Clean Harbors (CLH) 10-Q 2 Aug 17 2017 Q2 Quarterly report Financial data

DOCUMENT AND ENTITY INFORMATION

DOCUMENT AND ENTITY INFORMATION - shares	6 Months Ended
	Jun. 30, 2017	Jul. 28, 2017
Document and Entity Information [Abstract]
Entity Registrant Name	CLEAN HARBORS INC
Entity Central Index Key	822,818
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Jun. 30, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q2
Amendment Flag	false
Entity Common Stock, Shares Outstanding		57,154,060

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 446,366	$ 306,997
Accounts receivable, net of allowances aggregating $26,782 and $29,249, respectively	512,375	496,226
Unbilled accounts receivable	46,576	36,190
Deferred costs	21,054	18,914
Inventories and supplies	172,540	178,428
Prepaid expenses and other current assets	35,823	56,116
Total current assets	1,234,734	1,092,871
Property, plant and equipment, net	1,602,453	1,611,827
Other assets:
Goodwill	472,819	465,154
Permits and other intangibles, net	482,828	498,721
Other	13,448	13,347
Total other assets	969,095	977,222
Total assets	3,806,282	3,681,920
Current liabilities:
Current portion of long-term obligations	107,798	0
Accounts payable	224,218	229,534
Deferred revenue	72,089	64,397
Accrued expenses	191,495	190,721
Current portion of closure, post-closure and remedial liabilities	23,700	20,016
Total current liabilities	619,300	504,668
Other liabilities:
Closure and post-closure liabilities, less current portion of $6,745 and $6,220, respectively	53,048	52,111
Remedial liabilities, less current portion of $16,955 and $13,796, respectively	109,204	114,211
Long-term obligations, less current portion	1,626,505	1,633,272
Deferred taxes, unrecognized tax benefits and other long-term liabilities	297,288	293,417
Total other liabilities	2,086,045	2,093,011
Commitments and contingent liabilities (See Note 15)
Stockholders’ equity:
Authorized 80,000,000; shares issued and outstanding 57,153,687 and 57,297,978 shares, respectively	572	573
Shares held under employee participation plan	0	(469)
Additional paid-in capital	716,712	725,670
Accumulated other comprehensive loss	(193,177)	(214,326)
Accumulated earnings	576,830	572,793
Total stockholders’ equity	1,100,937	1,084,241
Total liabilities and stockholders’ equity	$ 3,806,282	$ 3,681,920

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Account receivable, allowances aggregating	$ 26,782	$ 29,249
Closure and post-closure liabilities, current portion	6,745	6,220
Remedial liabilities, current portion	$ 16,955	$ 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)	57,153,687	57,297,978
Common stock, outstanding shares (in shares)	57,153,687	57,297,978

UNAUDITED CONSOLIDATED STATEMEN

UNAUDITED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Revenues:
Service revenues	$ 610,940	$ 584,562	$ 1,171,154	$ 1,114,793
Product revenues	141,848	112,948	270,575	218,800
Total revenues	752,788	697,510	1,441,729	1,333,593
Cost of revenues (exclusive of items shown separately below)
Service revenues	412,356	388,684	803,443	762,670
Product revenues	107,447	91,318	212,945	181,611
Total cost of revenues	519,803	480,002	1,016,388	944,281
Selling, general and administrative expenses	112,294	107,063	224,515	211,547
Accretion of environmental liabilities	2,416	2,548	4,706	5,053
Depreciation and amortization	71,531	73,393	143,943	142,295
Income from operations	46,744	34,504	52,177	30,417
Other expense	(833)	(189)	(2,382)	(539)
Loss on early extinguishment of debt	(6,045)	0	(6,045)	0
Gain on sale of business	31,722	0	31,722	0
Interest expense, net of interest income of $311, $225, $520 and $375, respectively	(22,492)	(21,647)	(45,068)	(40,627)
Income (loss) before (benefit) provision for income taxes	49,096	12,668	30,404	(10,749)
Provision for income taxes	23,216	8,702	25,917	6,156
Net income (loss)	$ 25,880	$ 3,966	$ 4,487	$ (16,905)
Earnings (loss) per share:
Basic (in USD per share)	$ 0.45	$ 0.07	$ 0.08	$ (0.29)
Diluted (in USD per share)	$ 0.45	$ 0.07	$ 0.08	$ (0.29)
Shares used to compute loss per share - Basic (in shares)	57,190	57,549	57,226	57,599
Shares used to compute loss per share - Diluted (in shares)	57,336	57,678	57,349	57,599

UNAUDITED CONSOLIDATED STATEME5

UNAUDITED CONSOLIDATED STATEMENTS OF OPERATIONS (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Income Statement [Abstract]
Interest expense	$ 311	$ 225	$ 520	$ 375

UNAUDITED CONSOLIDATED STATEME6

UNAUDITED CONSOLIDATED STATEMENTS OF COMPREHENSIVE (LOSS) INCOME - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 25,880	$ 3,966	$ 4,487	$ (16,905)
Other comprehensive income (loss):
Unrealized gains on available-for-sale securities (net of taxes of $20, $0, $122 and $0, respectively)	27	0	159	0
Reclassification adjustment for losses on available-for-sale securities included in net income (loss) (net of taxes of $29, $0, $79 and $0, respectively)	47	0	143	0
Foreign currency translation adjustments	15,024	(1,178)	20,847	44,659
Other comprehensive income (loss)	15,098	(1,178)	21,149	44,659
Comprehensive income	$ 40,978	$ 2,788	$ 25,636	$ 27,754

UNAUDITED CONSOLIDATED STATEME7

UNAUDITED CONSOLIDATED STATEMENTS OF COMPREHENSIVE (LOSS) INCOME (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Statement of Comprehensive Income [Abstract]
Unrealized gains (losses) on available-for-sale securities, taxes	$ (20)	$ 0	$ (122)	$ 0
Reclassification adjustment for gains on available-for-sale securities included in net (loss) income taxes	$ (29)	$ 0	$ (79)	$ 0

UNAUDITED CONSOLIDATED STATEME8

UNAUDITED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Cash flows from operating activities:
Net income (loss)	$ 4,487	$ (16,905)
Adjustments to reconcile net loss to net cash from operating activities:
Depreciation and amortization	143,943	142,295
Allowance for doubtful accounts	3,580	3,228
Amortization of deferred financing costs and debt discount	1,660	1,772
Accretion of environmental liabilities	4,706	5,053
Changes in environmental liability estimates	(129)	(315)
Deferred income taxes	190	(6,521)
Stock-based compensation	5,172	4,739
Excess tax benefit of stock-based compensation	0	(2)
Net tax deficiency on stock based awards	0	(603)
Other expense	2,382	1,049
Gain on sale of business	(31,722)	0
Loss on early extinguishment of debt	6,045	0
Environmental expenditures	(6,102)	(6,454)
Changes in assets and liabilities, net of acquisitions
Accounts receivable and unbilled accounts receivable	(31,154)	993
Inventories and supplies	(6,307)	(1,113)
Other current assets	13,918	(4,789)
Accounts payable	(2,686)	(8,397)
Other current and long-term liabilities	8,948	6,021
Net cash from operating activities	116,931	120,051
Cash flows used in investing activities:
Additions to property, plant and equipment	(88,742)	(123,529)
Proceeds from sales of fixed assets	2,121	2,668
Acquisitions, net of cash acquired	(9,277)	(58,989)
Proceeds on sale of businesses, net of transactional costs	46,391	0
Additions to intangible assets, including costs to obtain or renew permits	(1,239)	(973)
Purchases of available-for-sale securities	0	(598)
Proceeds from sale of investments	376	0
Net cash used in investing activities	(50,370)	(181,421)
Cash flows from financing activities:
Change in uncashed checks	(8,361)	(11,022)
Proceeds from exercise of stock options	46	184
Issuance of restricted shares, net of shares remitted	(2,132)	(1,879)
Repurchases of common stock	(12,257)	(10,134)
Deferred financing costs paid	(4,727)	(2,614)
Excess tax benefit of stock-based compensation	0	2
Premiums paid on early extinguishment of debt	(4,665)	0
Principal payment on debt	(296,202)	0
Issuance of senior secured notes, net of discount	399,000	0
Issuance of senior unsecured notes, including premium	0	250,625
Net cash from financing activities	70,702	225,162
Effect of exchange rate change on cash	2,106	4,423
Increase in cash and cash equivalents	139,369	168,215
Cash and cash equivalents, beginning of period	306,997	184,708
Cash and cash equivalents, end of period	446,366	352,923
Cash payments for interest and income taxes:
Interest paid	50,432	44,275
Income taxes paid	13,407	23,872
Non-cash investing and financing activities:
Property, plant and equipment accrued	16,213	24,187
Transfer of inventory to property, plant and equipment	$ 12,641	$ 0

