DOCUMENT AND ENTITY INFORMATION - shares	9 Months Ended
DOCUMENT AND ENTITY INFORMATION - shares	Sep. 30, 2017	Oct. 27, 2017
Document and Entity Information [Abstract]
Entity Registrant Name	CLEAN HARBORS INC
Entity Central Index Key	0000822818
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Sep. 30, 2017
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Common Stock, Shares Outstanding		56,933,498

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 361,658	$ 306,997
Accounts receivable, net of allowances aggregating $28,537 and $29,249, respectively	531,696	496,226
Unbilled accounts receivable	40,933	36,190
Deferred costs	20,237	18,914
Inventories and supplies	173,097	178,428
Prepaid expenses and other current assets	32,637	56,116
Total current assets	1,160,258	1,092,871
Property, plant and equipment, net	1,611,971	1,611,827
Other assets:
Goodwill	478,728	465,154
Permits and other intangibles, net	477,639	498,721
Other	19,757	13,347
Total other assets	976,124	977,222
Total assets	3,748,353	3,681,920
Current liabilities:
Current portion of long-term obligations	4,000	0
Accounts payable	223,599	229,534
Deferred revenue	69,236	64,397
Accrued expenses	213,189	190,721
Current portion of closure, post-closure and remedial liabilities	19,516	20,016
Total current liabilities	529,540	504,668
Other liabilities:
Closure and post-closure liabilities, less current portion of $4,077 and $6,220, respectively	55,762	52,111
Remedial liabilities, less current portion of $15,439 and $13,796, respectively	110,074	114,211
Long-term obligations, less current portion	1,625,971	1,633,272
Deferred taxes, unrecognized tax benefits and other long-term liabilities	298,659	293,417
Total other liabilities	2,090,466	2,093,011
Commitments and contingent liabilities (See Note 15)
Stockholders’ equity:
Authorized 80,000,000; shares issued and outstanding 56,926,549 and 57,297,978 shares, respectively	569	573
Shares held under employee participation plan	0	(469)
Additional paid-in capital	708,358	725,670
Accumulated other comprehensive loss	(169,468)	(214,326)
Accumulated earnings	588,888	572,793
Total stockholders’ equity	1,128,347	1,084,241
Total liabilities and stockholders’ equity	$ 3,748,353	$ 3,681,920

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Account receivable, allowances aggregating	$ 28,537	$ 29,249
Closure and post-closure liabilities, current portion	4,077	6,220
Remedial liabilities, current portion	$ 15,439	$ 13,796
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)	56,926,549	57,297,978
Common stock, outstanding shares (in shares)	56,926,549	57,297,978

UNAUDITED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Revenues:
Service revenues	$ 612,352	$ 594,225	$ 1,783,506	$ 1,709,018
Product revenues	143,494	135,295	414,069	354,095
Total revenues	755,846	729,520	2,197,575	2,063,113
Cost of revenues (exclusive of items shown separately below)
Service revenues	412,369	385,542	1,215,812	1,148,212
Product revenues	107,226	106,373	320,171	287,984
Total cost of revenues	519,595	491,915	1,535,983	1,436,196
Selling, general and administrative expenses	113,252	110,954	337,767	322,501
Accretion of environmental liabilities	2,347	2,476	7,053	7,529
Depreciation and amortization	72,989	73,360	216,932	215,655
Goodwill impairment charge	0	34,013	0	34,013
Income from operations	47,663	16,802	99,840	47,219
Other expense	(432)	(198)	(2,814)	(737)
Loss on early extinguishment of debt	(1,846)	0	(7,891)	0
(Loss) gain on sale of businesses	(77)	16,431	31,645	16,431
Interest expense, net of interest income of $573, $196, $1,098 and $571, respectively	(20,675)	(21,565)	(65,743)	(62,192)
Income (loss) before (benefit) provision for income taxes	24,633	11,470	55,037	721
Provision for income taxes	12,575	21,725	38,492	27,881
Net income (loss)	$ 12,058	$ (10,255)	$ 16,545	$ (27,160)
Earnings (loss) per share:
Basic (in USD per share)	$ 0.21	$ (0.18)	$ 0.29	$ (0.47)
Diluted (in USD per share)	$ 0.21	$ (0.18)	$ 0.29	$ (0.47)
Shares used to compute loss per share - Basic (in shares)	57,033	57,487	57,149	57,575
Shares used to compute loss per share - Diluted (in shares)	57,195	57,487	57,280	57,575

UNAUDITED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 12,058	$ (10,255)	$ 16,545	$ (27,160)
Other comprehensive income (loss):
Unrealized gains (losses) on available-for-sale securities (net of tax (benefit) of $7, $(238), $129 and $(238), respectively)	11	(164)	170	(358)
Reclassification adjustment for losses on available-for-sale securities included in net income (loss) (net of taxes of $0, $0, $79 and $0, respectively)	0	0	143	0
Foreign currency translation adjustments	23,698	(1,147)	44,545	43,706
Other comprehensive income (loss)	23,709	(1,311)	44,858	43,348
Comprehensive income (loss)	$ 35,767	$ (11,566)	$ 61,403	$ 16,188

UNAUDITED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Statement of Comprehensive Income [Abstract]
Unrealized gains (losses) on available-for-sale securities, taxes	$ 7	$ (238)	$ 129	$ (238)
Reclassification adjustment for gains on available-for-sale securities included in net (loss) income taxes	$ 0	$ 0	$ 79	$ 0

UNAUDITED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Cash flows from operating activities:
Net income (loss)	$ 16,545	$ (27,160)
Adjustments to reconcile net income (loss) to net cash from operating activities:
Depreciation and amortization	216,932	215,655
Goodwill impairment charge	0	34,013
Allowance for doubtful accounts	5,635	6,203
Amortization of deferred financing costs and debt discount	2,562	2,685
Accretion of environmental liabilities	7,053	7,529
Changes in environmental liability estimates	(312)	(349)
Deferred income taxes	184	(28,826)
Stock-based compensation	9,212	7,735
Excess tax benefit of stock-based compensation	0	(21)
Net tax deficiency on stock based awards	0	(642)
Other expense	2,814	1,247
Gain on sale of business	(31,645)	(16,431)
Loss on early extinguishment of debt	7,891	0
Environmental expenditures	(10,078)	(9,374)
Changes in assets and liabilities, net of acquisitions
Accounts receivable and unbilled accounts receivable	(38,122)	(32,944)
Inventories and supplies	(4,975)	(13,722)
Other current assets	18,305	5,619
Accounts payable	(7,085)	(11,951)
Other current and long-term liabilities	26,553	39,561
Net cash from operating activities	221,469	178,827
Cash flows used in investing activities:
Additions to property, plant and equipment	(127,736)	(175,348)
Proceeds from sale and disposal of fixed assets	5,375	3,982
Acquisitions, net of cash acquired	(44,432)	(207,089)
Proceeds on sale of business	46,339	47,134
Additions to intangible assets, including costs to obtain or renew permits	(1,348)	(1,920)
Purchases of available-for-sale securities	0	(598)
Proceeds from sale of investments	376	0
Net cash used in investing activities	(121,426)	(333,839)
Cash flows from financing activities:
Change in uncashed checks	(8,657)	(7,084)
Proceeds from exercise of stock options	46	230
Issuance of restricted shares, net of shares remitted	(2,321)	(2,500)
Repurchases of common stock	(24,465)	(15,869)
Deferred financing costs paid	(5,746)	(2,614)
Excess tax benefit of stock-based compensation	0	21
Premiums paid on early extinguishment of debt	(6,028)	0
Principal payment on debt	(401,000)	0
Issuance of senior secured notes, net of discount	399,000	0
Issuance of senior unsecured notes, including premium	0	250,625
Net cash (used in) from financing activities	(49,171)	222,809
Effect of exchange rate change on cash	3,789	5,352
Increase in cash and cash equivalents	54,661	73,149
Cash and cash equivalents, beginning of period	306,997	184,708
Cash and cash equivalents, end of period	361,658	257,857
Cash payments for interest and income taxes:
Interest paid	67,550	66,261
Income taxes paid	14,321	27,196
Non-cash investing and financing activities:
Accrual for repurchased shares	0	479
Property, plant and equipment accrued	14,509	18,181
Transfer of inventory to property, plant and equipment	12,641	0
Receivable for estimated purchase price adjustment	$ 0	$ 1,910

UNAUDITED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - 9 months ended Sep. 30, 2017 - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Shares Held Under Employee Participation Plan	Additional Paid-in Capital	Accumulated Other Comprehensive Loss	Accumulated Earnings
Balance at beginning of period at Dec. 31, 2016	$ 1,084,241	$ 573	$ (469)	$ 725,670	$ (214,326)	$ 572,793
Balance beginning of period (in shares) at Dec. 31, 2016		57,298
Increase (Decrease) in Stockholders' Equity
Net income (loss)	16,545					16,545
Other comprehensive income	44,858				44,858
Stock-based compensation	9,212			9,212
Issuance of restricted shares, net of shares remitted	(2,321)	$ 1		(2,322)
Issuance of restricted shares, net of shares remitted (in shares)		100
Shares held under employee participation plan	0	$ 0	469	(469)
Shares held under employee participation plan (in shares)		(25)
Repurchases of common stock	$ (24,465)	$ (5)		(24,460)
Repurchases of common stock (in shares)	(500)	(448)
Exercise of stock options	$ 46			46
Exercise of stock options (in shares)		2
Balance at end of period at Sep. 30, 2017	1,128,347	$ 569	$ 0	708,358	$ (169,468)	588,888
Balance ending of period (in shares) at Sep. 30, 2017		56,927
Increase (Decrease) in Stockholders' Equity
Cumulative effect of change in accounting for stock based compensation	$ 231			$ 681		$ (450)

BASIS OF PRESENTATION	9 Months Ended
BASIS OF PRESENTATION	Sep. 30, 2017
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 connection with the financial statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2016, which includes the audited consolidated balance sheet as of December 31, 2016 from which the one presented herein was derived.

SIGNIFICANT ACCOUNTING POLICIES	9 Months Ended
SIGNIFICANT ACCOUNTING POLICIES	Sep. 30, 2017
Accounting Policies [Abstract]
SIGNIFICANT ACCOUNTING POLICIES	SIGNIFICANT ACCOUNTING POLICIES The Company's significant accounting policies are described in Note 2, "Significant Accounting Policies," in the Company's Annual Report on Form 10-K for the year ended December 31, 2016. There have been no material changes in these policies or their application. Reclassifications As disclosed in the Company's Annual Report on Form 10-K for the year ended December 31, 2016, in the fourth quarter of 2016 the Company changed the manner in which it manages its business, makes operating decisions and assesses the Company's performance. The Company's operations are now managed in six operating segments: Technical Services, Industrial Services, Field Services, Safety-Kleen, Oil and Gas Field Services and Lodging Services. For purposes of segment disclosure the Industrial Services and Field Services operating segments have been aggregated into a single reportable segment based upon their similar economic and other characteristics, and the Oil and Gas Field Services and Lodging Services operating segments have been combined as they do not meet the quantitative thresholds for separate presentation. The amounts presented for the three and nine months ended September 30, 2016 have been recast to reflect the impact of such changes. These reclassifications and adjustments had no effect on consolidated statements of operations, consolidated statements of comprehensive income (loss), consolidated statements of cash flows or consolidated statements of stockholders' equity for any of the periods presented. Recent Accounting Pronouncements Standards implemented In July 2015, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2015-11, Inventory (Topic 330). The amendment provides guidance regarding the measurement of inventory. Entities should measure inventory within the scope of this update at the lower of cost and net realizable value. The adoption of ASU 2015-11 was applied prospectively and as of January 1, 2017 did not have an impact on the Company's consolidated financial statements. In March 2016, the FASB issued ASU 2016-09, Compensation-Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting. The amendment simplifies several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities and classification on the statement of cash flows. Stock-based compensation excess tax benefits or deficiencies are now reflected in the Consolidated Statements of Operations as a component of the provision for income taxes, whereas they previously were recognized in equity. Additionally, the Consolidated Statements of Cash Flows now include excess tax benefits as an operating activity. Previously, income tax benefits at settlement of an award were reported as a reduction to operating cash flows and an increase to financing cash flows to the extent that those benefits exceeded the income tax benefits reported in earnings during the award's vesting period. The Company has elected to apply that change in cash flow classification on a prospective basis, leaving previously reported net cash from operating activities and net cash from financing activities in the accompanying consolidated statement of cash flows for the period ended September 30, 2016 unchanged. Finally, the Company has elected to account for forfeitures as they occur, rather than estimate expected forfeitures. As a result of the adoption of this update, the Company recorded a cumulative-effect adjustment that reduced beginning retained earnings by $0.5 million, net of tax. In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments (a consensus of the Emerging Issues Task Force). The amendment provides updated guidance on eight specific cash flow issues, including debt prepayment or debt extinguishment costs, settlement of zero-coupon debt instruments, contingent consideration payments made after a business combination, proceeds from settlement of insurance claims and corporate-owned life insurance, distributions received from equity method investees, beneficial interests in securitization transactions and separately identifiable cash flows and application of the predominance principle. The Company early adopted the amendments in the Update on a retrospective basis in the second quarter of fiscal year 2017. As a result of adoption, the Company has recorded cash paid in the second and third quarters of 2017 for debt prepayment and extinguishment costs as financing activities in the accompanying consolidated statements of cash flows. Standard to be implemented In May 2014, FASB issued ASU 2014-09, Revenue from Contracts with Customers (Topic 606). ASU 2014-09 outlines a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersedes most current revenue recognition guidance, including industry-specific guidance. In August 2015, FASB issued ASU 2015-14 which deferred the effective date of ASU 2014-09 for all entities by one year. In March 2016, FASB issued ASU 2016-08, which reduces the potential for diversity in practice arising from inconsistent application of the principal versus agent guidance, as well as the cost and complexity of applying Topic 606 both at transition and on an ongoing basis. In April 2016, FASB issued ASU 2016-10, which reduces the potential for diversity in initial application, as well as the cost and complexity of applying Topic 606 both at transition and on an ongoing basis. In May 2016, FASB issued ASU 2016-12, which provided narrow scope improvements and practical expedients on assessing collectability, presentation of sales taxes, noncash consideration, and completed contracts and contract modifications at transition. ASU 2014-09 is currently effective for annual reporting periods (including interim reporting periods within those periods) beginning after December 15, 2017. The guidance permits two methods of adoption: retrospectively to each prior reporting period presented (full retrospective method), or retrospectively with the cumulative effect of initially applying the guidance recognized at the date of initial application (the cumulative catch-up transition method). The Company expects that it will adopt ASU 2014‑09 beginning in the first quarter of 2018 and continues its evaluation of the impact of the new standard on its accounting policies, disclosures, processes, and system requirements. The Company has assigned internal resources to assist in this implementation project and believes that the project is progressing timely. The Company currently anticipates adopting this ASU using the modified retrospective method. While the Company’s impact assessment is not yet complete, based on the results of its work to date, it currently does not expect the application of the new standard to have a material impact to its consolidated financial statement results. As the Company completes its evaluation of this new standard, the Company's preliminary assessments could change. In October 2016, the FASB issued ASU 2016-16, Income Tax - Intra-Entity Transfers of Assets Other than Inventory. The amendment improves the accounting for the income tax consequences of intra-entity transfers of assets other than inventory. The amendment should be applied using a modified retrospective basis and are effective for annual reporting periods (including interim reporting periods within those periods) beginning after December 15, 2017. The Company is currently in the process of evaluating the impact of adoption on its consolidated financial statements. In February 2017, the FASB issued ASU 2017-05, Other Income-Gains and Losses from the Derecognition of Nonfinancial Assets (Subtopic 610-20): Clarifying the Scope of Asset Derecognition Guidance and Accounting for Partial Sales of Nonfinancial Assets. The amendment is meant to clarify the scope of ASC Subtopic 610-20, Other Income-Gains and Losses from the Derecognition of Nonfinancial Assets and to add guidance for partial sales of nonfinancial assets. The amendment should be applied using a full retrospective method or a modified retrospective method and are effective at the same time as ASU 2014-09. Further, the Company is required to adopt ASU 2017-05 at the same time that it adopts the guidance in ASU 2014-09. Adoption is not expected to have a material impact on the Company's consolidated financial statements. In May 2017, the FASB issued ASU 2017-09, Compensation-Stock Compensation (Topic 718): Scope of Modification Accounting. The amendment is meant to provide guidance about which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting in Topic 718. The amendment should be applied prospectively to an award modified on or after the adoption date and are effective for annual reporting periods (including interim reporting periods within those periods) beginning after December 15, 2017. Adoption is not expected to have a material impact on the Company's consolidated financial statements.

BUSINESS COMBINATIONS

9 Months Ended

Sep. 30, 2017

Business Combinations [Abstract]

BUSINESS COMBINATIONS

2017 Acquisitions

On September 22, 2017, the Company acquired a privately held company which manufactures and sells part washer machines and related equipment for approximately $2.1 million. The acquired company is included in the Safety-Kleen operating segment. In connection with this acquisition a preliminary goodwill amount of $0.7 million was recognized.

On July 14, 2017, the Company acquired Lonestar West Inc. ("Lonestar"), a public company headquartered in Alberta, Canada, for approximately CAD $41.8 million, ($33.1 million USD), net of cash acquired, which included an equity payout of CAD $0.72 per share to Lonestar shareholders and the assumption of approximately CAD $21.3 million ($16.8 million USD) in outstanding debt, which Clean Harbors subsequently repaid. The acquisition is expected to support the Company's growth in the daylight and hydro excavation services markets. In addition to increasing the size of the Company's hydro vac fleet, Lonestar's network of locations will provide the Company with direct access to key geographic markets in both the United States and Canada. The acquired company will be included in the Industrial and Field Services segment. In connection with this acquisition a preliminary goodwill amount of $3.0 million was recognized.

On January 31, 2017, the Company acquired a privately held company for a purchase price of approximately $11.9 million in cash, net of cash acquired, and subject to customary post-closing adjustments. The acquired business produces and distributes oil products and therefore complements the Company's closed loop model as it relates to the sale of its oil products. The acquired company is included in the Safety-Kleen operating segment. In connection with this acquisition a preliminary goodwill amount of $4.9 million was recognized.

2016 Acquisitions

During 2016, the Company acquired seven businesses that complement the strategy to create a closed loop model as it relates to the sale of the Company's oil products. These acquisitions provided the Company with three additional oil re-refineries while also expanding its used motor oil collection network and providing greater blending and packaging capabilities. These acquisitions also provided the Company with greater access to customers in the West Coast region of the United States and additional locations with Part B permits. Operations of these acquisitions are primarily being integrated into the Safety-Kleen operating segment with certain operations also being integrated into the Technical Services and Industrial Services operating segments. The combined purchase price for the seven acquisitions was $204.8 million in cash, net of cash acquired. Upon acquisition, the acquired entities were immediately integrated into the Company's operating segments. Therefore it is impracticable to measure earnings attributable to the acquired businesses.

The allocation of the purchase price was based on estimates of the fair value of assets acquired and liabilities assumed as of the acquisition dates. The Company believes that such information provides a reasonable basis for estimating the fair values of

assets acquired and liabilities assumed. The Company finalized the purchase accounting for the seven acquisitions in the second quarter of 2017.

The components and allocation of the purchase price consist of the following amounts (in thousands):



	At Acquisition Dates As Reported December 31, 2016			Measurement Period Adjustments			Final Allocations
Accounts receivable	$	15,767		$	475		$	16,242
Inventories and supplies	12,515			173			12,688
Prepaid expenses and other current assets	777			(25		)	752
Property, plant and equipment	143,025			891			143,916
Permits and other intangibles	28,856			—			28,856
Current liabilities	(20,258		)	353			(19,905		)
Closure and post-closure liabilities	(2,408		)	(596		)	(3,004		)
Remedial liabilities, less current portion	(2,041		)	(504		)	(2,545		)
Deferred taxes, unrecognized tax benefits and other long-term liabilities	(17,019		)	(3,200		)	(20,219		)
Total identifiable net assets	159,214			(2,433		)	156,781
Goodwill	45,791			2,186			47,977
Total purchase price, net of cash acquired	$	205,005		$	(247	)	$	204,758

Pro forma revenue and earnings amounts on a combined basis as if these acquisitions had been completed on January 1, 2016 are immaterial to the consolidated financial statements of the Company since that date.

