		$ 5,000,000
Notice of Intent to Sue under the Resource Conservation and Recovery Act
Loss Contingencies [Line Items]
Estimate of possible loss							$ 5,000,000
Notice of Intent to Sue under the Resource Conservation and Recovery Act | MADEP and Casella Waste Systems
Loss Contingencies [Line Items]
Estimate of possible loss							$ 10,000,000
Ontario County, New York Class Action Litigation
Loss Contingencies [Line Items]
Number of citizens seeking damages | numberOfPlantiffs	1
Notice of Intent to Sue for Violations of the CWA | NCES Landfil
Loss Contingencies [Line Items]
Estimate of possible loss			$ 1,415,000

COMMITMENTS AND CONTINGENCIES_2

COMMITMENTS AND CONTINGENCIES - Southbridge Landfill Environmental Remediation Liability (Details) - Southbridge Landfill - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	$ 4,596	$ 5,173
Accretion expense	30	34
Obligations incurred	27	0
Obligations settled	(12)	(141)
Ending balance	$ 4,641	$ 5,066

STOCKHOLDERS' EQUITY - Narrativ

STOCKHOLDERS' EQUITY - Narrative (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Jun. 30, 2017
Limited Partners' Capital Account [Line Items]
Fair value of stock awards vested	$ 4,979,000
Stock Options
Limited Partners' Capital Account [Line Items]
Stock-based compensation expense	0	$ 0
Aggregate intrinsic value of options exercised	296,000
Restricted Stock, Restricted Stock Units And Performance Stock Units
Limited Partners' Capital Account [Line Items]
Stock-based compensation expense	1,515,000	1,390,000
Restricted Stock
Limited Partners' Capital Account [Line Items]
Unrecognized stock-based compensation expense	$ 45,000
Restricted Stock | Non Employee Director
Limited Partners' Capital Account [Line Items]
Options, vesting period	3 years
Restricted Stock Unit
Limited Partners' Capital Account [Line Items]
Unrecognized stock-based compensation expense	$ 5,148,000
Maximum | Performance Stock Unit
Limited Partners' Capital Account [Line Items]
Unrecognized stock-based compensation expense	$ 7,356,000
Weighted average | Restricted Stock
Limited Partners' Capital Account [Line Items]
Unrecognized stock-based compensation, weighted average period	2 years 8 months 12 days
Weighted average | Restricted Stock Unit
Limited Partners' Capital Account [Line Items]
Unrecognized stock-based compensation, weighted average period	2 years 3 months 18 days
Weighted average | Performance Stock Unit
Limited Partners' Capital Account [Line Items]
Unrecognized stock-based compensation, weighted average period	2 years 1 month 6 days
2016 Plan
Limited Partners' Capital Account [Line Items]
Options granted, term	10 years
2016 Plan | Minimum
Limited Partners' Capital Account [Line Items]
Options, vesting period	1 year
2016 Plan | Maximum
Limited Partners' Capital Account [Line Items]
Options, vesting period	4 years
Amended and Restated 1997 Employee Stock Purchase Plan
Limited Partners' Capital Account [Line Items]
Stock-based compensation expense	$ 47,000	$ 41,000
Class A Common Stock | 2016 Plan
Limited Partners' Capital Account [Line Items]
Common stock, authorized shares			2,250,000
Number of shares available for future grant	1,121,000
Class A Common Stock | 2006 Incentive Plan
Limited Partners' Capital Account [Line Items]
Common stock, additional authorized shares			2,723,000

STOCKHOLDERS' EQUITY - Summary

STOCKHOLDERS' EQUITY - Summary of Stock Option Activity (Detail) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2020USD ($)$ / sharesshares
Stock Options
Beginning balance, outstanding (in shares) | shares	98
Granted (in shares) | shares	0
Exercised (in shares) | shares	(8)
Forfeited (in shares) | shares	0
Ending balance, outstanding (in shares) | shares	90
Exercisable at end of period (in shares) | shares	90
Weighted Average Exercise Price
Beginning balance, outstanding (in dollars per share) | $ / shares	$ 9.20
Granted (in dollars per share) | $ / shares	0
Exercised (in dollars per share) | $ / shares	12.48
Forfeited (in dollars per share) | $ / shares	0
Ending balance, outstanding (in dollars per share) | $ / shares	8.91
Exercisable at end of period (in dollars per share) | $ / shares	$ 8.91
Weighted Average Remaining Contractual Term (years) and Aggregate Intrinsic Value
Outstanding contractual term at end of period	5 years 6 months
Exercisable contractual term at end of period	5 years 6 months
Outstanding aggregate intrinsic value at end of period | $	$ 2,717
Exercisable aggregate intrinsic value at end of period | $	$ 2,717