UNAUDITED CONSOLIDATED STATEME9

UNAUDITED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - 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
Increase (Decrease) in Stockholders' Equity
Cumulative effect of change in accounting for stock based compensation	$ 231			$ 681		$ (450)
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)	4,487					4,487
Other comprehensive income	21,149				21,149
Stock-based compensation	5,172			5,172
Issuance of restricted shares, net of shares remitted	(2,132)	$ 1		(2,133)
Issuance of restricted shares, net of shares remitted (in shares)		93
Shares held under employee participation plan	0	$ 0	469	(469)
Shares held under employee participation plan (in shares)		(25)
Repurchases of common stock	$ (12,257)	$ (2)		(12,255)
Repurchases of common stock (in shares)	(200)	(214)
Exercise of stock options	$ 46			46
Exercise of stock options (in shares)		2
Balance at end of period at Jun. 30, 2017	$ 1,100,937	$ 572	$ 0	$ 716,712	$ (193,177)	$ 576,830
Balance ending of period (in shares) at Jun. 30, 2017		57,154

UNAUDITED CONSOLIDATED STATEM10

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

BASIS OF PRESENTATION

BASIS OF PRESENTATION	6 Months Ended
	Jun. 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

SIGNIFICANT ACCOUNTING POLICIES	6 Months Ended
	Jun. 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 six months ended June 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, 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 June 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 recorded cash paid in the second quarter 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. As the Company completes its evaluation of this new standard, the Company's preliminary assessments could change. 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 amendments in this Update are 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 amendments in this Update 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 amendments in this Update are 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 amendments in this Update 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

BUSINESS COMBINATIONS	6 Months Ended
	Jun. 30, 2017
Business Combinations [Abstract]
BUSINESS COMBINATIONS	BUSINESS COMBINATIONS 2017 Acquisitions 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 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 BUSINESS

DISPOSITION OF BUSINESS	6 Months Ended
	Jun. 30, 2017
Discontinued Operations and Disposal Groups [Abstract]
DISPOSITION OF BUSINESS	DISPOSITION OF BUSINESS 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 has sold for approximately $46.5 million ( $44.4 million net of $2.1 million in transactional related costs) subject to customary post-closing conditions. As a result of the sale, the Company recognized during the three and six months ended June 30, 2017, a pre-tax gain of $31.7 million which is included in 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 $ 7,216 Property, plant and equipment, net 8,773 Total other assets 1,681 Total assets divested $ 17,670 Total current liabilities 3,849 Total other liabilities 1,170 Total liabilities divested $ 5,019 Net carrying value divested $ 12,651 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 Six Months Ended June 30, June 30, 2017 2016 2017 2016 Income before provision for income taxes $ 1,873 $ 986 $ 2,771 $ 1,793 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 final sale proceeds. The following table presents the income before provision for income taxes attributable to the Catalyst Services business included in the Company's consolidated results of operations for three and six months ended June 30, 2016 (in thousands): Three Months Ended Six Months Ended June 30, 2016 June 30, 2016 Income before provision for income taxes $ 2,607 $ 1,508

INVENTORIES AND SUPPLIES

INVENTORIES AND SUPPLIES	6 Months Ended
	Jun. 30, 2017
Inventory Disclosure [Abstract]
INVENTORIES AND SUPPLIES	INVENTORIES AND SUPPLIES Inventories and supplies consisted of the following (in thousands): June 30, 2017 December 31, 2016 Oil and oil products $ 57,554 $ 52,158 Supplies and drums 92,995 90,610 Solvent and solutions 8,575 8,566 Modular camp accommodations 2,699 15,255 Other 10,717 11,839 Total inventories and supplies $ 172,540 $ 178,428 As of June 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. 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

PROPERTY, PLANT AND EQUIPMENT	6 Months Ended
	Jun. 30, 2017
Property, Plant and Equipment [Abstract]
PROPERTY, PLANT AND EQUIPMENT	PROPERTY, PLANT AND EQUIPMENT Property, plant and equipment consisted of the following (in thousands): June 30, 2017 December 31, 2016 Land $ 121,114 $ 120,575 Asset retirement costs (non-landfill) 14,861 14,567 Landfill assets 141,878 139,708 Buildings and improvements 406,030 373,160 Camp equipment 168,524 152,740 Vehicles 564,723 541,022 Equipment 1,605,581 1,483,736 Furniture and fixtures 5,524 5,492 Construction in progress 54,934 146,904 3,083,169 2,977,904 Less - accumulated depreciation and amortization 1,480,716 1,366,077 Total property, plant and equipment, net $ 1,602,453 $ 1,611,827 Interest in the amount of $0.1 million and $0.2 million was capitalized to fixed assets during the three and six months ended June 30, 2017 , respectively. Interest in the amount of $1.3 million and $2.5 million was capitalized to fixed assets during the three and six months ended June 30, 2016 , respectively. Depreciation expense, inclusive of landfill amortization, was $61.8 million and $125.2 million for the three and six months ended June 30, 2017 , respectively. Depreciation expense, inclusive of landfill amortization, was $63.5 million and $122.8 million for the three and six months ended June 30, 2016 , respectively.

