Cover - shares	9 Months Ended
Cover - shares	Sep. 30, 2019	Oct. 25, 2019
Cover page.
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2019
Document Transition Report	false
Entity File Number	001-34223
Entity Registrant Name	CLEAN HARBORS, INC
Entity Incorporation, State or Country Code	MA
Entity Tax Identification Number	04-2997780
Entity Address, Address Line One	42 Longwater Drive
Entity Address, City or Town	Norwell
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02061-9149
City Area Code	781
Local Phone Number	792-5000
Title of 12(b) Security	Common Stock, $0.01 par value
Trading Symbol	CLH
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		55,809,048
Entity Central Index Key	0000822818
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Amendment Flag	false

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 282,233	$ 226,507
Short-term marketable securities	46,877	52,856
Accounts receivable, net of allowances aggregating $37,998 and $44,315, respectively	641,667	606,952
Unbilled accounts receivable	58,842	54,794
Deferred costs	21,939	18,770
Inventories and supplies	210,827	199,479
Prepaid expenses and other current assets	38,199	42,800
Total current assets	1,300,584	1,202,158
Property, plant and equipment, net	1,593,993	1,561,978
Other assets:
Operating lease right-of-use assets	164,302
Goodwill	524,581	514,189
Permits and other intangibles, net	425,863	441,875
Other	12,539	18,121
Total other assets	1,127,285	974,185
Total assets	4,021,862	3,738,321
Current liabilities:
Current portion of long-term obligations	7,535	7,535
Accounts payable	277,545	276,461
Deferred revenue	73,157	61,843
Accrued expenses	253,455	233,405
Current portion of closure, post-closure and remedial liabilities	26,986	23,034
Current portion of operating lease liabilities	41,364
Total current liabilities	680,042	602,278
Other liabilities:
Closure and post-closure liabilities, less current portion of $9,896 and $9,592, respectively	64,263	60,339
Remedial liabilities, less current portion of $17,090 and $13,442, respectively	100,179	107,575
Long-term obligations, less current portion	1,555,257	1,565,021
Operating lease liabilities, less current portion	122,668
Deferred taxes, unrecognized tax benefits and other long-term liabilities	263,658	233,352
Total other liabilities	2,106,025	1,966,287
Commitments and contingent liabilities (See Note 16)
Stockholders’ equity:
Authorized 80,000,000 shares; issued and outstanding 55,807,524 and 55,847,261 shares, respectively	558	558
Additional paid-in capital	648,184	655,415
Accumulated other comprehensive loss	(223,690)	(223,371)
Accumulated earnings	810,743	737,154
Total stockholders’ equity	1,235,795	1,169,756
Total liabilities and stockholders’ equity	$ 4,021,862	$ 3,738,321

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Account receivable, allowances aggregating	$ 37,998	$ 44,315
Closure and post-closure liabilities, current portion	9,896	9,592
Remedial liabilities, current portion	$ 17,090	$ 13,442
Common stock, par value (in USD per share)	$ 0.01	$ 0.01
Common stock, authorized shares (in shares)	80,000,000	80,000,000
Common stock, issued shares (in shares)	55,807,524	55,847,261
Common stock, outstanding shares (in shares)	55,807,524	55,847,261

UNAUDITED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenues:
Total revenues	$ 891,668	$ 843,181	$ 2,541,185	$ 2,442,099
Cost of revenues: (exclusive of items shown separately below)
Total cost of revenues	612,754	580,685	1,772,051	1,710,694
Selling, general and administrative expenses	122,301	121,219	361,033	362,302
Accretion of environmental liabilities	2,490	2,450	7,624	7,328
Depreciation and amortization	73,756	73,082	223,328	220,686
Income from operations	80,367	65,745	177,149	141,089
Other (expense) income, net	(427)	(996)	1,992	(449)
Loss on early extinguishment of debt	(6,119)	(2,469)	(6,119)	(2,469)
Interest expense, net of interest income of $1,152, $736, $2,981 and $2,086, respectively	(19,702)	(19,916)	(59,681)	(60,955)
Income before provision for income taxes	54,119	42,364	113,341	77,216
Provision for income taxes	17,750	11,275	39,752	28,011
Net income	$ 36,369	$ 31,089	$ 73,589	$ 49,205
Earnings per share:
Basic (in USD per share)	$ 0.65	$ 0.55	$ 1.32	$ 0.88
Diluted (in USD per share)	$ 0.65	$ 0.55	$ 1.31	$ 0.87
Shares used to compute earnings per share - Basic (in shares)	55,850	56,059	55,858	56,222
Shares used to compute earnings per share - Diluted (in shares)	56,165	56,291	56,109	56,360
Service
Revenues:
Total revenues	$ 739,919	$ 685,183	$ 2,111,662	$ 2,001,681
Cost of revenues: (exclusive of items shown separately below)
Total cost of revenues	496,005	464,612	1,439,717	1,385,684
Product
Revenues:
Total revenues	151,749	157,998	429,523	440,418
Cost of revenues: (exclusive of items shown separately below)
Total cost of revenues	$ 116,749	$ 116,073	$ 332,334	$ 325,010

UNAUDITED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 36,369	$ 31,089	$ 73,589	$ 49,205
Other comprehensive (loss) income:
Unrealized gains (losses) on available-for-sale securities (net of tax of $2, $7, $60 and $95, respectively)	9	(932)	(84)	(1,138)
Reclassification adjustment for losses on available-for-sale securities included in net income	0	0	332	0
Unrealized loss on interest rate hedge	(3,865)	(310)	(17,896)	(310)
Reclassification adjustment for losses on interest rate hedge included in net income	614	0	1,369	0
Foreign currency translation adjustments (including a tax benefit of $5.6 million in the nine months ended September 30, 2018)	(6,177)	9,832	15,960	(11,650)
Other comprehensive (loss) income	(9,419)	8,590	(319)	(13,098)
Comprehensive income	$ 26,950	$ 39,679	$ 73,270	$ 36,107

UNAUDITED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Cash flows from operating activities:
Net income	$ 73,589	$ 49,205
Adjustments to reconcile net income to net cash from operating activities:
Depreciation and amortization	223,328	220,686
Allowance for doubtful accounts	(745)	6,869
Amortization of deferred financing costs and debt discount	2,908	2,841
Accretion of environmental liabilities	7,624	7,328
Changes in environmental liability estimates	(585)	(301)
Deferred income taxes	(973)	61
Other (income) expense, net	(1,992)	449
Stock-based compensation	14,664	10,726
Loss on early extinguishment of debt	6,119	2,469
Environmental expenditures	(12,804)	(7,238)
Changes in assets and liabilities, net of acquisitions
Accounts receivable and unbilled accounts receivable	(31,408)	(76,249)
Inventories and supplies	(11,982)	(20,534)
Other current and non-current assets	(5,425)	(523)
Accounts payable	3,035	22,041
Other current and long-term liabilities	19,322	29,385
Net cash from operating activities	284,675	247,215
Cash flows used in investing activities:
Additions to property, plant and equipment	(174,533)	(150,722)
Proceeds from sale and disposal of fixed assets	8,948	6,111
Acquisitions, net of cash acquired	(29,479)	(151,023)
Additions to intangible assets including costs to obtain or renew permits	(2,896)	(3,500)
Proceeds from sale of available-for-sale securities	41,612	20,123
Purchases of available-for-sale securities	(30,761)	(20,471)
Net cash used in investing activities	(187,109)	(299,482)
Cash flows used in financing activities:
Change in uncashed checks	(3,516)	(3,476)
Tax payments related to withholdings on vested restricted stock	(5,505)	(2,566)
Repurchases of common stock	(16,390)	(33,581)
Deferred financing costs paid	(10,053)	(3,938)
Premiums paid on early extinguishment of debt	(2,689)	(1,219)
Payments on finance lease	(327)	0
Principal payments on debt	(850,652)	(403,884)
Issuance of unsecured senior notes	845,000	0
Issuance of secured senior notes, net of discount	0	348,250
Borrowing from revolving credit facility	0	50,000
Net cash used in financing activities	(44,132)	(50,414)
Effect of exchange rate change on cash	2,292	(1,221)
Increase (decrease) in cash and cash equivalents	55,726	(103,902)
Cash and cash equivalents, beginning of period	226,507	319,399
Cash and cash equivalents, end of period	282,233	215,497
Cash payments for interest and income taxes:
Interest paid	52,440	58,312
Income taxes paid	23,797	16,071
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	42,105	0
Operating cash flows from finance lease	979	0
Financing cash flows from finance lease	327	0
Non-cash investing activities:
Property, plant and equipment accrued	14,875	13,834
ROU assets obtained in exchange for new operating lease liabilities	8,008	0
ROU assets obtained in exchange for new finance lease liabilities	$ 31,011	$ 0

UNAUDITED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Loss	Accumulated Earnings
Increase (Decrease) in Stockholders' Equity
Cumulative effect of change in accounting principle	$ (1,564)				$ (1,564)
Balance beginning of period at Dec. 31, 2017	1,188,202	$ 565	$ 686,962	$ (172,407)	673,082
Balance beginning of period (in shares) at Dec. 31, 2017		56,501
Increase (Decrease) in Stockholders' Equity
Net income (loss)	(12,631)				(12,631)
Other comprehensive (loss) income	(16,746)			(16,746)
Stock-based compensation	3,077		3,077
Issuance of restricted shares, net of shares remitted and tax withholdings	(548)	$ 0	(548)
Issuance of restricted shares, net of shares remitted and tax withholdings (in shares)		24
Repurchases of common stock	(14,264)	$ (3)	(14,261)
Repurchases of common stock (in shares)		(280)
Balance ending of period at Mar. 31, 2018	1,145,526	$ 562	675,230	(189,153)	658,887
Balance ending of period (in shares) at Mar. 31, 2018		56,245
Balance beginning of period at Dec. 31, 2017	1,188,202	$ 565	686,962	(172,407)	673,082
Balance beginning of period (in shares) at Dec. 31, 2017		56,501
Increase (Decrease) in Stockholders' Equity
Net income (loss)	49,205
Other comprehensive (loss) income	(13,098)
Repurchases of common stock	$ (33,600)
Repurchases of common stock (in shares)	(600)
Balance ending of period at Sep. 30, 2018	$ 1,197,324	$ 560	661,546	(185,505)	720,723
Balance ending of period (in shares) at Sep. 30, 2018		55,998
Balance beginning of period at Mar. 31, 2018	1,145,526	$ 562	675,230	(189,153)	658,887
Balance beginning of period (in shares) at Mar. 31, 2018		56,245
Increase (Decrease) in Stockholders' Equity
Net income (loss)	30,747				30,747
Other comprehensive (loss) income	(4,942)			(4,942)
Stock-based compensation	3,562		3,562
Issuance of restricted shares, net of shares remitted and tax withholdings	(1,627)	$ 1	(1,628)
Issuance of restricted shares, net of shares remitted and tax withholdings (in shares)		94
Repurchases of common stock	(12,218)	$ (2)	(12,216)
Repurchases of common stock (in shares)		(252)
Balance ending of period at Jun. 30, 2018	1,161,048	$ 561	664,948	(194,095)	689,634
Balance ending of period (in shares) at Jun. 30, 2018		56,087
Increase (Decrease) in Stockholders' Equity
Net income (loss)	31,089				31,089
Other comprehensive (loss) income	8,590			8,590
Stock-based compensation	4,087		4,087
Issuance of restricted shares, net of shares remitted and tax withholdings	(391)	$ 0	(391)
Issuance of restricted shares, net of shares remitted and tax withholdings (in shares)		15
Repurchases of common stock	$ (7,099)	$ (1)	(7,098)
Repurchases of common stock (in shares)	(100)	(104)
Balance ending of period at Sep. 30, 2018	$ 1,197,324	$ 560	661,546	(185,505)	720,723
Balance ending of period (in shares) at Sep. 30, 2018		55,998
Balance beginning of period at Dec. 31, 2018	1,169,756	$ 558	655,415	(223,371)	737,154
Balance beginning of period (in shares) at Dec. 31, 2018		55,847
Increase (Decrease) in Stockholders' Equity
Net income (loss)	976				976
Other comprehensive (loss) income	4,024			4,024
Stock-based compensation	5,809		5,809
Issuance of restricted shares, net of shares remitted and tax withholdings	(2,276)	$ 1	(2,277)
Issuance of restricted shares, net of shares remitted and tax withholdings (in shares)		78
Repurchases of common stock	(6,324)	$ (1)	(6,323)
Repurchases of common stock (in shares)		(97)
Balance ending of period at Mar. 31, 2019	1,171,965	$ 558	652,624	(219,347)	738,130
Balance ending of period (in shares) at Mar. 31, 2019		55,828
Balance beginning of period at Dec. 31, 2018	1,169,756	$ 558	655,415	(223,371)	737,154
Balance beginning of period (in shares) at Dec. 31, 2018		55,847
Increase (Decrease) in Stockholders' Equity
Net income (loss)	73,589
Other comprehensive (loss) income	(319)
Repurchases of common stock	$ (16,400)
Repurchases of common stock (in shares)	(200)
Balance ending of period at Sep. 30, 2019	$ 1,235,795	$ 558	648,184	(223,690)	810,743
Balance ending of period (in shares) at Sep. 30, 2019		55,808
Balance beginning of period at Mar. 31, 2019	1,171,965	$ 558	652,624	(219,347)	738,130
Balance beginning of period (in shares) at Mar. 31, 2019		55,828
Increase (Decrease) in Stockholders' Equity
Net income (loss)	36,244				36,244
Other comprehensive (loss) income	5,076			5,076
Stock-based compensation	3,834		3,834
Issuance of restricted shares, net of shares remitted and tax withholdings	(2,704)	$ 1	(2,705)
Issuance of restricted shares, net of shares remitted and tax withholdings (in shares)		105
Repurchases of common stock	(4,948)		(4,948)
Repurchases of common stock (in shares)		(74)
Balance ending of period at Jun. 30, 2019	1,209,467	$ 559	648,805	(214,271)	774,374
Balance ending of period (in shares) at Jun. 30, 2019		55,859
Increase (Decrease) in Stockholders' Equity
Net income (loss)	36,369				36,369
Other comprehensive (loss) income	(9,419)			(9,419)
Stock-based compensation	5,021		5,021
Issuance of restricted shares, net of shares remitted and tax withholdings	(525)		(525)
Issuance of restricted shares, net of shares remitted and tax withholdings (in shares)		17
Repurchases of common stock	$ (5,118)	$ (1)	(5,117)
Repurchases of common stock (in shares)	(100)	(68)
Balance ending of period at Sep. 30, 2019	$ 1,235,795	$ 558	$ 648,184	$ (223,690)	$ 810,743
Balance ending of period (in shares) at Sep. 30, 2019		55,808