DISPOSITION OF BUSINESSES

9 Months Ended

Sep. 30, 2017

Discontinued Operations and Disposal Groups [Abstract]

DISPOSITION OF BUSINESS

DISPOSITION OF BUSINESSES

2017 Disposition

On June 30, 2017, the Company completed the sale of its Transformer Services business, as part of its continuous focus on improving or divesting certain non-core operations. The Transformer Services business was a non-core business previously included within the Technical Services operating segment and was sold for approximately $46.5 million ($44.4 million net of $2.1 million in transactional related costs) subject to potential adjustments from customary post-closing conditions. As a result of the sale, the Company has recognized in the nine months ended September 30, 2017, a pre-tax gain $31.6 million which is included in (loss) gain on sale of business in the Company’s consolidated statement of operations.

The following table presents the carrying amounts of the Company's Transformer Services business that was disposed of on June 30, 2017 (in thousands):



	June 30, 2017
Total current assets	$	7,241
Property, plant and equipment, net	8,773
Total other assets	1,681
Total assets divested	$	17,695
Total current liabilities	3,849
Total other liabilities	1,170
Total liabilities divested	$	5,019
Net carrying value divested	$	12,676

The Company evaluated the disposition and determined it did not meet the “major effect” criteria for classification as a discontinued operation largely due to the nature and size of the operations of the disposed entity. However, the Company determined that the disposition represented an individually significant component of the Company’s business. The following table presents income attributable to the Transformer Services business included in the Company's consolidated results of operations for each of the periods shown and through its disposition on June 30, 2017 (in thousands):



	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2017		2016		2017		2016
Income before provision for income taxes	$	—	$	318	$	2,771	$	2,111

2016 Disposition

On September 1, 2016, the Company completed the sale of its Catalyst Services business, which was a non-core business previously included within the Industrial and Field Services segment. During the first quarter of 2017, the Company and the buyer of the Catalyst Services business agreed to final working capital amounts and as a result the Company received $2.0 million of additional final sale proceeds.

The following table presents the income before provision for (loss) income taxes attributable to the Catalyst Services business included in the Company's consolidated results of operations for three and nine months ended September 30, 2016 (in thousands):



	Three Months Ended			Nine Months Ended
	September 30, 2016			September 30, 2016
(Loss) income before provision for income taxes	$	(1,218	)	$	290

INVENTORIES AND SUPPLIES

9 Months Ended

Sep. 30, 2017

Inventory Disclosure [Abstract]

INVENTORIES AND SUPPLIES

Inventories and supplies consisted of the following (in thousands):



	September 30, 2017		December 31, 2016
Oil and oil products	$	57,602	$	52,158
Supplies and drums	93,654		90,610
Solvent and solutions	8,680		8,566
Modular camp accommodations	1,945		15,255
Other	11,216		11,839
Total inventories and supplies	$	173,097	$	178,428

As of September 30, 2017 and December 31, 2016, other inventories consisted primarily of cleaning fluids, such as absorbents and wipers, and automotive fluids, such as windshield washer fluid and antifreeze. Supplies and drums consist primarily of drums and containers as well as critical spare parts to support its incinerator and re-refinery operations. During the second quarter of 2017, $12.6 million of modular camp accommodations inventory was transferred to and included as camp equipment within the Company's property, plant and equipment amount as such assets will be utilized in the Company's ongoing camp and lodging operations.

PROPERTY, PLANT AND EQUIPMENT

9 Months Ended

Sep. 30, 2017

Property, Plant and Equipment [Abstract]

PROPERTY, PLANT AND EQUIPMENT

Property, plant and equipment consisted of the following (in thousands):



	September 30, 2017		December 31, 2016
Land	$	121,806	$	120,575
Asset retirement costs (non-landfill)	14,905		14,567
Landfill assets	143,503		139,708
Buildings and improvements	411,006		373,160
Camp equipment	171,163		152,740
Vehicles	613,767		541,022
Equipment	1,628,256		1,483,736
Furniture and fixtures	5,586		5,492
Construction in progress	52,523		146,904
	3,162,515		2,977,904
Less - accumulated depreciation and amortization	1,550,544		1,366,077
Total property, plant and equipment, net	$	1,611,971	$	1,611,827

Interest in the amount of $0.2 million and $0.4 million was capitalized to fixed assets during the three and nine months ended September 30, 2017, respectively. Interest in the amount of $1.5 million and $4.0 million was capitalized to fixed assets during the three and nine months ended September 30, 2016, respectively. Depreciation expense, inclusive of landfill amortization, was $64.0 million and $189.2 million for the three and nine months ended September 30, 2017, respectively. Depreciation expense, inclusive of landfill amortization, was $62.6 million and $185.4 million for the three and nine months ended September 30, 2016, respectively.

GOODWILL AND OTHER INTANGIBLE ASSETS

9 Months Ended

Sep. 30, 2017

Goodwill and Intangible Assets Disclosure [Abstract]

GOODWILL AND OTHER INTANGIBLE ASSETS

The changes in goodwill by segment for the nine months ended September 30, 2017 were as follows (in thousands):



	Technical Services			Industrial & Field Services		Safety-Kleen		Oil, Gas and Lodging Services		Totals
Balance at January 1, 2017	$	61,116		$	107,968	$	296,070	$	—	$	465,154
Increase from current period acquisitions	—			2,999		5,613		—		8,612
Measurement period adjustments from prior period acquisitions	—			—		2,186		—		2,186
Decrease from disposition of business	(1,300		)	—		—		—		(1,300		)
Foreign currency translation and other	338			1,398		2,340		—		4,076
Balance at September 30, 2017	$	60,154		$	112,365	$	306,209	$	—	$	478,728

The Company assesses goodwill for impairment on an annual basis as of December 31, or at an interim date when events or changes in the business environment would more likely than not reduce the fair value of a reporting unit below its carrying value. The Company conducted the annual impairment test of goodwill for all reporting units as of December 31, 2016 and determined that no adjustment to the carrying value of goodwill for any reporting units was necessary because the fair value of each of the reporting units exceeded that reporting unit's respective carrying value.

As a result of the sale of the Transformer Services business discussed in Note 4, "Disposition of Businesses", to the accompanying financial statements, the Company assessed qualitative factors to determine whether it was more likely than not that the fair value of the remaining Technical Services reporting unit was less than its carrying value. As a result of its qualitative assessment, the Company noted no indicators of impairment for the remaining Technical Services reporting unit existed as of the date of sale.

As of September 30, 2017 and December 31, 2016, the Company's total finite-lived and indefinite-lived intangible assets consisted of the following (in thousands):



	September 30, 2017							December 31, 2016
	Cost		Accumulated Amortization		Net		Weighted Average Remaining Amortization Period (in years)	Cost		Accumulated Amortization		Net		Weighted Average Remaining Amortization Period (in years)
Permits	$	174,571	$	72,788	$	101,783	21.2	$	171,637	$	67,301	$	104,336	18.9
Customer and supplier relationships	398,778		151,744		247,034		11.5	393,426		127,462		265,964		12.2
Other intangible assets	36,077		31,414		4,663		7.3	34,254		28,456		5,798		7.1
Total amortizable permits and other intangible assets	609,426		255,946		353,480		14.2	599,317		223,219		376,098		13.9
Trademarks and trade names	124,159		—		124,159		Indefinite	122,623		—		122,623		Indefinite
Total permits and other intangible assets	$	733,585	$	255,946	$	477,639		$	721,940	$	223,219	$	498,721

Amortization expense of permits and other intangible assets was $8.9 million and $27.7 million for the three and nine months ended September 30, 2017, respectively. Amortization expense of permits and other intangible assets was $10.8 million and $30.3 million for the three and nine months ended September 30, 2016, respectively.

The expected amortization of the net carrying amount of finite-lived intangible assets at September 30, 2017 was as follows (in thousands):



Years Ending December 31,	Expected Amortization
2017 (three months)	$	9,039
2018	34,463
2019	31,521
2020	29,206
2021	26,747
Thereafter	222,504
	$	353,480

- Definition

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

+ References + Details

ACCRUED EXPENSES

9 Months Ended

Sep. 30, 2017

Payables and Accruals [Abstract]

ACCRUED EXPENSES

Accrued expenses consisted of the following at September 30, 2017 and December 31, 2016 (in thousands):



	September 30, 2017		December 31, 2016
Insurance	$	59,552	$	63,061
Interest	18,321		21,536
Accrued compensation and benefits	52,408		34,641
Income, real estate, sales and other taxes	49,892		35,083
Other	33,016		36,400
	$	213,189	$	190,721

As of September 30, 2017 and December 31, 2016, other accrued expenses included accrued legal matters of $1.0 million and $3.8 million, respectively, and accrued severance charges of $1.3 million and $2.9 million, respectively.

CLOSURE AND POST-CLOSURE LIABILITIES

9 Months Ended

Sep. 30, 2017

Asset Retirement Obligation Disclosure [Abstract]

CLOSURE AND POST-CLOSURE LIABILITIES

The changes to closure and post-closure liabilities (also referred to as “asset retirement obligations”) from January 1, 2017 through September 30, 2017 were as follows (in thousands):



	Landfill Retirement Liability			Non-Landfill Retirement Liability			Total
Balance at January 1, 2017	$	30,630		$	27,701		$	58,331
Liabilities assumed in acquisitions	—			27			27
Measurement period adjustments from prior period acquisitions	—			596			596
New asset retirement obligations	1,376			—			1,376
Adjustment related to disposition of business	—			(1,170		)	(1,170		)
Accretion	1,658			1,882			3,540
Changes in estimates recorded to statement of operations	(131		)	(126		)	(257		)
Changes in estimates recorded to balance sheet	—			(284		)	(284		)
Expenditures	(2,269		)	(352		)	(2,621		)
Currency translation and other	182			119			301
Balance at September 30, 2017	$	31,446		$	28,393		$	59,839

All of the landfill facilities included in the above were active as of September 30, 2017. There were no significant charges (benefits) in 2017 resulting from changes in estimates for closure and post-closure liabilities.

New asset retirement obligations incurred during the first nine months of 2017 were discounted at the credit-adjusted risk-free rate of 6.32%.

REMEDIAL LIABILITIES

9 Months Ended

Sep. 30, 2017

Environmental Remediation Obligations [Abstract]

REMEDIAL LIABILITIES

The changes to remedial liabilities for the nine months ended September 30, 2017 were as follows (in thousands):



	Remedial Liabilities for Landfill Sites			Remedial Liabilities for Inactive Sites			Remedial Liabilities (Including Superfund) for Non-Landfill Operations			Total
Balance at January 1, 2017	$	1,777		$	64,151		$	62,079		$	128,007
Measurement period adjustments from prior period acquisitions	—			—			504			504
Accretion	64			1,976			1,473			3,513
Changes in estimates recorded to statement of operations	(34		)	(277		)	256			(55		)
Expenditures	(30		)	(3,099		)	(4,328		)	(7,457		)
Currency translation and other	(1		)	2,742			(1,740		)	1,001
Balance at September 30, 2017	$	1,776		$	65,493		$	58,244		$	125,513

In the nine months ended September 30, 2017, there were no significant charges (benefits) resulting from changes in estimates for remedial liabilities.

FINANCING ARRANGEMENTS

9 Months Ended

Sep. 30, 2017

Debt Disclosure [Abstract]

FINANCING ARRANGEMENTS

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



	September 30, 2017			December 31, 2016
Senior secured notes due June 30, 2024 ("Term Loan"), current	$	4,000		$	—
Current portion of long-term obligations, at carrying value	$	4,000		$	—

Senior secured notes due June 30, 2024	$	395,000		$	—
Senior unsecured notes, at 5.25%, due August 1, 2020 ("2020 Notes")	400,000			800,000
Senior unsecured notes, at 5.125%, due June 1, 2021 ("2021 Notes")	845,000			845,000
Long-term obligations	$	1,640,000		$	1,645,000
Unamortized debt issuance costs and debt discount/premium, net	(14,029		)	(11,728		)
Long-term obligations, at carrying value	$	1,625,971		$	1,633,272

Total current and long-term obligations, at carrying value	$	1,629,971		$	1,633,272

On June 30, 2017, the Company, and substantially all of the Company’s domestic subsidiaries as guarantors, entered into a $400.0 million senior secured Credit Agreement (the "Term Loan Agreement"). Loans under the Term Loan Agreement will mature on June 30, 2024 and may be prepaid at any time without premium or penalty other than customary breakage costs with respect to Eurodollar based loans or if the Company engages in certain repricing transactions before December 31, 2017, in which event a 1.0% prepayment premium would be due. The Company’s obligations under the Term Loan Agreement are guaranteed by all of the Company’s domestic restricted subsidiaries and secured by liens on substantially all of the assets of the Company and the guarantors.

Borrowings under the Term Loan Agreement will bear interest, at the Company’s election, at either of the following rates: (a) the sum of the Eurodollar Rate (as defined in the Term Loan Agreement) plus 2.00%, or (b) the sum of the Base Rate (as defined in the Term Loan Agreement) plus 1.00%, with the Eurodollar Rate being subject to a floor of 0.00%. The effective interest rate of the Term Loan on September 30, 2017 was 3.24%. The Term Loan Agreement contains representations and warranties, affirmative and negative covenants, and events of default, which the Company believes are usual and customary for an agreement of this type. Such covenants restrict the Company’s ability, among other matters, to incur debt, create liens on the Company’s assets, make restricted payments or investments or enter into transactions with affiliates. In accordance with the Term Loan Agreement required payments equal to .25% of the initial $400.0 million are due upon the last day of each calendar quarter.

Upon entering into the Term Loan Agreement on June 30, 2017, the Company used approximately $312.6 million of the proceeds to purchase approximately $296.2 million aggregate principal amount (the “Repurchased Notes”) of the Company’s previously outstanding 2020 Notes, pay accrued interest of approximately $6.4 million on the Repurchased Notes, premiums to repay the debt early of $4.7 million and expenses incurred of approximately $5.3 million in connection with the Term Loan financing and the tender offer for the 2020 Notes.

On June 30, 2017, the Company also delivered a notice of redemption to the holders of the approximately $503.8 million aggregate principal amount of 2020 Notes which remained outstanding after the purchase of the Repurchased Notes. Pursuant to that notice, the Company redeemed on August 1, 2017, approximately $103.8 million aggregate principal amount of 2020 Notes at a redemption price of 101.313%, plus accrued but unpaid interest. In conjunction with the redemption, the Company paid premiums to repay the debt early of $1.3 million and expenses incurred of approximately $0.8 million. The Company financed the redemption through the remaining net proceeds of the Term Loan financing described above, plus available cash.

At September 30, 2017, the fair value of the Term Loan debt was $399.8 million. At September 30, 2017 and December 31, 2016, the fair value of the Company's 2020 Notes was $405.6 million and $820.0 million, respectively, based on quoted market prices for the instrument. At September 30, 2017 and December 31, 2016, the fair value of the Company's 2021 Notes was $857.8 million and $861.9 million, respectively, based on quoted market prices for the instrument. The fair value of the Term Loan debt, 2020 Notes and 2021 Notes are considered a Level 2 measure according to the fair value hierarchy.

The Company also maintains a $400.0 million revolving credit facility under which as of September 30, 2017 and December 31, 2016, the Company had no outstanding loan balances. At September 30, 2017, approximately $238.3 million was available to borrow and outstanding letters of credit were $124.9 million. At December 31, 2016, $195.2 million was available to borrow and outstanding letters of credit were $132.6 million.

EARNINGS (LOSS) PER SHARE

9 Months Ended

Sep. 30, 2017

Earnings Per Share [Abstract]

EARNINGS (LOSS) PER SHARE

The following are computations of basic and diluted earnings (loss) per share (in thousands except for per share amounts):



	Three Months Ended					Nine Months Ended
	September 30,					September 30,
	2017		2016			2017		2016
Numerator for basic and diluted earnings (loss) per share:
Net income (loss)	$	12,058	$	(10,255	)	$	16,545	$	(27,160	)

Denominator:
Basic shares outstanding	57,033		57,487			57,149		57,575
Dilutive effect of equity-based compensation awards	162		—			131		—
Dilutive shares outstanding	57,195		57,487			57,280		57,575

Basic earnings (loss) per share:	$	0.21	$	(0.18	)	$	0.29	$	(0.47	)

Diluted earnings (loss) per share:	$	0.21	$	(0.18	)	$	0.29	$	(0.47	)

For the three and nine months ended September 30, 2017, the dilutive effect of all then outstanding restricted stock and performance awards is included in the EPS calculations above except for 301,300 of outstanding performance stock awards for which the performance criteria were not attained at that time and 3,724 and 19,485, respectively, of restricted stock awards which were antidilutive at that time.

As a result of the net loss reported for the three and nine months ended September 30, 2016, all then outstanding stock options, restricted stock awards and performance awards totaling 835,482 were excluded from the calculation of diluted earnings (loss) per share as their inclusion would have an antidilutive effect.

ACCUMULATED OTHER COMPREHENSIVE LOSS

9 Months Ended

Sep. 30, 2017

Equity [Abstract]

ACCUMULATED OTHER COMPREHENSIVE LOSS

The changes in accumulated other comprehensive loss by component and related tax effects for the nine months ended September 30, 2017 were as follows (in thousands):



	Foreign Currency Translation			Unrealized (Losses) Gains on Available-For-Sale Securities			Unfunded Pension Liability			Total
Balance at January 1, 2017	$	(212,211	)	$	(321	)	$	(1,794	)	$	(214,326	)
Other comprehensive income before reclassifications	44,545			299			—			44,844
Amounts reclassified out of accumulated other comprehensive loss	—			222			—			222
Tax effects	—			(208		)	—			(208		)
Other comprehensive income	$	44,545		$	313		$	—		$	44,858
Balance at September 30, 2017	$	(167,666	)	$	(8	)	$	(1,794	)	$	(169,468	)

The amounts reclassified out of accumulated other comprehensive loss into the consolidated statements of operations, with presentation location during the three and nine months ended September 30, 2017 were as follows (in thousands):



	For the Three Months Ended		For the Nine Months Ended
Comprehensive (Loss) Income Components	September 30, 2017		September 30, 2017		Location
Unrealized holding gains on available-for-sale investments	$	—	$	222	Other expense

There were no reclassifications out of accumulated other comprehensive loss into the consolidated statements of operations during the three and nine months ended September 30, 2016.

STOCK-BASED COMPENSATION

9 Months Ended

Sep. 30, 2017

Disclosure of Compensation Related Costs, Share-based Payments [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, 2017 was $4.0 million and $9.2 million, respectively. Total stock-based compensation cost charged to selling, general and administrative expenses for the three and nine months ended September 30, 2016 was $3.0 million and $7.7 million, respectively. The total income tax benefit recognized in the consolidated statements of operations from stock-based compensation was $1.2 million and $2.7 million for the three and nine months ended September 30, 2017, respectively. The total income tax benefit recognized in the consolidated statements of operations from stock-based compensation was $0.9 million and $2.3 million for the three and nine months ended September 30, 2016, 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 plans (the "Plans"). 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, 2017:



Restricted Stock	Number of Shares		Weighted Average Grant-Date Fair Value
Balance at January 1, 2017	510,041		$	52.65
Granted	295,568		$	56.00
Vested	(115,365	)	$	53.89
Forfeited	(47,784	)	$	51.35
Balance at September 30, 2017	642,460		$	54.07

As of September 30, 2017, there was $27.8 million of total unrecognized compensation cost arising from restricted stock awards under the Company's Plans. This cost is expected to be recognized over a weighted average period of 2.9 years. The total fair value of restricted stock vested during the three and nine months ended September 30, 2017 was $0.5 million and $6.2 million, respectively. The total fair value of restricted stock vested during the three and nine months ended September 30, 2016 was $1.8 million and $7.9 million, respectively.