GOODWILL AND OTHER INTANGIBLE A

GOODWILL AND OTHER INTANGIBLE ASSETS	6 Months Ended
	Jun. 30, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
GOODWILL AND OTHER INTANGIBLE ASSETS	GOODWILL AND OTHER INTANGIBLE ASSETS The changes in goodwill by segment for the six months ended June 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 — — 4,916 — 4,916 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 157 615 1,091 — 1,863 Balance at June 30, 2017 $ 59,973 $ 108,583 $ 304,263 $ — $ 472,819 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 Business," 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 June 30, 2017. As of June 30, 2017 and December 31, 2016 , the Company's total finite-lived and indefinite-lived intangible assets consisted of the following (in thousands): June 30, 2017 December 31, 2016 Cost Accumulated Net Weighted Cost Accumulated Net Weighted Permits $ 173,174 $ 70,698 $ 102,476 21.4 $ 171,637 $ 67,301 $ 104,336 18.9 Customer and supplier relationships 395,911 143,038 252,873 11.9 393,426 127,462 265,964 12.2 Other intangible assets 34,673 30,166 4,507 7.5 34,254 28,456 5,798 7.1 Total amortizable permits and other intangible assets 603,758 243,902 359,856 14.5 599,317 223,219 376,098 13.9 Trademarks and trade names 122,972 — 122,972 Indefinite 122,623 — 122,623 Indefinite Total permits and other intangible assets $ 726,730 $ 243,902 $ 482,828 $ 721,940 $ 223,219 $ 498,721 Amortization expense of permits and other intangible assets was $9.7 million and $18.8 million for the three and six months ended June 30, 2017 , respectively. Amortization expense of permits and other intangible assets was $9.9 million and $19.5 million for the three and six months ended June 30, 2016 , respectively. The expected amortization of the net carrying amount of finite-lived intangible assets at June 30, 2017 was as follows (in thousands): Years Ending December 31, Expected Amortization 2017 (six months) $ 18,078 2018 34,091 2019 31,238 2020 28,756 2021 26,557 Thereafter 221,136 $ 359,856

ACCRUED EXPENSES

ACCRUED EXPENSES	6 Months Ended
	Jun. 30, 2017
Payables and Accruals [Abstract]
ACCRUED EXPENSES	ACCRUED EXPENSES Accrued expenses consisted of the following at June 30, 2017 and December 31, 2016 (in thousands): June 30, 2017 December 31, 2016 Insurance $ 58,816 $ 63,061 Interest 15,006 21,536 Accrued compensation and benefits 45,159 34,641 Income, real estate, sales and other taxes 37,474 35,083 Other 35,040 36,400 $ 191,495 $ 190,721 As of June 30, 2017 and December 31, 2016 , other accrued expenses included accrued legal matters of $3.1 million and $3.8 million , respectively, and accrued severance charges of $1.8 million and $2.9 million , respectively.

CLOSURE AND POST-CLOSURE LIABIL

CLOSURE AND POST-CLOSURE LIABILITIES	6 Months Ended
	Jun. 30, 2017
Asset Retirement Obligation Disclosure [Abstract]
CLOSURE AND POST-CLOSURE LIABILITIES	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 June 30, 2017 were as follows (in thousands): Landfill Non-Landfill Total Balance at January 1, 2017 $ 30,630 $ 27,701 $ 58,331 Measurement period adjustments from prior period acquisitions — 596 596 New asset retirement obligations 894 — 894 Adjustment related to disposition of business — (1,170 ) (1,170 ) Accretion 1,094 1,270 2,364 Changes in estimates recorded to statement of operations — (262 ) (262 ) Changes in estimates recorded to balance sheet — (287 ) (287 ) Expenditures (556 ) (254 ) (810 ) Currency translation and other 82 55 137 Balance at June 30, 2017 $ 32,144 $ 27,649 $ 59,793 All of the landfill facilities included in the above were active as of June 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 six months of 2017 were discounted at the credit-adjusted risk-free rate of 6.32% .

REMEDIAL LIABILITIES

REMEDIAL LIABILITIES	6 Months Ended
	Jun. 30, 2017
Environmental Remediation Obligations [Abstract]
REMEDIAL LIABILITIES	REMEDIAL LIABILITIES The changes to remedial liabilities for the six months ended June 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 43 1,332 967 2,342 Changes in estimates recorded to statement of operations (36 ) (120 ) 289 133 Expenditures (19 ) (2,068 ) (3,205 ) (5,292 ) Currency translation and other (1 ) 2,712 (2,246 ) 465 Balance at June 30, 2017 $ 1,764 $ 66,007 $ 58,388 $ 126,159 In the six months ended June 30, 2017 , there were no significant charges (benefits) resulting from changes in estimates for remedial liabilities.

FINANCING ARRANGEMENTS

FINANCING ARRANGEMENTS	6 Months Ended
	Jun. 30, 2017
Debt Disclosure [Abstract]
FINANCING ARRANGEMENTS	FINANCING ARRANGEMENTS The following table is a summary of the Company’s financing arrangements (in thousands): June 30, 2017 December 31, 2016 Senior secured notes due June 30, 2024 ("Term Loan"), current $ 4,000 $ — Senior unsecured notes, at 5.25%, due August 1, 2020 ("2020 Notes"), current 103,798 — Current portion of long-term obligations, at carrying value $ 107,798 $ — Senior secured notes due June 30, 2024 $ 396,000 $ — Senior unsecured notes, at 5.25%, due August 1, 2020 400,000 800,000 Senior unsecured notes, at 5.125%, due June 1, 2021 ("2021 Notes") 845,000 845,000 Long-term obligations $ 1,641,000 $ 1,645,000 Unamortized debt issuance costs and debt discount/premium, net (14,495 ) (11,728 ) Long-term obligations, at carrying value $ 1,626,505 $ 1,633,272 Total current and long-term obligations, at carrying value $ 1,734,303 $ 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") with Goldman Sachs Lending Partners LLC, as administrative agent and collateral agent (the “Agent”), and certain other financial institutions. 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 June 30, 2017 was 3.23% . 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. 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. The Company financed the redemption through the remaining net proceeds of the Term Loan financing described above, plus available cash. At June 30, 2017 , the fair value of the Term Loan debt was $400.0 million . At June 30, 2017 and December 31, 2016 , the fair value of the Company's 2020 Notes was $510.7 million and $820.0 million , respectively, based on quoted market prices for the instrument. At June 30, 2017 and December 31, 2016 , the fair value of the Company's 2021 Notes was $863.0 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 June 30, 2017 and December 31, 2016 , the Company had no outstanding loan balances. At June 30, 2017 , approximately $225.3 million was available to borrow and outstanding letters of credit were $125.9 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

EARNINGS (LOSS) PER SHARE	6 Months Ended
	Jun. 30, 2017
Earnings Per Share [Abstract]
EARNINGS (LOSS) PER SHARE	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 Six Months Ended June 30, June 30, 2017 2016 2017 2016 Numerator for basic and diluted earnings (loss) per share: Net income (loss) $ 25,880 $ 3,966 $ 4,487 $ (16,905 ) Denominator: Basic shares outstanding 57,190 57,549 57,226 57,599 Dilutive effect of equity-based compensation awards 146 129 123 — Dilutive shares outstanding 57,336 57,678 57,349 57,599 Basic earnings (loss) per share: $ 0.45 $ 0.07 $ 0.08 $ (0.29 ) Diluted earnings (loss) per share: $ 0.45 $ 0.07 $ 0.08 $ (0.29 ) For the three months ended June 30, 2017 and 2016, the dilutive effect of all then outstanding options, restricted stock and performance awards is included in the EPS calculations above except for 142,503 and 348,197 , respectively, of outstanding performance stock awards for which the performance criteria were not attained at that time and 14,699 and 9,537 , respectively, of restricted stock awards which were antidilutive at that time. For the six months ended June 30, 2017 , the dilutive effect of all then outstanding options, restricted stock and performance awards is included in the EPS calculations above except for 142,503 of outstanding performance stock awards for which the performance criteria were not attained at that time and 21,013 of restricted stock awards which were antidilutive at that time. As a result of the net loss reported for the six months ended June 30, 2016, all then outstanding stock options, restricted stock awards and performance awards totaling 886,685 were excluded from the calculation of diluted earnings (loss) per share as their inclusion would have an antidilutive effect.