SIGNIFICANT ACCOUNTING POLICIES	9 Months Ended
SIGNIFICANT ACCOUNTING POLICIES	Sep. 30, 2019
Accounting Policies [Abstract]
SIGNIFICANT ACCOUNTING POLICIES	SIGNIFICANT ACCOUNTING POLICIES The Company's significant accounting policies are described in Note 2, "Significant Accounting Policies," and Note 3, "Revenues," in the Company's Annual Report on Form 10-K for the year ended December 31, 2018. There have been no material changes in these policies or their application except for the changes described below. Recent Accounting Pronouncements Standards implemented In February 2016, the Financial Accounting Standards Board ("FASB") issued ASU 2016-02, Leases (Topic 842). The amendment increases transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet and disclosing key information about leasing arrangements. The Company adopted Topic 842 on January 1, 2019 using the modified retrospective method of adoption. Prior period amounts have not been adjusted and continue to be reported in accordance with the Company's historical accounting methodology pursuant to ASC 840, Leases. As permitted under the transition guidance, the Company elected to apply the package of three practical expedients for all existing leases which, among other things, allowed us to maintain the lease classification for all existing leases at the adoption date. The adoption of Topic 842 resulted in the recognition of right-of-use (“ROU”) assets of $185.5 million and total current and noncurrent lease liabilities of $188.5 million at adoption. Additionally, Topic 842 required new and expanded disclosures to enable users of financial statements to assess the amount, timing and uncertainty of cash flows arising from leases. The standard did not have a material impact on the consolidated statements of operations or cash flows. Leases The Company’s leases predominately relate to real estate and equipment such as vehicles and industrial equipment utilized in operations as well as rail cars utilized in connection with the Company’s transportation needs. Contracts are reviewed at inception to determine if the arrangement is a lease and, if so, whether it is an operating or finance lease. For all of its leases, the Company has elected not to separate lease and nonlease components, such as common area maintenance. The Company generally enters into real estate leases with five to ten-year terms and non-real estate leases with two to seven-year terms. In the normal course of business, the Company also enters into short-term leases having terms of less than one-year. These leases are generally equipment leases entered into for short periods of time (e.g. daily, weekly or monthly), and done so to satisfy immediate and/or short-term operational needs of the business which can arise based upon the nature of particular services performed or seasonality factors. The Company has elected not to recognize ROU assets and lease liabilities for these short-term leases. Expense for all such short-term leases is disclosed as short-term lease cost as shown in Note 17, "Leases." Operating and finance leases with terms exceeding one year are recognized as ROU assets and lease liabilities and measured based on the present value of the future lease payments over the lease term at commencement date. When applicable, the ROU asset includes any lease payments made at or before the commencement date and initial direct costs incurred and is reduced by lease incentives received under the lease agreement, if any. Certain of the Company's real estate leases contain escalating future lease payments. Escalating lease payments that are based upon explicit amounts contained in the lease or an index (e.g., consumer price index) are included in its determination of future lease payments to determine the ROU asset and lease liability recognized at the commencement date. Any differences in the future lease payments from initial recognition are not anticipated to be material and will be recorded as variable lease cost in the period incurred. The variable lease cost will also include the Company’s portion of property tax, utilities and common area maintenance. A significant portion of the Company’s real estate lease agreements include renewal periods at the Company’s option. The Company includes these renewal periods in the lease term only when renewal is reasonably certain based upon facts and circumstances specific to the lease and known by the Company. The Company uses its incremental borrowing rate on collateralized debt based on the information available at the lease commencement date in determining the present value of future lease payments as the implicit rate is typically not readily determinable.

REVENUES

9 Months Ended

Sep. 30, 2019

Revenue from Contract with Customer [Abstract]

REVENUES

Revenue Recognition

The Company generates services and product revenues through the following operating segments: Environmental Services and Safety-Kleen. The Company recognizes revenue when control of the promised goods or services is transferred to the Company's customers, in an amount that reflects the consideration the Company expects to be entitled to in exchange for those goods or services. Product revenues are recognized when the products are delivered and control transfers to the customer.

Nature of Goods and Services

The majority of the Company’s contracts are for services, which are recognized based on time and materials incurred at contractually agreed-upon rates. The Company’s payment terms vary by the type and location of its customers and the products or services offered. The periods between invoicing and when payments are due are not significant. Any amounts billed to customers related to shipping and handling are classified as revenue and the Company's shipping and handling costs are included in costs of revenues. In the course of the Company's operations, it collects sales tax and other excise taxes from its customers and recognizes a current liability which is then relieved when the taxes are remitted to the appropriate governmental authorities. The Company excludes sales and other excise taxes that it collects from customers from its revenues.

Disaggregation of Revenue

The following table presents the Company’s third-party revenues disaggregated by revenue source (in thousands):



	For the Three Months Ended September 30, 2019
	Environmental Services		Safety-Kleen		Corporate			Total
Primary Geographical Markets
United States	$	450,638	$	313,979	$	(265	)	$	764,352
Canada	99,484		27,438		394			127,316
Total third-party revenues	$	550,122	$	341,417	$	129		$	891,668

Sources of Revenue ⁽¹⁾
Technical Services	$	292,506	$	—	$	—		$	292,506
Field and Emergency Response Services	95,546		—		—			95,546
Industrial Services	131,855		—		—			131,855
Oil, Gas and Lodging Services and Other	30,215		—		129			30,344
Safety-Kleen Environmental Services	—		217,439		—			217,439
Safety-Kleen Oil⁽²⁾	—		123,978		—			123,978
Total third-party revenues	$	550,122	$	341,417	$	129		$	891,668



	For the Three Months Ended September 30, 2018
	Environmental Services		Safety-Kleen		Corporate			Total
Primary Geographical Markets
United States	$	410,792	$	307,497	$	(66	)	$	718,223
Canada	98,021		26,404		533			124,958
Total third-party revenues	$	508,813	$	333,901	$	467		$	843,181

Sources of Revenue⁽¹⁾
Technical Services	$	264,769	$	—	$	—		$	264,769
Field and Emergency Response Services	77,025		—		—			77,025
Industrial Services	134,323		—		—			134,323
Oil, Gas and Lodging Services and Other	32,696		—		467			33,163
Safety-Kleen Environmental Services	—		200,681		—			200,681
Safety-Kleen Oil⁽²⁾	—		133,220		—			133,220
Total third-party revenues	$	508,813	$	333,901	$	467		$	843,181



	For the Nine Months Ended September 30, 2019
	Environmental Services		Safety-Kleen		Corporate		Total
Primary Geographical Markets
United States	$	1,270,556	$	917,240	$	531	$	2,188,327
Canada	279,558		72,906		394		352,858
Total third-party revenues	$	1,550,114	$	990,146	$	925	$	2,541,185

Sources of Revenue⁽¹⁾
Technical Services	$	820,333	$	—	$	—	$	820,333
Field and Emergency Response Services	253,894		—		—		253,894
Industrial Services	383,964		—		—		383,964
Oil, Gas and Lodging Services and Other	91,923		—		925		92,848
Safety-Kleen Environmental Services	—		640,956		—		640,956
Safety-Kleen Oil⁽²⁾	—		349,190		—		349,190
Total third-party revenues	$	1,550,114	$	990,146	$	925	$	2,541,185



	For the Nine Months Ended September 30, 2018
	Environmental Services		Safety-Kleen		Corporate		Total
Primary Geographical Markets
United States	$	1,162,891	$	901,198	$	442	$	2,064,531
Canada	305,526		71,336		706		377,568
Total third-party revenues	$	1,468,417	$	972,534	$	1,148	$	2,442,099

Sources of Revenue⁽¹⁾
Technical Services	$	758,081	$	—	$	—	$	758,081
Field and Emergency Response Services	223,052		—		—		223,052
Industrial Services	399,132		—		—		399,132
Oil, Gas and Lodging Services and Other	88,152		—		1,148		89,300
Safety-Kleen Environmental Services	—		594,876		—		594,876
Safety-Kleen Oil⁽²⁾	—		377,658		—		377,658
Total third-party revenues	$	1,468,417	$	972,534	$	1,148	$	2,442,099

______________________


(1)	All revenue except oil and oil product sales within Safety-Kleen Oil and product sales within Safety-Kleen Environmental Services, which include various automotive related fluids, shop supplies and direct blended oil sales, are recognized over time. Safety-Kleen Oil and Safety-Kleen Environmental Services product sales are recognized at a point in time.


(2)	Safety-Kleen Oil was formerly known as Kleen Performance Products.

Technical Services. Technical Services revenues are generated from fees charged for waste material management and disposal services including onsite environmental management services, collection and transportation, packaging, recycling, treatment and disposal of waste. Revenue is primarily generated by short-term projects, most of which are governed by master service agreements that are long-term in nature. These master service agreements are typically entered into with the Company's larger customers and outline the pricing and legal frameworks for such arrangements. Services are provided based on purchase orders or agreements with the customer and include prices based upon units of volume of waste and transportation and other fees. Collection and transportation revenues are recognized over time, as the customer receives and consumes the benefits of the services as they are being performed and the Company has a right to payment for performance completed to date. The Company uses the input method to recognize revenue over time, based on time and materials incurred. Revenues for treatment and disposal of waste are recognized upon completion of treatment, final disposition in a landfill or incineration or when the waste is shipped to a third party for processing and disposal. The Company periodically enters into bundled arrangements for the collection and transportation and disposal of waste. For such arrangements, transportation and disposal are considered distinct performance obligations and the Company allocates revenue to each based on their relative standalone selling price (i.e., the estimated price that a customer would pay for the services on a standalone basis). Revenues from waste that is not yet completely processed and disposed and the related costs are deferred. The revenue is recognized and the deferred costs are expensed when the related services are completed. The period between collection and transportation and the final processing and disposal ranges depending on the location of the customer, but generally is measured in days.

Field and Emergency Response Services. Field Services revenues are generated from cleanup services at customer sites, including municipalities and utilities, or other locations on a scheduled or emergency response basis. Services include confined space entry for tank cleaning, site decontamination, large remediation projects, demolition, spill cleanup on land and water, railcar cleaning, product recovery and transfer and vacuum services. Additional services include filtration and water treatment services. Response services for environmental emergencies include any scale from man-made disasters such as oil spills, to natural disasters such as hurricanes. These services are provided based on purchase orders or agreements with customers and include prices generally based upon daily, hourly or job rates for equipment, materials and personnel. The Company recognizes revenue for these services over time, as the customer receives and consumes the benefits of the service as they are being performed and the Company has a right to payment for performance completed to date. The Company uses the input method to recognize revenue over time, based on time and materials incurred. The duration of such services can be over a number of hours, days or even months for larger scale projects.

Industrial Services. Industrial Services revenues are generated from industrial and specialty services provided to refineries, mines, upgraders, chemical plants, pulp and paper mills, manufacturing facilities, power generation facilities and other industrial customers throughout North America. Services include in-plant cleaning and maintenance services, plant outage and turnaround services, decoking and pigging, chemical cleaning, high and ultra-high pressure water cleaning, pipeline inspection and coating services, large tank and surface impoundment cleaning, oilfield transport, daylighting, production services and directional boring services supporting drilling, completions and production programs. These services are provided based on purchase orders or agreements with the customer and include prices based upon daily, hourly or job rates for equipment, materials and personnel. The Company recognizes revenue for these services over time, as the customer receives and consumes the benefits of the services as they are being performed and the Company has a right to payment for performance completed to date. The Company uses the input method to recognize revenue over time, based on time and materials incurred.

Oil, Gas and Lodging Services and Other. Oil, Gas and Lodging Services and Other is primarily comprised of revenues generated from providing Oil and Gas Field Services that support upstream activities such as exploration and drilling for oil and gas companies and Lodging Services to customers in Western Canada. The Company recognizes Oil and Gas Field Services revenue over time, as the customer receives and consumes the benefits of the services as they are being performed and the Company has a right to payment for performance completed to date. The Company uses the input method to recognize revenue over time, based on time and materials incurred. Revenue for lodging accommodation services is recognized over time based on passage of time.

Safety-Kleen Environmental Services. Safety-Kleen Environmental Services revenues are generated from providing parts washer services, containerized waste handling and disposal services, oil collection services, direct sales of blended oil products and other complementary services and product sales through a network of branch locations. Containerized waste services consist of profiling, collecting, transporting and recycling or disposing of a wide variety of waste. Other products and services include vacuum services, sale of complementary supply products including automotive fluids and shop supplies and other environmental services.

Revenues from parts washer services include fees charged to customers for their use of parts washer equipment, to clean and maintain parts washer equipment and to remove and replace used cleaning fluids. Parts washer services are considered a single performance obligation due to the highly integrated and interdependent nature of the arrangement. Revenue from parts washer services is recognized over the service interval as the customer receives the benefit of the services. Collection and transportation revenues are recognized over time, as the customer receives and consumes the benefits of the services as they are being performed and the Company has a right to payment for performance completed to date. The Company uses the input method to recognize revenue over time, based on time and materials incurred. Product revenue is recognized upon the transfer of control whereby control transfers when the products are delivered to the customer.

Safety-Kleen Oil. Safety-Kleen Oil revenues are generated from sales of high-quality base and blended lubricating oils to third-party distributors, government agencies, fleets, railroads and industrial customers. The business also sells recycled fuel oil to asphalt plants, industrial plants, blenders, pulp and paper companies, vacuum gas oil producers and marine diesel oil producers. Revenue for oil products is recognized at a point in time, upon the transfer of control. Control generally transfers when the products are delivered to the customer.

Contract Balances



(in thousands)	September 30, 2019		December 31, 2018
Receivables	$	641,667	$	606,952
Contract assets (unbilled receivables)	58,842		54,794
Contract liabilities (deferred revenue)	73,157		61,843

The timing of revenue recognition, billings and cash collections results in billed accounts receivable, unbilled receivables (contract assets) and customer advances and deposits or deferred revenue (contract liabilities) on the consolidated balance sheets. Generally, billing occurs subsequent to revenue recognition, as a right to payment is not just subject to passage of time, resulting in contract assets. Contract assets are generally classified as current. The Company sometimes receives advances or deposits from its customers before revenue is recognized, resulting in contract liabilities. These assets and liabilities are reported on the consolidated balance sheets on a contract-by-contract basis at the end of each reporting period. The contract liability balances at the beginning of each period presented were fully recognized in the subsequent three-month period.

Variable Consideration

The nature of the Company's contracts give rise to certain types of variable consideration, including in limited cases volume discounts. Accordingly, management establishes a revenue allowance to cover the estimated amounts of revenue that may need to be credited to customers' accounts in future periods. The Company estimates the amount of variable consideration to include in the estimated transaction price based on historical experience, anticipated performance and its best judgment at the time and to the extent it is probable that a significant reversal of cumulative revenue recognized will not occur when the uncertainty associated with the variable consideration is resolved.

Contract Costs

Contract costs include direct and incremental costs to obtain or fulfill a contract. The Company’s contract costs that are subject to capitalization are comprised of costs associated with parts washer services and costs associated with the treatment and disposal of waste. Parts washer costs include costs of solvent, commissions paid relating to revenue generated from parts washer services and transportation costs associated with transferring the product picked up from the services as it is returned to the Company’s facilities or a third-party site. Costs related to the treatment of waste include costs for waste receiving, drum movement and storage, waste consolidation and transportation between facilities. Deferred costs associated with parts washer services are amortized ratably over the average service interval, which ranges between seven and 14 weeks. Deferred costs related to treatment and disposal of waste are recognized when the corresponding waste is disposed of and are included in deferred costs within total current assets in the Company’s Consolidated Balance Sheets. The deferred contract cost balances at the beginning of each period presented were fully recognized in cost of revenue in the subsequent three-month period.

BUSINESS COMBINATIONS

9 Months Ended

Sep. 30, 2019

Business Combinations [Abstract]

BUSINESS COMBINATIONS

2019 Acquisitions

On May 31, 2019, the Company acquired a privately-owned business which expands the environmental services and hazardous materials management services of the Company for $14.9 million. The acquired company is included in the Environmental Services segment. In connection with this acquisition, a preliminary goodwill amount of $7.5 million was recognized.