Performance Stock Awards

The following information relates to performance stock awards that have been granted to employees under the Company's Plans. 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, 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, 2017:



Performance Stock	Number of Shares		Weighted Average Grant-Date Fair Value
Balance at January 1, 2017	220,882		$	54.69
Granted	167,964		$	55.84
Vested	(25,168	)	$	54.84
Forfeited	(25,544	)	$	56.19
Balance at September 30, 2017	338,134		$	55.25

As of September 30, 2017, there was $1.5 million of total unrecognized compensation cost arising from unvested performance stock awards deemed probable of vesting under the Company's Plans. No performance awards vested during the three months ended September 30, 2017. The total fair value of performance awards vested during the nine months ended September 30, 2017 was $1.4 million. No performance awards vested during the three months ended September 30, 2016. The total fair value of performance awards vested during the nine months ended September 30, 2016 was $0.4 million.

Common Stock Repurchases

On October 31, 2017, the Company's board of directors authorized the repurchase of up to an additional $300 million of the Company's common stock, resulting in a total of $375.7 million currently being available for stock repurchase. During the three and nine months ended September 30, 2017, the Company repurchased and retired a total of 0.2 million shares and 0.5 million respectively, of the Company's common stock for a total cost of $12.2 million and $24.5 million, respectively. During the three and nine months ended September 30, 2016, the Company repurchased and retired a total of 0.1 million shares and 0.3 million shares, respectively, of the Company's common stock for a total cost of $6.2 million and $16.3 million, respectively. Through September 30, 2017, the Company had repurchased and retired a total of 4.3 million shares of the Company's common stock for a total cost of $224.3 million under this program. As of September 30, 2017, an additional $75.7 million remained available for repurchase of shares under the previously authorized program.

COMMITMENTS AND CONTINGENCIES	9 Months Ended
COMMITMENTS AND CONTINGENCIES	Sep. 30, 2017
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, 2017 and December 31, 2016, the Company had recorded reserves of $19.1 million and $22.0 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, 2017 and December 31, 2016, the Company also believed that it was reasonably possible that the amount of these potential liabilities could be as much as $1.8 million and $1.9 million more, respectively. 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, 2017 and December 31, 2016, the $19.1 million and $22.0 million, respectively, of reserves consisted of (i) $18.1 million and $18.2 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) $1.0 million and $3.8 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, 2017, the principal legal and administrative proceedings in which the Company was involved, or which had been terminated during 2017, 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 to a company unrelated to the Mercier Subsidiary two permits to dump organic liquids into lagoons on the property. 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 (Cdn) in general damages and $10.0 million (Cdn) 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 currently 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 or results of operations. 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, 2017 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, 2017, 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 warn adequately the product user of potential risks, including an 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 of 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, 2017. From January 1, 2017 to September 30, 2017, 25 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, three (including the BR Facility described below) involve facilities that are now owned or leased by the Company and 126 involve third party sites to which either the Company or the prior owners of certain of the Company’s facilities shipped wastes. Of the 126 third party sites, 33 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 11 of the 126 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 Environmental Protection Agency (the "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. The Company is currently performing corrective actions at the BR Facility under an order issued by the Louisiana Department of Environmental Quality, and has begun conducting the remedial investigation and feasibility study 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. Third Party Sites. Of the 126 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 one other entity, the Company does not have an indemnity agreement with respect to any of the 126 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, 2017 and December 31, 2016, there were five 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.

INCOME TAXES	9 Months Ended
INCOME TAXES	Sep. 30, 2017
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, 2017 was 51.0% and 69.9% compared to 47.8% and 80.3% for the same periods in 2016. The variations in the effective income tax rates for the three and nine months ended September 30, 2017 as compared to more customary relationships between pre-tax income and the provision for income taxes were primarily due to the Company not recognizing income tax benefits from current operating losses related to certain Canadian entities and in the second quarter of 2017 the tax expense associated with the gain on the sale of the Transformer Services business. As of September 30, 2017 and December 31, 2016, the Company had recorded $1.8 million and $1.7 million, respectively, of liabilities for unrecognized tax benefits and $0.4 million and $0.3 million of interest, respectively. Due to expiring statute of limitation periods, the Company believes that total unrecognized tax benefits will decrease by $0.4 million within the next 12 months.

SEGMENT REPORTING

9 Months Ended

Sep. 30, 2017

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 its business, makes operating decisions and assesses performance. The Company's operations are managed in six operating segments: Technical Services, Industrial Services, Field Services, Safety-Kleen, Oil and Gas Field Services and Lodging Services. For purposes of segment disclosure the Industrial Services and Field Services operating segments have been aggregated into a single reportable segment based upon their similar economic and other characteristics, and the Oil and Gas Field Services and Lodging Services operating segments have been combined as they do not meet the quantitative thresholds for separate presentation.

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 negative intersegment revenues are due to more transfers out of customer revenues to other segments than transfers in of customer revenues from other segments. The operations not managed through the Company’s operating segments described above are recorded as “Corporate Items.” Corporate Items revenues consist of two different operations for which the revenues are insignificant. Corporate Items cost of revenues represents certain central services that are not allocated to the Company's operating segments for internal reporting purposes. Corporate Items selling, general and administrative expenses include typical corporate items such as legal, accounting and other items of a general corporate nature that are not allocated to the Company’s operating segments.

The following table reconciles third party revenues to direct revenues for the three and nine months ended September 30, 2017 and 2016 (in thousands):



	For the Three Months Ended September 30, 2017											For the Three Months Ended September 30, 2016
	Third party revenues		Intersegment revenues, net			Corporate Items, net			Direct revenues			Third party revenues		Intersegment revenues, net			Corporate Items, net			Direct revenues
Technical Services	$	246,329	$	41,366		$	637		$	288,332		$	232,482	$	38,795		$	492		$	271,769
Industrial and Field Services	163,808		(10,262		)	45			153,591			172,191		(10,867		)	(32		)	161,292
Safety-Kleen	315,028		(31,757		)	3			283,274			297,082		(28,716		)	1			268,367
Oil, Gas and Lodging Services	30,026		653			79			30,758			27,644		788			105			28,537
Corporate Items	655		—			(764		)	(109		)	121		—			(566		)	(445		)
Total	$	755,846	$	—		$	—		$	755,846		$	729,520	$	—		$	—		$	729,520



	For the Nine Months Ended September 30, 2017											For the Nine Months Ended September 30, 2016
	Third party revenues		Intersegment revenues, net			Corporate Items, net			Direct revenues			Third party revenues		Intersegment revenues, net			Corporate Items, net			Direct revenues
Technical Services	$	731,034	$	121,411		$	1,767		$	854,212		$	680,717	$	109,217		$	1,547		$	791,481
Industrial and Field Services	465,264		(27,688		)	16			437,592			467,019		(25,464		)	(348		)	441,207
Safety-Kleen	910,885		(95,465		)	4			815,424			821,758		(86,329		)	368			735,797
Oil, Gas and Lodging Services	89,403		1,742			218			91,363			91,555		2,576			288			94,419
Corporate Items	989		—			(2,005		)	(1,016		)	2,064		—			(1,855		)	209
Total	$	2,197,575	$	—		$	—		$	2,197,575		$	2,063,113	$	—		$	—		$	2,063,113

The primary financial measure by which the Company evaluates the performance of its segments is "Adjusted EBITDA" which consists of net income (loss) plus accretion of environmental liabilities, depreciation and amortization, other expense, interest expense, net, loss on early extinguishment of debt, goodwill impairment charge, provision for income taxes and excludes (loss) gain on sale of business. 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,
	2017			2016			2017			2016
Adjusted EBITDA:
Technical Services	$	72,338		$	72,333		$	203,906		$	201,622
Industrial and Field Services	13,255			18,234			36,652			38,627
Safety-Kleen	70,305			70,053			182,953			165,342
Oil, Gas and Lodging Services	912			24			969			135
Corporate Items	(33,811		)	(33,993		)	(100,655		)	(101,310		)
Total	$	122,999		$	126,651		$	323,825		$	304,416
Reconciliation to Consolidated Statements of Operations:
Accretion of environmental liabilities	2,347			2,476			7,053			7,529
Depreciation and amortization	72,989			73,360			216,932			215,655
Goodwill impairment charge	—			34,013			—			34,013
Income from operations	47,663			16,802			99,840			47,219
Other expense	432			198			2,814			737
Loss on early extinguishment of debt	1,846			—			7,891			—
Loss (gain) on sale of business	77			(16,431		)	(31,645		)	(16,431		)
Interest expense, net of interest income	20,675			21,565			65,743			62,192
Income before provision for income taxes	$	24,633		$	11,470		$	55,037		$	721

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



	September 30, 2017
	Technical Services		Industrial and Field Services		Safety-Kleen		Oil, Gas and Lodging Services		Corporate Items		Totals
Property, plant and equipment, net	$	507,069	$	264,662	$	585,493	$	177,106	$	77,641	$	1,611,971
Goodwill	60,154		112,365		306,209		—		—		478,728
Permits and other intangibles, net	75,260		17,139		377,458		7,782		—		477,639
Total assets	$	848,578	$	485,297	$	1,475,764	$	239,308	$	699,406	$	3,748,353



	December 31, 2016
	Technical Services		Industrial and Field Services		Safety-Kleen		Oil, Gas and Lodging Services		Corporate Items		Totals
Property, plant and equipment, net	$	521,134	$	245,143	$	584,647	$	182,038	$	78,865	$	1,611,827
Goodwill	61,116		107,968		296,070		—		—		465,154
Permits and other intangibles, net	78,625		17,817		391,390		10,889		—		498,721
Total assets	$	862,957	$	446,826	$	1,474,755	$	253,242	$	644,140	$	3,681,920

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



	September 30, 2017		December 31, 2016
United States	$	3,005,644	$	2,960,337
Canada	742,709		721,583
Total	$	3,748,353	$	3,681,920

GUARANTOR AND NON-GUARANTOR SUBSIDIARIES FINANCIAL INFORMATION

9 Months Ended

Sep. 30, 2017

Guarantor and Non-Guarantor Subsidiaries Financial Information [Abstract]

GUARANTOR AND NON-GUARANTOR SUBSIDIARIES FINANCIAL INFORMATION

The 2020 Notes and the 2021 Notes (collectively, the "Notes") are guaranteed by substantially all of the Company’s subsidiaries organized in the United States. Each guarantor for the Notes is a 100% owned subsidiary of Clean Harbors, Inc. and its guarantee is both full and unconditional and joint and several. The guarantees are, however, subject to customary release provisions under which, in particular, the guarantee of any domestic restricted subsidiary will be released if the Company sells such subsidiary to an unrelated third party in accordance with the terms of the indentures which govern the Notes. The Notes are not guaranteed by the Company’s subsidiaries organized outside the United States. The following supplemental condensed consolidating financial information for the parent company, the guarantor subsidiaries and the non-guarantor subsidiaries, respectively, is presented in conformity with the requirements of Rule 3-10 of SEC Regulation S-X (“Rule 3-10”).

Following is the condensed consolidating balance sheet at September 30, 2017 (in thousands):



	Clean Harbors, Inc.		Guarantor Subsidiaries		Non-Guarantor Subsidiaries		Consolidating Adjustments			Total
Assets:
Cash and cash equivalents	$	51,514	$	221,552	$	88,592	$	—		$	361,658
Intercompany receivables	230,084		451,146		38,451		(719,681		)	—
Accounts receivables, net	—		435,058		96,638		—			531,696
Other current assets	897		215,847		51,871		(1,711		)	266,904
Property, plant and equipment, net	—		1,182,922		429,049		—			1,611,971
Investments in subsidiaries	2,933,843		585,660		—		(3,519,503		)	—
Intercompany debt receivable	—		92,938		21,000		(113,938		)	—
Goodwill	—		415,056		63,672		—			478,728
Permits and other intangibles, net	—		415,708		61,931		—			477,639
Other long-term assets	2,448		13,312		5,065		(1,068		)	19,757
Total assets	$	3,218,786	$	4,029,199	$	856,269	$	(4,355,901	)	$	3,748,353
Liabilities and Stockholders’ Equity:
Current liabilities	$	22,595	$	385,734	$	122,922	$	(1,711	)	$	529,540
Intercompany payables	441,873		266,776		11,032		(719,681		)	—
Closure, post-closure and remedial liabilities, net	—		148,791		17,045		—			165,836
Long-term obligations	1,625,971		—		—		—			1,625,971
Intercompany debt payable	—		21,000		92,938		(113,938		)	—
Other long-term liabilities	—		278,700		21,027		(1,068		)	298,659
Total liabilities	2,090,439		1,101,001		264,964		(836,398		)	2,620,006
Stockholders’ equity	1,128,347		2,928,198		591,305		(3,519,503		)	1,128,347
Total liabilities and stockholders’ equity	$	3,218,786	$	4,029,199	$	856,269	$	(4,355,901	)	$	3,748,353

Following is the condensed consolidating balance sheet at December 31, 2016 (in thousands):



	Clean Harbors, Inc.		Guarantor Subsidiaries		Non-Guarantor Subsidiaries		Consolidating Adjustments			Total
Assets:
Cash and cash equivalents	$	51,417	$	155,943	$	99,637	$	—		$	306,997
Intercompany receivables	200,337		354,836		49,055		(604,228		)	—
Accounts receivables, net	—		417,029		79,197		—			496,226
Other current assets	3,096		234,408		69,257		(17,113		)	289,648
Property, plant and equipment, net	—		1,211,210		400,617		—			1,611,827
Investments in subsidiaries	2,851,571		580,124		—		(3,431,695		)	—
Intercompany debt receivable	—		86,409		24,701		(111,110		)	—
Goodwill	—		412,638		52,516		—			465,154
Permits and other intangibles, net	—		435,594		63,127		—			498,721
Other long-term assets	2,446		7,582		4,387		(1,068		)	13,347
Total assets	$	3,108,867	$	3,895,773	$	842,494	$	(4,165,214	)	$	3,681,920
Liabilities and Stockholders’ Equity:
Current liabilities	$	21,805	$	366,831	$	133,145	$	(17,113	)	$	504,668
Intercompany payables	365,848		237,058		1,322		(604,228		)	—
Closure, post-closure and remedial liabilities, net	—		150,682		15,640		—			166,322
Long-term obligations	1,633,272		—		—		—			1,633,272
Intercompany debt payable	3,701		21,000		86,409		(111,110		)	—
Other long-term liabilities	—		275,649		18,836		(1,068		)	293,417
Total liabilities	2,024,626		1,051,220		255,352		(733,519		)	2,597,679
Stockholders’ equity	1,084,241		2,844,553		587,142		(3,431,695		)	1,084,241
Total liabilities and stockholders’ equity	$	3,108,867	$	3,895,773	$	842,494	$	(4,165,214	)	$	3,681,920

Following is the consolidating statement of operations for the three months ended September 30, 2017 (in thousands):



	Clean Harbors, Inc.			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Consolidating Adjustments			Total
Revenues
Service revenues	$	—		$	473,428		$	152,997		$	(14,073	)	$	612,352
Product revenues	—			127,355			19,435			(3,296		)	143,494
Total revenues	—			600,783			172,432			(17,369		)	755,846
Cost of revenues (exclusive of items shown separately below)
Service cost of revenues	—			306,291			120,151			(14,073		)	412,369
Product cost of revenues	—			97,353			13,169			(3,296		)	107,226
Total cost of revenues	—			403,644			133,320			(17,369		)	519,595
Selling, general and administrative expenses	19			92,299			20,934			—			113,252
Accretion of environmental liabilities	—			2,092			255			—			2,347
Depreciation and amortization	—			50,917			22,072			—			72,989
(Loss) income from operations	(19		)	51,831			(4,149		)	—			47,663
Other expense	—			(305		)	(127		)	—			(432		)
Loss on early extinguishment of debt	(1,846		)	—			—			—			(1,846		)
Loss on sale of business	—			(77		)	—			—			(77		)
Interest (expense) income	(21,135		)	517			(57		)	—			(20,675		)
Equity in earnings of subsidiaries, net of taxes	25,858			(5,620		)	—			(20,238		)	—
Intercompany interest income (expense)	—			1,372			(1,372		)	—			—
Income (loss) before (benefit) provision for income taxes	2,858			47,718			(5,705		)	(20,238		)	24,633
(Benefit) provision for income taxes	(9,200		)	20,824			951			—			12,575
Net income (loss)	12,058			26,894			(6,656		)	(20,238		)	12,058
Other comprehensive income	23,709			23,709			20,263			(43,972		)	23,709
Comprehensive income	$	35,767		$	50,603		$	13,607		$	(64,210	)	$	35,767

Following is the consolidating statement of operations for the three months ended September 30, 2016 (in thousands):



	Clean Harbors, Inc.			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Consolidating Adjustments			Total
Revenues
Service revenues	$	—		$	461,139		$	145,780		$	(12,694	)	$	594,225
Product revenues	—			118,106			20,072			(2,883		)	135,295
Total revenues	—			579,245			165,852			(15,577		)	729,520
Cost of revenues (exclusive of items shown separately below)
Service cost of revenues	(598		)	288,764			110,070			(12,694		)	385,542
Product cost of revenues	—			94,050			15,206			(2,883		)	106,373
Total cost of revenues	(598		)	382,814			125,276			(15,577		)	491,915
Selling, general and administrative expenses	23			88,652			22,279			—			110,954
Accretion of environmental liabilities	—			2,243			233			—			2,476
Depreciation and amortization	—			51,957			21,403			—			73,360
Goodwill impairment charge	—			—			34,013			—			34,013
Income (loss) from operations	575			53,579			(37,352		)	—			16,802
Other expense	—			(188		)	(10		)	—			(198		)
Gain on sale of business	—			1,288			15,143			—			16,431
Interest (expense) income	(23,042		)	1,456			21			—			(21,565		)
Equity in earnings of subsidiaries, net of taxes	3,225			(22,341		)	—			19,116			—
Intercompany interest income (expense)	—			5,235			(5,235		)	—			—
(Loss) income before (benefit) provision for income taxes	(19,242		)	39,029			(27,433		)	19,116			11,470
(Benefit) provision for income taxes	(8,987		)	35,803			(5,091		)	—			21,725
Net (loss) income	(10,255		)	3,226			(22,342		)	19,116			(10,255		)
Other comprehensive loss	(1,311		)	(1,311		)	(3,927		)	5,238			(1,311		)
Comprehensive (loss) income	$	(11,566	)	$	1,915		$	(26,269	)	$	24,354		$	(11,566	)

Following is the consolidating statement of operations for the nine months ended September 30, 2017 (in thousands):



	Clean Harbors, Inc.			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Consolidating Adjustments			Total
Revenues
Service revenues	$	—		$	1,391,534		$	431,992		$	(40,020	)	$	1,783,506
Product revenues	—			369,864			53,496			(9,291		)	414,069
Total revenues	—			1,761,398			485,488			(49,311		)	2,197,575
Cost of revenues (exclusive of items shown separately below)
Service cost of revenues	—			907,396			348,436			(40,020		)	1,215,812
Product cost of revenues	—			292,503			36,959			(9,291		)	320,171
Total cost of revenues	—			1,199,899			385,395			(49,311		)	1,535,983
Selling, general and administrative expenses	70			276,974			60,723			—			337,767
Accretion of environmental liabilities	—			6,328			725			—			7,053
Depreciation and amortization	—			154,754			62,178			—			216,932
(Loss) income from operations	(70		)	123,443			(23,533		)	—			99,840
Other expense	(222		)	(2,100		)	(492		)	—			(2,814		)
Loss on early extinguishment of debt	(7,891		)	—			—			—			(7,891		)
Gain on sale of business	—			31,645			—			—			31,645
Interest (expense) income	(66,408		)	876			(211		)	—			(65,743		)
Equity in earnings of subsidiaries, net of taxes	61,388			(32,776		)	—			(28,612		)	—
Intercompany interest income (expense)	—			3,937			(3,937		)	—			—
(Loss) income before (benefit) provision for income taxes	(13,203		)	125,025			(28,173		)	(28,612		)	55,037
(Benefit) provision for income taxes	(29,748		)	62,442			5,798			—			38,492
Net income (loss)	16,545			62,583			(33,971		)	(28,612		)	16,545
Other comprehensive income	44,858			44,858			38,132			(82,990		)	44,858
Comprehensive income	$	61,403		$	107,441		$	4,161		$	(111,602	)	$	61,403