ACCUMULATED OTHER COMPREHENSIVE

ACCUMULATED OTHER COMPREHENSIVE LOSS	6 Months Ended
	Jun. 30, 2017
Equity [Abstract]
ACCUMULATED OTHER COMPREHENSIVE LOSS	ACCUMULATED OTHER COMPREHENSIVE LOSS The changes in accumulated other comprehensive loss by component and related tax effects for the six months ended June 30, 2017 were as follows (in thousands): Foreign Currency Translation Unrealized 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 20,847 281 — 21,128 Amounts reclassified out of accumulated other comprehensive loss — 222 — 222 Tax effects (201 ) — (201 ) Other comprehensive income $ 20,847 $ 302 $ — $ 21,149 Balance at June 30, 2017 $ (191,364 ) $ (19 ) $ (1,794 ) $ (193,177 ) The amounts reclassified out of accumulated other comprehensive loss into the consolidated statements of operations, with presentation location during the three and six months ended June 30, 2017 were as follow (in thousands): For the Three Months Ended For the Six Months Ended Comprehensive (Loss) Income Components June 30, 2017 June 30, 2017 Location Unrealized holding gains on available-for-sale investments $ 76 $ 222 Other expense There were no reclassifications out of accumulated other comprehensive loss into the consolidated statements of operations during the three and six months ended June 30, 2016.

STOCK-BASED COMPENSATION

STOCK-BASED COMPENSATION	6 Months Ended
	Jun. 30, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
STOCK-BASED COMPENSATION	STOCK-BASED COMPENSATION Total stock-based compensation cost charged to selling, general and administrative expenses for the three and six months ended June 30, 2017 was $2.9 million and $5.2 million , respectively. Total stock-based compensation cost charged to selling, general and administrative expenses for the three and six months ended June 30, 2016 was $2.6 million and $4.7 million , respectively. The total income tax benefit recognized in the consolidated statements of operations from stock-based compensation was $0.8 million and $1.5 million for the three and six months ended June 30, 2017 , respectively. The total income tax benefit recognized in the consolidated statements of operations from stock-based compensation was $0.8 million and $1.4 million for the three and six months ended June 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 six months ended June 30, 2017 : Restricted Stock Number of Shares Weighted Average Grant-Date Fair Value Balance at January 1, 2017 510,041 $ 52.65 Granted 161,250 $ 56.15 Vested (105,064 ) $ 54.17 Forfeited (34,374 ) $ 51.50 Balance at June 30, 2017 531,853 $ 53.49 As of June 30, 2017 , there was $23.8 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 2.6 years. The total fair value of restricted stock vested during the three and six months ended June 30, 2017 was $4.5 million and $6.0 million , respectively. The total fair value of restricted stock vested during the three and six months ended June 30, 2016 was $2.3 million and $6.1 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 six months ended June 30, 2017 : Performance Stock Number of Shares Weighted Average Grant-Date Fair Value Balance at January 1, 2017 220,882 $ 54.69 Granted 588 $ 54.44 Vested (25,168 ) $ 54.84 Forfeited (16,187 ) $ 56.24 Balance at June 30, 2017 180,115 $ 54.70 As of June 30, 2017 , there was $0.9 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 June 30, 2017 . The total fair value of performance awards vested during the six months ended June 30, 2017 was $1.4 million . No performance awards vested during the three months ended June 30, 2016. The total fair value of performance awards vested during the six months ended June 30, 2016 was $0.4 million . Common Stock Repurchases On March 13, 2015, the Company's board of directors authorized the repurchase of up to $300 million of the Company's common stock. During the three and six months ended June 30, 2017 , the Company repurchased and retired a total of 0.1 million shares and 0.2 million respectively, of the Company's common stock for a total cost of $5.5 million and $12.3 million , respectively. During the three and six months ended June 30, 2016 , the Company repurchased and retired a total of 0.1 million shares and 0.2 million shares, respectively, of the Company's common stock for a total cost of $5.1 million and $10.1 million , respectively. Through June 30, 2017 , the Company has repurchased and retired a total of 4.1 million shares of the Company's common stock for a total cost of $212.1 million under this program. As of June 30, 2017 , an additional $87.9 million remains available for repurchase of shares under the current authorized program.

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	6 Months Ended
	Jun. 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 June 30, 2017 and December 31, 2016 , the Company had recorded reserves of $20.8 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 June 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 June 30, 2017 and December 31, 2016 , the $20.8 million and $22.0 million , respectively, of reserves consisted of (i) $17.7 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) $3.1 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 June 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 June 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 62 proceedings (excluding cases which have been settled but not formally dismissed) as of June 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 June 30, 2017 . From January 1, 2017 to June 30, 2017 , 17 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 June 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

INCOME TAXES	6 Months Ended
	Jun. 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 six months ended June 30, 2017 was 47.3% and 85.2% compared to 68.7% and 57.3% for the same periods in 2016 . The variations in the effective income tax rates for the three and six months ended June 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 June 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

SEGMENT REPORTING	6 Months Ended
	Jun. 30, 2017
Segment Reporting [Abstract]
SEGMENT REPORTING	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 six months ended June 30, 2017 and 2016 (in thousands): For the Three Months Ended June 30, 2017 For the Three Months Ended June 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 $ 254,487 $ 40,001 $ 408 $ 294,896 $ 229,130 $ 35,578 $ 667 $ 265,375 Industrial and Field Services 167,899 (9,067 ) (133 ) 158,699 164,641 (7,922 ) (303 ) 156,416 Safety-Kleen 302,956 (31,639 ) (2 ) 271,315 277,715 (29,092 ) 1 248,624 Oil, Gas and Lodging Services 27,245 705 45 27,995 24,860 1,436 79 26,375 Corporate Items 201 — (318 ) (117 ) 1,164 — (444 ) 720 Total $ 752,788 $ — $ — $ 752,788 $ 697,510 $ — $ — $ 697,510 For the Six Months Ended June 30, 2017 For the Six Months Ended June 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 $ 484,705 $ 80,045 $ 1,130 $ 565,880 $ 448,235 $ 70,422 $ 1,055 $ 519,712 Industrial and Field Services 301,456 (17,426 ) (29 ) 284,001 294,828 (14,597 ) (316 ) 279,915 Safety-Kleen 595,857 (63,708 ) 1 532,150 524,676 (57,613 ) 367 467,430 Oil, Gas and Lodging Services 59,377 1,089 139 60,605 63,911 1,788 183 65,882 Corporate Items 334 — (1,241 ) (907 ) 1,943 — (1,289 ) 654 Total $ 1,441,729 $ — $ — $ 1,441,729 $ 1,333,593 $ — $ — $ 1,333,593 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, provision for income taxes and excludes 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 Six Months Ended June 30, June 30, 2017 2016 2017 2016 Adjusted EBITDA: Technical Services $ 73,080 $ 68,891 $ 131,567 $ 129,289 Industrial and Field Services 21,484 19,960 23,397 20,393 Safety-Kleen 60,281 55,234 112,649 95,289 Oil, Gas and Lodging Services 268 (1,199 ) 58 111 Corporate Items (34,422 ) (32,441 ) (66,845 ) (67,317 ) Total $ 120,691 $ 110,445 $ 200,826 $ 177,765 Reconciliation to Consolidated Statements of Operations: Accretion of environmental liabilities 2,416 2,548 4,706 5,053 Depreciation and amortization 71,531 73,393 143,943 142,295 Income from operations 46,744 34,504 52,177 30,417 Other expense 833 189 2,382 539 Loss on early extinguishment of debt 6,045 — 6,045 — Gain on sale of business (31,722 ) — (31,722 ) — Interest expense, net of interest income 22,492 21,647 45,068 40,627 Income (loss) before provision for income taxes $ 49,096 $ 12,668 $ 30,404 $ (10,749 ) The following table presents certain assets by reportable segment and in the aggregate (in thousands): June 30, 2017 Technical Industrial and Field Safety-Kleen Oil, Gas and Lodging Corporate Totals Property, plant and equipment, net $ 512,058 $ 243,195 $ 590,282 $ 181,001 $ 75,917 $ 1,602,453 Goodwill 59,973 108,583 304,263 — — 472,819 Permits and other intangibles, net 76,022 17,135 381,020 8,651 — 482,828 Total assets $ 851,852 $ 457,253 $ 1,477,660 $ 246,195 $ 773,322 $ 3,806,282 December 31, 2016 Technical Industrial and Field Safety-Kleen Oil, Gas and Lodging Corporate 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): June 30, 2017 December 31, 2016 United States $ 3,088,199 $ 2,960,337 Canada 718,083 721,583 Total $ 3,806,282 $ 3,681,920