On March 1, 2019, the Company acquired certain assets of a privately-owned business for $10.4 million. The acquired business complements the Safety-Kleen segment's core service offerings, such as used motor oil collection, parts washers, oil filter recycling and vacuum services. In connection with this acquisition, a preliminary goodwill amount of $5.2 million was recognized.

2018 Acquisitions

On August 31, 2018, the Company acquired a privately-owned business which expands the environmental services and waste oil capabilities of the Company for a $26.7 million purchase price, net of cash. The acquired company is included in the Safety-Kleen and Environmental Services segments. In connection with this acquisition, a goodwill amount of $12.3 million was recognized. The results of operations of this acquired business were not material in 2019.

On February 23, 2018, the Company completed the acquisition of the U.S. Industrial Cleaning Business of Veolia Environmental Services North America LLC (the "Veolia Business"). The acquisition provides significant scale and industrial services capabilities while increasing the size of the Company's existing U.S. Industrial Services business. The Company acquired the Veolia Business for a purchase price of $124.5 million. The amount of pre-tax (loss) income for the three and nine months ended September 30, 2018 was $(0.8) million and $2.5 million, respectively. The Veolia Business was integrated into the Environmental Services segment.

The Company finalized purchase accounting for the Veolia Business in the first quarter of 2019. The components and allocation of the purchase price for the Veolia Business consist of the following amounts (in thousands):



	Final Allocation
Accounts receivable, including unbilled receivables	$	39,558
Inventories and supplies	1,126
Prepaid expenses and other current assets	828
Property, plant and equipment	72,243
Permits and other intangibles	5,140
Current liabilities	(18,372		)
Closure and post-closure liabilities	(354		)
Total identifiable net assets	100,169
Goodwill	24,331
Total purchase price	$	124,500

The weighted average amortization period for the intangibles acquired is 8.2 years. The excess of the total purchase price, which includes the aggregate cash consideration paid in excess of the fair value of the tangible net assets and intangible assets acquired, was recorded as goodwill. The goodwill recognized is attributable to the expected operating synergies and growth potential that the Company expects to realize from this acquisition. Goodwill generated from the acquisition is deductible for tax purposes.

FINANCING ARRANGEMENTS

9 Months Ended

Sep. 30, 2019

Debt Disclosure [Abstract]

FINANCING ARRANGEMENTS

The following table is a summary of the Company’s financing arrangements (in thousands):



Current Obligations:	September 30, 2019			December 31, 2018
Secured senior term loans ("Term Loans")	$	7,535		$	7,535

Long-Term Obligations:
Secured senior Term Loans due June 30, 2024	$	729,045		$	734,697
Unsecured senior notes, at 4.875%, due July 15, 2027 ("2027 Notes")	545,000			—
Unsecured senior notes, at 5.125%, due July 15, 2029 ("2029 Notes")	300,000			—
Unsecured senior notes, at 5.125%, due June 1, 2021 ("2021 Notes")	—			845,000
Long-term obligations, at par	$	1,574,045		$	1,579,697
Unamortized debt issuance costs and premium, net	(18,788		)	(14,676		)
Long-term obligations, at carrying value	$	1,555,257		$	1,565,021

Financing Activities

On July 2, 2019, the Company completed a private placement of $545.0 million aggregate principal amount of 2027 Notes and $300.0 million aggregate principal amount of 2029 Notes (collectively, the "New Notes").

The 2027 Notes will mature on July 15, 2027, and the 2029 Notes will mature on July 15, 2029. Interest payments on each series of the New Notes will be paid semiannually on January 15 and July 15, commencing on January 15, 2020.

The Company also maintains a $400.0 million revolving credit facility under which the Company had no outstanding loan balance as of September 30, 2019 and December 31, 2018. At September 30, 2019, approximately $231.1 million was available to borrow and outstanding letters of credit were $147.2 million. At December 31, 2018, $235.4 million was available to borrow and outstanding letters of credit were $130.1 million.

The Company may redeem all or any portion of the 2027 Notes prior to July 15, 2022 or the 2029 Notes prior to July 15, 2024 at a redemption price equal to 100% of the principal amount redeemed plus a make whole premium as of the date of redemption including accrued and unpaid interest, if any, up to the date of redemption. Additionally, prior to July 15, 2022 for the 2027 Notes and July 15, 2024 for the 2029 Notes, the Company may use cash proceeds of one or more equity offerings to redeem up to 35% in aggregate principal of the 2027 Notes or the 2029 Notes at a redemption price equal to 104.875% or 105.125%, respectively, plus accrued and unpaid interest thereon, if any, up to the date of redemption.

After the dates in the preceding paragraph, the Company may redeem all or any portion of the New Notes which remain outstanding at any time upon proper notice at the following redemption prices if redeemed during the twelve-month period commencing on July 15 of the years set forth below plus accrued and unpaid interest, if any, up to the date of redemption:

2027 Notes



Year	Percentage
2022	102.438	%
2023	101.219	%
2024 and thereafter	100.000	%

2029 Notes



Year	Percentage
2024	102.563	%
2025	101.281	%
2026 and thereafter	100.000	%

The New Notes and the related indenture contain various customary non-financial covenants and are guaranteed by substantially all of the Company’s current and future domestic subsidiaries.

Concurrently with the closing of the New Notes on July 2, 2019, the Company purchased, using a portion of the net proceeds from the sale of the New Notes, an aggregate principal amount of $701.0 million of the 2021 Notes. The total amount paid in purchasing the 2021 Notes was $706.2 million including $3.1 million of accrued interest. On July 17, 2019, the Company redeemed the remaining $144.0 million outstanding 2021 Notes, including $0.9 million of accrued interest, using the remaining net proceeds from the sale of the New Notes and available cash. In connection with this early repurchase and redemption of the 2021 Notes, the Company recorded a loss on early extinguishment of debt of $6.1 million during the three months ended September 30, 2019. With the repurchase and redemption of the 2021 Notes, none of the Company’s outstanding debt is registered under the Securities Act of 1933, as amended.

As of September 30, 2019 and December 31, 2018, the estimated fair value of the Company’s outstanding long-term obligations, including the current portion, was $1.6 billion. The Company’s estimates of fair value of its long-term obligations, including the current portion, are based on quoted market prices or other available market data which are considered Level 2 measures according to the fair value hierarchy. Level 2 utilizes quoted market prices in markets that are not active, broker or dealer quotation, or alternative pricing sources with reasonable levels of price transparency for similar assets and liabilities.

Cash Flow Hedges

The Company’s strategy to hedge against fluctuations in variable interest rates involves entering into interest rate derivative agreements. Although the interest rate on all $736.6 million aggregate principal amount of Term Loans which were outstanding on September 30, 2019 is variable under the related Term Loan Agreement, the Company has effectively fixed the interest rate on $350.0 million aggregate principal amount of the Term Loans outstanding by entering into interest rate swap agreements with a notional amount of $350.0 million. Under the terms of the interest rate swap agreements, the Company receives interest based on the one-month LIBOR index and pays interest at a weighted average annual interest rate of approximately 2.92%. When combined with the 1.75% interest rate margin for Eurocurrency borrowings, the effective annual interest rate on such $350.0 million aggregate principal amount of Term Loans is therefore approximately 4.67%.

The Company recognizes derivative instruments as either assets or liabilities on the balance sheet at fair value. No ineffectiveness has been identified on these swaps and, therefore, all unrealized changes in fair value are recorded in accumulated other comprehensive loss. Amounts are reclassified from accumulated other comprehensive loss into interest expense on the statement of operations in the same period or periods during which the hedged transaction affects earnings.

As of September 30, 2019 and December 31, 2018, the Company has recorded a derivative liability with a fair value of $25.3 million and $8.8 million, respectively, within accrued expenses in connection with these cash flow hedges.

The fair value of the interest rate swaps 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 interest rate swaps and as such is considered a Level 2 measure according to the fair value hierarchy

STOCK-BASED COMPENSATION

9 Months Ended

Sep. 30, 2019

Share-based Payment Arrangement [Abstract]

STOCK-BASED COMPENSATION

Total stock-based compensation cost charged to selling, general and administrative expenses for the three and nine months ended September 30, 2019 was $5.0 million and $14.7 million, respectively. Total stock-based compensation cost charged to selling, general and administrative expenses for the three and nine months ended September 30, 2018 was $4.1 million and $10.7 million, respectively. The total income tax benefit recognized in the consolidated statements of operations from stock-based compensation expense was $1.0 million and $2.8 million for the three and nine months ended September 30, 2019, respectively. The total income tax benefit recognized in the consolidated statements of operations from stock-based compensation was $0.8 million and $2.0 million for the three and nine months ended September 30, 2018, respectively.

Restricted Stock Awards

The following information relates to restricted stock awards that have been granted to employees and directors under the Company's equity incentive plan adopted in 2010 (the "2010 Plan"). The restricted stock awards are not transferable until vested and the restrictions generally lapse upon the achievement of continued employment over a three-to-five-year period or service as a director until the following annual meeting of shareholders. The fair value of each restricted stock grant is based on the closing price of the Company's common stock on the date of grant and is amortized to expense over its vesting period.

The following table summarizes information about restricted stock awards for the nine months ended September 30, 2019:



Restricted Stock	Number of Shares		Weighted Average Grant-Date Fair Value
Balance at January 1, 2019	657,240		$	54.65
Granted	168,261		68.39
Vested	(230,214	)	53.97
Forfeited	(53,458	)	55.27
Balance at September 30, 2019	541,829		59.14

As of September 30, 2019, there was $24.0 million of total unrecognized compensation cost arising from restricted stock awards under the Company's 2010 Plan. This cost is expected to be recognized over a weighted average period of 2.75 years. The total fair value of restricted stock vested during the three and nine months ended September 30, 2019 was $4.2 million and $15.3 million, respectively. The total fair value of restricted stock vested during the three and nine months ended September 30, 2018 was $1.1 million and $9.4 million, respectively.

Performance Stock Awards

The following information relates to performance stock awards that have been granted to employees under the Company's 2010 Plan. Performance stock awards are subject to performance criteria established by the compensation committee of the Company's board of directors prior to or at the date of grant. The vesting of the performance stock awards is based on achieving such targets typically based on revenue, Adjusted EBITDA margin, Adjusted Free Cash Flow and Total Recordable Incident Rate. In addition, performance stock awards include continued service conditions. The fair value of each performance stock award is based on the closing price of the Company's common stock on the date of grant and is amortized to expense over the service period if achievement of performance measures is considered probable.

The following table summarizes information about performance stock awards for the nine months ended September 30, 2019:



Performance Stock	Number of Shares		Weighted Average Grant-Date Fair Value
Balance at January 1, 2019	213,490		$	55.71
Granted	121,075		70.53
Vested	(51,996	)	55.77
Forfeited	(27,308	)	56.53
Balance at September 30, 2019	255,261		62.64

As of September 30, 2019, there was $4.5 million of total unrecognized compensation cost arising from unvested performance stock awards deemed probable of vesting under the Company's 2010 Plan. No performance awards vested during the three months ended September 30, 2019 and September 30, 2018. The total fair value of performance awards vested during the nine months ended September 30, 2019 and September 30, 2018 was $2.9 million and $0.5 million, respectively.

Common Stock Repurchases

The Company's board of directors has authorized the repurchase of up to $600.0 million of the Company's common stock. During the three and nine months ended September 30, 2019, the Company repurchased and retired a total of approximately 0.1 million and 0.2 million shares, respectively, of the Company's common stock for total costs of approximately $5.1 million and $16.4 million, respectively. During the three and nine months ended September 30, 2018, the Company repurchased and retired a total of approximately 0.1 million and 0.6 million shares, respectively, of the Company's common stock for total costs of approximately $7.1 million and $33.6 million, respectively. Through September 30, 2019, the Company has repurchased and retired a total of approximately 5.8 million shares of its common stock for approximately $310.3 million under this program. As of September 30, 2019, an additional $289.7 million remained available for repurchase of shares under this program.