STOCKHOLDERS' EQUITY - Summar_2

STOCKHOLDERS' EQUITY - Summary of Restricted Stock, Restricted Stock Unit and Performance-based Stock Unit Activity (Detail) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2020USD ($)$ / sharesshares
Restricted Stock, Restricted Stock Units And Performance Stock Units
Restricted Stock, Restricted Stock Units, and Performance Stock Units
Outstanding, beginning of period (in shares)	393
Granted (in shares)	138
Forfeited (in shares)	(2)
Outstanding, end of period (in shares)	421
Weighted Average Grant Date Fair Value
Outstanding at beginning of period (in dollars per share) | $ / shares	$ 28.23
Granted (in dollars per share) | $ / shares	47
Forfeited (in dollars per share) | $ / shares	25.41
Outstanding at end of period (in dollars per share) | $ / shares	$ 36.63
Weighted Average Remaining Contractual Term (years) and Aggregate Intrinsic Value
Contractual term at end of period	2 years 2 months 12 days
Aggregate intrinsic value at end of period | $	$ 16,455
Restricted Stock, Restricted Stock Units And Performance Stock Units | Class A Common Stock
Restricted Stock, Restricted Stock Units, and Performance Stock Units
Class A Common Stock Vested (in shares)	(108)
Weighted Average Grant Date Fair Value
Class A Common Stock Vested (in dollars per share) | $ / shares	$ 19.44
Performance Stock Unit
Weighted Average Remaining Contractual Term (years) and Aggregate Intrinsic Value
Percentage of attainment level	100.00%
Performance Stock Unit | Class A Common Stock
Weighted Average Remaining Contractual Term (years) and Aggregate Intrinsic Value
Number of additional shares	289
Unvested | Restricted Stock, Restricted Stock Units And Performance Stock Units
Restricted Stock, Restricted Stock Units, and Performance Stock Units
Outstanding, end of period (in shares)	710
Weighted Average Grant Date Fair Value
Outstanding at end of period (in dollars per share) | $ / shares	$ 37.60
Weighted Average Remaining Contractual Term (years) and Aggregate Intrinsic Value
Contractual term at end of period	2 years
Aggregate intrinsic value at end of period | $	$ 27,755

STOCKHOLDERS' EQUITY - Summar_3

STOCKHOLDERS' EQUITY - Summary of Changes in Balances of Each Component of Accumulated Other Comprehensive Income (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2020USD ($)
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	$ 122,753
Ending balance	117,996
Interest Rate Swaps
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(6,041)
Other comprehensive loss	(7,790)
accumulated other comprehensive loss	489
Income tax benefit related to items of other comprehensive loss	112
Net current-period other comprehensive loss	(7,189)
Ending balance	$ (13,230)

STOCKHOLDERS' EQUITY - Summar_4

STOCKHOLDERS' EQUITY - Summary of Reclassifications Out of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense	$ 5,952	$ 6,460
Income before income taxes	1,068	(1,685)
Provision for income taxes	109	29
Net income (loss)	959	(1,714)
Interest rate swaps | Interest Rate Swaps | Amount Reclassified Out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense	489	25
Income before income taxes	489	25
Provision for income taxes	(112)	0
Net income (loss)	$ 601	$ 25

EARNINGS PER SHARE (Details)

EARNINGS PER SHARE (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Numerator:
Net income (loss)	$ 959	$ (1,714)
Denominators:
Shares to be issued - acquisition	36	36
Unvested restricted stock (in shares)	(1)	(9)
Effect of weighted average shares outstanding (in shares)	(338)	(1,354)
Weighted average common shares outstanding, basic	48,005	45,913
Impact of potentially dilutive securities:
Dilutive effect of stock options and other stock awards (in shares)	257	0
Weighted average common shares outstanding, diluted	48,262	45,913
Anti-dilutive potentially issuable shares	0	1,422
Class A Common Stock
Denominators:
Common stock, shares outstanding	47,320	46,252	46,803
Class B Common Stock
Denominators:
Common stock, shares outstanding	988	988	988

OTHER ITEMS AND CHARGES (Detail

OTHER ITEMS AND CHARGES (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Site Contingency [Line Items]
Expense from acquisition activities	$ 1,009	$ 677
Southbridge Landfill
Site Contingency [Line Items]
Legal and other costs	$ 613	$ 555