Following is the consolidating statement of operations for the nine months ended September 30, 2016 (in thousands):



	Clean Harbors, Inc.			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Consolidating Adjustments			Total
Revenues
Service revenues	$	—		$	1,345,629		$	399,216		$	(35,827	)	$	1,709,018
Product revenues	—			303,342			58,176			(7,423		)	354,095
Total revenues	—			1,648,971			457,392			(43,250		)	2,063,113
Cost of revenues (exclusive of items shown separately below)
Service cost of revenues	(1,185		)	864,071			321,153			(35,827		)	1,148,212
Product cost of revenues	—			252,512			42,895			(7,423		)	287,984
Total cost of revenues	(1,185		)	1,116,583			364,048			(43,250		)	1,436,196
Selling, general and administrative expenses	84			253,189			69,228			—			322,501
Accretion of environmental liabilities	—			6,846			683			—			7,529
Depreciation and amortization	—			151,348			64,307			—			215,655
Goodwill impairment charge	—			—			34,013			—			34,013
Income (loss) from operations	1,101			121,005			(74,887		)	—			47,219
Other income (expense)	—			124			(861		)	—			(737		)
Gain on sale of business	—			1,288			15,143						16,431
Interest (expense) income	(66,147		)	3,851			104			—			(62,192		)
Equity in earnings of subsidiaries, net of taxes	11,867			(58,031		)	—			46,164			—
Intercompany interest income (expense)	—			15,891			(15,891		)	—			—
(Loss) income before (benefit) provision for income taxes	(53,179		)	84,128			(76,392		)	46,164			721
(Benefit) provision for income taxes	(26,019		)	72,260			(18,360		)	—			27,881
Net (loss) income	(27,160		)	11,868			(58,032		)	46,164			(27,160		)
Other comprehensive income	43,348			43,348			24,403			(67,751		)	43,348
Comprehensive income (loss)	$	16,188		$	55,216		$	(33,629	)	$	(21,587	)	$	16,188

Following is the condensed consolidating statement of cash flows for the nine months ended September 30, 2017 (in thousands):



	Clean Harbors, Inc.			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Consolidating Adjustments			Total
Net cash from operating activities	$	16,196		$	169,715		$	35,558		$	—		$	221,469
Cash flows from (used in) investing activities:
Additions to property, plant and equipment	—			(105,564		)	(22,172		)	—			(127,736		)
Proceeds from sale and disposal of fixed assets	—			1,625			3,750			—			5,375
Acquisitions, net of cash acquired	—			(11,427		)	(33,005		)	—			(44,432		)
Proceeds on sale of business, net of transactional costs	—			46,158			181			—			46,339
Additions to intangible assets, including costs to obtain or renew permits	—			(1,018		)	(330		)	—			(1,348		)
Proceeds from sale of investments	376			—			—			—			376
Intercompany	—			(27,740		)	—			27,740			—
Intercompany debt	—			—			3,701			(3,701		)	—
Net cash from (used in) investing activities	376			(97,966		)	(47,875		)	24,039			(121,426		)

Cash flows used in financing activities:
Change in uncashed checks	—			(6,140		)	(2,517		)	—			(8,657		)
Proceeds from exercise of stock options	46			—			—			—			46
Issuance of restricted shares, net of shares remitted	(2,321		)	—			—			—			(2,321		)
Repurchases of common stock	(24,465		)	—			—			—			(24,465		)
Deferred financing costs paid	(5,746		)	—			—			—			(5,746		)
Premiums paid on early extinguishment of debt	(6,028		)	—			—			—			(6,028		)
Principal payment on debt	(401,000		)	—			—			—			(401,000		)
Issuance of senior secured notes, net of discount	399,000			—			—			—			399,000
Intercompany	27,740			—			—			(27,740		)	—
Intercompany debt	(3,701		)	—			—			3,701			—
Net cash used in financing activities	(16,475		)	(6,140		)	(2,517		)	(24,039		)	(49,171		)
Effect of exchange rate change on cash	—			—			3,789			—			3,789
Increase (decrease) in cash and cash equivalents	97			65,609			(11,045		)	—			54,661
Cash and cash equivalents, beginning of period	51,417			155,943			99,637			—			306,997
Cash and cash equivalents, end of period	$	51,514		$	221,552		$	88,592		$	—		$	361,658

Following is the condensed consolidating statement of cash flows for the nine months ended September 30, 2016 (in thousands):



	Clean Harbors, Inc.			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Consolidating Adjustments			Total
Net cash from operating activities	$	43,033		$	128,182		$	7,612		$	—		$	178,827
Cash flows used in investing activities:
Additions to property, plant and equipment	—			(152,836		)	(22,512		)	—			(175,348		)
Proceeds from sale and disposal of fixed assets	—			950			3,032			—			3,982
Acquisitions, net of cash acquired	—			(197,089		)	(10,000		)	—			(207,089		)
Proceeds on sale of business	—			18,885			28,249			—			47,134
Additions to intangible assets, including costs to obtain or renew permits	—			(949		)	(971		)	—			(1,920		)
Purchases of available-for-sale securities	(102		)	—			(496		)	—			(598		)
Intercompany	—			(18,118		)	—			18,118			—
Investment in subsidiaries	(250,625		)	—			—			250,625			—
Net cash used in investing activities	(250,727		)	(349,157		)	(2,698		)	268,743			(333,839		)

Cash flows from (used in) financing activities:
Change in uncashed checks	—			(6,064		)	(1,020		)	—			(7,084		)
Proceeds from exercise of stock options	230			—			—			—			230
Issuance of restricted shares, net of shares remitted	(2,500		)	—			—			—			(2,500		)
Repurchases of common stock	(15,869		)	—			—			—			(15,869		)
Excess tax benefit of stock-based compensation	21			—			—			—			21
Deferred financing costs paid	(2,614		)	—			—			—			(2,614		)
Issuance of senior unsecured notes, including premium	250,625			250,625			—			(250,625		)	250,625
Intercompany	18,118			—			—			(18,118		)	—
Intercompany debt	—			63,118			(63,118		)	—			—
Net cash from (used in) financing activities	248,011			307,679			(64,138		)	(268,743		)	222,809
Effect of exchange rate change on cash	—			—			5,352			—			5,352
Increase (decrease) in cash and cash equivalents	40,317			86,704			(53,872		)	—			73,149
Cash and cash equivalents, beginning of period	11,017			83,479			90,212			—			184,708
Cash and cash equivalents, end of period	$	51,334		$	170,183		$	36,340		$	—		$	257,857

SIGNIFICANT ACCOUNTING POLICIES (Policies)	9 Months Ended
SIGNIFICANT ACCOUNTING POLICIES (Policies)	Sep. 30, 2017
Accounting Policies [Abstract]
Reclassifications	As disclosed in the Company's Annual Report on Form 10-K for the year ended December 31, 2016, in the fourth quarter of 2016 the Company changed the manner in which it manages its business, makes operating decisions and assesses the Company's performance. The Company's operations are now managed in six operating segments: Technical Services, Industrial Services, Field Services, Safety-Kleen, Oil and Gas Field Services and Lodging Services. For purposes of segment disclosure the Industrial Services and Field Services operating segments have been aggregated into a single reportable segment based upon their similar economic and other characteristics, and the Oil and Gas Field Services and Lodging Services operating segments have been combined as they do not meet the quantitative thresholds for separate presentation. The amounts presented for the three and nine months ended September 30, 2016 have been recast to reflect the impact of such changes. These reclassifications and adjustments had no effect on consolidated statements of operations, consolidated statements of comprehensive income (loss), consolidated statements of cash flows or consolidated statements of stockholders' equity for any of the periods presented.
Recent Accounting Pronouncements	In July 2015, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2015-11, Inventory (Topic 330). The amendment provides guidance regarding the measurement of inventory. Entities should measure inventory within the scope of this update at the lower of cost and net realizable value. The adoption of ASU 2015-11 was applied prospectively and as of January 1, 2017 did not have an impact on the Company's consolidated financial statements. In March 2016, the FASB issued ASU 2016-09, Compensation-Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting. The amendment simplifies several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities and classification on the statement of cash flows. Stock-based compensation excess tax benefits or deficiencies are now reflected in the Consolidated Statements of Operations as a component of the provision for income taxes, whereas they previously were recognized in equity. Additionally, the Consolidated Statements of Cash Flows now include excess tax benefits as an operating activity. Previously, income tax benefits at settlement of an award were reported as a reduction to operating cash flows and an increase to financing cash flows to the extent that those benefits exceeded the income tax benefits reported in earnings during the award's vesting period. The Company has elected to apply that change in cash flow classification on a prospective basis, leaving previously reported net cash from operating activities and net cash from financing activities in the accompanying consolidated statement of cash flows for the period ended September 30, 2016 unchanged. Finally, the Company has elected to account for forfeitures as they occur, rather than estimate expected forfeitures. As a result of the adoption of this update, the Company recorded a cumulative-effect adjustment that reduced beginning retained earnings by $0.5 million, net of tax. In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments (a consensus of the Emerging Issues Task Force). The amendment provides updated guidance on eight specific cash flow issues, including debt prepayment or debt extinguishment costs, settlement of zero-coupon debt instruments, contingent consideration payments made after a business combination, proceeds from settlement of insurance claims and corporate-owned life insurance, distributions received from equity method investees, beneficial interests in securitization transactions and separately identifiable cash flows and application of the predominance principle. The Company early adopted the amendments in the Update on a retrospective basis in the second quarter of fiscal year 2017. As a result of adoption, the Company has recorded cash paid in the second and third quarters of 2017 for debt prepayment and extinguishment costs as financing activities in the accompanying consolidated statements of cash flows. Standard to be implemented In May 2014, FASB issued ASU 2014-09, Revenue from Contracts with Customers (Topic 606). ASU 2014-09 outlines a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersedes most current revenue recognition guidance, including industry-specific guidance. In August 2015, FASB issued ASU 2015-14 which deferred the effective date of ASU 2014-09 for all entities by one year. In March 2016, FASB issued ASU 2016-08, which reduces the potential for diversity in practice arising from inconsistent application of the principal versus agent guidance, as well as the cost and complexity of applying Topic 606 both at transition and on an ongoing basis. In April 2016, FASB issued ASU 2016-10, which reduces the potential for diversity in initial application, as well as the cost and complexity of applying Topic 606 both at transition and on an ongoing basis. In May 2016, FASB issued ASU 2016-12, which provided narrow scope improvements and practical expedients on assessing collectability, presentation of sales taxes, noncash consideration, and completed contracts and contract modifications at transition. ASU 2014-09 is currently effective for annual reporting periods (including interim reporting periods within those periods) beginning after December 15, 2017. The guidance permits two methods of adoption: retrospectively to each prior reporting period presented (full retrospective method), or retrospectively with the cumulative effect of initially applying the guidance recognized at the date of initial application (the cumulative catch-up transition method). The Company expects that it will adopt ASU 2014‑09 beginning in the first quarter of 2018 and continues its evaluation of the impact of the new standard on its accounting policies, disclosures, processes, and system requirements. The Company has assigned internal resources to assist in this implementation project and believes that the project is progressing timely. The Company currently anticipates adopting this ASU using the modified retrospective method. While the Company’s impact assessment is not yet complete, based on the results of its work to date, it currently does not expect the application of the new standard to have a material impact to its consolidated financial statement results. As the Company completes its evaluation of this new standard, the Company's preliminary assessments could change. In October 2016, the FASB issued ASU 2016-16, Income Tax - Intra-Entity Transfers of Assets Other than Inventory. The amendment improves the accounting for the income tax consequences of intra-entity transfers of assets other than inventory. The amendment should be applied using a modified retrospective basis and are effective for annual reporting periods (including interim reporting periods within those periods) beginning after December 15, 2017. The Company is currently in the process of evaluating the impact of adoption on its consolidated financial statements. In February 2017, the FASB issued ASU 2017-05, Other Income-Gains and Losses from the Derecognition of Nonfinancial Assets (Subtopic 610-20): Clarifying the Scope of Asset Derecognition Guidance and Accounting for Partial Sales of Nonfinancial Assets. The amendment is meant to clarify the scope of ASC Subtopic 610-20, Other Income-Gains and Losses from the Derecognition of Nonfinancial Assets and to add guidance for partial sales of nonfinancial assets. The amendment should be applied using a full retrospective method or a modified retrospective method and are effective at the same time as ASU 2014-09. Further, the Company is required to adopt ASU 2017-05 at the same time that it adopts the guidance in ASU 2014-09. Adoption is not expected to have a material impact on the Company's consolidated financial statements. In May 2017, the FASB issued ASU 2017-09, Compensation-Stock Compensation (Topic 718): Scope of Modification Accounting. The amendment is meant to provide guidance about which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting in Topic 718. The amendment should be applied prospectively to an award modified on or after the adoption date and are effective for annual reporting periods (including interim reporting periods within those periods) beginning after December 15, 2017. Adoption is not expected to have a material impact on the Company's consolidated financial statements.

BUSINESS COMBINATIONS (Tables)

9 Months Ended

Sep. 30, 2017

Business Combinations [Abstract]

Schedule of Business Acquisitions, by Acquisition

The components and allocation of the purchase price consist of the following amounts (in thousands):



	At Acquisition Dates As Reported December 31, 2016			Measurement Period Adjustments			Final Allocations
Accounts receivable	$	15,767		$	475		$	16,242
Inventories and supplies	12,515			173			12,688
Prepaid expenses and other current assets	777			(25		)	752
Property, plant and equipment	143,025			891			143,916
Permits and other intangibles	28,856			—			28,856
Current liabilities	(20,258		)	353			(19,905		)
Closure and post-closure liabilities	(2,408		)	(596		)	(3,004		)
Remedial liabilities, less current portion	(2,041		)	(504		)	(2,545		)
Deferred taxes, unrecognized tax benefits and other long-term liabilities	(17,019		)	(3,200		)	(20,219		)
Total identifiable net assets	159,214			(2,433		)	156,781
Goodwill	45,791			2,186			47,977
Total purchase price, net of cash acquired	$	205,005		$	(247	)	$	204,758

DISPOSITION OF BUSINESSES (Tables)

9 Months Ended

Sep. 30, 2017

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Disposition of Business

The following table presents the carrying amounts of the Company's Transformer Services business that was disposed of on June 30, 2017 (in thousands):



	June 30, 2017
Total current assets	$	7,241
Property, plant and equipment, net	8,773
Total other assets	1,681
Total assets divested	$	17,695
Total current liabilities	3,849
Total other liabilities	1,170
Total liabilities divested	$	5,019
Net carrying value divested	$	12,676

Transformer Services

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Disposition of Business

The following table presents income attributable to the Transformer Services business included in the Company's consolidated results of operations for each of the periods shown and through its disposition on June 30, 2017 (in thousands):



	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2017		2016		2017		2016
Income before provision for income taxes	$	—	$	318	$	2,771	$	2,111

Catalyst Services

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Disposition of Business



	Three Months Ended			Nine Months Ended
	September 30, 2016			September 30, 2016
(Loss) income before provision for income taxes	$	(1,218	)	$	290

- Definition

Tabular disclosure of information related to a disposal group. Includes, but is not limited to, a discontinued operation, disposal classified as held-for-sale or disposed of by means other than sale or disposal of an individually significant component.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 45
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=65878427&loc=SL51721533-107759

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 4B
-URI http://asc.fasb.org/extlink&oid=64827811&loc=SL51721665-107760

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=64827811&loc=d3e1474-107760

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=64827811&loc=d3e1361-107760

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=64827811&loc=SL51721683-107760

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 50
-Paragraph 3A
-URI http://asc.fasb.org/extlink&oid=84176398&loc=SL51724579-110230

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 5C
-URI http://asc.fasb.org/extlink&oid=64827811&loc=SL51721675-107760

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 4A
-URI http://asc.fasb.org/extlink&oid=64827811&loc=SL51721663-107760

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=84176398&loc=d3e2941-110230

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 5B
-URI http://asc.fasb.org/extlink&oid=64827811&loc=SL51721673-107760

Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 3A
-URI http://asc.fasb.org/extlink&oid=64827811&loc=SL51721659-107760

Reference 12: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 5A
-URI http://asc.fasb.org/extlink&oid=64827811&loc=SL51721671-107760

Reference 13: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 5D
-URI http://asc.fasb.org/extlink&oid=64827811&loc=SL51721677-107760

+ Details

INVENTORIES AND SUPPLIES (Tables)

9 Months Ended

Sep. 30, 2017

Inventory Disclosure [Abstract]

Schedule of Inventory

Inventories and supplies consisted of the following (in thousands):



	September 30, 2017		December 31, 2016
Oil and oil products	$	57,602	$	52,158
Supplies and drums	93,654		90,610
Solvent and solutions	8,680		8,566
Modular camp accommodations	1,945		15,255
Other	11,216		11,839
Total inventories and supplies	$	173,097	$	178,428

PROPERTY, PLANT AND EQUIPMENT (Tables)

9 Months Ended

Sep. 30, 2017

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment

Property, plant and equipment consisted of the following (in thousands):



	September 30, 2017		December 31, 2016
Land	$	121,806	$	120,575
Asset retirement costs (non-landfill)	14,905		14,567
Landfill assets	143,503		139,708
Buildings and improvements	411,006		373,160
Camp equipment	171,163		152,740
Vehicles	613,767		541,022
Equipment	1,628,256		1,483,736
Furniture and fixtures	5,586		5,492
Construction in progress	52,523		146,904
	3,162,515		2,977,904
Less - accumulated depreciation and amortization	1,550,544		1,366,077
Total property, plant and equipment, net	$	1,611,971	$	1,611,827

GOODWILL AND OTHER INTANGIBLE ASSETS (Tables)

9 Months Ended

Sep. 30, 2017

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of changes to goodwill

The changes in goodwill by segment for the nine months ended September 30, 2017 were as follows (in thousands):



	Technical Services			Industrial & Field Services		Safety-Kleen		Oil, Gas and Lodging Services		Totals
Balance at January 1, 2017	$	61,116		$	107,968	$	296,070	$	—	$	465,154
Increase from current period acquisitions	—			2,999		5,613		—		8,612
Measurement period adjustments from prior period acquisitions	—			—		2,186		—		2,186
Decrease from disposition of business	(1,300		)	—		—		—		(1,300		)
Foreign currency translation and other	338			1,398		2,340		—		4,076
Balance at September 30, 2017	$	60,154		$	112,365	$	306,209	$	—	$	478,728

Summary of indefinite-lived intangible assets

As of September 30, 2017 and December 31, 2016, the Company's total finite-lived and indefinite-lived intangible assets consisted of the following (in thousands):



	September 30, 2017							December 31, 2016
	Cost		Accumulated Amortization		Net		Weighted Average Remaining Amortization Period (in years)	Cost		Accumulated Amortization		Net		Weighted Average Remaining Amortization Period (in years)
Permits	$	174,571	$	72,788	$	101,783	21.2	$	171,637	$	67,301	$	104,336	18.9
Customer and supplier relationships	398,778		151,744		247,034		11.5	393,426		127,462		265,964		12.2
Other intangible assets	36,077		31,414		4,663		7.3	34,254		28,456		5,798		7.1
Total amortizable permits and other intangible assets	609,426		255,946		353,480		14.2	599,317		223,219		376,098		13.9
Trademarks and trade names	124,159		—		124,159		Indefinite	122,623		—		122,623		Indefinite
Total permits and other intangible assets	$	733,585	$	255,946	$	477,639		$	721,940	$	223,219	$	498,721

Schedule of finite-lived intangible assets

As of September 30, 2017 and December 31, 2016, the Company's total finite-lived and indefinite-lived intangible assets consisted of the following (in thousands):



	September 30, 2017							December 31, 2016
	Cost		Accumulated Amortization		Net		Weighted Average Remaining Amortization Period (in years)	Cost		Accumulated Amortization		Net		Weighted Average Remaining Amortization Period (in years)
Permits	$	174,571	$	72,788	$	101,783	21.2	$	171,637	$	67,301	$	104,336	18.9
Customer and supplier relationships	398,778		151,744		247,034		11.5	393,426		127,462		265,964		12.2
Other intangible assets	36,077		31,414		4,663		7.3	34,254		28,456		5,798		7.1
Total amortizable permits and other intangible assets	609,426		255,946		353,480		14.2	599,317		223,219		376,098		13.9
Trademarks and trade names	124,159		—		124,159		Indefinite	122,623		—		122,623		Indefinite
Total permits and other intangible assets	$	733,585	$	255,946	$	477,639		$	721,940	$	223,219	$	498,721