COMMITMENTS AND CONTINGENCIES	9 Months Ended
COMMITMENTS AND CONTINGENCIES	Sep. 30, 2019
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES Legal and Administrative Proceedings The Company and its subsidiaries are subject to legal proceedings and claims arising in the ordinary course of business. Actions filed against the Company arise from commercial and employment-related claims including alleged class actions related to sales practices and wage and hour claims. The plaintiffs in these actions may be seeking damages or injunctive relief or both. These actions are in various jurisdictions and stages of proceedings, and some are covered in part by insurance. In addition, the Company’s waste management services operations are regulated by federal, state, provincial and local laws enacted to regulate discharge of materials into the environment, remediation of contaminated soil and groundwater or otherwise protect the environment. This ongoing regulation results in the Company frequently becoming a party to legal or administrative proceedings involving all levels of governmental authorities and other interested parties. The issues involved in such proceedings generally relate to alleged violations of existing permits and licenses or alleged responsibility under federal or state Superfund laws to remediate contamination at properties owned either by the Company or by other parties (“third-party sites”) to which either the Company or the prior owners of certain of the Company’s facilities shipped wastes. At September 30, 2019 and December 31, 2018, the Company had recorded reserves of $24.0 million and $25.4 million, respectively, in the Company's financial statements for actual or probable liabilities related to the legal and administrative proceedings in which the Company was then involved, the principal of which are described below. At September 30, 2019 and December 31, 2018, the Company also believed that it was reasonably possible that the amount of these potential liabilities could be as much as $1.8 million more. The Company periodically adjusts the aggregate amount of these reserves when actual or probable liabilities are paid or otherwise discharged, new claims arise or additional relevant information about existing or probable claims becomes available. As of September 30, 2019 and December 31, 2018, the $24.0 million and $25.4 million, respectively, of reserves consisted of (i) $18.1 million and $17.9 million, respectively, related to pending legal or administrative proceedings, including Superfund liabilities, which were included in remedial liabilities on the consolidated balance sheets, and (ii) $5.9 million and $7.5 million, respectively, primarily related to federal, state and provincial enforcement actions, which were included in accrued expenses on the consolidated balance sheets. As of September 30, 2019, the principal legal and administrative proceedings in which the Company was involved, or which had been terminated during 2019, were as follows: Ville Mercier. In September 2002, the Company acquired the stock of a subsidiary (the "Mercier Subsidiary") which owns a hazardous waste incinerator in Ville Mercier, Quebec (the "Mercier Facility"). The property adjacent to the Mercier Facility, which is also owned by the Mercier Subsidiary, is now contaminated as a result of actions dating back to 1968, when the Government of Quebec issued two permits to dump organic liquids into lagoons on the property to a company unrelated to the Mercier Subsidiary. In 1999, Ville Mercier and three neighboring municipalities filed separate legal proceedings against the Mercier Subsidiary and the Government of Quebec. In 2012, the municipalities amended their existing statement of claim to seek $2.9 million (CAD) in general damages and $10.0 million (CAD) in punitive damages, plus interest and costs, as well as injunctive relief. Both the Government of Quebec and the Company have filed summary judgment motions against the municipalities. The parties are attempting to negotiate a resolution and hearings on the motions have been delayed. In September 2007, the Quebec Minister of Sustainable Development, Environment and Parks issued a notice pursuant to Section 115.1 of the Environment Quality Act, superseding notices issued in 1992, which are the subject of the pending litigation. The more recent notice notifies the Mercier Subsidiary that, if the Mercier Subsidiary does not take certain remedial measures at the site, the Minister intends to undertake those measures at the site and claim direct and indirect costs related to such measures. The Company has accrued for costs expected to be incurred relative to the resolution of this matter and believes this matter will not have future material effect on its financial position, results of operations or cash flows. Safety-Kleen Legal Proceedings. On December 28, 2012, the Company acquired Safety-Kleen, Inc. ("Safety-Kleen") and thereby became subject to the legal proceedings in which Safety-Kleen was a party on that date. In addition to certain Superfund proceedings in which Safety-Kleen has been named as a potentially responsible party as described below under “Superfund Proceedings,” the principal such legal proceedings involving Safety-Kleen which were outstanding as of September 30, 2019 were as follows: Product Liability Cases. Safety-Kleen has been named as a defendant in various lawsuits that are currently pending in various courts and jurisdictions throughout the United States, including approximately 59 proceedings (excluding cases which have been settled but not formally dismissed) as of September 30, 2019, wherein persons claim personal injury resulting from the use of Safety-Kleen's parts cleaning equipment or cleaning products. These proceedings typically involve allegations that the solvent used in Safety-Kleen's parts cleaning equipment contains contaminants and/or that Safety-Kleen's recycling process does not effectively remove the contaminants that become entrained in the solvent during their use. In addition, certain claimants assert that Safety-Kleen failed to adequately warn the product user of potential risks, including a historic failure to warn that solvent contains trace amounts of toxic or hazardous substances such as benzene. Safety-Kleen maintains insurance that it believes will provide coverage for these product liability claims (over amounts accrued for self-insured retentions and deductibles in certain limited cases), except for punitive damages to the extent not insurable under state law or excluded from insurance coverage. Safety-Kleen also believes that these claims lack merit and has historically vigorously defended, and intends to continue to vigorously defend, itself and the safety of its products against all these claims. Such matters are subject to many uncertainties and outcomes are not predictable with assurance. Consequently, Safety-Kleen is unable to ascertain the ultimate aggregate amount of monetary liability or financial impact with respect to these matters as of September 30, 2019. From January 1, 2019 to September 30, 2019, 21 product liability claims were settled or dismissed. Due to the nature of these claims and the related insurance, the Company did not incur any expense as Safety-Kleen's insurance provided coverage in full for all such claims. Safety-Kleen may be named in similar, additional lawsuits in the future, including claims for which insurance coverage may not be available. Superfund Proceedings The Company has been notified that either the Company (which, since December 28, 2012, includes Safety-Kleen) or the prior owners of certain of the Company's facilities for which the Company may have certain indemnification obligations have been identified as potentially responsible parties ("PRPs") or potential PRPs in connection with 129 sites which are subject to or are proposed to become subject to proceedings under federal or state Superfund laws. Of the 129 sites, five (including the BR Facility described below) involve facilities that are now owned or leased by the Company and 124 involve third-party sites to which either the Company or the prior owners of certain of the Company’s facilities shipped wastes. Of the 124 third-party sites, 31 are now settled, 16 are currently requiring expenditures on remediation and 77 are not currently requiring expenditures on remediation. In connection with each site, the Company has estimated the extent, if any, to which it may be subject, either directly or as a result of any indemnification obligations, for cleanup and remediation costs, related legal and consulting costs associated with PRP investigations, settlements and related legal and administrative proceedings. The amount of such actual and potential liability is inherently difficult to estimate because of, among other relevant factors, uncertainties as to the legal liability, if any, of the Company or the prior owners of certain of the Company's facilities to contribute a portion of the cleanup costs, the assumptions that must be made in calculating the estimated cost and timing of remediation, the identification of other PRPs and their respective capability and obligation to contribute to remediation efforts and the existence and legal standing of indemnification agreements, if any, with prior owners, which may either benefit the Company or subject the Company to potential indemnification obligations. The Company believes its potential liability could exceed $100,000 at ten of the 124 third-party sites. BR Facility. The Company acquired in 2002 a former hazardous waste incinerator and landfill in Baton Rouge (the "BR Facility"), for which operations had been previously discontinued by the prior owner. In September 2007, the U.S. Environmental Protection Agency ("EPA")" issued a special notice letter to the Company related to the Devil's Swamp Lake Site ("Devil's Swamp") in East Baton Rouge Parish, Louisiana. Devil's Swamp includes a lake located downstream of an outfall ditch where wastewater and storm water have been discharged, and Devil's Swamp is proposed to be included on the National Priorities List due to the presence of Contaminants of Concern ("COC") cited by the EPA. These COCs include substances of the kind found in wastewater and storm water discharged from the BR Facility in past operations. The EPA originally requested COC generators to submit a good faith offer to conduct a remedial investigation feasibility study directed towards the eventual remediation of the site. In 2018, the Company completed performing corrective actions at the BR Facility under an order issued by the Louisiana Department of Environmental Quality and has also completed conducting the remedial investigation and feasibility study for Devil's Swamp under an order issued by the EPA. The Company cannot presently estimate the potential additional liability for the Devil's Swamp cleanup until a final remedy is selected by the EPA with issuance of a Record of Decision. Third-Party Sites. Of the 124 third-party sites at which the Company has been notified it is a PRP or potential PRP or may have indemnification obligations, Clean Harbors has an indemnification agreement at 11 of these sites with ChemWaste, a former subsidiary of Waste Management, Inc., and at six additional of these third-party sites, Safety-Kleen has a similar indemnification agreement with McKesson Corporation. These agreements indemnify the Company (which now includes Safety-Kleen) with respect to any liability at the 17 sites for waste disposed prior to the Company's (or Safety-Kleen's) acquisition of the former subsidiaries of Waste Management and McKesson which had shipped wastes to those sites. Accordingly, Waste Management or McKesson are paying all costs of defending those subsidiaries in those 17 cases, including legal fees and settlement costs. However, there can be no guarantee that the Company's ultimate liabilities for those sites will not exceed the amount recorded or that indemnities applicable to any of these sites will be available to pay all or a portion of related costs. Except for the indemnification agreements which the Company holds from ChemWaste, McKesson and two other entities, the Company does not have an indemnity agreement with respect to any of the 124 third-party sites discussed above. Federal, State and Provincial Enforcement Actions From time to time, the Company pays fines or penalties in regulatory proceedings relating primarily to waste treatment, storage or disposal facilities. As of September 30, 2019 and December 31, 2018, there were ten proceedings for which the Company reasonably believes that the sanctions could equal or exceed $100,000. The Company believes that the fines or other penalties in these or any of the other regulatory proceedings will, individually or in the aggregate, not have a material effect on its financial condition, results of operations or cash flows.

LEASES

9 Months Ended

Sep. 30, 2019

Leases [Abstract]

LEASES

As of September 30, 2019, the Company’s leases were all operating leases except for two leases associated with the Company’s corporate headquarters, which were amended during 2019, resulting in the classification as finance leases.

The Company’s lease expense was as follows (in thousands):



	For the Three Months Ended September 30, 2019		For the Nine Months Ended September 30, 2019
Operating lease cost	$	14,056	$	41,406
Finance lease cost:
Amortization of ROU asset	245		735
Interest on lease liability	367		979
Total finance lease cost	612		1,714
Short-term lease cost	22,258		60,295
Variable lease cost	2,139		6,372
Total lease cost	$	39,065	$	109,787

Other information related to leases was as follows (in thousands, except lease term and discount rate):



Supplemental Lease Balance Sheet Information:	September 30, 2019
ROU assets:
Operating leases	$	164,302
Finance leases (included in property, plant and equipment, net)	30,276
Current portion of lease liabilities:
Operating leases	41,364
Finance leases (included in accrued expenses)	440
Long-term portion of lease liabilities:
Operating leases	122,668
Finance leases (included in deferred taxes, unrecognized tax benefits and other long-term liabilities)	32,228



Weighted Average Remaining Lease Term (years)	September 30, 2019
Operating leases	5.1
Finance leases	22.8
Weighted Average Discount Rate
Operating leases	5.33	%
Finance leases	4.99	%

At September 30, 2019, the Company's future lease payments under non-cancelable leases that have lease terms in excess of one year were as follows (in thousands):



Years Ending December 31,	Operating Leases			Finance Leases
2019 (three months)	$	13,856		$	535
2020	48,577			2,194
2021	36,506			2,244
2022	28,814			2,297
2023	20,793			2,356
2024	13,930			2,411
Thereafter	27,697			51,151
Total future lease payments	190,173			63,188
Amount representing interest	(26,141		)	(30,520		)
Total lease liabilities	$	164,032		$	32,668

At September 30, 2019, none of the Company's executed leases that had not yet commenced will create significant rights or obligations in the future and its sublease transactions are not material. Additionally, the Company does not have any related party leases and there were no restrictions or covenants imposed by its leases.

Disclosures related to periods prior to adoption of Topic 842

The following is a summary of future minimum payments under operating leases that have initial or remaining non-cancelable lease terms in excess of one year at December 31, 2018 (in thousands):



Year	Total Operating Leases
2019	$	56,480
2020	45,467
2021	33,564
2022	24,509
2023	15,253
Thereafter	35,778
Total minimum lease payments	$	211,051

During the years ended December 31, 2018, 2017 and 2016, rent expense including short-term rentals was approximately $141.1 million, $125.4 million and $121.9 million, respectively.

LEASES

The Company’s lease expense was as follows (in thousands):



	For the Three Months Ended September 30, 2019		For the Nine Months Ended September 30, 2019
Operating lease cost	$	14,056	$	41,406
Finance lease cost:
Amortization of ROU asset	245		735
Interest on lease liability	367		979
Total finance lease cost	612		1,714
Short-term lease cost	22,258		60,295
Variable lease cost	2,139		6,372
Total lease cost	$	39,065	$	109,787

Other information related to leases was as follows (in thousands, except lease term and discount rate):



Supplemental Lease Balance Sheet Information:	September 30, 2019
ROU assets:
Operating leases	$	164,302
Finance leases (included in property, plant and equipment, net)	30,276
Current portion of lease liabilities:
Operating leases	41,364
Finance leases (included in accrued expenses)	440
Long-term portion of lease liabilities:
Operating leases	122,668
Finance leases (included in deferred taxes, unrecognized tax benefits and other long-term liabilities)	32,228



Weighted Average Remaining Lease Term (years)	September 30, 2019
Operating leases	5.1
Finance leases	22.8
Weighted Average Discount Rate
Operating leases	5.33	%
Finance leases	4.99	%

At September 30, 2019, the Company's future lease payments under non-cancelable leases that have lease terms in excess of one year were as follows (in thousands):



Years Ending December 31,	Operating Leases			Finance Leases
2019 (three months)	$	13,856		$	535
2020	48,577			2,194
2021	36,506			2,244
2022	28,814			2,297
2023	20,793			2,356
2024	13,930			2,411
Thereafter	27,697			51,151
Total future lease payments	190,173			63,188
Amount representing interest	(26,141		)	(30,520		)
Total lease liabilities	$	164,032		$	32,668

Disclosures related to periods prior to adoption of Topic 842

The following is a summary of future minimum payments under operating leases that have initial or remaining non-cancelable lease terms in excess of one year at December 31, 2018 (in thousands):



Year	Total Operating Leases
2019	$	56,480
2020	45,467
2021	33,564
2022	24,509
2023	15,253
Thereafter	35,778
Total minimum lease payments	$	211,051

During the years ended December 31, 2018, 2017 and 2016, rent expense including short-term rentals was approximately $141.1 million, $125.4 million and $121.9 million, respectively.

SEGMENT REPORTING

9 Months Ended

Sep. 30, 2019

Segment Reporting [Abstract]

SEGMENT REPORTING

Segment reporting is prepared on the same basis that the Company's chief executive officer, who is the Company's chief operating decision maker, manages the business, makes operating decisions and assesses performance. The Company's operations are managed in two operating segments: Environmental Services and Safety-Kleen.

Third-party revenue is revenue billed to outside customers by a particular segment. Direct revenue is revenue allocated to the segment providing the product or service. Intersegment revenues represent the sharing of third-party revenues among the segments based on products and services provided by each segment as if the products and services were sold directly to the third-party. The intersegment revenues are shown net. The operations not managed through the Company’s operating segments described above are recorded as “Corporate Items.”

The following table reconciles third-party revenues to direct revenues for the three and nine months ended September 30, 2019 and September 30, 2018 (in thousands):



	For the Three Months Ended September 30, 2019											For the Three Months Ended September 30, 2018
	Third-party revenues		Intersegment revenues, net			Corporate Items, net			Direct revenues			Third-party revenues		Intersegment revenues, net			Corporate Items, net			Direct revenues
Environmental Services	$	550,122	$	35,274		$	1,476		$	586,872		$	508,813	$	33,022		$	1,145		$	542,980
Safety-Kleen	341,417		(35,274		)	2			306,145			333,901		(33,022		)	6			300,885
Corporate Items	129		—			(1,478		)	(1,349		)	467		—			(1,151		)	(684		)
Total	$	891,668	$	—		$	—		$	891,668		$	843,181	$	—		$	—		$	843,181



	For the Nine Months Ended September 30, 2019											For the Nine Months Ended September 30, 2018
	Third-party revenues		Intersegment revenues, net			Corporate Items, net			Direct revenues			Third-party revenues		Intersegment revenues, net			Corporate Items, net			Direct revenues
Environmental Services	$	1,550,114	$	105,555		$	3,301		$	1,658,970		$	1,468,417	$	99,278		$	2,546		$	1,570,241
Safety-Kleen	990,146		(105,555		)	15			884,606			972,534		(99,278		)	28			873,284
Corporate Items	925		—			(3,316		)	(2,391		)	1,148		—			(2,574		)	(1,426		)
Total	$	2,541,185	$	—		$	—		$	2,541,185		$	2,442,099	$	—		$	—		$	2,442,099

The primary financial measure by which the Company evaluates the performance of its segments is "Adjusted EBITDA," which consists of net income plus accretion of environmental liabilities, depreciation and amortization, interest expense, net of interest income, provision for income taxes and other gains or non-cash charges not deemed representative of fundamental segment results and excludes other expense (income), net. Transactions between the segments are accounted for at the Company’s best estimate based on similar transactions with outside customers.