GUARANTOR AND NON-GUARANTOR SUB

GUARANTOR AND NON-GUARANTOR SUBSIDIARIES FINANCIAL INFORMATION	6 Months Ended
	Jun. 30, 2017
Guarantor and Non-Guarantor Subsidiaries Financial Information [Abstract]
GUARANTOR AND NON-GUARANTOR SUBSIDIARIES FINANCIAL INFORMATION	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 June 30, 2017 (in thousands): Clean Harbors, Inc. Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating Adjustments Total Assets: Cash and cash equivalents $ 51,391 $ 303,996 $ 90,979 $ — $ 446,366 Intercompany receivables 220,885 314,705 38,312 (573,902 ) — Accounts receivables, net — 419,338 93,037 — 512,375 Other current assets 897 222,283 59,658 (6,845 ) 275,993 Property, plant and equipment, net — 1,198,630 403,823 — 1,602,453 Investments in subsidiaries 2,893,232 570,837 — (3,464,069 ) — Intercompany debt receivable — 89,441 24,701 (114,142 ) — Goodwill — 416,775 56,044 — 472,819 Permits and other intangibles, net — 421,793 61,035 — 482,828 Other long-term assets 2,363 7,555 4,598 (1,068 ) 13,448 Total assets $ 3,168,768 $ 3,965,353 $ 832,187 $ (4,160,026 ) $ 3,806,282 Liabilities and Stockholders’ Equity: Current liabilities $ 123,095 $ 375,919 $ 127,131 $ (6,845 ) $ 619,300 Intercompany payables 314,530 257,453 1,919 (573,902 ) — Closure, post-closure and remedial liabilities, net — 145,777 16,475 — 162,252 Long-term obligations 1,626,505 — — — 1,626,505 Intercompany debt payable 3,701 21,000 89,441 (114,142 ) — Other long-term liabilities — 278,833 19,523 (1,068 ) 297,288 Total liabilities 2,067,831 1,078,982 254,489 (695,957 ) 2,705,345 Stockholders’ equity 1,100,937 2,886,371 577,698 (3,464,069 ) 1,100,937 Total liabilities and stockholders’ equity $ 3,168,768 $ 3,965,353 $ 832,187 $ (4,160,026 ) $ 3,806,282 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 June 30, 2017 (in thousands): Clean Harbors, Inc. Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating Adjustments Total Revenues Service revenues $ — $ 474,801 $ 147,924 $ (11,785 ) $ 610,940 Product revenues — 125,859 18,730 (2,741 ) 141,848 Total revenues — 600,660 166,654 (14,526 ) 752,788 Cost of revenues (exclusive of items shown separately below) Service cost of revenues — 306,960 117,181 (11,785 ) 412,356 Product cost of revenues — 98,645 11,543 (2,741 ) 107,447 Total cost of revenues — 405,605 128,724 (14,526 ) 519,803 Selling, general and administrative expenses 27 92,504 19,763 — 112,294 Accretion of environmental liabilities — 2,181 235 — 2,416 Depreciation and amortization — 51,937 19,594 — 71,531 (Loss) income from operations (27 ) 48,433 (1,662 ) — 46,744 Other expense (76 ) (406 ) (351 ) — (833 ) Loss on early extinguishment of debt (6,045 ) — — — (6,045 ) Gain on sale of business — 31,722 — — 31,722 Interest (expense) income (22,614 ) 240 (118 ) — (22,492 ) Equity in earnings of subsidiaries, net of taxes 43,167 (5,332 ) — (37,835 ) — Intercompany interest income (expense) — 1,268 (1,268 ) — — Income (loss) before (benefit) provision for income taxes 14,405 75,925 (3,399 ) (37,835 ) 49,096 (Benefit) provision for income taxes (11,475 ) 31,981 2,710 — 23,216 Net income (loss) 25,880 43,944 (6,109 ) (37,835 ) 25,880 Other comprehensive income 15,098 15,098 12,837 (27,935 ) 15,098 Comprehensive income $ 40,978 $ 59,042 $ 6,728 $ (65,770 ) $ 40,978 Following is the consolidating statement of operations for the three months ended June 30, 2016 (in thousands): Clean Harbors, Inc. Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating Adjustments Total Revenues Service revenues $ — $ 456,013 $ 139,413 $ (10,864 ) $ 584,562 Product revenues — 95,648 19,391 (2,091 ) 112,948 Total revenues — 551,661 158,804 (12,955 ) 697,510 Cost of revenues (exclusive of items shown separately below) Service cost of revenues (587 ) 292,343 107,792 (10,864 ) 388,684 Product cost of revenues — 79,108 14,301 (2,091 ) 91,318 Total cost of revenues (587 ) 371,451 122,093 (12,955 ) 480,002 Selling, general and administrative expenses 37 83,882 23,144 — 107,063 Accretion of environmental liabilities — 2,313 235 — 2,548 Depreciation and amortization — 50,696 22,697 — 73,393 Income (loss) from operations 550 43,319 (9,365 ) — 34,504 Other income (expense) — 400 (589 ) — (189 ) Interest (expense) income (22,962 ) 1,284 31 — (21,647 ) Equity in earnings of subsidiaries, net of taxes 17,413 (9,195 ) — (8,218 ) — Intercompany interest income (expense) — 5,497 (5,497 ) — — (Loss) income before (benefit) provision for income taxes (4,999 ) 41,305 (15,420 ) (8,218 ) 12,668 (Benefit) provision for income taxes (8,965 ) 23,892 (6,225 ) — 8,702 Net income (loss) 3,966 17,413 (9,195 ) (8,218 ) 3,966 Other comprehensive loss (1,178 ) (1,178 ) (597 ) 1,775 (1,178 ) Comprehensive income (loss) $ 2,788 $ 16,235 $ (9,792 ) $ (6,443 ) $ 2,788 Following is the consolidating statement of operations for the six months ended June 30, 2017 (in thousands): Clean Harbors, Inc. Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating Adjustments Total Revenues Service revenues $ — $ 918,106 $ 278,995 $ (25,947 ) $ 1,171,154 Product revenues — 242,509 34,061 (5,995 ) 270,575 Total revenues — 1,160,615 313,056 (31,942 ) 1,441,729 Cost of revenues (exclusive of items shown separately below) Service cost of revenues — 601,105 228,285 (25,947 ) 803,443 Product cost of revenues — 195,150 23,790 (5,995 ) 212,945 Total cost of revenues — 796,255 252,075 (31,942 ) 1,016,388 Selling, general and administrative expenses 51 184,675 39,789 — 224,515 Accretion of environmental liabilities — 4,236 470 — 4,706 Depreciation and amortization — 103,837 40,106 — 143,943 (Loss) income from operations (51 ) 71,612 (19,384 ) — 52,177 Other expense (222 ) (1,795 ) (365 ) — (2,382 ) Loss on early extinguishment of debt (6,045 ) — — — (6,045 ) Gain on sale of business — 31,722 — — 31,722 Interest (expense) income (45,273 ) 359 (154 ) — (45,068 ) Equity in earnings of subsidiaries, net of taxes 35,530 (27,156 ) — (8,374 ) — Intercompany interest income (expense) — 2,565 (2,565 ) — — (Loss) income before (benefit) provision for income taxes (16,061 ) 77,307 (22,468 ) (8,374 ) 30,404 (Benefit) provision for income taxes (20,548 ) 41,618 4,847 — 25,917 Net income (loss) 4,487 35,689 (27,315 ) (8,374 ) 4,487 Other comprehensive income 21,149 21,149 17,869 (39,018 ) 21,149 Comprehensive income (loss) $ 25,636 $ 56,838 $ (9,446 ) $ (47,392 ) $ 25,636 Following is the consolidating statement of operations for the six months ended June 30, 2016 (in thousands): Clean Harbors, Inc. Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating Adjustments Total Revenues Service revenues $ — $ 884,490 $ 253,436 $ (23,133 ) $ 1,114,793 Product revenues — 185,236 38,104 (4,540 ) 218,800 Total revenues — 1,069,726 291,540 (27,673 ) 1,333,593 Cost of revenues (exclusive of items shown separately below) Service cost of revenues (587 ) 575,307 211,083 (23,133 ) 762,670 Product cost of revenues — 158,462 27,689 (4,540 ) 181,611 Total cost of revenues (587 ) 733,769 238,772 (27,673 ) 944,281 Selling, general and administrative expenses 61 164,537 46,949 — 211,547 Accretion of environmental liabilities — 4,603 450 — 5,053 Depreciation and amortization — 99,391 42,904 — 142,295 Income (loss) from operations 526 67,426 (37,535 ) — 30,417 Other income (expense) — 312 (851 ) — (539 ) Interest (expense) income (43,105 ) 2,395 83 — (40,627 ) Equity in earnings of subsidiaries, net of taxes 8,642 (35,690 ) — 27,048 — Intercompany interest income (expense) — 10,656 (10,656 ) — — (Loss) income before (benefit) provision for income taxes (33,937 ) 45,099 (48,959 ) 27,048 (10,749 ) (Benefit) provision for income taxes (17,032 ) 36,457 (13,269 ) — 6,156 Net (loss) income (16,905 ) 8,642 (35,690 ) 27,048 (16,905 ) Other comprehensive income 44,659 44,659 28,330 (72,989 ) 44,659 Comprehensive income (loss) $ 27,754 $ 53,301 $ (7,360 ) $ (45,941 ) $ 27,754 Following is the condensed consolidating statement of cash flows for the six months ended June 30, 2017 (in thousands): Clean Harbors, Inc. Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating Adjustments Total Net cash (used in) from operating activities $ (93,808 ) $ 206,496 $ 4,243 $ — $ 116,931 Cash flows from (used in) investing activities: Additions to property, plant and equipment — (75,152 ) (13,590 ) — (88,742 ) Proceeds from sales of fixed assets — 984 1,137 — 2,121 Acquisitions, net of cash acquired — (9,277 ) — — (9,277 ) Proceeds on sale of businesses, net of transactional costs — 46,210 181 — 46,391 Additions to intangible assets, including costs to obtain or renew permits — (888 ) (351 ) — (1,239 ) Proceeds from sale of investments 376 — — — 376 Intercompany — (14,343 ) — 14,343 — Net cash from (used in) investing activities 376 (52,466 ) (12,623 ) 14,343 (50,370 ) Cash flows from (used in) financing activities: Change in uncashed checks — (5,977 ) (2,384 ) — (8,361 ) Proceeds from exercise of stock options 46 — — — 46 Issuance of restricted shares, net of shares remitted (2,132 ) — — — (2,132 ) Repurchases of common stock (12,257 ) — — — (12,257 ) Deferred financing costs paid (4,727 ) — — — (4,727 ) Premiums paid on early extinguishment of debt (4,665 ) — — — (4,665 ) Principal payment on debt (296,202 ) — — — (296,202 ) Issuance of senior secured notes, net of discount 399,000 — — — 399,000 Intercompany 14,343 — — (14,343 ) — Net cash from (used in) financing activities 93,406 (5,977 ) (2,384 ) (14,343 ) 70,702 Effect of exchange rate change on cash — — 2,106 — 2,106 (Decrease) increase in cash and cash equivalents (26 ) 148,053 (8,658 ) — 139,369 Cash and cash equivalents, beginning of period 51,417 155,943 99,637 — 306,997 Cash and cash equivalents, end of period $ 51,391 $ 303,996 $ 90,979 $ — $ 446,366 Following is the condensed consolidating statement of cash flows for the six months ended June 30, 2016 (in thousands): Clean Harbors, Inc. Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating Adjustments Total Net cash from operating activities $ 42,990 $ 65,860 $ 11,201 $ — $ 120,051 Cash flows used in investing activities: Additions to property, plant and equipment — (105,175 ) (18,354 ) — (123,529 ) Proceeds from sales of fixed assets — 694 1,974 — 2,668 Acquisitions, net of cash acquired — (48,989 ) (10,000 ) — (58,989 ) Additions to intangible assets, including costs to obtain or renew permits — (908 ) (65 ) — (973 ) Purchases of available-for-sale securities (102 ) — (496 ) — (598 ) Intercompany — (11,827 ) — 11,827 — Investment in subsidiaries (250,625 ) — — 250,625 — Net cash used in investing activities (250,727 ) (166,205 ) (26,941 ) 262,452 (181,421 ) Cash flows from (used in) financing activities: Change in uncashed checks — (9,266 ) (1,756 ) — (11,022 ) Proceeds from exercise of stock options 184 — — — 184 Issuance of restricted shares, net of shares remitted (1,879 ) — — — (1,879 ) Repurchases of common stock (10,134 ) — — — (10,134 ) Excess tax benefit of stock-based compensation 2 — — — 2 Deferred financing costs paid (2,614 ) — — — (2,614 ) Issuance of senior unsecured notes, including premium 250,625 250,625 — (250,625 ) 250,625 Intercompany 11,827 — — (11,827 ) — Net cash from (used in) financing activities 248,011 241,359 (1,756 ) (262,452 ) 225,162 Effect of exchange rate change on cash — — 4,423 — 4,423 Increase (decrease) in cash and cash equivalents 40,274 141,014 (13,073 ) — 168,215 Cash and cash equivalents, beginning of period 11,017 83,479 90,212 — 184,708 Cash and cash equivalents, end of period $ 51,291 $ 224,493 $ 77,139 $ — $ 352,923

SUBSEQUENT EVENTS

SUBSEQUENT EVENTS	6 Months Ended
	Jun. 30, 2017
Subsequent Events [Abstract]
SUBSEQUENT EVENTS	SUBSEQUENT EVENTS On July 14, 2017, the Company acquired Lonestar West Inc. ("Lonestar"), a public company headquartered in Alberta, Canada, for approximately CAD $43.0 million ( $34.0 million USD) in cash which includes an equity payout of CAD $0.72 per share to Lonestar shareholders and the assumption of approximately CAD $22.0 million ( $17.4 million USD) in outstanding debt, which Clean Harbors subsequently repaid. Due to the timing of the acquisition of Lonestar, preliminary opening balance sheet amounts and purchase accounting adjustments are still being prepared and the purchase price is subject to customary post-closing adjustments. The acquisition will accelerate the Company's growth in the daylighting 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.