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, 2017 was as follows (in thousands):



Years Ending December 31,	Expected Amortization
2017 (three months)	$	9,039
2018	34,463
2019	31,521
2020	29,206
2021	26,747
Thereafter	222,504
	$	353,480

CLOSURE AND POST-CLOSURE LIABILITIES (Tables)

9 Months Ended

Sep. 30, 2017

Asset Retirement Obligation Disclosure [Abstract]

Schedule of closure and post-closure liabilities

The changes to closure and post-closure liabilities (also referred to as “asset retirement obligations”) from January 1, 2017 through September 30, 2017 were as follows (in thousands):



	Landfill Retirement Liability			Non-Landfill Retirement Liability			Total
Balance at January 1, 2017	$	30,630		$	27,701		$	58,331
Liabilities assumed in acquisitions	—			27			27
Measurement period adjustments from prior period acquisitions	—			596			596
New asset retirement obligations	1,376			—			1,376
Adjustment related to disposition of business	—			(1,170		)	(1,170		)
Accretion	1,658			1,882			3,540
Changes in estimates recorded to statement of operations	(131		)	(126		)	(257		)
Changes in estimates recorded to balance sheet	—			(284		)	(284		)
Expenditures	(2,269		)	(352		)	(2,621		)
Currency translation and other	182			119			301
Balance at September 30, 2017	$	31,446		$	28,393		$	59,839

REMEDIAL LIABILITIES (Tables)

9 Months Ended

Sep. 30, 2017

Environmental Remediation Obligations [Abstract]

Changes to remedial liabilities

The changes to remedial liabilities for the nine months ended September 30, 2017 were as follows (in thousands):



	Remedial Liabilities for Landfill Sites			Remedial Liabilities for Inactive Sites			Remedial Liabilities (Including Superfund) for Non-Landfill Operations			Total
Balance at January 1, 2017	$	1,777		$	64,151		$	62,079		$	128,007
Measurement period adjustments from prior period acquisitions	—			—			504			504
Accretion	64			1,976			1,473			3,513
Changes in estimates recorded to statement of operations	(34		)	(277		)	256			(55		)
Expenditures	(30		)	(3,099		)	(4,328		)	(7,457		)
Currency translation and other	(1		)	2,742			(1,740		)	1,001
Balance at September 30, 2017	$	1,776		$	65,493		$	58,244		$	125,513

FINANCING ARRANGEMENTS (Tables)

9 Months Ended

Sep. 30, 2017

Debt Disclosure [Abstract]

Summary of the entity's financial arrangements

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



	September 30, 2017			December 31, 2016
Senior secured notes due June 30, 2024 ("Term Loan"), current	$	4,000		$	—
Current portion of long-term obligations, at carrying value	$	4,000		$	—

Senior secured notes due June 30, 2024	$	395,000		$	—
Senior unsecured notes, at 5.25%, due August 1, 2020 ("2020 Notes")	400,000			800,000
Senior unsecured notes, at 5.125%, due June 1, 2021 ("2021 Notes")	845,000			845,000
Long-term obligations	$	1,640,000		$	1,645,000
Unamortized debt issuance costs and debt discount/premium, net	(14,029		)	(11,728		)
Long-term obligations, at carrying value	$	1,625,971		$	1,633,272

Total current and long-term obligations, at carrying value	$	1,629,971		$	1,633,272

- 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://www.xbrl.org/2003/role/presentationRef
-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://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21475-112644

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-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 4: http://www.xbrl.org/2003/role/presentationRef
-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://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21538-112644

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21506-112644

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28541-108399

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21521-112644

+ Details

EARNINGS (LOSS) PER SHARE (Tables)

9 Months Ended

Sep. 30, 2017

Earnings Per Share [Abstract]

Reconciliation of basic and diluted earnings per share computations

The following are computations of basic and diluted earnings (loss) per share (in thousands except for per share amounts):



	Three Months Ended					Nine Months Ended
	September 30,					September 30,
	2017		2016			2017		2016
Numerator for basic and diluted earnings (loss) per share:
Net income (loss)	$	12,058	$	(10,255	)	$	16,545	$	(27,160	)

Denominator:
Basic shares outstanding	57,033		57,487			57,149		57,575
Dilutive effect of equity-based compensation awards	162		—			131		—
Dilutive shares outstanding	57,195		57,487			57,280		57,575

Basic earnings (loss) per share:	$	0.21	$	(0.18	)	$	0.29	$	(0.47	)

Diluted earnings (loss) per share:	$	0.21	$	(0.18	)	$	0.29	$	(0.47	)

ACCUMULATED OTHER COMPREHENSIVE LOSS (Tables)

9 Months Ended

Sep. 30, 2017

Equity [Abstract]

Schedule of accumulated other comprehensive loss

The changes in accumulated other comprehensive loss by component and related tax effects for the nine months ended September 30, 2017 were as follows (in thousands):



	Foreign Currency Translation			Unrealized (Losses) Gains on Available-For-Sale Securities			Unfunded Pension Liability			Total
Balance at January 1, 2017	$	(212,211	)	$	(321	)	$	(1,794	)	$	(214,326	)
Other comprehensive income before reclassifications	44,545			299			—			44,844
Amounts reclassified out of accumulated other comprehensive loss	—			222			—			222
Tax effects	—			(208		)	—			(208		)
Other comprehensive income	$	44,545		$	313		$	—		$	44,858
Balance at September 30, 2017	$	(167,666	)	$	(8	)	$	(1,794	)	$	(169,468	)

Reclassification out of accumulated other comprehensive loss



	For the Three Months Ended		For the Nine Months Ended
Comprehensive (Loss) Income Components	September 30, 2017		September 30, 2017		Location
Unrealized holding gains on available-for-sale investments	$	—	$	222	Other expense

STOCK-BASED COMPENSATION (Tables)

9 Months Ended

Sep. 30, 2017

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Summary of restricted stock awards

The following table summarizes information about restricted stock awards for the nine months ended September 30, 2017:



Restricted Stock	Number of Shares		Weighted Average Grant-Date Fair Value
Balance at January 1, 2017	510,041		$	52.65
Granted	295,568		$	56.00
Vested	(115,365	)	$	53.89
Forfeited	(47,784	)	$	51.35
Balance at September 30, 2017	642,460		$	54.07

Summary of performance stock awards

The following table summarizes information about performance stock awards for the nine months ended September 30, 2017:



Performance Stock	Number of Shares		Weighted Average Grant-Date Fair Value
Balance at January 1, 2017	220,882		$	54.69
Granted	167,964		$	55.84
Vested	(25,168	)	$	54.84
Forfeited	(25,544	)	$	56.19
Balance at September 30, 2017	338,134		$	55.25

SEGMENT REPORTING (Tables)

9 Months Ended

Sep. 30, 2017

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, 2017 and 2016 (in thousands):



	For the Three Months Ended September 30, 2017											For the Three Months Ended September 30, 2016
	Third party revenues		Intersegment revenues, net			Corporate Items, net			Direct revenues			Third party revenues		Intersegment revenues, net			Corporate Items, net			Direct revenues
Technical Services	$	246,329	$	41,366		$	637		$	288,332		$	232,482	$	38,795		$	492		$	271,769
Industrial and Field Services	163,808		(10,262		)	45			153,591			172,191		(10,867		)	(32		)	161,292
Safety-Kleen	315,028		(31,757		)	3			283,274			297,082		(28,716		)	1			268,367
Oil, Gas and Lodging Services	30,026		653			79			30,758			27,644		788			105			28,537
Corporate Items	655		—			(764		)	(109		)	121		—			(566		)	(445		)
Total	$	755,846	$	—		$	—		$	755,846		$	729,520	$	—		$	—		$	729,520



	For the Nine Months Ended September 30, 2017											For the Nine Months Ended September 30, 2016
	Third party revenues		Intersegment revenues, net			Corporate Items, net			Direct revenues			Third party revenues		Intersegment revenues, net			Corporate Items, net			Direct revenues
Technical Services	$	731,034	$	121,411		$	1,767		$	854,212		$	680,717	$	109,217		$	1,547		$	791,481
Industrial and Field Services	465,264		(27,688		)	16			437,592			467,019		(25,464		)	(348		)	441,207
Safety-Kleen	910,885		(95,465		)	4			815,424			821,758		(86,329		)	368			735,797
Oil, Gas and Lodging Services	89,403		1,742			218			91,363			91,555		2,576			288			94,419
Corporate Items	989		—			(2,005		)	(1,016		)	2,064		—			(1,855		)	209
Total	$	2,197,575	$	—		$	—		$	2,197,575		$	2,063,113	$	—		$	—		$	2,063,113

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,
	2017			2016			2017			2016
Adjusted EBITDA:
Technical Services	$	72,338		$	72,333		$	203,906		$	201,622
Industrial and Field Services	13,255			18,234			36,652			38,627
Safety-Kleen	70,305			70,053			182,953			165,342
Oil, Gas and Lodging Services	912			24			969			135
Corporate Items	(33,811		)	(33,993		)	(100,655		)	(101,310		)
Total	$	122,999		$	126,651		$	323,825		$	304,416
Reconciliation to Consolidated Statements of Operations:
Accretion of environmental liabilities	2,347			2,476			7,053			7,529
Depreciation and amortization	72,989			73,360			216,932			215,655
Goodwill impairment charge	—			34,013			—			34,013
Income from operations	47,663			16,802			99,840			47,219
Other expense	432			198			2,814			737
Loss on early extinguishment of debt	1,846			—			7,891			—
Loss (gain) on sale of business	77			(16,431		)	(31,645		)	(16,431		)
Interest expense, net of interest income	20,675			21,565			65,743			62,192
Income before provision for income taxes	$	24,633		$	11,470		$	55,037		$	721

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, 2017
	Technical Services		Industrial and Field Services		Safety-Kleen		Oil, Gas and Lodging Services		Corporate Items		Totals
Property, plant and equipment, net	$	507,069	$	264,662	$	585,493	$	177,106	$	77,641	$	1,611,971
Goodwill	60,154		112,365		306,209		—		—		478,728
Permits and other intangibles, net	75,260		17,139		377,458		7,782		—		477,639
Total assets	$	848,578	$	485,297	$	1,475,764	$	239,308	$	699,406	$	3,748,353



	December 31, 2016
	Technical Services		Industrial and Field Services		Safety-Kleen		Oil, Gas and Lodging Services		Corporate Items		Totals
Property, plant and equipment, net	$	521,134	$	245,143	$	584,647	$	182,038	$	78,865	$	1,611,827
Goodwill	61,116		107,968		296,070		—		—		465,154
Permits and other intangibles, net	78,625		17,817		391,390		10,889		—		498,721
Total assets	$	862,957	$	446,826	$	1,474,755	$	253,242	$	644,140	$	3,681,920

Total assets by geographical area

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



	September 30, 2017		December 31, 2016
United States	$	3,005,644	$	2,960,337
Canada	742,709		721,583
Total	$	3,748,353	$	3,681,920

GUARANTOR AND NON-GUARANTOR SUBSIDIARIES FINANCIAL INFORMATION (Tables)

9 Months Ended

Sep. 30, 2017

Guarantor and Non-Guarantor Subsidiaries Financial Information [Abstract]

Schedule of condensed consolidating balance sheet

Following is the condensed consolidating balance sheet at September 30, 2017 (in thousands):



	Clean Harbors, Inc.		Guarantor Subsidiaries		Non-Guarantor Subsidiaries		Consolidating Adjustments			Total
Assets:
Cash and cash equivalents	$	51,514	$	221,552	$	88,592	$	—		$	361,658
Intercompany receivables	230,084		451,146		38,451		(719,681		)	—
Accounts receivables, net	—		435,058		96,638		—			531,696
Other current assets	897		215,847		51,871		(1,711		)	266,904
Property, plant and equipment, net	—		1,182,922		429,049		—			1,611,971
Investments in subsidiaries	2,933,843		585,660		—		(3,519,503		)	—
Intercompany debt receivable	—		92,938		21,000		(113,938		)	—
Goodwill	—		415,056		63,672		—			478,728
Permits and other intangibles, net	—		415,708		61,931		—			477,639
Other long-term assets	2,448		13,312		5,065		(1,068		)	19,757
Total assets	$	3,218,786	$	4,029,199	$	856,269	$	(4,355,901	)	$	3,748,353
Liabilities and Stockholders’ Equity:
Current liabilities	$	22,595	$	385,734	$	122,922	$	(1,711	)	$	529,540
Intercompany payables	441,873		266,776		11,032		(719,681		)	—
Closure, post-closure and remedial liabilities, net	—		148,791		17,045		—			165,836
Long-term obligations	1,625,971		—		—		—			1,625,971
Intercompany debt payable	—		21,000		92,938		(113,938		)	—
Other long-term liabilities	—		278,700		21,027		(1,068		)	298,659
Total liabilities	2,090,439		1,101,001		264,964		(836,398		)	2,620,006
Stockholders’ equity	1,128,347		2,928,198		591,305		(3,519,503		)	1,128,347
Total liabilities and stockholders’ equity	$	3,218,786	$	4,029,199	$	856,269	$	(4,355,901	)	$	3,748,353

Following is the condensed consolidating balance sheet at December 31, 2016 (in thousands):



	Clean Harbors, Inc.		Guarantor Subsidiaries		Non-Guarantor Subsidiaries		Consolidating Adjustments			Total
Assets:
Cash and cash equivalents	$	51,417	$	155,943	$	99,637	$	—		$	306,997
Intercompany receivables	200,337		354,836		49,055		(604,228		)	—
Accounts receivables, net	—		417,029		79,197		—			496,226
Other current assets	3,096		234,408		69,257		(17,113		)	289,648
Property, plant and equipment, net	—		1,211,210		400,617		—			1,611,827
Investments in subsidiaries	2,851,571		580,124		—		(3,431,695		)	—
Intercompany debt receivable	—		86,409		24,701		(111,110		)	—
Goodwill	—		412,638		52,516		—			465,154
Permits and other intangibles, net	—		435,594		63,127		—			498,721
Other long-term assets	2,446		7,582		4,387		(1,068		)	13,347
Total assets	$	3,108,867	$	3,895,773	$	842,494	$	(4,165,214	)	$	3,681,920
Liabilities and Stockholders’ Equity:
Current liabilities	$	21,805	$	366,831	$	133,145	$	(17,113	)	$	504,668
Intercompany payables	365,848		237,058		1,322		(604,228		)	—
Closure, post-closure and remedial liabilities, net	—		150,682		15,640		—			166,322
Long-term obligations	1,633,272		—		—		—			1,633,272
Intercompany debt payable	3,701		21,000		86,409		(111,110		)	—
Other long-term liabilities	—		275,649		18,836		(1,068		)	293,417
Total liabilities	2,024,626		1,051,220		255,352		(733,519		)	2,597,679
Stockholders’ equity	1,084,241		2,844,553		587,142		(3,431,695		)	1,084,241
Total liabilities and stockholders’ equity	$	3,108,867	$	3,895,773	$	842,494	$	(4,165,214	)	$	3,681,920

Schedule of condensed consolidating statement of income

Following is the consolidating statement of operations for the three months ended September 30, 2017 (in thousands):



	Clean Harbors, Inc.			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Consolidating Adjustments			Total
Revenues
Service revenues	$	—		$	473,428		$	152,997		$	(14,073	)	$	612,352
Product revenues	—			127,355			19,435			(3,296		)	143,494
Total revenues	—			600,783			172,432			(17,369		)	755,846
Cost of revenues (exclusive of items shown separately below)
Service cost of revenues	—			306,291			120,151			(14,073		)	412,369
Product cost of revenues	—			97,353			13,169			(3,296		)	107,226
Total cost of revenues	—			403,644			133,320			(17,369		)	519,595
Selling, general and administrative expenses	19			92,299			20,934			—			113,252
Accretion of environmental liabilities	—			2,092			255			—			2,347
Depreciation and amortization	—			50,917			22,072			—			72,989
(Loss) income from operations	(19		)	51,831			(4,149		)	—			47,663
Other expense	—			(305		)	(127		)	—			(432		)
Loss on early extinguishment of debt	(1,846		)	—			—			—			(1,846		)
Loss on sale of business	—			(77		)	—			—			(77		)
Interest (expense) income	(21,135		)	517			(57		)	—			(20,675		)
Equity in earnings of subsidiaries, net of taxes	25,858			(5,620		)	—			(20,238		)	—
Intercompany interest income (expense)	—			1,372			(1,372		)	—			—
Income (loss) before (benefit) provision for income taxes	2,858			47,718			(5,705		)	(20,238		)	24,633
(Benefit) provision for income taxes	(9,200		)	20,824			951			—			12,575
Net income (loss)	12,058			26,894			(6,656		)	(20,238		)	12,058
Other comprehensive income	23,709			23,709			20,263			(43,972		)	23,709
Comprehensive income	$	35,767		$	50,603		$	13,607		$	(64,210	)	$	35,767

Following is the consolidating statement of operations for the three months ended September 30, 2016 (in thousands):



	Clean Harbors, Inc.			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Consolidating Adjustments			Total
Revenues
Service revenues	$	—		$	461,139		$	145,780		$	(12,694	)	$	594,225
Product revenues	—			118,106			20,072			(2,883		)	135,295
Total revenues	—			579,245			165,852			(15,577		)	729,520
Cost of revenues (exclusive of items shown separately below)
Service cost of revenues	(598		)	288,764			110,070			(12,694		)	385,542
Product cost of revenues	—			94,050			15,206			(2,883		)	106,373
Total cost of revenues	(598		)	382,814			125,276			(15,577		)	491,915
Selling, general and administrative expenses	23			88,652			22,279			—			110,954
Accretion of environmental liabilities	—			2,243			233			—			2,476
Depreciation and amortization	—			51,957			21,403			—			73,360
Goodwill impairment charge	—			—			34,013			—			34,013
Income (loss) from operations	575			53,579			(37,352		)	—			16,802
Other expense	—			(188		)	(10		)	—			(198		)
Gain on sale of business	—			1,288			15,143			—			16,431
Interest (expense) income	(23,042		)	1,456			21			—			(21,565		)
Equity in earnings of subsidiaries, net of taxes	3,225			(22,341		)	—			19,116			—
Intercompany interest income (expense)	—			5,235			(5,235		)	—			—
(Loss) income before (benefit) provision for income taxes	(19,242		)	39,029			(27,433		)	19,116			11,470
(Benefit) provision for income taxes	(8,987		)	35,803			(5,091		)	—			21,725
Net (loss) income	(10,255		)	3,226			(22,342		)	19,116			(10,255		)
Other comprehensive loss	(1,311		)	(1,311		)	(3,927		)	5,238			(1,311		)
Comprehensive (loss) income	$	(11,566	)	$	1,915		$	(26,269	)	$	24,354		$	(11,566	)

Following is the consolidating statement of operations for the nine months ended September 30, 2017 (in thousands):



	Clean Harbors, Inc.			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Consolidating Adjustments			Total
Revenues
Service revenues	$	—		$	1,391,534		$	431,992		$	(40,020	)	$	1,783,506
Product revenues	—			369,864			53,496			(9,291		)	414,069
Total revenues	—			1,761,398			485,488			(49,311		)	2,197,575
Cost of revenues (exclusive of items shown separately below)
Service cost of revenues	—			907,396			348,436			(40,020		)	1,215,812
Product cost of revenues	—			292,503			36,959			(9,291		)	320,171
Total cost of revenues	—			1,199,899			385,395			(49,311		)	1,535,983
Selling, general and administrative expenses	70			276,974			60,723			—			337,767
Accretion of environmental liabilities	—			6,328			725			—			7,053
Depreciation and amortization	—			154,754			62,178			—			216,932
(Loss) income from operations	(70		)	123,443			(23,533		)	—			99,840
Other expense	(222		)	(2,100		)	(492		)	—			(2,814		)
Loss on early extinguishment of debt	(7,891		)	—			—			—			(7,891		)
Gain on sale of business	—			31,645			—			—			31,645
Interest (expense) income	(66,408		)	876			(211		)	—			(65,743		)
Equity in earnings of subsidiaries, net of taxes	61,388			(32,776		)	—			(28,612		)	—
Intercompany interest income (expense)	—			3,937			(3,937		)	—			—
(Loss) income before (benefit) provision for income taxes	(13,203		)	125,025			(28,173		)	(28,612		)	55,037
(Benefit) provision for income taxes	(29,748		)	62,442			5,798			—			38,492
Net income (loss)	16,545			62,583			(33,971		)	(28,612		)	16,545
Other comprehensive income	44,858			44,858			38,132			(82,990		)	44,858
Comprehensive income	$	61,403		$	107,441		$	4,161		$	(111,602	)	$	61,403