The following table presents Adjusted EBITDA information used by management by reported segment (in thousands):



	For the Three Months Ended						For the Nine Months Ended
	September 30,						September 30,
	2019			2018			2019			2018
Adjusted EBITDA:
Environmental Services	$	121,658		$	102,419		$	329,036		$	273,035
Safety-Kleen	81,326			79,502			215,578			214,455
Corporate Items	(46,371		)	(40,644		)	(136,513		)	(118,387		)
Total	156,613			141,277			408,101			369,103
Reconciliation to Consolidated Statements of Operations:
Accretion of environmental liabilities	2,490			2,450			7,624			7,328
Depreciation and amortization	73,756			73,082			223,328			220,686
Income from operations	80,367			65,745			177,149			141,089
Other expense (income), net	427			996			(1,992		)	449
Loss on early extinguishment of debt	6,119			2,469			6,119			2,469
Interest expense, net of interest income	19,702			19,916			59,681			60,955
Income before provision for income taxes	$	54,119		$	42,364		$	113,341		$	77,216

The following table presents certain assets by reportable segment and in the aggregate (in thousands):



	September 30, 2019		December 31, 2018
Property, plant and equipment, net:
Environmental Services	$	946,367	$	951,867
Safety-Kleen	556,247		553,220
Corporate Items	91,379		56,891
Total property, plant and equipment, net	$	1,593,993	$	1,561,978

Goodwill and Permits and other intangibles, net:
Environmental Services
Goodwill	$	212,638	$	207,019
Permits and other intangibles, net	91,292		93,313
Total Environmental Services	303,930		300,332

Safety-Kleen
Goodwill	$	311,943	$	307,170
Permits and other intangibles, net	334,571		348,562
Total Safety-Kleen	646,514		655,732

Total	$	950,444	$	956,064

The following table presents the total assets by reportable segment (in thousands):



	September 30, 2019		December 31, 2018
Environmental Services	$	1,750,343	$	1,640,706
Safety-Kleen	1,501,838		1,431,381
Corporate Items	769,681		666,234
Total	$	4,021,862	$	3,738,321

The following table presents the total assets by geographical area (in thousands):



	September 30, 2019		December 31, 2018
United States	$	3,339,899	$	3,090,311
Canada	681,963		648,010
Total	$	4,021,862	$	3,738,321

SIGNIFICANT ACCOUNTING POLICIES (Policies)	9 Months Ended
SIGNIFICANT ACCOUNTING POLICIES (Policies)	Sep. 30, 2019
Accounting Policies [Abstract]
Recent Accounting Pronouncements	Recent Accounting Pronouncements Standards implemented In February 2016, the Financial Accounting Standards Board ("FASB") issued ASU 2016-02, Leases (Topic 842). The amendment increases transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet and disclosing key information about leasing arrangements. The Company adopted Topic 842 on January 1, 2019 using the modified retrospective method of adoption. Prior period amounts have not been adjusted and continue to be reported in accordance with the Company's historical accounting methodology pursuant to ASC 840, Leases. As permitted under the transition guidance, the Company elected to apply the package of three practical expedients for all existing leases which, among other things, allowed us to maintain the lease classification for all existing leases at the adoption date. The adoption of Topic 842 resulted in the recognition of right-of-use (“ROU”) assets of $185.5 million and total current and noncurrent lease liabilities of $188.5 million at adoption. Additionally, Topic 842 required new and expanded disclosures to enable users of financial statements to assess the amount, timing and uncertainty of cash flows arising from leases. The standard did not have a material impact on the consolidated statements of operations or cash flows. Leases The Company’s leases predominately relate to real estate and equipment such as vehicles and industrial equipment utilized in operations as well as rail cars utilized in connection with the Company’s transportation needs. Contracts are reviewed at inception to determine if the arrangement is a lease and, if so, whether it is an operating or finance lease. For all of its leases, the Company has elected not to separate lease and nonlease components, such as common area maintenance. The Company generally enters into real estate leases with five to ten-year terms and non-real estate leases with two to seven-year terms. In the normal course of business, the Company also enters into short-term leases having terms of less than one-year. These leases are generally equipment leases entered into for short periods of time (e.g. daily, weekly or monthly), and done so to satisfy immediate and/or short-term operational needs of the business which can arise based upon the nature of particular services performed or seasonality factors. The Company has elected not to recognize ROU assets and lease liabilities for these short-term leases. Expense for all such short-term leases is disclosed as short-term lease cost as shown in Note 17, "Leases." Operating and finance leases with terms exceeding one year are recognized as ROU assets and lease liabilities and measured based on the present value of the future lease payments over the lease term at commencement date. When applicable, the ROU asset includes any lease payments made at or before the commencement date and initial direct costs incurred and is reduced by lease incentives received under the lease agreement, if any. Certain of the Company's real estate leases contain escalating future lease payments. Escalating lease payments that are based upon explicit amounts contained in the lease or an index (e.g., consumer price index) are included in its determination of future lease payments to determine the ROU asset and lease liability recognized at the commencement date. Any differences in the future lease payments from initial recognition are not anticipated to be material and will be recorded as variable lease cost in the period incurred. The variable lease cost will also include the Company’s portion of property tax, utilities and common area maintenance. A significant portion of the Company’s real estate lease agreements include renewal periods at the Company’s option. The Company includes these renewal periods in the lease term only when renewal is reasonably certain based upon facts and circumstances specific to the lease and known by the Company. The Company uses its incremental borrowing rate on collateralized debt based on the information available at the lease commencement date in determining the present value of future lease payments as the implicit rate is typically not readily determinable.

REVENUES (Tables)

9 Months Ended

Sep. 30, 2019

Revenue from Contract with Customer [Abstract]

Disaggregation of Revenue

The following table presents the Company’s third-party revenues disaggregated by revenue source (in thousands):



	For the Three Months Ended September 30, 2019
	Environmental Services		Safety-Kleen		Corporate			Total
Primary Geographical Markets
United States	$	450,638	$	313,979	$	(265	)	$	764,352
Canada	99,484		27,438		394			127,316
Total third-party revenues	$	550,122	$	341,417	$	129		$	891,668

Sources of Revenue ⁽¹⁾
Technical Services	$	292,506	$	—	$	—		$	292,506
Field and Emergency Response Services	95,546		—		—			95,546
Industrial Services	131,855		—		—			131,855
Oil, Gas and Lodging Services and Other	30,215		—		129			30,344
Safety-Kleen Environmental Services	—		217,439		—			217,439
Safety-Kleen Oil⁽²⁾	—		123,978		—			123,978
Total third-party revenues	$	550,122	$	341,417	$	129		$	891,668



	For the Three Months Ended September 30, 2018
	Environmental Services		Safety-Kleen		Corporate			Total
Primary Geographical Markets
United States	$	410,792	$	307,497	$	(66	)	$	718,223
Canada	98,021		26,404		533			124,958
Total third-party revenues	$	508,813	$	333,901	$	467		$	843,181

Sources of Revenue⁽¹⁾
Technical Services	$	264,769	$	—	$	—		$	264,769
Field and Emergency Response Services	77,025		—		—			77,025
Industrial Services	134,323		—		—			134,323
Oil, Gas and Lodging Services and Other	32,696		—		467			33,163
Safety-Kleen Environmental Services	—		200,681		—			200,681
Safety-Kleen Oil⁽²⁾	—		133,220		—			133,220
Total third-party revenues	$	508,813	$	333,901	$	467		$	843,181



	For the Nine Months Ended September 30, 2019
	Environmental Services		Safety-Kleen		Corporate		Total
Primary Geographical Markets
United States	$	1,270,556	$	917,240	$	531	$	2,188,327
Canada	279,558		72,906		394		352,858
Total third-party revenues	$	1,550,114	$	990,146	$	925	$	2,541,185

Sources of Revenue⁽¹⁾
Technical Services	$	820,333	$	—	$	—	$	820,333
Field and Emergency Response Services	253,894		—		—		253,894
Industrial Services	383,964		—		—		383,964
Oil, Gas and Lodging Services and Other	91,923		—		925		92,848
Safety-Kleen Environmental Services	—		640,956		—		640,956
Safety-Kleen Oil⁽²⁾	—		349,190		—		349,190
Total third-party revenues	$	1,550,114	$	990,146	$	925	$	2,541,185



	For the Nine Months Ended September 30, 2018
	Environmental Services		Safety-Kleen		Corporate		Total
Primary Geographical Markets
United States	$	1,162,891	$	901,198	$	442	$	2,064,531
Canada	305,526		71,336		706		377,568
Total third-party revenues	$	1,468,417	$	972,534	$	1,148	$	2,442,099

Sources of Revenue⁽¹⁾
Technical Services	$	758,081	$	—	$	—	$	758,081
Field and Emergency Response Services	223,052		—		—		223,052
Industrial Services	399,132		—		—		399,132
Oil, Gas and Lodging Services and Other	88,152		—		1,148		89,300
Safety-Kleen Environmental Services	—		594,876		—		594,876
Safety-Kleen Oil⁽²⁾	—		377,658		—		377,658
Total third-party revenues	$	1,468,417	$	972,534	$	1,148	$	2,442,099

______________________


(1)	All revenue except oil and oil product sales within Safety-Kleen Oil and product sales within Safety-Kleen Environmental Services, which include various automotive related fluids, shop supplies and direct blended oil sales, are recognized over time. Safety-Kleen Oil and Safety-Kleen Environmental Services product sales are recognized at a point in time.


(2)	Safety-Kleen Oil was formerly known as Kleen Performance Products.

Contract Balances



(in thousands)	September 30, 2019		December 31, 2018
Receivables	$	641,667	$	606,952
Contract assets (unbilled receivables)	58,842		54,794
Contract liabilities (deferred revenue)	73,157		61,843

GOODWILL AND OTHER INTANGIBLE ASSETS (Tables)

9 Months Ended

Sep. 30, 2019

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of changes to goodwill

The changes in goodwill by segment for the nine months ended September 30, 2019 were as follows (in thousands):



	Environmental Services			Safety-Kleen			Totals
Balance at January 1, 2019	$	207,019		$	307,170		$	514,189
Increase from current period acquisitions	7,514			5,225			12,739
Measurement period adjustments from prior period acquisitions	(2,675		)	(1,355		)	(4,030		)
Foreign currency translation	780			903			1,683
Balance at September 30, 2019	$	212,638		$	311,943		$	524,581

Summary of indefinite-lived intangible assets

As of September 30, 2019 and December 31, 2018, the Company's total intangible assets consisted of the following (in thousands):



	September 30, 2019						December 31, 2018
	Cost		Accumulated Amortization		Net		Cost		Accumulated Amortization		Net
Permits	$	182,667	$	84,899	$	97,768	$	177,583	$	79,358	$	98,225
Customer and supplier relationships	400,498		200,766		199,732		393,487		179,824		213,663
Other intangible assets	37,932		32,329		5,603		37,262		29,743		7,519
Total amortizable permits and other intangible assets	621,097		317,994		303,103		608,332		288,925		319,407
Trademarks and trade names	122,760		—		122,760		122,468		—		122,468
Total permits and other intangible assets	$	743,857	$	317,994	$	425,863	$	730,800	$	288,925	$	441,875

Schedule of finite-lived intangible assets

As of September 30, 2019 and December 31, 2018, the Company's total intangible assets consisted of the following (in thousands):



	September 30, 2019						December 31, 2018
	Cost		Accumulated Amortization		Net		Cost		Accumulated Amortization		Net
Permits	$	182,667	$	84,899	$	97,768	$	177,583	$	79,358	$	98,225
Customer and supplier relationships	400,498		200,766		199,732		393,487		179,824		213,663
Other intangible assets	37,932		32,329		5,603		37,262		29,743		7,519
Total amortizable permits and other intangible assets	621,097		317,994		303,103		608,332		288,925		319,407
Trademarks and trade names	122,760		—		122,760		122,468		—		122,468
Total permits and other intangible assets	$	743,857	$	317,994	$	425,863	$	730,800	$	288,925	$	441,875

Schedule of expected amortization for the net carrying amount of finite lived intangible assets

The expected amortization of the net carrying amount of finite-lived intangible assets at September 30, 2019 was as follows (in thousands):



Years Ending December 31,	Expected Amortization
2019 (three months)	$	8,305
2020	31,942
2021	28,667
2022	28,406
2023	24,193
Thereafter	181,590
	$	303,103

FINANCING ARRANGEMENTS (Tables)

9 Months Ended

Sep. 30, 2019

Debt Disclosure [Abstract]

Summary of the entity's financial arrangements

The following table is a summary of the Company’s financing arrangements (in thousands):



Current Obligations:	September 30, 2019			December 31, 2018
Secured senior term loans ("Term Loans")	$	7,535		$	7,535

Long-Term Obligations:
Secured senior Term Loans due June 30, 2024	$	729,045		$	734,697
Unsecured senior notes, at 4.875%, due July 15, 2027 ("2027 Notes")	545,000			—
Unsecured senior notes, at 5.125%, due July 15, 2029 ("2029 Notes")	300,000			—
Unsecured senior notes, at 5.125%, due June 1, 2021 ("2021 Notes")	—			845,000
Long-term obligations, at par	$	1,574,045		$	1,579,697
Unamortized debt issuance costs and premium, net	(18,788		)	(14,676		)
Long-term obligations, at carrying value	$	1,555,257		$	1,565,021

Summary of redemption prices

2027 Notes



Year	Percentage
2022	102.438	%
2023	101.219	%
2024 and thereafter	100.000	%

2029 Notes



Year	Percentage
2024	102.563	%
2025	101.281	%
2026 and thereafter	100.000	%

- Definition

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28541-108399

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21506-112644

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(e),(f))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399

Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21521-112644

Reference 7: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21538-112644

Reference 8: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823

Reference 9: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21475-112644

+ Details

LEASES (Tables)

9 Months Ended

Sep. 30, 2019

Leases [Abstract]

Schedule of Lease Expense

The Company’s lease expense was as follows (in thousands):



	For the Three Months Ended September 30, 2019		For the Nine Months Ended September 30, 2019
Operating lease cost	$	14,056	$	41,406
Finance lease cost:
Amortization of ROU asset	245		735
Interest on lease liability	367		979
Total finance lease cost	612		1,714
Short-term lease cost	22,258		60,295
Variable lease cost	2,139		6,372
Total lease cost	$	39,065	$	109,787



Weighted Average Remaining Lease Term (years)	September 30, 2019
Operating leases	5.1
Finance leases	22.8
Weighted Average Discount Rate
Operating leases	5.33	%
Finance leases	4.99	%

Supplemental Lease Balance Sheet Information

Other information related to leases was as follows (in thousands, except lease term and discount rate):



Supplemental Lease Balance Sheet Information:	September 30, 2019
ROU assets:
Operating leases	$	164,302
Finance leases (included in property, plant and equipment, net)	30,276
Current portion of lease liabilities:
Operating leases	41,364
Finance leases (included in accrued expenses)	440
Long-term portion of lease liabilities:
Operating leases	122,668
Finance leases (included in deferred taxes, unrecognized tax benefits and other long-term liabilities)	32,228

Schedule of Operating Lease Maturity

At September 30, 2019, the Company's future lease payments under non-cancelable leases that have lease terms in excess of one year were as follows (in thousands):



Years Ending December 31,	Operating Leases			Finance Leases
2019 (three months)	$	13,856		$	535
2020	48,577			2,194
2021	36,506			2,244
2022	28,814			2,297
2023	20,793			2,356
2024	13,930			2,411
Thereafter	27,697			51,151
Total future lease payments	190,173			63,188
Amount representing interest	(26,141		)	(30,520		)
Total lease liabilities	$	164,032		$	32,668

Schedule of Finance Lease Maturity

At September 30, 2019, the Company's future lease payments under non-cancelable leases that have lease terms in excess of one year were as follows (in thousands):



Years Ending December 31,	Operating Leases			Finance Leases
2019 (three months)	$	13,856		$	535
2020	48,577			2,194
2021	36,506			2,244
2022	28,814			2,297
2023	20,793			2,356
2024	13,930			2,411
Thereafter	27,697			51,151
Total future lease payments	190,173			63,188
Amount representing interest	(26,141		)	(30,520		)
Total lease liabilities	$	164,032		$	32,668

Summary of Future Minimum Payments Under Operating Leases

The following is a summary of future minimum payments under operating leases that have initial or remaining non-cancelable lease terms in excess of one year at December 31, 2018 (in thousands):



Year	Total Operating Leases
2019	$	56,480
2020	45,467
2021	33,564
2022	24,509
2023	15,253
Thereafter	35,778
Total minimum lease payments	$	211,051