SIGNIFICANT ACCOUNTING POLICI30

SIGNIFICANT ACCOUNTING POLICIES (Policies)	6 Months Ended
	Jun. 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 six months ended June 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, 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 June 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 recorded cash paid in the second quarter 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. As the Company completes its evaluation of this new standard, the Company's preliminary assessments could change. 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 amendments in this Update are 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 amendments in this Update 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 amendments in this Update are 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 amendments in this Update 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)

BUSINESS COMBINATIONS (Tables)	6 Months Ended
	Jun. 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 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 BUSINESS (Tables

DISPOSITION OF BUSINESS (Tables)	6 Months Ended
	Jun. 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 $ 7,216 Property, plant and equipment, net 8,773 Total other assets 1,681 Total assets divested $ 17,670 Total current liabilities 3,849 Total other liabilities 1,170 Total liabilities divested $ 5,019 Net carrying value divested $ 12,651
Transformer Services
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposition of Business	Three Months Ended Six Months Ended June 30, June 30, 2017 2016 2017 2016 Income before provision for income taxes $ 1,873 $ 986 $ 2,771 $ 1,793
Catalyst Services
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposition of Business	The following table presents the income before provision for income taxes attributable to the Catalyst Services business included in the Company's consolidated results of operations for three and six months ended June 30, 2016 (in thousands): Three Months Ended Six Months Ended June 30, 2016 June 30, 2016 Income before provision for income taxes $ 2,607 $ 1,508

INVENTORIES AND SUPPLIES (Table

INVENTORIES AND SUPPLIES (Tables)	6 Months Ended
	Jun. 30, 2017
Inventory Disclosure [Abstract]
Schedule of Inventory	Inventories and supplies consisted of the following (in thousands): June 30, 2017 December 31, 2016 Oil and oil products $ 57,554 $ 52,158 Supplies and drums 92,995 90,610 Solvent and solutions 8,575 8,566 Modular camp accommodations 2,699 15,255 Other 10,717 11,839 Total inventories and supplies $ 172,540 $ 178,428

PROPERTY, PLANT AND EQUIPMENT (

PROPERTY, PLANT AND EQUIPMENT (Tables)	6 Months Ended
	Jun. 30, 2017
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	Property, plant and equipment consisted of the following (in thousands): June 30, 2017 December 31, 2016 Land $ 121,114 $ 120,575 Asset retirement costs (non-landfill) 14,861 14,567 Landfill assets 141,878 139,708 Buildings and improvements 406,030 373,160 Camp equipment 168,524 152,740 Vehicles 564,723 541,022 Equipment 1,605,581 1,483,736 Furniture and fixtures 5,524 5,492 Construction in progress 54,934 146,904 3,083,169 2,977,904 Less - accumulated depreciation and amortization 1,480,716 1,366,077 Total property, plant and equipment, net $ 1,602,453 $ 1,611,827

GOODWILL AND OTHER INTANGIBLE35

GOODWILL AND OTHER INTANGIBLE ASSETS (Tables)	6 Months Ended
	Jun. 30, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of changes to goodwill	The changes in goodwill by segment for the six months ended June 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 — — 4,916 — 4,916 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 157 615 1,091 — 1,863 Balance at June 30, 2017 $ 59,973 $ 108,583 $ 304,263 $ — $ 472,819
Summary of indefinite-lived intangible assets	As of June 30, 2017 and December 31, 2016 , the Company's total finite-lived and indefinite-lived intangible assets consisted of the following (in thousands): June 30, 2017 December 31, 2016 Cost Accumulated Net Weighted Cost Accumulated Net Weighted Permits $ 173,174 $ 70,698 $ 102,476 21.4 $ 171,637 $ 67,301 $ 104,336 18.9 Customer and supplier relationships 395,911 143,038 252,873 11.9 393,426 127,462 265,964 12.2 Other intangible assets 34,673 30,166 4,507 7.5 34,254 28,456 5,798 7.1 Total amortizable permits and other intangible assets 603,758 243,902 359,856 14.5 599,317 223,219 376,098 13.9 Trademarks and trade names 122,972 — 122,972 Indefinite 122,623 — 122,623 Indefinite Total permits and other intangible assets $ 726,730 $ 243,902 $ 482,828 $ 721,940 $ 223,219 $ 498,721
Schedule of finite-lived intangible assets	As of June 30, 2017 and December 31, 2016 , the Company's total finite-lived and indefinite-lived intangible assets consisted of the following (in thousands): June 30, 2017 December 31, 2016 Cost Accumulated Net Weighted Cost Accumulated Net Weighted Permits $ 173,174 $ 70,698 $ 102,476 21.4 $ 171,637 $ 67,301 $ 104,336 18.9 Customer and supplier relationships 395,911 143,038 252,873 11.9 393,426 127,462 265,964 12.2 Other intangible assets 34,673 30,166 4,507 7.5 34,254 28,456 5,798 7.1 Total amortizable permits and other intangible assets 603,758 243,902 359,856 14.5 599,317 223,219 376,098 13.9 Trademarks and trade names 122,972 — 122,972 Indefinite 122,623 — 122,623 Indefinite Total permits and other intangible assets $ 726,730 $ 243,902 $ 482,828 $ 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 June 30, 2017 was as follows (in thousands): Years Ending December 31, Expected Amortization 2017 (six months) $ 18,078 2018 34,091 2019 31,238 2020 28,756 2021 26,557 Thereafter 221,136 $ 359,856

ACCRUED EXPENSES (Tables)

ACCRUED EXPENSES (Tables)	6 Months Ended
	Jun. 30, 2017
Payables and Accruals [Abstract]
Accrued expenses	Accrued expenses consisted of the following at June 30, 2017 and December 31, 2016 (in thousands): June 30, 2017 December 31, 2016 Insurance $ 58,816 $ 63,061 Interest 15,006 21,536 Accrued compensation and benefits 45,159 34,641 Income, real estate, sales and other taxes 37,474 35,083 Other 35,040 36,400 $ 191,495 $ 190,721

CLOSURE AND POST-CLOSURE LIAB37

CLOSURE AND POST-CLOSURE LIABILITIES (Tables)	6 Months Ended
	Jun. 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 June 30, 2017 were as follows (in thousands): Landfill Non-Landfill Total Balance at January 1, 2017 $ 30,630 $ 27,701 $ 58,331 Measurement period adjustments from prior period acquisitions — 596 596 New asset retirement obligations 894 — 894 Adjustment related to disposition of business — (1,170 ) (1,170 ) Accretion 1,094 1,270 2,364 Changes in estimates recorded to statement of operations — (262 ) (262 ) Changes in estimates recorded to balance sheet — (287 ) (287 ) Expenditures (556 ) (254 ) (810 ) Currency translation and other 82 55 137 Balance at June 30, 2017 $ 32,144 $ 27,649 $ 59,793

REMEDIAL LIABILITIES (Tables)