Following is the consolidating statement of operations for the nine months ended September 30, 2016 (in thousands):



	Clean Harbors, Inc.			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Consolidating Adjustments			Total
Revenues
Service revenues	$	—		$	1,345,629		$	399,216		$	(35,827	)	$	1,709,018
Product revenues	—			303,342			58,176			(7,423		)	354,095
Total revenues	—			1,648,971			457,392			(43,250		)	2,063,113
Cost of revenues (exclusive of items shown separately below)
Service cost of revenues	(1,185		)	864,071			321,153			(35,827		)	1,148,212
Product cost of revenues	—			252,512			42,895			(7,423		)	287,984
Total cost of revenues	(1,185		)	1,116,583			364,048			(43,250		)	1,436,196
Selling, general and administrative expenses	84			253,189			69,228			—			322,501
Accretion of environmental liabilities	—			6,846			683			—			7,529
Depreciation and amortization	—			151,348			64,307			—			215,655
Goodwill impairment charge	—			—			34,013			—			34,013
Income (loss) from operations	1,101			121,005			(74,887		)	—			47,219
Other income (expense)	—			124			(861		)	—			(737		)
Gain on sale of business	—			1,288			15,143						16,431
Interest (expense) income	(66,147		)	3,851			104			—			(62,192		)
Equity in earnings of subsidiaries, net of taxes	11,867			(58,031		)	—			46,164			—
Intercompany interest income (expense)	—			15,891			(15,891		)	—			—
(Loss) income before (benefit) provision for income taxes	(53,179		)	84,128			(76,392		)	46,164			721
(Benefit) provision for income taxes	(26,019		)	72,260			(18,360		)	—			27,881
Net (loss) income	(27,160		)	11,868			(58,032		)	46,164			(27,160		)
Other comprehensive income	43,348			43,348			24,403			(67,751		)	43,348
Comprehensive income (loss)	$	16,188		$	55,216		$	(33,629	)	$	(21,587	)	$	16,188

Schedule of condensed consolidating statement of cash flows

Following is the condensed consolidating statement of cash flows for the nine months ended September 30, 2017 (in thousands):



	Clean Harbors, Inc.			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Consolidating Adjustments			Total
Net cash from operating activities	$	16,196		$	169,715		$	35,558		$	—		$	221,469
Cash flows from (used in) investing activities:
Additions to property, plant and equipment	—			(105,564		)	(22,172		)	—			(127,736		)
Proceeds from sale and disposal of fixed assets	—			1,625			3,750			—			5,375
Acquisitions, net of cash acquired	—			(11,427		)	(33,005		)	—			(44,432		)
Proceeds on sale of business, net of transactional costs	—			46,158			181			—			46,339
Additions to intangible assets, including costs to obtain or renew permits	—			(1,018		)	(330		)	—			(1,348		)
Proceeds from sale of investments	376			—			—			—			376
Intercompany	—			(27,740		)	—			27,740			—
Intercompany debt	—			—			3,701			(3,701		)	—
Net cash from (used in) investing activities	376			(97,966		)	(47,875		)	24,039			(121,426		)

Cash flows used in financing activities:
Change in uncashed checks	—			(6,140		)	(2,517		)	—			(8,657		)
Proceeds from exercise of stock options	46			—			—			—			46
Issuance of restricted shares, net of shares remitted	(2,321		)	—			—			—			(2,321		)
Repurchases of common stock	(24,465		)	—			—			—			(24,465		)
Deferred financing costs paid	(5,746		)	—			—			—			(5,746		)
Premiums paid on early extinguishment of debt	(6,028		)	—			—			—			(6,028		)
Principal payment on debt	(401,000		)	—			—			—			(401,000		)
Issuance of senior secured notes, net of discount	399,000			—			—			—			399,000
Intercompany	27,740			—			—			(27,740		)	—
Intercompany debt	(3,701		)	—			—			3,701			—
Net cash used in financing activities	(16,475		)	(6,140		)	(2,517		)	(24,039		)	(49,171		)
Effect of exchange rate change on cash	—			—			3,789			—			3,789
Increase (decrease) in cash and cash equivalents	97			65,609			(11,045		)	—			54,661
Cash and cash equivalents, beginning of period	51,417			155,943			99,637			—			306,997
Cash and cash equivalents, end of period	$	51,514		$	221,552		$	88,592		$	—		$	361,658

Following is the condensed consolidating statement of cash flows for the nine months ended September 30, 2016 (in thousands):



	Clean Harbors, Inc.			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Consolidating Adjustments			Total
Net cash from operating activities	$	43,033		$	128,182		$	7,612		$	—		$	178,827
Cash flows used in investing activities:
Additions to property, plant and equipment	—			(152,836		)	(22,512		)	—			(175,348		)
Proceeds from sale and disposal of fixed assets	—			950			3,032			—			3,982
Acquisitions, net of cash acquired	—			(197,089		)	(10,000		)	—			(207,089		)
Proceeds on sale of business	—			18,885			28,249			—			47,134
Additions to intangible assets, including costs to obtain or renew permits	—			(949		)	(971		)	—			(1,920		)
Purchases of available-for-sale securities	(102		)	—			(496		)	—			(598		)
Intercompany	—			(18,118		)	—			18,118			—
Investment in subsidiaries	(250,625		)	—			—			250,625			—
Net cash used in investing activities	(250,727		)	(349,157		)	(2,698		)	268,743			(333,839		)

Cash flows from (used in) financing activities:
Change in uncashed checks	—			(6,064		)	(1,020		)	—			(7,084		)
Proceeds from exercise of stock options	230			—			—			—			230
Issuance of restricted shares, net of shares remitted	(2,500		)	—			—			—			(2,500		)
Repurchases of common stock	(15,869		)	—			—			—			(15,869		)
Excess tax benefit of stock-based compensation	21			—			—			—			21
Deferred financing costs paid	(2,614		)	—			—			—			(2,614		)
Issuance of senior unsecured notes, including premium	250,625			250,625			—			(250,625		)	250,625
Intercompany	18,118			—			—			(18,118		)	—
Intercompany debt	—			63,118			(63,118		)	—			—
Net cash from (used in) financing activities	248,011			307,679			(64,138		)	(268,743		)	222,809
Effect of exchange rate change on cash	—			—			5,352			—			5,352
Increase (decrease) in cash and cash equivalents	40,317			86,704			(53,872		)	—			73,149
Cash and cash equivalents, beginning of period	11,017			83,479			90,212			—			184,708
Cash and cash equivalents, end of period	$	51,334		$	170,183		$	36,340		$	—		$	257,857

SIGNIFICANT ACCOUNTING POLICIES (Narrative) (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2017 USD ($) segment	Sep. 30, 2016 USD ($)
Accounting Policies [Abstract]
Number of operating segments \| segment	6
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of change in accounting for stock based compensation	$ 231
Accumulated Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of change in accounting for stock based compensation	$ (450)
Accumulated Earnings \| Accounting Standards Updated 2016-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of change in accounting for stock based compensation		$ (500)

BUSINESS COMBINATIONS (2017 Acquisitions) (Details) CAD / shares in Units, $ in Thousands, CAD in Millions					9 Months Ended
	Sep. 22, 2017 USD ($)	Jul. 14, 2017 CAD CAD / shares	Jul. 14, 2017 USD ($)	Jan. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jul. 14, 2017 USD ($)
Business Acquisition [Line Items]
Goodwill recognized					$ 8,612
Washer Machines and Related Equipment
Business Acquisition [Line Items]
Purchase price	$ 2,100
Goodwill recognized	$ 700
Lonestar
Business Acquisition [Line Items]
Goodwill recognized			$ 3,000
Cash paid to acquire Lonestar		CAD 41.8	$ 33,100
Equity payout (in CAD per share) \| CAD / shares		CAD 0.72
Debt outstanding assumed		CAD 21.3				$ 16,800
2017 Acquisitions
Business Acquisition [Line Items]
Purchase price				$ 11,900
Goodwill recognized				$ 4,900

BUSINESS COMBINATIONS (2016 Acquisitions) (Details) - 2016 Acquisitions $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($) rerefinery acquisition
Business Acquisition [Line Items]
Number of acquisitions \| acquisition	7
Number of re-refineries acquired \| rerefinery	3
Purchase price \| $	$ 204.8

BUSINESS COMBINATIONS (Assets Acquired and Liabilities Assumed) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Goodwill	$ 478,728	$ 465,154
2016 Acquisitions
Business Acquisition [Line Items]
Accounts receivable	16,242
Measurement period adjustments, accounts receivable	475
Inventories and supplies	12,688
Measurement period adjustment, inventories and supplies	173
Prepaid and other current assets	752
Measurement period adjustment, prepaid and other current assets	(25)
Property, plant and equipment	143,916
Measurement period adjustments, property, plant and equipment	891
Permits and other intangibles	28,856
Measurement period adjustments, permits and other intangibles	0
Current liabilities	(19,905)
Measurement period adjustments, current liabilities	353
Closure and post-closure liabilities	(3,004)
Measurement period adjustments, closure and post-closure liabilities	(596)
Remedial liabilities, less current portion	(2,545)
Measurement period adjustments, remedial liabilities, less current portion	(504)
Deferred taxes, unrecognized tax benefits and other long-term liabilities	(20,219)
Measurement period adjustments, deferred taxes, unrecognized tax benefits and other long-term liabilities	(3,200)
Total identifiable net assets	156,781
Measurement period adjustments, total identifiable net assets	(2,433)
Goodwill	47,977
Measurement period adjustments, goodwill	2,186
Total purchase price, net of cash acquired	204,758
Measurement period adjustments, total purchase price, net of cash acquired	$ (247)
At Acquisition Dates \| 2016 Acquisitions
Business Acquisition [Line Items]
Accounts receivable		15,767
Inventories and supplies		12,515
Prepaid and other current assets		777
Property, plant and equipment		143,025
Permits and other intangibles		28,856
Current liabilities		(20,258)
Closure and post-closure liabilities		(2,408)
Remedial liabilities, less current portion		(2,041)
Deferred taxes, unrecognized tax benefits and other long-term liabilities		(17,019)
Total identifiable net assets		159,214
Goodwill		45,791
Total purchase price, net of cash acquired		$ 205,005

DISPOSITION OF BUSINESSES (Narrative) (Details) - Transformer Services - USD ($) $ in Millions		9 Months Ended
	Jun. 30, 2017	Sep. 30, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds, net of transactional related costs		$ 44.4
Transactional related costs		2.1
Disposal Group, Disposed of by Sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Final sale proceeds	$ 46.5
Proceeds, net of transactional related costs	44.4
Transactional related costs	$ 2.1
Pre-tax gain		$ 31.6

DISPOSITION OF BUSINESSES (Summary of Carry Amounts of Transformer Services) (Details) - Transformer Services - Disposal Group, Disposed of by Sale, Not Discontinued Operations $ in Thousands	Jun. 30, 2017 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total current assets	$ 7,241
Property, plant and equipment, net	8,773
Total other assets	1,681
Total assets divested	17,695
Total current liabilities	3,849
Total other liabilities	1,170
Total liabilities divested	5,019
Net carrying value divested	$ 12,676

DISPOSITION OF BUSINESSES (Income (Loss) Attributable to Transformer Services) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Transformer Services \| Disposal Group, Disposed of by Sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income before provision for income taxes	$ 0	$ 318	$ 2,771	$ 2,111

DISPOSITION OF BUSINESSES (Income (Loss) Attributable to Catalyst Services) (Details) - Catalyst Services - Disposal Group, Disposed of by Sale, Not Discontinued Operations - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2016	Sep. 30, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Additional final sale proceeds			$ 2,000
Income before provision for income taxes	$ (1,218)	$ 290

INVENTORIES AND SUPPLIES (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
INVENTORIES AND SUPPLIES (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Inventory Disclosure [Abstract]
Oil and oil products		$ 57,602		$ 52,158
Supplies and drums		93,654		90,610
Solvent and solutions		8,680		8,566
Modular camp accommodations		1,945		15,255
Other		11,216		11,839
Total inventories and supplies		173,097		$ 178,428
Transfer of inventory to property, plant and equipment	$ 12,600	$ 12,641	$ 0

PROPERTY, PLANT AND EQUIPMENT (Schedule of Property, Plant and Equipment) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	$ 3,162,515	$ 2,977,904
Less - accumulated depreciation and amortization	1,550,544	1,366,077
Total property, plant and equipment, net	1,611,971	1,611,827
Land
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	121,806	120,575
Asset retirement costs (non-landfill)
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	14,905	14,567
Landfill assets
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	143,503	139,708
Buildings and improvements
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	411,006	373,160
Camp equipment
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	171,163	152,740
Vehicles
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	613,767	541,022
Equipment
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	1,628,256	1,483,736
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	5,586	5,492
Construction in progress
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	$ 52,523	$ 146,904

PROPERTY, PLANT AND EQUIPMENT (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Property, Plant and Equipment [Abstract]
Interest costs capitalized adjustment	$ 0.2	$ 1.5	$ 0.4	$ 4.0
Depreciation inclusive of amortization	$ 64.0	$ 62.6	$ 189.2	$ 185.4

GOODWILL AND OTHER INTANGIBLE ASSETS (Rollforward of Goodwill) (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2017 USD ($)
Goodwill [Roll Forward]
Balance at beginning of year	$ 465,154
Increase from current period acquisitions	8,612
Measurement period adjustments from prior period acquisitions	2,186
Decrease from disposition of business	(1,300)
Foreign currency translation and other	4,076
Balance at end of year	478,728
Technical Services
Goodwill [Roll Forward]
Balance at beginning of year	61,116
Increase from current period acquisitions	0
Measurement period adjustments from prior period acquisitions	0
Decrease from disposition of business	(1,300)
Foreign currency translation and other	338
Balance at end of year	60,154
Industrial and Field Services
Goodwill [Roll Forward]
Balance at beginning of year	107,968
Increase from current period acquisitions	2,999
Measurement period adjustments from prior period acquisitions	0
Decrease from disposition of business	0
Foreign currency translation and other	1,398
Balance at end of year	112,365
Safety-Kleen
Goodwill [Roll Forward]
Balance at beginning of year	296,070
Increase from current period acquisitions	5,613
Measurement period adjustments from prior period acquisitions	2,186
Decrease from disposition of business	0
Foreign currency translation and other	2,340
Balance at end of year	306,209
Oil, Gas and Lodging Services
Goodwill [Roll Forward]
Balance at beginning of year	0
Increase from current period acquisitions	0
Measurement period adjustments from prior period acquisitions	0
Decrease from disposition of business	0
Foreign currency translation and other	0
Balance at end of year	$ 0

GOODWILL AND OTHER INTANGIBLE ASSETS (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization of permits and other intangible assets	$ 8.9	$ 10.8	$ 27.7	$ 30.3

GOODWILL AND OTHER INTANGIBLE ASSETS (Amortizable Other Intangible Assets) (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Schedule of Finite-lived and Indefinite-lived Intangible Assets [Line Items]
Cost	$ 609,426	$ 599,317
Accumulated Amortization	255,946	223,219
Net	$ 353,480	$ 376,098
Weighted Average Remaining Amortization Period (in years)	14 years 2 months 4 days	13 years 9 months 40 days
Total permits and other intangible assets, Cost	$ 733,585	$ 721,940
Total permits and other intangible assets, Net	477,639	498,721
Trademarks and trade names
Schedule of Finite-lived and Indefinite-lived Intangible Assets [Line Items]
Trademarks and trade names	124,159	122,623
Permits
Schedule of Finite-lived and Indefinite-lived Intangible Assets [Line Items]
Cost	174,571	171,637
Accumulated Amortization	72,788	67,301
Net	$ 101,783	$ 104,336
Weighted Average Remaining Amortization Period (in years)	21 years 2 months 4 days	18 years 9 months 40 days
Customer and supplier relationships
Schedule of Finite-lived and Indefinite-lived Intangible Assets [Line Items]
Cost	$ 398,778	$ 393,426
Accumulated Amortization	151,744	127,462
Net	$ 247,034	$ 265,964
Weighted Average Remaining Amortization Period (in years)	11 years 6 months 6 days	12 years 2 months
Other intangible assets
Schedule of Finite-lived and Indefinite-lived Intangible Assets [Line Items]
Cost	$ 36,077	$ 34,254
Accumulated Amortization	31,414	28,456
Net	$ 4,663	$ 5,798
Weighted Average Remaining Amortization Period (in years)	7 years 3 months	7 years 1 month

GOODWILL AND OTHER INTANGIBLE ASSETS (Expected Future Amortization) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
2017 (three months)	$ 9,039
2018	34,463
2019	31,521
2020	29,206
2021	26,747
Thereafter	222,504
Net	$ 353,480	$ 376,098

ACCRUED EXPENSES (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Payables and Accruals [Abstract]
Insurance	$ 59,552	$ 63,061
Interest	18,321	21,536
Accrued compensation and benefits	52,408	34,641
Income, real estate, sales and other taxes	49,892	35,083
Other	33,016	36,400
Total accrued expenses	213,189	190,721
Accrued legal matters	1,000	3,800
Accrued severance charges	$ 1,300	$ 2,900

CLOSURE AND POST-CLOSURE LIABILITIES (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2017 USD ($)
Changes to post-closure liabilities
Beginning balance	$ 58,331
Liabilities assumed in acquisitions	27
Measurement period adjustments from prior period acquisitions	596
New asset retirement obligations	1,376
Adjustment related to disposition of business	(1,170)
Accretion	3,540
Changes in estimates recorded to statement of operations	(257)
Changes in estimates recorded to balance sheet	(284)
Expenditures	(2,621)
Currency translation and other	301
Ending balance	$ 59,839
Credit-adjusted risk-free rate	6.32%
Landfill Retirement Liability
Changes to post-closure liabilities
Beginning balance	$ 30,630
Liabilities assumed in acquisitions	0
Measurement period adjustments from prior period acquisitions	0
New asset retirement obligations	1,376
Adjustment related to disposition of business	0
Accretion	1,658
Changes in estimates recorded to statement of operations	(131)
Changes in estimates recorded to balance sheet	0
Expenditures	(2,269)
Currency translation and other	182
Ending balance	31,446
Non-Landfill Retirement Liability
Changes to post-closure liabilities
Beginning balance	27,701
Liabilities assumed in acquisitions	27
Measurement period adjustments from prior period acquisitions	596
New asset retirement obligations	0
Adjustment related to disposition of business	(1,170)
Accretion	1,882
Changes in estimates recorded to statement of operations	(126)
Changes in estimates recorded to balance sheet	(284)
Expenditures	(352)
Currency translation and other	119
Ending balance	$ 28,393

REMEDIAL LIABILITIES (Details) $ in Thousands	9 Months Ended
REMEDIAL LIABILITIES (Details) $ in Thousands	Sep. 30, 2017 USD ($)
Accrual for Environmental Loss Contingencies [Roll Forward]
Balance at beginning of year	$ 128,007
Measurement period adjustments from prior period acquisitions	504
Accretion	3,513
Changes in estimates recorded to statement of operations	(55)
Expenditures	(7,457)
Currency translation and other	1,001
Balance at end of year	125,513
Remedial Liabilities for Landfill Sites
Accrual for Environmental Loss Contingencies [Roll Forward]
Balance at beginning of year	1,777
Measurement period adjustments from prior period acquisitions	0
Accretion	64
Changes in estimates recorded to statement of operations	(34)
Expenditures	(30)
Currency translation and other	(1)
Balance at end of year	1,776
Remedial Liabilities for Inactive Sites
Accrual for Environmental Loss Contingencies [Roll Forward]
Balance at beginning of year	64,151
Measurement period adjustments from prior period acquisitions	0
Accretion	1,976
Changes in estimates recorded to statement of operations	(277)
Expenditures	(3,099)
Currency translation and other	2,742
Balance at end of year	65,493
Remedial Liabilities (Including Superfund) for Non-Landfill Operations
Accrual for Environmental Loss Contingencies [Roll Forward]
Balance at beginning of year	62,079
Measurement period adjustments from prior period acquisitions	504
Accretion	1,473
Changes in estimates recorded to statement of operations	256
Expenditures	(4,328)
Currency translation and other	(1,740)
Balance at end of year	$ 58,244