SEGMENT REPORTING (Tables)

9 Months Ended

Sep. 30, 2019

Segment Reporting [Abstract]

Reconciliation of third party revenues to direct revenues

The following table reconciles third-party revenues to direct revenues for the three and nine months ended September 30, 2019 and September 30, 2018 (in thousands):



	For the Three Months Ended September 30, 2019											For the Three Months Ended September 30, 2018
	Third-party revenues		Intersegment revenues, net			Corporate Items, net			Direct revenues			Third-party revenues		Intersegment revenues, net			Corporate Items, net			Direct revenues
Environmental Services	$	550,122	$	35,274		$	1,476		$	586,872		$	508,813	$	33,022		$	1,145		$	542,980
Safety-Kleen	341,417		(35,274		)	2			306,145			333,901		(33,022		)	6			300,885
Corporate Items	129		—			(1,478		)	(1,349		)	467		—			(1,151		)	(684		)
Total	$	891,668	$	—		$	—		$	891,668		$	843,181	$	—		$	—		$	843,181



	For the Nine Months Ended September 30, 2019											For the Nine Months Ended September 30, 2018
	Third-party revenues		Intersegment revenues, net			Corporate Items, net			Direct revenues			Third-party revenues		Intersegment revenues, net			Corporate Items, net			Direct revenues
Environmental Services	$	1,550,114	$	105,555		$	3,301		$	1,658,970		$	1,468,417	$	99,278		$	2,546		$	1,570,241
Safety-Kleen	990,146		(105,555		)	15			884,606			972,534		(99,278		)	28			873,284
Corporate Items	925		—			(3,316		)	(2,391		)	1,148		—			(2,574		)	(1,426		)
Total	$	2,541,185	$	—		$	—		$	2,541,185		$	2,442,099	$	—		$	—		$	2,442,099

Reconciliation to consolidated statements of income from adjusted EBITDA

The following table presents Adjusted EBITDA information used by management by reported segment (in thousands):



	For the Three Months Ended						For the Nine Months Ended
	September 30,						September 30,
	2019			2018			2019			2018
Adjusted EBITDA:
Environmental Services	$	121,658		$	102,419		$	329,036		$	273,035
Safety-Kleen	81,326			79,502			215,578			214,455
Corporate Items	(46,371		)	(40,644		)	(136,513		)	(118,387		)
Total	156,613			141,277			408,101			369,103
Reconciliation to Consolidated Statements of Operations:
Accretion of environmental liabilities	2,490			2,450			7,624			7,328
Depreciation and amortization	73,756			73,082			223,328			220,686
Income from operations	80,367			65,745			177,149			141,089
Other expense (income), net	427			996			(1,992		)	449
Loss on early extinguishment of debt	6,119			2,469			6,119			2,469
Interest expense, net of interest income	19,702			19,916			59,681			60,955
Income before provision for income taxes	$	54,119		$	42,364		$	113,341		$	77,216

PP&E, intangible assets and total assets by segment

The following table presents certain assets by reportable segment and in the aggregate (in thousands):



	September 30, 2019		December 31, 2018
Property, plant and equipment, net:
Environmental Services	$	946,367	$	951,867
Safety-Kleen	556,247		553,220
Corporate Items	91,379		56,891
Total property, plant and equipment, net	$	1,593,993	$	1,561,978

Goodwill and Permits and other intangibles, net:
Environmental Services
Goodwill	$	212,638	$	207,019
Permits and other intangibles, net	91,292		93,313
Total Environmental Services	303,930		300,332

Safety-Kleen
Goodwill	$	311,943	$	307,170
Permits and other intangibles, net	334,571		348,562
Total Safety-Kleen	646,514		655,732

Total	$	950,444	$	956,064

Schedule of assets by reported segment

The following table presents the total assets by reportable segment (in thousands):



	September 30, 2019		December 31, 2018
Environmental Services	$	1,750,343	$	1,640,706
Safety-Kleen	1,501,838		1,431,381
Corporate Items	769,681		666,234
Total	$	4,021,862	$	3,738,321

Total assets by geographical area

The following table presents the total assets by geographical area (in thousands):



	September 30, 2019		December 31, 2018
United States	$	3,339,899	$	3,090,311
Canada	681,963		648,010
Total	$	4,021,862	$	3,738,321

SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Jan. 01, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease right-of-use assets	$ 164,302
Total current and noncurrent lease liabilities	$ 164,032
Real Estate Leases \| Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Term of leases (in years)	5 years
Real Estate Leases \| Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Term of leases (in years)	10 years
Non-Real Estate Leases \| Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Term of leases (in years)	2 years
Non-Real Estate Leases \| Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Term of leases (in years)	7 years
Short Term Leases
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Term of leases (in years)	1 year
Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease right-of-use assets		$ 185,500
Total current and noncurrent lease liabilities		$ 188,500

REVENUES - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disaggregation of Revenue [Line Items]
Total third party revenues	$ 891,668	$ 843,181	$ 2,541,185	$ 2,442,099
Technical Services
Disaggregation of Revenue [Line Items]
Total third party revenues	292,506	264,769	820,333	758,081
Field and Emergency Response Services
Disaggregation of Revenue [Line Items]
Total third party revenues	95,546	77,025	253,894	223,052
Industrial Services
Disaggregation of Revenue [Line Items]
Total third party revenues	131,855	134,323	383,964	399,132
Oil, Gas and Lodging Services and Other
Disaggregation of Revenue [Line Items]
Total third party revenues	30,344	33,163	92,848	89,300
Safety-Kleen Environmental Services
Disaggregation of Revenue [Line Items]
Total third party revenues	217,439	200,681	640,956	594,876
Safety-Kleen Oil
Disaggregation of Revenue [Line Items]
Total third party revenues	123,978	133,220	349,190	377,658
United States
Disaggregation of Revenue [Line Items]
Total third party revenues	764,352	718,223	2,188,327	2,064,531
Canada
Disaggregation of Revenue [Line Items]
Total third party revenues	127,316	124,958	352,858	377,568
Environmental Services
Disaggregation of Revenue [Line Items]
Total third party revenues	586,872	542,980	1,658,970	1,570,241
Safety-Kleen
Disaggregation of Revenue [Line Items]
Total third party revenues	306,145	300,885	884,606	873,284
Operating segments \| Environmental Services
Disaggregation of Revenue [Line Items]
Total third party revenues	550,122	508,813	1,550,114	1,468,417
Operating segments \| Environmental Services \| Technical Services
Disaggregation of Revenue [Line Items]
Total third party revenues	292,506	264,769	820,333	758,081
Operating segments \| Environmental Services \| Field and Emergency Response Services
Disaggregation of Revenue [Line Items]
Total third party revenues	95,546	77,025	253,894	223,052
Operating segments \| Environmental Services \| Industrial Services
Disaggregation of Revenue [Line Items]
Total third party revenues	131,855	134,323	383,964	399,132
Operating segments \| Environmental Services \| Oil, Gas and Lodging Services and Other
Disaggregation of Revenue [Line Items]
Total third party revenues	30,215	32,696	91,923	88,152
Operating segments \| Environmental Services \| Safety-Kleen Environmental Services
Disaggregation of Revenue [Line Items]
Total third party revenues	0	0	0	0
Operating segments \| Environmental Services \| Safety-Kleen Oil
Disaggregation of Revenue [Line Items]
Total third party revenues	0	0	0	0
Operating segments \| Environmental Services \| United States
Disaggregation of Revenue [Line Items]
Total third party revenues	450,638	410,792	1,270,556	1,162,891
Operating segments \| Environmental Services \| Canada
Disaggregation of Revenue [Line Items]
Total third party revenues	99,484	98,021	279,558	305,526
Operating segments \| Safety-Kleen
Disaggregation of Revenue [Line Items]
Total third party revenues	341,417	333,901	990,146	972,534
Operating segments \| Safety-Kleen \| Technical Services
Disaggregation of Revenue [Line Items]
Total third party revenues	0	0	0	0
Operating segments \| Safety-Kleen \| Field and Emergency Response Services
Disaggregation of Revenue [Line Items]
Total third party revenues	0	0	0	0
Operating segments \| Safety-Kleen \| Industrial Services
Disaggregation of Revenue [Line Items]
Total third party revenues	0	0	0	0
Operating segments \| Safety-Kleen \| Oil, Gas and Lodging Services and Other
Disaggregation of Revenue [Line Items]
Total third party revenues	0	0	0	0
Operating segments \| Safety-Kleen \| Safety-Kleen Environmental Services
Disaggregation of Revenue [Line Items]
Total third party revenues	217,439	200,681	640,956	594,876
Operating segments \| Safety-Kleen \| Safety-Kleen Oil
Disaggregation of Revenue [Line Items]
Total third party revenues	123,978	133,220	349,190	377,658
Operating segments \| Safety-Kleen \| United States
Disaggregation of Revenue [Line Items]
Total third party revenues	313,979	307,497	917,240	901,198
Operating segments \| Safety-Kleen \| Canada
Disaggregation of Revenue [Line Items]
Total third party revenues	27,438	26,404	72,906	71,336
Corporate Items
Disaggregation of Revenue [Line Items]
Total third party revenues	129	467	925	1,148
Corporate Items \| Technical Services
Disaggregation of Revenue [Line Items]
Total third party revenues	0	0	0	0
Corporate Items \| Field and Emergency Response Services
Disaggregation of Revenue [Line Items]
Total third party revenues	0	0	0	0
Corporate Items \| Industrial Services
Disaggregation of Revenue [Line Items]
Total third party revenues	0	0	0	0
Corporate Items \| Oil, Gas and Lodging Services and Other
Disaggregation of Revenue [Line Items]
Total third party revenues	129	467	925	1,148
Corporate Items \| Safety-Kleen Environmental Services
Disaggregation of Revenue [Line Items]
Total third party revenues	0	0	0	0
Corporate Items \| Safety-Kleen Oil
Disaggregation of Revenue [Line Items]
Total third party revenues	0	0	0	0
Corporate Items \| United States
Disaggregation of Revenue [Line Items]
Total third party revenues	(265)	(66)	531	442
Corporate Items \| Canada
Disaggregation of Revenue [Line Items]
Total third party revenues	$ 394	$ 533	$ 394	$ 706

REVENUES - Contract Balances (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Receivables	$ 641,667	$ 606,952
Contract assets (unbilled receivables)	58,842	54,794
Contract liabilities (deferred revenue)	$ 73,157	$ 61,843

BUSINESS COMBINATIONS - 2018 Acquisitions (Details) - USD ($) $ in Thousands			3 Months Ended	9 Months Ended
	Aug. 31, 2018	Feb. 23, 2018	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Business Acquisition [Line Items]
Goodwill recognized				$ 12,739
Acquired Company Included in Safety-Kleen and Environmental Services Segments
Business Acquisition [Line Items]
Goodwill recognized	$ 12,300
Purchase price	$ 26,700
Veolia Division
Business Acquisition [Line Items]
Purchase price		$ 124,500
Weighted average amortization period (in years)		8 years 2 months 12 days
Pre-tax (loss) income			$ (800)		$ 2,500

BUSINESS COMBINATIONS - Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Mar. 31, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Goodwill	$ 524,581		$ 514,189
Veolia Division
Business Acquisition [Line Items]
Accounts receivable, including unbilled receivables		$ 39,558
Inventories and supplies		1,126
Prepaid expenses and other current assets		828
Property, plant and equipment		72,243
Permits and other intangibles		5,140
Current liabilities		(18,372)
Closure and post-closure liabilities		(354)
Total identifiable net assets		100,169
Goodwill		24,331
Total purchase price		$ 124,500

INVENTORIES AND SUPPLIES (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Inventory Disclosure [Abstract]
Oil and oil products	$ 75,171	$ 70,823
Supplies and drums	112,220	104,609
Solvent and solutions	9,905	10,657
Other	13,531	13,390
Total inventories and supplies	$ 210,827	$ 199,479

PROPERTY, PLANT AND EQUIPMENT - Schedule of Property, Plant and Equipment (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	$ 3,539,804	$ 3,332,595
Less - accumulated depreciation and amortization	1,945,811	1,770,617
Total property, plant and equipment, net	1,593,993	1,561,978
Land
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	134,809	123,734
Asset retirement costs (non-landfill)
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	15,349	15,148
Landfill assets
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	172,453	154,918
Buildings and improvements
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	485,686	440,188
Camp equipment
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	156,786	152,998
Vehicles
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	786,575	721,735
Equipment
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	1,745,483	1,697,490
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	5,373	5,453
Construction in progress
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	$ 37,290	$ 20,931

GOODWILL AND OTHER INTANGIBLE ASSETS - Rollforward of Goodwill (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2019 USD ($)
Goodwill [Roll Forward]
Balance at January 1, 2019	$ 514,189
Increase from current period acquisitions	12,739
Measurement period adjustments from prior period acquisitions	(4,030)
Foreign currency translation	1,683
Balance at September 30, 2019	524,581
Environmental Services
Goodwill [Roll Forward]
Balance at January 1, 2019	207,019
Increase from current period acquisitions	7,514
Measurement period adjustments from prior period acquisitions	(2,675)
Foreign currency translation	780
Balance at September 30, 2019	212,638
Safety-Kleen
Goodwill [Roll Forward]
Balance at January 1, 2019	307,170
Increase from current period acquisitions	5,225
Measurement period adjustments from prior period acquisitions	(1,355)
Foreign currency translation	903
Balance at September 30, 2019	$ 311,943

GOODWILL AND OTHER INTANGIBLE ASSETS - Amortizable Other Intangible Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Schedule of Finite-lived and Indefinite-lived Intangible Assets [Line Items]
Cost	$ 621,097	$ 608,332
Accumulated Amortization	317,994	288,925
Net	303,103	319,407
Total permits and other intangible assets, Cost	743,857	730,800
Total permits and other intangible assets, Net	425,863	441,875
Trademarks and trade names
Schedule of Finite-lived and Indefinite-lived Intangible Assets [Line Items]
Accumulated Amortization	0	0
Trademarks and trade names	122,760	122,468
Permits
Schedule of Finite-lived and Indefinite-lived Intangible Assets [Line Items]
Cost	182,667	177,583
Accumulated Amortization	84,899	79,358
Net	97,768	98,225
Customer and supplier relationships
Schedule of Finite-lived and Indefinite-lived Intangible Assets [Line Items]
Cost	400,498	393,487
Accumulated Amortization	200,766	179,824
Net	199,732	213,663
Other intangible assets
Schedule of Finite-lived and Indefinite-lived Intangible Assets [Line Items]
Cost	37,932	37,262
Accumulated Amortization	32,329	29,743
Net	$ 5,603	$ 7,519

GOODWILL AND OTHER INTANGIBLE ASSETS - Expected Future Amortization (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
2019 (three months)	$ 8,305
2020	31,942
2021	28,667
2022	28,406
2023	24,193
Thereafter	181,590
Net	$ 303,103	$ 319,407

ACCRUED EXPENSES (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Payables and Accruals [Abstract]
Insurance	$ 69,641	$ 70,217
Interest	10,605	3,930
Compensation and benefits	69,369	77,881
Income, real estate, sales and other taxes	40,306	25,670
Other	63,534	55,707
Total accrued expenses	$ 253,455	$ 233,405