FAIR VALUE OF FINANCIAL INSTR_3

FAIR VALUE OF FINANCIAL INSTRUMENTS - Recurring Fair Value Measurements (Detail) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Assets:
Restricted investment securities - landfill closure	$ 1,410	$ 1,586
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Liabilities:
Interest rate swaps	0	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Landfill
Assets:
Restricted investment securities - landfill closure	1,410	1,586
Recurring | Significant Other Observable Inputs (Level 2)
Liabilities:
Interest rate swaps	13,026	5,427
Recurring | Significant Other Observable Inputs (Level 2) | Landfill
Assets:
Restricted investment securities - landfill closure	0	0
Recurring | Significant Unobservable Inputs (Level 3)
Liabilities:
Interest rate swaps	0	0
Recurring | Significant Unobservable Inputs (Level 3) | Landfill
Assets:
Restricted investment securities - landfill closure	$ 0	$ 0

FAIR VALUE OF FINANCIAL INSTR_4

FAIR VALUE OF FINANCIAL INSTRUMENTS - Additional Information (Detail) $ in Thousands	Mar. 31, 2020USD ($)
Fair Value | Fixed Rate Bonds
Debt Instrument [Line Items]
Fair value of fixed rate debt	$ 120,327
Carrying Value
Debt Instrument [Line Items]
Carrying value of revolver debt	61,000
Carrying Value | Fixed Rate Bonds
Debt Instrument [Line Items]
Fair value of fixed rate debt	122,000
Carrying Value | Term Loan Facility | Secured Debt
Debt Instrument [Line Items]
Fair value of fixed rate debt	$ 350,000

SEGMENT REPORTING - Summary of

SEGMENT REPORTING - Summary of Financial Information by Reportable Segment (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Segment Reporting Information [Line Items]
Revenues	$ 182,910	$ 163,664
Depreciation and amortization	21,406	17,489
Operating Income (Loss)	7,012	4,442
Total assets	957,640		$ 932,182
Operating
Segment Reporting Information [Line Items]
Revenues	182,910	163,664
Depreciation and amortization	21,406	17,489
Operating Income (Loss)	7,012	4,442
Total assets	957,640	828,313
Operating | Eastern
Segment Reporting Information [Line Items]
Revenues	50,143	46,997
Depreciation and amortization	5,958	5,260
Operating Income (Loss)	975	(626)
Total assets	206,334	195,851
Operating | Western
Segment Reporting Information [Line Items]
Revenues	85,206	74,151
Depreciation and amortization	13,232	10,234
Operating Income (Loss)	5,642	5,378
Total assets	599,815	494,066
Operating | Resource Solutions
Segment Reporting Information [Line Items]
Revenues	47,561	42,516
Depreciation and amortization	1,610	1,294
Operating Income (Loss)	1,003	401
Total assets	93,199	86,222
Operating | Corporate entities
Segment Reporting Information [Line Items]
Revenues	0	0
Depreciation and amortization	606	701
Operating Income (Loss)	(608)	(711)
Total assets	58,292	52,174
Inter-company revenues
Segment Reporting Information [Line Items]
Revenues	(40,279)	(33,376)
Inter-company revenues | Eastern
Segment Reporting Information [Line Items]
Revenues	11,839	10,771
Inter-company revenues | Western
Segment Reporting Information [Line Items]
Revenues	25,546	20,218
Inter-company revenues | Resource Solutions
Segment Reporting Information [Line Items]
Revenues	2,894	2,387
Inter-company revenues | Corporate entities
Segment Reporting Information [Line Items]
Revenues	$ 0	$ 0

SEGMENT REPORTING - Summary o_2

SEGMENT REPORTING - Summary of Revenues Attributable to Services Provided by Company (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Revenue from External Customer [Line Items]
Revenues	$ 182,910	$ 163,664
Solid waste operations
Revenue from External Customer [Line Items]
Revenues	135,349	121,148
Collection
Revenue from External Customer [Line Items]
Revenues	94,577	83,080
Disposal
Revenue from External Customer [Line Items]
Revenues	38,625	36,054
Power generation
Revenue from External Customer [Line Items]
Revenues	1,026	1,136
Processing
Revenue from External Customer [Line Items]
Revenues	1,121	878
Resource solutions operations
Revenue from External Customer [Line Items]
Revenues	47,561	42,516
Organics
Revenue from External Customer [Line Items]
Revenues	14,932	13,596
Customer solutions
Revenue from External Customer [Line Items]
Revenues	21,663	18,154
Recycling
Revenue from External Customer [Line Items]
Revenues	$ 10,966	$ 10,766