FINANCING ARRANGEMENTS (Summary of Financing Arrangements) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Debt Instrument [Line Items]
Current portion of long-term obligations	$ 4,000		$ 4,000		$ 0
Long-term obligations	1,640,000		1,640,000		1,645,000
Unamortized debt issuance costs and debt discount/premium, net	(14,029)		(14,029)		(11,728)
Long-term obligations, at carrying value	1,625,971		1,625,971		1,633,272
Total current and long-term obligations, at carrying value	1,629,971		1,629,971		1,633,272
Service revenues	612,352	$ 594,225	1,783,506	$ 1,709,018
Secured debt \| Term Loan Agreement
Debt Instrument [Line Items]
Current portion of long-term obligations	4,000		4,000		0
Long-term obligations	395,000		395,000		0
Unsecured debt \| Senior unsecured notes, at 5.25%, due August 1, 2020 (2020 Notes)
Debt Instrument [Line Items]
Long-term obligations	$ 400,000		$ 400,000		800,000
Interest rate	5.25%		5.25%
Unsecured debt \| Senior unsecured notes, at 5.125%, due June 1, 2021 (2021 Notes)
Debt Instrument [Line Items]
Long-term obligations	$ 845,000		$ 845,000		$ 845,000
Interest rate	5.125%		5.125%

FINANCING ARRANGEMENTS (Narrative) (Details) - USD ($)		6 Months Ended	9 Months Ended
FINANCING ARRANGEMENTS (Narrative) (Details) - USD ($)	Aug. 01, 2017	Jun. 30, 2017	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Debt Instrument [Line Items]
Premiums to repay debt early			$ 6,028,000	$ 0
Outstanding loan balances			0		$ 0
Available to borrow and outstanding letters of credit			238,300,000		195,200,000
Outstanding letters of credit			124,900,000		132,600,000
Secured debt \| Term Loan Agreement
Debt Instrument [Line Items]
Senior secured credit agreement amount		$ 400,000,000.0	$ 400,000,000.0
Prepayment premium			1.00%
Effective interest rate			3.24%
Debt Instrument, Periodic Payment, Percentage of Face Amount			0.25%
Amount used to repurchase notes		312,600,000
Repurchased amount		296,200,000
Accrued interest paid		6,400,000
Premiums to repay debt early		4,700,000
Expenses incurred from financing		5,300,000
Debt fair value			$ 399,800,000
Unsecured debt \| Senior unsecured notes, at 5.25%, due August 1, 2020 (2020 Notes)
Debt Instrument [Line Items]
Senior secured credit agreement amount		$ 503,800,000
Repurchased amount	$ 103,800,000
Premiums to repay debt early	$ 800,000
Redemption price percentage	101.313%
Early Repayment of Senior Debt	$ 1,300,000
Debt fair value			405,600,000		820,000,000
Unsecured debt \| Senior unsecured notes, at 5.125%, due June 1, 2021 (2021 Notes)
Debt Instrument [Line Items]
Debt fair value			857,800,000		861,900,000
Revolving Credit Facility \| Line of Credit
Debt Instrument [Line Items]
Revolving credit facility maximum borrowing capacity			$ 400,000,000.0		$ 400,000,000
Eurodollar \| Term Loan Agreement
Debt Instrument [Line Items]
Basis spread on variable rate			2.00%
Base Rate \| Term Loan Agreement
Debt Instrument [Line Items]
Basis spread on variable rate			1.00%
Minimum \| Base Rate \| Term Loan Agreement
Debt Instrument [Line Items]
Basis spread on variable rate			0.00%

EARNINGS (LOSS) 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, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Numerator for basic and diluted earnings (loss) per share:
Net income (loss)	$ 12,058	$ (10,255)	$ 16,545	$ (27,160)
Denominator:
Basic shares outstanding (in shares)	57,033	57,487	57,149	57,575
Dilutive effect of equity-based compensation awards (in shares)	162	0	131	0
Dilutive shares outstanding (in shares)	57,195	57,487	57,280	57,575
Basic loss per share (in USD per share)	$ 0.21	$ (0.18)	$ 0.29	$ (0.47)
Diluted loss per share (in USD per share)	$ 0.21	$ (0.18)	$ 0.29	$ (0.47)

EARNINGS (LOSS) PER SHARE (Narrative) (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares excluded from computation of earning per share (in shares)	301,300	835,482
Performance Shares
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares excluded from computation of earning per share (in shares)			301,300
Restricted Stock Units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares excluded from computation of earning per share (in shares)		3,724	19,485

ACCUMULATED OTHER COMPREHENSIVE LOSS (Changes in Accumulated Other Comprehensive Loss by Component) (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2017 USD ($)
Components of Other Accumulated Income, Net of Tax [Roll Forward]
Balance at beginning of period	$ 1,084,241
Other comprehensive income before reclassifications	44,844
Amounts reclassified out of accumulated other comprehensive loss	222
Tax effects	(208)
Other comprehensive income	44,858
Balance at end of period	1,128,347
Foreign Currency Translation
Components of Other Accumulated Income, Net of Tax [Roll Forward]
Balance at beginning of period	(212,211)
Other comprehensive income before reclassifications	44,545
Amounts reclassified out of accumulated other comprehensive loss	0
Tax effects	0
Other comprehensive income	44,545
Balance at end of period	(167,666)
Unrealized (Losses) Gains on Available-For-Sale Securities
Components of Other Accumulated Income, Net of Tax [Roll Forward]
Balance at beginning of period	(321)
Other comprehensive income before reclassifications	299
Amounts reclassified out of accumulated other comprehensive loss	222
Tax effects	(208)
Other comprehensive income	313
Balance at end of period	(8)
Unfunded Pension Liability
Components of Other Accumulated Income, Net of Tax [Roll Forward]
Balance at beginning of period	(1,794)
Other comprehensive income before reclassifications	0
Amounts reclassified out of accumulated other comprehensive loss	0
Tax effects	0
Other comprehensive income	0
Balance at end of period	(1,794)
Total
Components of Other Accumulated Income, Net of Tax [Roll Forward]
Balance at beginning of period	(214,326)
Balance at end of period	$ (169,468)

ACCUMULATED OTHER COMPREHENSIVE LOSS (Reclassified Out of Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Unrealized holding gains on available-for-sale investments	$ (432)	$ (198)	$ (2,814)	$ (737)
Reclassification out of Accumulated Other Comprehensive Income \| Accumulated Net Investment Gain (Loss) Including Portion Attributable to Noncontrolling Interest
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Unrealized holding gains on available-for-sale investments	$ 0	$ 0	$ 222	$ 0

STOCK-BASED COMPENSATION (Narrative) (Details) - USD ($) shares in Millions	3 Months Ended		9 Months Ended		31 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Oct. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 4,000,000	$ 3,000,000	$ 9,200,000	$ 7,700,000
Income tax benefit	$ 1,200,000	$ 900,000	$ 2,700,000	$ 2,300,000
Repurchases of common stock (in shares)	0.2	0.1	0.5	0.3	4.3
Repurchases of common stock	$ 12,200,000	$ 6,200,000	$ 24,465,000	$ 16,300,000	$ 224,300,000
Stock repurchase program, remaining authorized repurchase amount	75,700,000		75,700,000		75,700,000
Restricted stock awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost	27,800,000		$ 27,800,000		27,800,000
Period for recognition (in years)			2 years 10 months 31 days
Fair value restricted stock	500,000	1,800,000	$ 6,200,000	7,900,000
Performance stock awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost	1,500,000		1,500,000		$ 1,500,000
Fair value restricted stock	$ 0	$ 0	$ 1,400,000	$ 400,000
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)			3 years
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)			5 years
Subsequent Event
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized for repurchase						$ 300,000,000
Stock repurchase program, remaining authorized repurchase amount						$ 375,700,000

STOCK-BASED COMPENSATION (Restricted Stock) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Restricted stock awards
Number of Shares
Beginning balance (in shares)			510,041
Granted (in shares)			295,568
Vested (in shares)			(115,365)
Forfeited (in shares)			(47,784)
Ending balance (in shares)	642,460		642,460
Weighted Average Grant-Date Fair Value
Beginning of period (in USD per share)			$ 52.65
Granted (in USD per share)			56.00
Vested (in USD per share)			53.89
Forfeited (in USD per share)			51.35
End of period (in USD per share)	$ 54.07		$ 54.07
Unrecognized compensation cost	$ 27.8		$ 27.8
Period for recognition (in years)			2 years 10 months 31 days
Fair value restricted stock	$ 0.5	$ 1.8	$ 6.2	$ 7.9
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, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Number of Shares
Beginning balance (in shares)			220,882
Granted (in shares)			167,964
Vested (in shares)			(25,168)
Forfeited (in shares)			(25,544)
Ending balance (in shares)	338,134		338,134
Weighted Average Grant-Date Fair Value
Beginning of period (in USD per share)			$ 54.69
Granted (in USD per share)			55.84
Vested (in USD per share)			54.84
Forfeited (in USD per share)			56.19
End of period (in USD per share)	$ 55.25		$ 55.25
Unrecognized compensation cost	$ 1.5		$ 1.5
Fair value restricted stock	$ 0.0	$ 0.0	$ 1.4	$ 0.4

COMMITMENTS AND CONTINGENCIES (Details) CAD in Millions	9 Months Ended	12 Months Ended
COMMITMENTS AND CONTINGENCIES (Details) CAD in Millions	Sep. 30, 2017 USD ($) proceeding site claim	Dec. 31, 2012 CAD	Dec. 31, 1999 municipality	Dec. 31, 1968 permit	Dec. 31, 2016 USD ($) proceeding
Contingencies [Line Items]
Recorded reserves for actual or probable liabilities \| $	$ 19,100,000				$ 22,000,000
Number of proceedings, potential sanctions equal to or exceed $100,000 \| proceeding	59
Number of product liability claims settled or dismissed \| claim	25
Legal and Administrative Proceedings
Contingencies [Line Items]
Recorded reserves for actual or probable liabilities \| $	$ 18,100,000				18,200,000
Possible increase in legal and administrative proceedings \| $	$ 1,800,000				1,900,000
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 \| CAD		CAD 2.9
Punitive damages sought \| CAD		CAD 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	3
Notices received from owners of third party sites seeking indemnification from the company	126
Number of sites for which environmental remediation expense is settled	33
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	11
Notices received from owners of third party sites seeking indemnification 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
Safety-Kleen
Contingencies [Line Items]
Notices received from owners of third party sites seeking indemnification from the company	6
Federal and State Enforcement Actions
Contingencies [Line Items]
Recorded reserves for actual or probable liabilities \| $	$ 1,000,000				$ 3,800,000
Number of proceedings, potential sanctions equal to or exceed $100,000 \| proceeding	5				5
Federal and State Enforcement Actions \| Minimum
Contingencies [Line Items]
Minimum potential liability \| $	$ 100,000

INCOME TAXES (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
INCOME TAXES (Details) - USD ($) $ in Millions	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Effective income tax rate	51.00%	47.80%	69.90%	80.30%
Unrecognized tax benefits	$ 1.8		$ 1.8		$ 1.7
Interest on unrecognized tax benefits	$ 0.4		0.4		$ 0.3
Reduction in unrecognized tax benefits from expiring statue of limitations			$ 0.4

SEGMENT REPORTING (Narrative) (Details)	9 Months Ended
SEGMENT REPORTING (Narrative) (Details)	Sep. 30, 2017 segment
Segment Reporting [Abstract]
Number of operating segments	6

SEGMENT REPORTING (Third Party Revenues to Direct Revenues) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Segment Reporting Information [Line Items]
Total revenues	$ 755,846	$ 729,520	$ 2,197,575	$ 2,063,113
Intersegment revenues, net
Segment Reporting Information [Line Items]
Total revenues	0	0	0	0
Corporate Items, net
Segment Reporting Information [Line Items]
Total revenues	0	0	0	0
Direct revenues
Segment Reporting Information [Line Items]
Total revenues	755,846	729,520	2,197,575	2,063,113
Technical Services
Segment Reporting Information [Line Items]
Total revenues	246,329	232,482	731,034	680,717
Technical Services \| Intersegment revenues, net
Segment Reporting Information [Line Items]
Total revenues	41,366	38,795	121,411	109,217
Technical Services \| Corporate Items, net
Segment Reporting Information [Line Items]
Total revenues	637	492	1,767	1,547
Technical Services \| Direct revenues
Segment Reporting Information [Line Items]
Total revenues	288,332	271,769	854,212	791,481
Industrial and Field Services
Segment Reporting Information [Line Items]
Total revenues	163,808	172,191	465,264	467,019
Industrial and Field Services \| Intersegment revenues, net
Segment Reporting Information [Line Items]
Total revenues	(10,262)	(10,867)	(27,688)	(25,464)
Industrial and Field Services \| Corporate Items, net
Segment Reporting Information [Line Items]
Total revenues	45	(32)	16	(348)
Industrial and Field Services \| Direct revenues
Segment Reporting Information [Line Items]
Total revenues	153,591	161,292	437,592	441,207
Safety-Kleen
Segment Reporting Information [Line Items]
Total revenues	315,028	297,082	910,885	821,758
Safety-Kleen \| Intersegment revenues, net
Segment Reporting Information [Line Items]
Total revenues	(31,757)	(28,716)	(95,465)	(86,329)
Safety-Kleen \| Corporate Items, net
Segment Reporting Information [Line Items]
Total revenues	3	1	4	368
Safety-Kleen \| Direct revenues
Segment Reporting Information [Line Items]
Total revenues	283,274	268,367	815,424	735,797
Oil, Gas and Lodging Services
Segment Reporting Information [Line Items]
Total revenues	30,026	27,644	89,403	91,555
Oil, Gas and Lodging Services \| Intersegment revenues, net
Segment Reporting Information [Line Items]
Total revenues	653	788	1,742	2,576
Oil, Gas and Lodging Services \| Corporate Items, net
Segment Reporting Information [Line Items]
Total revenues	79	105	218	288
Oil, Gas and Lodging Services \| Direct revenues
Segment Reporting Information [Line Items]
Total revenues	30,758	28,537	91,363	94,419
Corporate Items
Segment Reporting Information [Line Items]
Total revenues	655	121	989	2,064
Corporate Items \| Intersegment revenues, net
Segment Reporting Information [Line Items]
Total revenues	0	0	0	0
Corporate Items \| Corporate Items, net
Segment Reporting Information [Line Items]
Total revenues	(764)	(566)	(2,005)	(1,855)
Corporate Items \| Direct revenues
Segment Reporting Information [Line Items]
Total revenues	$ (109)	$ (445)	$ (1,016)	$ 209

SEGMENT REPORTING (Adjusted EBITDA Information) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Segment Reporting Information [Line Items]
Adjusted EBITDA	$ 122,999	$ 126,651	$ 323,825	$ 304,416
Reconciliation to Consolidated Statements of Operations:
Accretion of environmental liabilities	2,347	2,476	7,053	7,529
Depreciation and amortization	72,989	73,360	216,932	215,655
Goodwill impairment charge	0	34,013	0	34,013
Income from operations	47,663	16,802	99,840	47,219
Other expense	432	198	2,814	737
Loss on early extinguishment of debt	1,846	0	7,891	0
Gain on sale of business	77	(16,431)	(31,645)	(16,431)
Interest expense, net of interest income	20,675	21,565	65,743	62,192
Income (loss) before (benefit) provision for income taxes	24,633	11,470	55,037	721
Technical Services
Segment Reporting Information [Line Items]
Adjusted EBITDA	72,338	72,333	203,906	201,622
Industrial and Field Services
Segment Reporting Information [Line Items]
Adjusted EBITDA	13,255	18,234	36,652	38,627
Safety-Kleen
Segment Reporting Information [Line Items]
Adjusted EBITDA	70,305	70,053	182,953	165,342
Oil, Gas and Lodging Services
Segment Reporting Information [Line Items]
Adjusted EBITDA	912	24	969	135
Corporate Items
Segment Reporting Information [Line Items]
Adjusted EBITDA	$ (33,811)	$ (33,993)	$ (100,655)	$ (101,310)

SEGMENT REPORTING (Assets by Reportable Segment) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Property, plant and equipment, net	$ 1,611,971	$ 1,611,827
Goodwill	478,728	465,154
Permits and other intangibles, net	477,639	498,721
Total assets	3,748,353	3,681,920
Technical Services
Segment Reporting Information [Line Items]
Property, plant and equipment, net	507,069	521,134
Goodwill	60,154	61,116
Permits and other intangibles, net	75,260	78,625
Total assets	848,578	862,957
Industrial and Field Services
Segment Reporting Information [Line Items]
Property, plant and equipment, net	264,662	245,143
Goodwill	112,365	107,968
Permits and other intangibles, net	17,139	17,817
Total assets	485,297	446,826
Safety-Kleen
Segment Reporting Information [Line Items]
Property, plant and equipment, net	585,493	584,647
Goodwill	306,209	296,070
Permits and other intangibles, net	377,458	391,390
Total assets	1,475,764	1,474,755
Oil, Gas and Lodging Services
Segment Reporting Information [Line Items]
Property, plant and equipment, net	177,106	182,038
Goodwill	0	0
Permits and other intangibles, net	7,782	10,889
Total assets	239,308	253,242
Corporate Items
Segment Reporting Information [Line Items]
Property, plant and equipment, net	77,641	78,865
Goodwill	0	0
Permits and other intangibles, net	0	0
Total assets	$ 699,406	$ 644,140

SEGMENT REPORTING (Total Assets by Geographical Area) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Revenues from External Customers and Long-Lived Assets [Line Items]
Total assets	$ 3,748,353	$ 3,681,920
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Total assets	3,005,644	2,960,337
Canada
Revenues from External Customers and Long-Lived Assets [Line Items]
Total assets	$ 742,709	$ 721,583