CLOSURE AND POST-CLOSURE LIABILITIES (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2019 USD ($)
Changes to post-closure liabilities
Balance at January 1, 2019	$ 69,931
Liabilities assumed in acquisitions	220
New asset retirement obligations	1,644
Accretion	4,213
Changes in estimates recorded to statement of operations	142
Changes in estimates recorded to balance sheet	3,803
Expenditures	(6,105)
Currency translation and other	311
Balance at September 30, 2019	$ 74,159
Credit-adjusted risk-free rate	6.02%
Landfill Retirement Liability
Changes to post-closure liabilities
Balance at January 1, 2019	$ 37,809
Liabilities assumed in acquisitions	0
New asset retirement obligations	1,644
Accretion	2,113
Changes in estimates recorded to statement of operations	0
Changes in estimates recorded to balance sheet	3,803
Expenditures	(4,310)
Currency translation and other	142
Balance at September 30, 2019	41,201
Non-Landfill Retirement Liability
Changes to post-closure liabilities
Balance at January 1, 2019	32,122
Liabilities assumed in acquisitions	220
New asset retirement obligations	0
Accretion	2,100
Changes in estimates recorded to statement of operations	142
Changes in estimates recorded to balance sheet	0
Expenditures	(1,795)
Currency translation and other	169
Balance at September 30, 2019	$ 32,958

REMEDIAL LIABILITIES (Details) $ in Thousands	9 Months Ended
REMEDIAL LIABILITIES (Details) $ in Thousands	Sep. 30, 2019 USD ($)
Accrual for Environmental Loss Contingencies [Roll Forward]
Balance at January 1, 2019	$ 121,017
Accretion	3,411
Changes in estimates recorded to statement of operations	(727)
Expenditures	(6,699)
Currency translation and other	267
Balance at June 30, 2019	117,269
Remedial Liabilities for Landfill Sites
Accrual for Environmental Loss Contingencies [Roll Forward]
Balance at January 1, 2019	1,838
Accretion	66
Changes in estimates recorded to statement of operations	23
Expenditures	(44)
Currency translation and other	0
Balance at June 30, 2019	1,883
Remedial Liabilities for Inactive Sites
Accrual for Environmental Loss Contingencies [Roll Forward]
Balance at January 1, 2019	65,315
Accretion	2,002
Changes in estimates recorded to statement of operations	(100)
Expenditures	(3,658)
Currency translation and other	18
Balance at June 30, 2019	63,577
Remedial Liabilities (Including Superfund) for Non-Landfill Operations
Accrual for Environmental Loss Contingencies [Roll Forward]
Balance at January 1, 2019	53,864
Accretion	1,343
Changes in estimates recorded to statement of operations	(650)
Expenditures	(2,997)
Currency translation and other	249
Balance at June 30, 2019	$ 51,809

FINANCING ARRANGEMENTS - Summary of Financing Arrangements (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Current portion of long-term obligations	$ 7,535	$ 7,535
Long-term obligations, at par	1,574,045	1,579,697
Unamortized debt issuance costs and premium, net	(18,788)	(14,676)
Long-term obligations, at carrying value	1,555,257	1,565,021
Secured debt \| Term Loan Agreement
Debt Instrument [Line Items]
Current portion of long-term obligations	7,535	7,535
Long-term obligations, at par	729,045	734,697
Unsecured debt \| Unsecured senior notes, at 4.875%, due July 15, 2027 (2027 Notes)
Debt Instrument [Line Items]
Long-term obligations, at par	$ 545,000	0
Interest rate (as a percentage)	4.875%
Unsecured debt \| Unsecured senior notes, at 5.125%, due July 15, 2029 (2029 Notes)
Debt Instrument [Line Items]
Long-term obligations, at par	$ 300,000	0
Interest rate (as a percentage)	5.125%
Unsecured debt \| Unsecured senior notes, at 5.125%, due June 1, 2021 (2021 Notes)
Debt Instrument [Line Items]
Long-term obligations, at par	$ 0	$ 845,000
Interest rate (as a percentage)	5.125%

FINANCING ARRANGEMENTS - Narrative (Details) - USD ($)			3 Months Ended			9 Months Ended
FINANCING ARRANGEMENTS - Narrative (Details) - USD ($)	Jul. 17, 2019	Jul. 02, 2019	Sep. 30, 2019	Jun. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Debt Instrument [Line Items]
Available to borrow and outstanding letters of credit			$ 231,100,000			$ 231,100,000		$ 235,400,000
Outstanding letters of credit			147,200,000			147,200,000		130,100,000
Loss on early extinguishment			6,119,000	$ 6,100,000	$ 2,469,000	6,119,000	$ 2,469,000
Debt fair value			$ 1,600,000,000			$ 1,600,000,000		1,600,000,000
Effective interest rate percentage			4.67%			4.67%
Derivative liability			$ 25,300,000			$ 25,300,000		8,800,000
Term Loan Agreement
Debt Instrument [Line Items]
Debt outstanding			736,600,000			736,600,000
Term Loans with Interest Rate Swap Agreements
Debt Instrument [Line Items]
Debt outstanding			$ 350,000,000.0			$ 350,000,000.0
Unsecured debt
Debt Instrument [Line Items]
Redemption percentage of principal amount						100.00%
Redemption percentage (up to)						35.00%
Unsecured debt \| 2021 Notes
Debt Instrument [Line Items]
Purchased notes	$ 144,000,000.0	$ 701,000,000.0
Repayments of debt		706,200,000
Accrued interest	$ 900,000	3,100,000
Interest rate (as a percentage)			5.125%			5.125%
Unsecured debt \| Unsecured senior notes, at 4.875%, due July 15, 2027 (2027 Notes)
Debt Instrument [Line Items]
Debt aggregate principal amount		545,000,000.0
Redemption percentage of principal amount						104.875%
Interest rate (as a percentage)			4.875%			4.875%
Unsecured debt \| Unsecured senior notes, at 5.125%, due July 15, 2029 (2029 Notes)
Debt Instrument [Line Items]
Debt aggregate principal amount		$ 300,000,000.0
Redemption percentage of principal amount						105.125%
Interest rate (as a percentage)			5.125%			5.125%
Revolving Credit Facility \| Line of Credit
Debt Instrument [Line Items]
Revolving credit facility maximum borrowing capacity			$ 400,000,000.0			$ 400,000,000.0		400,000,000.0
Debt outstanding			0			$ 0		$ 0
Eurodollar
Debt Instrument [Line Items]
Interest rate percentage						1.75%
Interest Rate Swap
Debt Instrument [Line Items]
Notional amount of interest rate swap agreements			$ 350,000,000.0			$ 350,000,000.0
Interest rate percentage						2.92%

FINANCING ARRANGEMENTS - Summary of Redemption Prices (Details) - Unsecured debt	9 Months Ended
	Sep. 30, 2019
Debt Instrument, Redemption [Line Items]
Redemption percentage of principal amount	100.00%
Unsecured senior notes, at 4.875%, due July 15, 2027 (2027 Notes)
Debt Instrument, Redemption [Line Items]
Redemption percentage of principal amount	104.875%
Unsecured senior notes, at 4.875%, due July 15, 2027 (2027 Notes) \| Debt Instrument, Redemption, Period One
Debt Instrument, Redemption [Line Items]
Redemption percentage of principal amount	102.438%
Unsecured senior notes, at 4.875%, due July 15, 2027 (2027 Notes) \| Debt Instrument, Redemption, Period Two
Debt Instrument, Redemption [Line Items]
Redemption percentage of principal amount	101.219%
Unsecured senior notes, at 4.875%, due July 15, 2027 (2027 Notes) \| Debt Instrument, Redemption, Period Three
Debt Instrument, Redemption [Line Items]
Redemption percentage of principal amount	100.00%
Unsecured senior notes, at 5.125%, due July 15, 2029 (2029 Notes)
Debt Instrument, Redemption [Line Items]
Redemption percentage of principal amount	105.125%
Unsecured senior notes, at 5.125%, due July 15, 2029 (2029 Notes) \| Debt Instrument, Redemption, Period One
Debt Instrument, Redemption [Line Items]
Redemption percentage of principal amount	102.563%
Unsecured senior notes, at 5.125%, due July 15, 2029 (2029 Notes) \| Debt Instrument, Redemption, Period Two
Debt Instrument, Redemption [Line Items]
Redemption percentage of principal amount	101.281%
Unsecured senior notes, at 5.125%, due July 15, 2029 (2029 Notes) \| Debt Instrument, Redemption, Period Three
Debt Instrument, Redemption [Line Items]
Redemption percentage of principal amount	100.00%

INCOME TAXES (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
INCOME TAXES (Details) - USD ($) $ in Millions	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Effective income tax rate	32.80%	26.60%	35.10%	36.30%
Unrecognized tax benefits	$ 4.6		$ 4.6		$ 3.2
Interest on unrecognized tax benefits	1.2		1.2		$ 0.8
Reduction in unrecognized tax benefits from expiring statue of limitations within next 12 months	$ 1.0		$ 1.0

EARNINGS PER SHARE - Computation of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018
Numerator for basic and diluted earnings per share:
Net income	$ 36,369	$ 36,244	$ 976	$ 31,089	$ 30,747	$ (12,631)	$ 73,589	$ 49,205
Denominator:
Basic shares outstanding (in shares)	55,850			56,059			55,858	56,222
Dilutive effect of outstanding stock awards (in shares)	315			232			251	138
Dilutive shares outstanding (in shares)	56,165			56,291			56,109	56,360
Basic income (in USD per share)	$ 0.65			$ 0.55			$ 1.32	$ 0.88
Diluted income (in USD per share)	$ 0.65			$ 0.55			$ 1.31	$ 0.87

- Definition

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(19))
-URI http://asc.fasb.org/extlink&oid=116637232&loc=SL114874131-224263

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=117326831&loc=d3e1337-109256

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 55
-Paragraph 52
-URI http://asc.fasb.org/extlink&oid=117327953&loc=d3e4984-109258

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(21))
-URI http://asc.fasb.org/extlink&oid=116634182&loc=SL114868664-224227

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22694-107794

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=117326831&loc=d3e1252-109256

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(23))
-URI http://asc.fasb.org/extlink&oid=116637391&loc=SL114874048-224260

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 60B
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=117326831&loc=SL5780133-109256

+ Details

- Definition

The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 55
-Paragraph 52
-URI http://asc.fasb.org/extlink&oid=117327953&loc=d3e4984-109258

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=117326831&loc=d3e1252-109256

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(23))
-URI http://asc.fasb.org/extlink&oid=116637391&loc=SL114874048-224260

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22694-107794

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=117326831&loc=d3e1337-109256

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(21))
-URI http://asc.fasb.org/extlink&oid=116634182&loc=SL114868664-224227

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 60B
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=117326831&loc=SL5780133-109256

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(19))
-URI http://asc.fasb.org/extlink&oid=116637232&loc=SL114874131-224263

+ Details

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

ACCUMULATED OTHER COMPREHENSIVE LOSS - Changes in Accumulated Other Comprehensive Loss by Component (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018
Components of Other Accumulated Income, Net of Tax [Roll Forward]
Balance beginning of period	$ 1,209,467	$ 1,171,965	$ 1,169,756	$ 1,161,048	$ 1,145,526	$ 1,188,202	$ 1,169,756	$ 1,188,202
Other comprehensive income (loss) before tax effects							(1,960)
Tax impact related to items in other comprehensive income (loss)							(60)
Amounts reclassified out of accumulated other comprehensive loss							1,701
Other comprehensive (loss) income	(9,419)	5,076	4,024	8,590	(4,942)	(16,746)	(319)	(13,098)
Balance ending of period	1,235,795	1,209,467	1,171,965	1,197,324	1,161,048	1,145,526	1,235,795	1,197,324
Foreign Currency Translation
Components of Other Accumulated Income, Net of Tax [Roll Forward]
Balance beginning of period			(212,925)				(212,925)
Other comprehensive income (loss) before tax effects							15,960
Tax impact related to items in other comprehensive income (loss)							0
Amounts reclassified out of accumulated other comprehensive loss							0
Other comprehensive (loss) income							15,960
Balance ending of period	(196,965)						(196,965)
Unrealized (Losses) Gains on Available-For-Sale Securities
Components of Other Accumulated Income, Net of Tax [Roll Forward]
Balance beginning of period			(69)				(69)
Other comprehensive income (loss) before tax effects							(24)
Tax impact related to items in other comprehensive income (loss)							(60)
Amounts reclassified out of accumulated other comprehensive loss							332
Other comprehensive (loss) income							248
Balance ending of period	179						179
Unrealized Losses on Interest Rate Hedge
Components of Other Accumulated Income, Net of Tax [Roll Forward]
Balance beginning of period			(8,773)				(8,773)
Other comprehensive income (loss) before tax effects							(17,896)
Tax impact related to items in other comprehensive income (loss)							0
Amounts reclassified out of accumulated other comprehensive loss							1,369
Other comprehensive (loss) income							(16,527)
Balance ending of period	(25,300)						(25,300)
Unfunded Pension Liability
Components of Other Accumulated Income, Net of Tax [Roll Forward]
Balance beginning of period			(1,604)				(1,604)
Other comprehensive income (loss) before tax effects							0
Tax impact related to items in other comprehensive income (loss)							0
Amounts reclassified out of accumulated other comprehensive loss							0
Other comprehensive (loss) income							0
Balance ending of period	(1,604)						(1,604)
Total
Components of Other Accumulated Income, Net of Tax [Roll Forward]
Balance beginning of period	(214,271)	(219,347)	(223,371)	(194,095)	(189,153)	(172,407)	(223,371)	(172,407)
Other comprehensive (loss) income	(9,419)	5,076	4,024	8,590	(4,942)	(16,746)
Balance ending of period	$ (223,690)	$ (214,271)	$ (219,347)	$ (185,505)	$ (194,095)	$ (189,153)	$ (223,690)	$ (185,505)

ACCUMULATED OTHER COMPREHENSIVE LOSS - Reclassified Out of Accumulated Other Comprehensive Loss (Details) - Reclassification out of Accumulated Other Comprehensive Income - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income		$ 0		$ 0
Unrealized loss on interest rate hedge
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense, net of interest income	$ (614,000)		$ (1,369,000)
Unrealized loss on available-for-sale securities
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other (expense) income, net	$ 0		$ (332,000)

- Definition

The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 1A
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118930883&loc=SL7669619-108580

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=109239629&loc=SL4573702-111684

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 1B
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118930883&loc=SL7669625-108580

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=109239629&loc=SL4573702-111684

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-URI http://asc.fasb.org/extlink&oid=115929826&loc=d3e8736-108599

Reference 6: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 55
-Paragraph 4J
-URI http://asc.fasb.org/extlink&oid=116874947&loc=SL4591551-111686

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3000-108585

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 45
-Paragraph 19
-URI http://asc.fasb.org/extlink&oid=108774443&loc=SL4569616-111683

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=115929826&loc=d3e8933-108599

Reference 10: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 55
-Paragraph 4K
-URI http://asc.fasb.org/extlink&oid=116874947&loc=SL4591552-111686

+ Details

STOCK-BASED COMPENSATION - Restricted Stock (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Restricted stock awards
Number of Shares
Beginning balance (in shares)			657,240
Granted (in shares)			168,261
Vested (in shares)			(230,214)
Forfeited (in shares)			(53,458)
Ending balance (in shares)	541,829		541,829
Weighted Average Grant-Date Fair Value
Beginning of period (in USD per share)			$ 54.65
Granted (in USD per share)			68.39
Vested (in USD per share)			53.97
Forfeited (in USD per share)			55.27
End of period (in USD per share)	$ 59.14		$ 59.14
Unrecognized compensation cost	$ 24.0		$ 24.0
Period for recognition (in years)			2 years 9 months
Fair value restricted stock	$ 4.2	$ 1.1	$ 15.3	$ 9.4
Minimum
Weighted Average Grant-Date Fair Value
Vesting period (in years)			3 years
Maximum
Weighted Average Grant-Date Fair Value
Vesting period (in years)			5 years

STOCK-BASED COMPENSATION - Performance Stock Awards (Details) - Performance stock awards - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Number of Shares
Beginning balance (in shares)			213,490
Granted (in shares)			121,075
Vested (in shares)	0	0	(51,996)
Forfeited (in shares)			(27,308)
Ending balance (in shares)	255,261		255,261
Weighted Average Grant-Date Fair Value
Beginning of period (in USD per share)			$ 55.71
Granted (in USD per share)			70.53
Vested (in USD per share)			55.77
Forfeited (in USD per share)			56.53
End of period (in USD per share)	$ 62.64		$ 62.64
Unrecognized compensation cost	$ 4.5		$ 4.5
Fair value restricted stock			$ 2.9	$ 0.5

STOCK-BASED COMPENSATION - Common Stock Repurchases (Details) - USD ($) shares in Millions	3 Months Ended						9 Months Ended		67 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019
Share-based Payment Arrangement [Abstract]
Authorized repurchase amount	$ 600,000,000.0						$ 600,000,000.0		$ 600,000,000.0
Repurchases of common stock (in shares)	0.1			0.1			0.2	0.6	5.8
Repurchases of common stock	$ 5,118,000	$ 4,948,000	$ 6,324,000	$ 7,099,000	$ 12,218,000	$ 14,264,000	$ 16,400,000	$ 33,600,000	$ 310,300,000
Remaining available repurchase amount	$ 289,700,000						$ 289,700,000		$ 289,700,000

COMMITMENTS AND CONTINGENCIES (Details) $ in Millions	9 Months Ended	12 Months Ended
COMMITMENTS AND CONTINGENCIES (Details) $ in Millions	Sep. 30, 2019 USD ($) site proceeding claim	Dec. 31, 2012 CAD ($)	Dec. 31, 1999 municipality	Dec. 31, 1968 permit	Dec. 31, 2018 USD ($) proceeding
Contingencies [Line Items]
Recorded reserves for actual or probable liabilities \| $	$ 24,000,000.0				$ 25,400,000
Number of proceedings as defendant \| proceeding	59
Number of product liability claims settled or dismissed \| claim	21
Legal and Administrative Proceedings
Contingencies [Line Items]
Recorded reserves for actual or probable liabilities \| $	$ 18,100,000				17,900,000
Possible increase in legal and administrative proceedings \| $	$ 1,800,000				1,800,000
Ville Mercier
Contingencies [Line Items]
Number of permits issued by government, for dumping organic liquid \| permit				2
Number of neighboring municipalities filing separate legal proceedings against the Mercier Subsidiary and the Government of Quebec \| municipality			3
General damages sought \| $		$ 2.9
Punitive damages sought \| $		$ 10.0
Superfund Proceedings
Contingencies [Line Items]
Number of sites owned by third party excluded from cleanup or related liabilities	129
Number of sites owned by the entity subject to proceedings under federal or state superfund laws	5
Number of sites owned by third parties	124
Number of sites for which environmental remediation expense is settled	31
Third party sites requiring expenditure on remediation	16
Number of sites not currently requiring expenditures on remediation	77
Number of sites which potential liability could exceed $100,000	10
Notices received from owners of third parties sites seeking indemnifications from the company	17
Superfund Proceedings \| Minimum
Contingencies [Line Items]
Minimum potential liability \| $	$ 100,000
ChemWaste
Contingencies [Line Items]
Indemnification agreement with third party sites	11
Kleen Performance Products
Contingencies [Line Items]
Notices received from owners of third parties sites seeking indemnifications from the company	6
Federal and State Enforcement Actions
Contingencies [Line Items]
Recorded reserves for actual or probable liabilities \| $	$ 5,900,000				$ 7,500,000
Number of proceedings as defendant \| proceeding	10				10
Federal and State Enforcement Actions \| Minimum
Contingencies [Line Items]
Minimum potential liability \| $	$ 100,000				$ 100,000

LEASES - Lease Expense (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
LEASES - Lease Expense (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2019
Leases [Abstract]
Operating lease cost	$ 14,056	$ 41,406
Finance lease cost:
Amortization of ROU asset	245	735
Interest on lease liability	367	979
Total finance lease cost	612	1,714
Short-term lease cost	22,258	60,295
Variable lease cost	2,139	6,372
Total lease cost	$ 39,065	$ 109,787

LEASES - Supplemental Finance Lease Balance Sheet information (Details) $ in Thousands	Sep. 30, 2019 USD ($)
ROU assets:
Operating leases	$ 164,302
Finance leases (included in property, plant and equipment, net)	30,276
Current portion of lease liabilities:
Operating leases	41,364
Finance leases (included in accrued expenses)	440
Long-term portion of lease liabilities:
Operating leases	122,668
Finance leases (included in deferred taxes, unrecognized tax benefits and other long-term liabilities)	$ 32,228

LEASES - Leases Other Information (Details)	Sep. 30, 2019
Weighted Average Remaining Lease Term (years)
Operating leases (in years)	5 years 1 month 6 days
Finance leases (in years)	22 years 9 months 18 days
Weighted Average Discount Rate
Operating leases (as a percentage)	5.33%
Finance leases (as a percentage)	4.99%

LEASES - Schedule of Future Lease Payments (Details) $ in Thousands	Sep. 30, 2019 USD ($)
Operating Leases
2019 (three months)	$ 13,856
2020	48,577
2021	36,506
2022	28,814
2023	20,793
2024	13,930
Thereafter	27,697
Total future lease payments	190,173
Amount representing interest	(26,141)
Total lease liabilities	164,032
Finance Leases
2019 (three months)	535
2020	2,194
2021	2,244
2022	2,297
2023	2,356
2024	2,411
Thereafter	51,151
Total future lease payments	63,188
Amount representing interest	(30,520)
Total lease liabilities	$ 32,668

LEASES - Summary of Future Minimum Payments Under Operating Leases (Details) $ in Thousands	Dec. 31, 2018 USD ($)
Leases [Abstract]
2019	$ 56,480
2020	45,467
2021	33,564
2022	24,509
2023	15,253
Thereafter	35,778
Total minimum lease payments	$ 211,051

SEGMENT REPORTING - Third Party Revenues to Direct Revenues (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Segment Reporting Information [Line Items]
Total revenues	$ 891,668	$ 843,181	$ 2,541,185	$ 2,442,099
Corporate Items
Segment Reporting Information [Line Items]
Total revenues	129	467	925	1,148
Corporate Items, net
Segment Reporting Information [Line Items]
Total revenues	(1,478)	(1,151)	(3,316)	(2,574)
Operating and Corporate non-segment
Segment Reporting Information [Line Items]
Total revenues	(1,349)	(684)	(2,391)	(1,426)
Environmental Services
Segment Reporting Information [Line Items]
Total revenues	586,872	542,980	1,658,970	1,570,241
Environmental Services \| Operating segments
Segment Reporting Information [Line Items]
Total revenues	550,122	508,813	1,550,114	1,468,417
Environmental Services \| Intersegment revenues, net
Segment Reporting Information [Line Items]
Total revenues	35,274	33,022	105,555	99,278
Environmental Services \| Corporate Items, net
Segment Reporting Information [Line Items]
Total revenues	1,476	1,145	3,301	2,546
Safety-Kleen
Segment Reporting Information [Line Items]
Total revenues	306,145	300,885	884,606	873,284
Safety-Kleen \| Operating segments
Segment Reporting Information [Line Items]
Total revenues	341,417	333,901	990,146	972,534
Safety-Kleen \| Intersegment revenues, net
Segment Reporting Information [Line Items]
Total revenues	(35,274)	(33,022)	(105,555)	(99,278)
Safety-Kleen \| Corporate Items, net
Segment Reporting Information [Line Items]
Total revenues	$ 2	$ 6	$ 15	$ 28

SEGMENT REPORTING - Adjusted EBITDA Information (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Segment Reporting Information [Line Items]
Adjusted EBITDA	$ 156,613		$ 141,277	$ 408,101	$ 369,103
Reconciliation to Consolidated Statements of Operations:
Accretion of environmental liabilities	2,490		2,450	7,624	7,328
Depreciation and amortization	73,756		73,082	223,328	220,686
Income from operations	80,367		65,745	177,149	141,089
Other expense (income), net	427		996	(1,992)	449
Loss on early extinguishment of debt	6,119	$ 6,100	2,469	6,119	2,469
Interest expense, net of interest income	19,702		19,916	59,681	60,955
Income before provision for income taxes	54,119		42,364	113,341	77,216
Operating segments \| Environmental Services
Segment Reporting Information [Line Items]
Adjusted EBITDA	121,658		102,419	329,036	273,035
Operating segments \| Safety-Kleen
Segment Reporting Information [Line Items]
Adjusted EBITDA	81,326		79,502	215,578	214,455
Corporate Items
Segment Reporting Information [Line Items]
Adjusted EBITDA	$ (46,371)		$ (40,644)	$ (136,513)	$ (118,387)

SEGMENT REPORTING - Assets by Reportable Segment (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Property, plant and equipment, net	$ 1,593,993	$ 1,561,978
Goodwill	524,581	514,189
Permits and other intangibles, net	425,863	441,875
Intangible Assets, Net (Including Goodwill)	950,444	956,064
Total assets	4,021,862	3,738,321
Environmental Services
Segment Reporting Information [Line Items]
Goodwill	212,638	207,019
Safety-Kleen
Segment Reporting Information [Line Items]
Goodwill	311,943	307,170
Operating segments \| Environmental Services
Segment Reporting Information [Line Items]
Property, plant and equipment, net	946,367	951,867
Goodwill	212,638	207,019
Permits and other intangibles, net	91,292	93,313
Intangible Assets, Net (Including Goodwill)	303,930	300,332
Total assets	1,750,343	1,640,706
Operating segments \| Safety-Kleen
Segment Reporting Information [Line Items]
Property, plant and equipment, net	556,247	553,220
Goodwill	311,943	307,170
Permits and other intangibles, net	334,571	348,562
Intangible Assets, Net (Including Goodwill)	646,514	655,732
Total assets	1,501,838	1,431,381
Corporate Items
Segment Reporting Information [Line Items]
Property, plant and equipment, net	91,379	56,891
Total assets	$ 769,681	$ 666,234

UNAUDITED CONSOLIDATED STATEMENTS OF OPERATIONS (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Statement [Abstract]
Interest income	$ 1,152	$ 736	$ 2,981	$ 2,086

BASIS OF PRESENTATION	9 Months Ended
BASIS OF PRESENTATION	Sep. 30, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
BASIS OF PRESENTATION	BASIS OF PRESENTATION The accompanying consolidated interim financial statements are unaudited and include the accounts of Clean Harbors, Inc. and its subsidiaries (collectively, “Clean Harbors,” the “Company” or "we") and have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”) and, in the opinion of management, include all adjustments which are of a normal recurring nature, necessary for a fair presentation of the financial position, results of operations and cash flows for the periods presented. Management has made estimates and assumptions affecting the amounts reported in the Company's consolidated interim financial statements and accompanying footnotes; actual results could differ from those estimates and judgments. The results for interim periods are not necessarily indicative of results for the entire year or any other interim periods. The financial statements presented herein should be read in conjunction with the financial statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2018.

PROPERTY, PLANT AND EQUIPMENT - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Property, Plant and Equipment [Abstract]
Interest costs capitalized adjustment	$ 0.1	$ 0.1	$ 0.3	$ 0.5
Depreciation inclusive of amortization	$ 65.3	$ 64.9	$ 196.7	$ 194.7

EARNINGS PER SHARE - Narrative (Details) - shares	3 Months Ended		9 Months Ended
EARNINGS PER SHARE - Narrative (Details) - shares	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Performance stock awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from computation of earning per share (in shares)	147,075	304,644	147,075	304,644
Restricted stock awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from computation of earning per share (in shares)	3,567	6,565	14,223	91,743

LEASES - Narrative (Details) $ in Millions	12 Months Ended
LEASES - Narrative (Details) $ in Millions	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Sep. 30, 2019 Leases
Leases [Abstract]
Number of finance leases \| Leases				2
Rent expense \| $	$ 141.1	$ 125.4	$ 121.9

UNAUDITED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Parenthetical) - $ / shares	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018
Statement of Stockholders' Equity [Abstract]
Common stock, par value (in USD per share)	$ 0.01	$ 0.01	$ 0.01

INCOME TAXES	9 Months Ended
INCOME TAXES	Sep. 30, 2019
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXES The Company records a tax provision or benefit on an interim basis using an estimated annual effective tax rate. This rate is applied to the current period ordinary income or loss to determine the income tax provision or benefit allocated to the interim period. Losses from jurisdictions for which no benefit can be recognized and the income tax effects of unusual or infrequent items are excluded from the estimated annual effective tax rate and are recognized in the impacted interim period. The estimated annual effective tax rate may be significantly impacted by projected earnings mix by tax jurisdiction. Adjustments to the estimated annual effective income tax rate are recognized in the period when such estimates are revised. The Company’s effective tax rate for the three and nine months ended September 30, 2019 was 32.8% and 35.1%, respectively, compared to 26.6% and 36.3% for the comparable periods in 2018. As of September 30, 2019 and December 31, 2018, the Company had recorded $4.6 million and $3.2 million, respectively, of liabilities for unrecognized tax benefits and $1.2 million and $0.8 million of interest, respectively. The Company's tax years 2014-2016 are currently under audit by the Internal Revenue Service (“IRS”). While the examination has recently commenced and ultimate outcomes are unknown, the Company believes the examination will not result in material adjustments to previously filed returns. Due to expiring statute of limitation periods, the Company believes that total unrecognized tax benefits will decrease by $1.0 million within the next 12 months.

REVENUES - Narrative (Details)	Sep. 30, 2019
Minimum
Business Acquisition [Line Items]
Amortization period (in days)	49 days
Maximum
Business Acquisition [Line Items]
Amortization period (in days)	98 days

BUSINESS COMBINATIONS - 2019 Acquisitions (Details) - USD ($) $ in Thousands			9 Months Ended
	May 31, 2019	Mar. 01, 2019	Sep. 30, 2019
Business Acquisition [Line Items]
Goodwill recognized			$ 12,739
Private Held Company
Business Acquisition [Line Items]
Purchase price	$ 14,900	$ 10,400
Goodwill recognized	$ 7,500	$ 5,200

SEGMENT REPORTING - Narrative (Details)	9 Months Ended
SEGMENT REPORTING - Narrative (Details)	Sep. 30, 2019 segment
Segment Reporting [Abstract]
Number of operating segments	2

SEGMENT REPORTING - Total Assets by Geographical Area (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Revenues from External Customers and Long-Lived Assets [Line Items]
Total assets	$ 4,021,862	$ 3,738,321
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Total assets	3,339,899	3,090,311
Canada
Revenues from External Customers and Long-Lived Assets [Line Items]
Total assets	$ 681,963	$ 648,010