GUARANTOR AND NON-GUARANTOR SUBSIDIARIES FINANCIAL INFORMATION (Condensed Consolidating Balance Sheets) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2015
ASSETS
Cash and cash equivalents	$ 361,658	$ 306,997	$ 257,857	$ 184,708
Intercompany receivables	0	0
Accounts receivables, net	531,696	496,226
Other current assets	266,904	289,648
Property, plant and equipment, net	1,611,971	1,611,827
Investments in subsidiaries	0	0
Intercompany debt receivable	0	0
Goodwill	478,728	465,154
Permits and other intangibles, net	477,639	498,721
Other long-term assets	19,757	13,347
Total assets	3,748,353	3,681,920
LIABILITIES AND STOCKHOLDERS' EQUITY
Current liabilities	529,540	504,668
Intercompany payables	0	0
Closure, post-closure and remedial liabilities, net	165,836	166,322
Long-term obligations, less current portion	1,625,971	1,633,272
Intercompany debt payable	0	0
Other long-term liabilities	298,659	293,417
Total liabilities	2,620,006	2,597,679
Stockholders’ equity	1,128,347	1,084,241
Total liabilities and stockholders’ equity	3,748,353	3,681,920
Reportable Legal Entities \| Clean Harbors, Inc.
ASSETS
Cash and cash equivalents	51,514	51,417	51,334	11,017
Intercompany receivables	230,084	200,337
Accounts receivables, net	0	0
Other current assets	897	3,096
Property, plant and equipment, net	0	0
Investments in subsidiaries	2,933,843	2,851,571
Intercompany debt receivable	0	0
Goodwill	0	0
Permits and other intangibles, net	0	0
Other long-term assets	2,448	2,446
Total assets	3,218,786	3,108,867
LIABILITIES AND STOCKHOLDERS' EQUITY
Current liabilities	22,595	21,805
Intercompany payables	441,873	365,848
Closure, post-closure and remedial liabilities, net	0	0
Long-term obligations, less current portion	1,625,971	1,633,272
Intercompany debt payable	0	3,701
Other long-term liabilities	0	0
Total liabilities	2,090,439	2,024,626
Stockholders’ equity	1,128,347	1,084,241
Total liabilities and stockholders’ equity	3,218,786	3,108,867
Reportable Legal Entities \| Guarantor Subsidiaries
ASSETS
Cash and cash equivalents	221,552	155,943	170,183	83,479
Intercompany receivables	451,146	354,836
Accounts receivables, net	435,058	417,029
Other current assets	215,847	234,408
Property, plant and equipment, net	1,182,922	1,211,210
Investments in subsidiaries	585,660	580,124
Intercompany debt receivable	92,938	86,409
Goodwill	415,056	412,638
Permits and other intangibles, net	415,708	435,594
Other long-term assets	13,312	7,582
Total assets	4,029,199	3,895,773
LIABILITIES AND STOCKHOLDERS' EQUITY
Current liabilities	385,734	366,831
Intercompany payables	266,776	237,058
Closure, post-closure and remedial liabilities, net	148,791	150,682
Long-term obligations, less current portion	0	0
Intercompany debt payable	21,000	21,000
Other long-term liabilities	278,700	275,649
Total liabilities	1,101,001	1,051,220
Stockholders’ equity	2,928,198	2,844,553
Total liabilities and stockholders’ equity	4,029,199	3,895,773
Reportable Legal Entities \| Non-Guarantor Subsidiaries
ASSETS
Cash and cash equivalents	88,592	99,637	36,340	90,212
Intercompany receivables	38,451	49,055
Accounts receivables, net	96,638	79,197
Other current assets	51,871	69,257
Property, plant and equipment, net	429,049	400,617
Investments in subsidiaries	0	0
Intercompany debt receivable	21,000	24,701
Goodwill	63,672	52,516
Permits and other intangibles, net	61,931	63,127
Other long-term assets	5,065	4,387
Total assets	856,269	842,494
LIABILITIES AND STOCKHOLDERS' EQUITY
Current liabilities	122,922	133,145
Intercompany payables	11,032	1,322
Closure, post-closure and remedial liabilities, net	17,045	15,640
Long-term obligations, less current portion	0	0
Intercompany debt payable	92,938	86,409
Other long-term liabilities	21,027	18,836
Total liabilities	264,964	255,352
Stockholders’ equity	591,305	587,142
Total liabilities and stockholders’ equity	856,269	842,494
Consolidating Adjustments
ASSETS
Cash and cash equivalents	0	0	$ 0	$ 0
Intercompany receivables	(719,681)	(604,228)
Accounts receivables, net	0	0
Other current assets	(1,711)	(17,113)
Property, plant and equipment, net	0	0
Investments in subsidiaries	(3,519,503)	(3,431,695)
Intercompany debt receivable	(113,938)	(111,110)
Goodwill	0	0
Permits and other intangibles, net	0	0
Other long-term assets	(1,068)	(1,068)
Total assets	(4,355,901)	(4,165,214)
LIABILITIES AND STOCKHOLDERS' EQUITY
Current liabilities	(1,711)	(17,113)
Intercompany payables	(719,681)	(604,228)
Closure, post-closure and remedial liabilities, net	0	0
Long-term obligations, less current portion	0	0
Intercompany debt payable	(113,938)	(111,110)
Other long-term liabilities	(1,068)	(1,068)
Total liabilities	(836,398)	(733,519)
Stockholders’ equity	(3,519,503)	(3,431,695)
Total liabilities and stockholders’ equity	$ (4,355,901)	$ (4,165,214)

GUARANTOR AND NON-GUARANTOR SUBSIDIARIES FINANCIAL INFORMATION (Consolidating Statement of Operations) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Revenues:
Service revenues	$ 612,352	$ 594,225	$ 1,783,506	$ 1,709,018
Product revenues	143,494	135,295	414,069	354,095
Total revenues	755,846	729,520	2,197,575	2,063,113
Cost of revenues (exclusive of items shown separately below)
Service cost of revenues	412,369	385,542	1,215,812	1,148,212
Product cost of revenues	107,226	106,373	320,171	287,984
Total cost of revenues	519,595	491,915	1,535,983	1,436,196
Selling, general and administrative expenses	113,252	110,954	337,767	322,501
Accretion of environmental liabilities	2,347	2,476	7,053	7,529
Depreciation and amortization	72,989	73,360	216,932	215,655
Goodwill impairment charge	0	34,013	0	34,013
Income from operations	47,663	16,802	99,840	47,219
Unrealized holding gains on available-for-sale investments	(432)	(198)	(2,814)	(737)
Loss on early extinguishment of debt	(1,846)	0	(7,891)	0
(Loss) gain on sale of businesses	(77)	16,431	31,645	16,431
Interest (expense) income	(20,675)	(21,565)	(65,743)	(62,192)
Equity in earnings of subsidiaries, net of taxes	0	0	0	0
Intercompany interest income (expense)	0	0	0	0
Income (loss) before (benefit) provision for income taxes	24,633	11,470	55,037	721
(Benefit) provision for income taxes	12,575	21,725	38,492	27,881
Net income (loss)	12,058	(10,255)	16,545	(27,160)
Other comprehensive income	23,709	(1,311)	44,858	43,348
Comprehensive income (loss)	35,767	(11,566)	61,403	16,188
Reportable Legal Entities \| Clean Harbors, Inc.
Revenues:
Service revenues	0	0	0	0
Product revenues	0	0	0	0
Total revenues	0	0	0	0
Cost of revenues (exclusive of items shown separately below)
Service cost of revenues	0	(598)	0	(1,185)
Product cost of revenues	0	0	0	0
Total cost of revenues	0	(598)	0	(1,185)
Selling, general and administrative expenses	19	23	70	84
Accretion of environmental liabilities	0	0	0	0
Depreciation and amortization	0	0	0	0
Goodwill impairment charge		0		0
Income from operations	(19)	575	(70)	1,101
Unrealized holding gains on available-for-sale investments	0	0	(222)	0
Loss on early extinguishment of debt	(1,846)		(7,891)
(Loss) gain on sale of businesses	0	0	0	0
Interest (expense) income	(21,135)	(23,042)	(66,408)	(66,147)
Equity in earnings of subsidiaries, net of taxes	25,858	3,225	61,388	11,867
Intercompany interest income (expense)	0	0	0	0
Income (loss) before (benefit) provision for income taxes	2,858	(19,242)	(13,203)	(53,179)
(Benefit) provision for income taxes	(9,200)	(8,987)	(29,748)	(26,019)
Net income (loss)	12,058	(10,255)	16,545	(27,160)
Other comprehensive income	23,709	(1,311)	44,858	43,348
Comprehensive income (loss)	35,767	(11,566)	61,403	16,188
Reportable Legal Entities \| Guarantor Subsidiaries
Revenues:
Service revenues	473,428	461,139	1,391,534	1,345,629
Product revenues	127,355	118,106	369,864	303,342
Total revenues	600,783	579,245	1,761,398	1,648,971
Cost of revenues (exclusive of items shown separately below)
Service cost of revenues	306,291	288,764	907,396	864,071
Product cost of revenues	97,353	94,050	292,503	252,512
Total cost of revenues	403,644	382,814	1,199,899	1,116,583
Selling, general and administrative expenses	92,299	88,652	276,974	253,189
Accretion of environmental liabilities	2,092	2,243	6,328	6,846
Depreciation and amortization	50,917	51,957	154,754	151,348
Goodwill impairment charge		0		0
Income from operations	51,831	53,579	123,443	121,005
Unrealized holding gains on available-for-sale investments	(305)	(188)	(2,100)	124
Loss on early extinguishment of debt	0		0
(Loss) gain on sale of businesses	(77)	1,288	31,645	1,288
Interest (expense) income	517	1,456	876	3,851
Equity in earnings of subsidiaries, net of taxes	(5,620)	(22,341)	(32,776)	(58,031)
Intercompany interest income (expense)	1,372	5,235	3,937	15,891
Income (loss) before (benefit) provision for income taxes	47,718	39,029	125,025	84,128
(Benefit) provision for income taxes	20,824	35,803	62,442	72,260
Net income (loss)	26,894	3,226	62,583	11,868
Other comprehensive income	23,709	(1,311)	44,858	43,348
Comprehensive income (loss)	50,603	1,915	107,441	55,216
Reportable Legal Entities \| Non-Guarantor Subsidiaries
Revenues:
Service revenues	152,997	145,780	431,992	399,216
Product revenues	19,435	20,072	53,496	58,176
Total revenues	172,432	165,852	485,488	457,392
Cost of revenues (exclusive of items shown separately below)
Service cost of revenues	120,151	110,070	348,436	321,153
Product cost of revenues	13,169	15,206	36,959	42,895
Total cost of revenues	133,320	125,276	385,395	364,048
Selling, general and administrative expenses	20,934	22,279	60,723	69,228
Accretion of environmental liabilities	255	233	725	683
Depreciation and amortization	22,072	21,403	62,178	64,307
Goodwill impairment charge		34,013		34,013
Income from operations	(4,149)	(37,352)	(23,533)	(74,887)
Unrealized holding gains on available-for-sale investments	(127)	(10)	(492)	(861)
Loss on early extinguishment of debt	0		0
(Loss) gain on sale of businesses	0	15,143	0	15,143
Interest (expense) income	(57)	21	(211)	104
Equity in earnings of subsidiaries, net of taxes	0	0	0	0
Intercompany interest income (expense)	(1,372)	(5,235)	(3,937)	(15,891)
Income (loss) before (benefit) provision for income taxes	(5,705)	(27,433)	(28,173)	(76,392)
(Benefit) provision for income taxes	951	(5,091)	5,798	(18,360)
Net income (loss)	(6,656)	(22,342)	(33,971)	(58,032)
Other comprehensive income	20,263	(3,927)	38,132	24,403
Comprehensive income (loss)	13,607	(26,269)	4,161	(33,629)
Consolidating Adjustments
Revenues:
Service revenues	(14,073)	(12,694)	(40,020)	(35,827)
Product revenues	(3,296)	(2,883)	(9,291)	(7,423)
Total revenues	(17,369)	(15,577)	(49,311)	(43,250)
Cost of revenues (exclusive of items shown separately below)
Service cost of revenues	(14,073)	(12,694)	(40,020)	(35,827)
Product cost of revenues	(3,296)	(2,883)	(9,291)	(7,423)
Total cost of revenues	(17,369)	(15,577)	(49,311)	(43,250)
Selling, general and administrative expenses	0	0	0	0
Accretion of environmental liabilities	0	0	0	0
Depreciation and amortization	0	0	0	0
Goodwill impairment charge		0		0
Income from operations	0	0	0	0
Unrealized holding gains on available-for-sale investments	0	0	0	0
Loss on early extinguishment of debt	0		0
(Loss) gain on sale of businesses	0	0	0
Interest (expense) income	0	0	0	0
Equity in earnings of subsidiaries, net of taxes	(20,238)	19,116	(28,612)	46,164
Intercompany interest income (expense)	0	0	0	0
Income (loss) before (benefit) provision for income taxes	(20,238)	19,116	(28,612)	46,164
(Benefit) provision for income taxes	0	0	0	0
Net income (loss)	(20,238)	19,116	(28,612)	46,164
Other comprehensive income	(43,972)	5,238	(82,990)	(67,751)
Comprehensive income (loss)	$ (64,210)	$ 24,354	$ (111,602)	$ (21,587)

GUARANTOR AND NON-GUARANTOR SUBSIDIARIES FINANCIAL INFORMATION (Condensed Consolidating Statements of Cash Flows) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Condensed consolidating statement of cash flows
Net cash from operating activities	$ 221,469	$ 178,827
Cash flows from (used in) investing activities:
Additions to property, plant and equipment	(127,736)	(175,348)
Proceeds from sale and disposal of fixed assets	5,375	3,982
Acquisitions, net of cash acquired	(44,432)	(207,089)
Proceeds on sale of business	46,339	47,134
Additions to intangible assets, including costs to obtain or renew permits	(1,348)	(1,920)
Purchases of available-for-sale securities	0	(598)
Proceeds from sale of investments	376	0
Intercompany	0	0
Intercompany debt	0
Investment in subsidiaries		0
Net cash used in investing activities	(121,426)	(333,839)
Cash flows used in financing activities:
Change in uncashed checks	(8,657)	(7,084)
Proceeds from exercise of stock options	46	230
Issuance of restricted shares, net of shares remitted	(2,321)	(2,500)
Repurchases of common stock	(24,465)	(15,869)
Deferred financing costs paid	(5,746)	(2,614)
Excess tax benefit of stock-based compensation	0	21
Premiums paid on early extinguishment of debt	(6,028)	0
Principal payment on debt	(401,000)	0
Issuance of senior secured notes, net of discount	399,000	0
Issuance of senior unsecured notes, including premium	0	250,625
Intercompany	0	0
Intercompany debt	0	0
Net cash (used in) from financing activities	(49,171)	222,809
Effect of exchange rate change on cash	3,789	5,352
Increase (decrease) in cash and cash equivalents	54,661	73,149
Cash and cash equivalents, beginning of period	306,997	184,708
Cash and cash equivalents, end of period	361,658	257,857
Consolidating Adjustments
Condensed consolidating statement of cash flows
Net cash from operating activities	0	0
Cash flows from (used in) investing activities:
Additions to property, plant and equipment	0	0
Proceeds from sale and disposal of fixed assets	0	0
Acquisitions, net of cash acquired	0	0
Proceeds on sale of business	0	0
Additions to intangible assets, including costs to obtain or renew permits	0	0
Purchases of available-for-sale securities		0
Proceeds from sale of investments	0
Intercompany	27,740	18,118
Intercompany debt	3,701
Investment in subsidiaries		250,625
Net cash used in investing activities	24,039	268,743
Cash flows used in financing activities:
Change in uncashed checks	0	0
Proceeds from exercise of stock options	0	0
Issuance of restricted shares, net of shares remitted	0	0
Repurchases of common stock	0	0
Deferred financing costs paid	0	0
Excess tax benefit of stock-based compensation		0
Premiums paid on early extinguishment of debt	0
Principal payment on debt	0
Issuance of senior secured notes, net of discount	0
Issuance of senior unsecured notes, including premium		(250,625)
Intercompany	(27,740)	(18,118)
Intercompany debt	3,701	0
Net cash (used in) from financing activities	(24,039)	(268,743)
Effect of exchange rate change on cash	0	0
Increase (decrease) in cash and cash equivalents	0	0
Cash and cash equivalents, beginning of period	0	0
Cash and cash equivalents, end of period	0	0
Clean Harbors, Inc.
Cash flows used in financing activities:
Intercompany debt		0
Clean Harbors, Inc. \| Reportable Legal Entities
Condensed consolidating statement of cash flows
Net cash from operating activities	16,196	43,033
Cash flows from (used in) investing activities:
Additions to property, plant and equipment	0	0
Proceeds from sale and disposal of fixed assets	0	0
Acquisitions, net of cash acquired	0	0
Proceeds on sale of business	0	0
Additions to intangible assets, including costs to obtain or renew permits	0	0
Purchases of available-for-sale securities		(102)
Proceeds from sale of investments	376
Intercompany	0	0
Intercompany debt	0
Investment in subsidiaries		(250,625)
Net cash used in investing activities	376	(250,727)
Cash flows used in financing activities:
Change in uncashed checks	0	0
Proceeds from exercise of stock options	46	230
Issuance of restricted shares, net of shares remitted	(2,321)	(2,500)
Repurchases of common stock	(24,465)	(15,869)
Deferred financing costs paid	(5,746)	(2,614)
Excess tax benefit of stock-based compensation		21
Premiums paid on early extinguishment of debt	(6,028)
Principal payment on debt	(401,000)
Issuance of senior secured notes, net of discount	399,000
Issuance of senior unsecured notes, including premium		250,625
Intercompany	27,740	18,118
Intercompany debt	(3,701)
Net cash (used in) from financing activities	(16,475)	248,011
Effect of exchange rate change on cash	0	0
Increase (decrease) in cash and cash equivalents	97	40,317
Cash and cash equivalents, beginning of period	51,417	11,017
Cash and cash equivalents, end of period	51,514	51,334
Guarantor Subsidiaries \| Reportable Legal Entities
Condensed consolidating statement of cash flows
Net cash from operating activities	169,715	128,182
Cash flows from (used in) investing activities:
Additions to property, plant and equipment	(105,564)	(152,836)
Proceeds from sale and disposal of fixed assets	1,625	950
Acquisitions, net of cash acquired	(11,427)	(197,089)
Proceeds on sale of business	46,158	18,885
Additions to intangible assets, including costs to obtain or renew permits	(1,018)	(949)
Purchases of available-for-sale securities		0
Proceeds from sale of investments	0
Intercompany	(27,740)	(18,118)
Intercompany debt	0
Investment in subsidiaries		0
Net cash used in investing activities	(97,966)	(349,157)
Cash flows used in financing activities:
Change in uncashed checks	(6,140)	(6,064)
Proceeds from exercise of stock options	0	0
Issuance of restricted shares, net of shares remitted	0	0
Repurchases of common stock	0	0
Deferred financing costs paid	0	0
Excess tax benefit of stock-based compensation		0
Premiums paid on early extinguishment of debt	0
Principal payment on debt	0
Issuance of senior secured notes, net of discount	0
Issuance of senior unsecured notes, including premium		250,625
Intercompany	0	0
Intercompany debt	0	63,118
Net cash (used in) from financing activities	(6,140)	307,679
Effect of exchange rate change on cash	0	0
Increase (decrease) in cash and cash equivalents	65,609	86,704
Cash and cash equivalents, beginning of period	155,943	83,479
Cash and cash equivalents, end of period	221,552	170,183
Non-Guarantor Subsidiaries \| Reportable Legal Entities
Condensed consolidating statement of cash flows
Net cash from operating activities	35,558	7,612
Cash flows from (used in) investing activities:
Additions to property, plant and equipment	(22,172)	(22,512)
Proceeds from sale and disposal of fixed assets	3,750	3,032
Acquisitions, net of cash acquired	(33,005)	(10,000)
Proceeds on sale of business	181	28,249
Additions to intangible assets, including costs to obtain or renew permits	(330)	(971)
Purchases of available-for-sale securities		(496)
Proceeds from sale of investments	0
Intercompany	0	0
Intercompany debt	(3,701)
Investment in subsidiaries		0
Net cash used in investing activities	(47,875)	(2,698)
Cash flows used in financing activities:
Change in uncashed checks	(2,517)	(1,020)
Proceeds from exercise of stock options	0	0
Issuance of restricted shares, net of shares remitted	0	0
Repurchases of common stock	0	0
Deferred financing costs paid	0	0
Excess tax benefit of stock-based compensation		0
Premiums paid on early extinguishment of debt	0
Principal payment on debt	0
Issuance of senior secured notes, net of discount	0
Issuance of senior unsecured notes, including premium		0
Intercompany	0	0
Intercompany debt	0	(63,118)
Net cash (used in) from financing activities	(2,517)	(64,138)
Effect of exchange rate change on cash	3,789	5,352
Increase (decrease) in cash and cash equivalents	(11,045)	(53,872)
Cash and cash equivalents, beginning of period	99,637	90,212
Cash and cash equivalents, end of period	$ 88,592	$ 36,340

UNAUDITED CONSOLIDATED STATEMENTS OF STOCKHOLDERS'S EQUITY (Parenthetical) - $ / shares	Sep. 30, 2017	Dec. 31, 2016
Statement of Stockholders' Equity [Abstract]
Common stock, par value (in USD per share)	$ 0.01	$ 0.01

GUARANTOR AND NON-GUARANTOR SUBSIDIARIES FINANCIAL INFORMATION (Narrative) (Details)	9 Months Ended
	Sep. 30, 2017
Guarantor and Non-Guarantor Subsidiaries Financial Information [Abstract]
Ownership percentage of U.S. guarantor subsidiaries	100.00%