REMEDIAL LIABILITIES (Tables)	6 Months Ended
	Jun. 30, 2017
Environmental Remediation Obligations [Abstract]
Changes to remedial liabilities	The changes to remedial liabilities for the six months ended June 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 43 1,332 967 2,342 Changes in estimates recorded to statement of operations (36 ) (120 ) 289 133 Expenditures (19 ) (2,068 ) (3,205 ) (5,292 ) Currency translation and other (1 ) 2,712 (2,246 ) 465 Balance at June 30, 2017 $ 1,764 $ 66,007 $ 58,388 $ 126,159

FINANCING ARRANGEMENTS (Tables)

FINANCING ARRANGEMENTS (Tables)	6 Months Ended
	Jun. 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): June 30, 2017 December 31, 2016 Senior secured notes due June 30, 2024 ("Term Loan"), current $ 4,000 $ — Senior unsecured notes, at 5.25%, due August 1, 2020 ("2020 Notes"), current 103,798 — Current portion of long-term obligations, at carrying value $ 107,798 $ — Senior secured notes due June 30, 2024 $ 396,000 $ — Senior unsecured notes, at 5.25%, due August 1, 2020 400,000 800,000 Senior unsecured notes, at 5.125%, due June 1, 2021 ("2021 Notes") 845,000 845,000 Long-term obligations $ 1,641,000 $ 1,645,000 Unamortized debt issuance costs and debt discount/premium, net (14,495 ) (11,728 ) Long-term obligations, at carrying value $ 1,626,505 $ 1,633,272 Total current and long-term obligations, at carrying value $ 1,734,303 $ 1,633,272

EARNINGS (LOSS) PER SHARE (Tabl

EARNINGS (LOSS) PER SHARE (Tables)	6 Months Ended
	Jun. 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 Six Months Ended June 30, June 30, 2017 2016 2017 2016 Numerator for basic and diluted earnings (loss) per share: Net income (loss) $ 25,880 $ 3,966 $ 4,487 $ (16,905 ) Denominator: Basic shares outstanding 57,190 57,549 57,226 57,599 Dilutive effect of equity-based compensation awards 146 129 123 — Dilutive shares outstanding 57,336 57,678 57,349 57,599 Basic earnings (loss) per share: $ 0.45 $ 0.07 $ 0.08 $ (0.29 ) Diluted earnings (loss) per share: $ 0.45 $ 0.07 $ 0.08 $ (0.29 )

ACCUMULATED OTHER COMPREHENSI41

ACCUMULATED OTHER COMPREHENSIVE LOSS (Tables)	6 Months Ended
	Jun. 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 six months ended June 30, 2017 were as follows (in thousands): Foreign Currency Translation Unrealized 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 20,847 281 — 21,128 Amounts reclassified out of accumulated other comprehensive loss — 222 — 222 Tax effects (201 ) — (201 ) Other comprehensive income $ 20,847 $ 302 $ — $ 21,149 Balance at June 30, 2017 $ (191,364 ) $ (19 ) $ (1,794 ) $ (193,177 )
Reclassification out of accumulated other comprehensive loss	The amounts reclassified out of accumulated other comprehensive loss into the consolidated statements of operations, with presentation location during the three and six months ended June 30, 2017 were as follow (in thousands): For the Three Months Ended For the Six Months Ended Comprehensive (Loss) Income Components June 30, 2017 June 30, 2017 Location Unrealized holding gains on available-for-sale investments $ 76 $ 222 Other expense

STOCK-BASED COMPENSATION (Table

STOCK-BASED COMPENSATION (Tables)	6 Months Ended
	Jun. 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 six months ended June 30, 2017 : Restricted Stock Number of Shares Weighted Average Grant-Date Fair Value Balance at January 1, 2017 510,041 $ 52.65 Granted 161,250 $ 56.15 Vested (105,064 ) $ 54.17 Forfeited (34,374 ) $ 51.50 Balance at June 30, 2017 531,853 $ 53.49
Summary of performance stock awards	The following table summarizes information about performance stock awards for the six months ended June 30, 2017 : Performance Stock Number of Shares Weighted Average Grant-Date Fair Value Balance at January 1, 2017 220,882 $ 54.69 Granted 588 $ 54.44 Vested (25,168 ) $ 54.84 Forfeited (16,187 ) $ 56.24 Balance at June 30, 2017 180,115 $ 54.70

SEGMENT REPORTING (Tables)

SEGMENT REPORTING (Tables)	6 Months Ended
	Jun. 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 six months ended June 30, 2017 and 2016 (in thousands): For the Three Months Ended June 30, 2017 For the Three Months Ended June 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 $ 254,487 $ 40,001 $ 408 $ 294,896 $ 229,130 $ 35,578 $ 667 $ 265,375 Industrial and Field Services 167,899 (9,067 ) (133 ) 158,699 164,641 (7,922 ) (303 ) 156,416 Safety-Kleen 302,956 (31,639 ) (2 ) 271,315 277,715 (29,092 ) 1 248,624 Oil, Gas and Lodging Services 27,245 705 45 27,995 24,860 1,436 79 26,375 Corporate Items 201 — (318 ) (117 ) 1,164 — (444 ) 720 Total $ 752,788 $ — $ — $ 752,788 $ 697,510 $ — $ — $ 697,510 For the Six Months Ended June 30, 2017 For the Six Months Ended June 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 $ 484,705 $ 80,045 $ 1,130 $ 565,880 $ 448,235 $ 70,422 $ 1,055 $ 519,712 Industrial and Field Services 301,456 (17,426 ) (29 ) 284,001 294,828 (14,597 ) (316 ) 279,915 Safety-Kleen 595,857 (63,708 ) 1 532,150 524,676 (57,613 ) 367 467,430 Oil, Gas and Lodging Services 59,377 1,089 139 60,605 63,911 1,788 183 65,882 Corporate Items 334 — (1,241 ) (907 ) 1,943 — (1,289 ) 654 Total $ 1,441,729 $ — $ — $ 1,441,729 $ 1,333,593 $ — $ — $ 1,333,593
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 Six Months Ended June 30, June 30, 2017 2016 2017 2016 Adjusted EBITDA: Technical Services $ 73,080 $ 68,891 $ 131,567 $ 129,289 Industrial and Field Services 21,484 19,960 23,397 20,393 Safety-Kleen 60,281 55,234 112,649 95,289 Oil, Gas and Lodging Services 268 (1,199 ) 58 111 Corporate Items (34,422 ) (32,441 ) (66,845 ) (67,317 ) Total $ 120,691 $ 110,445 $ 200,826 $ 177,765 Reconciliation to Consolidated Statements of Operations: Accretion of environmental liabilities 2,416 2,548 4,706 5,053 Depreciation and amortization 71,531 73,393 143,943 142,295 Income from operations 46,744 34,504 52,177 30,417 Other expense 833 189 2,382 539 Loss on early extinguishment of debt 6,045 — 6,045 — Gain on sale of business (31,722 ) — (31,722 ) — Interest expense, net of interest income 22,492 21,647 45,068 40,627 Income (loss) before provision for income taxes $ 49,096 $ 12,668 $ 30,404 $ (10,749 )
PP&E, intangible assets and total assets by segment	The following table presents certain assets by reportable segment and in the aggregate (in thousands): June 30, 2017 Technical Industrial and Field Safety-Kleen Oil, Gas and Lodging Corporate Totals Property, plant and equipment, net $ 512,058 $ 243,195 $ 590,282 $ 181,001 $ 75,917 $ 1,602,453 Goodwill 59,973 108,583 304,263 — — 472,819 Permits and other intangibles, net 76,022 17,135 381,020 8,651 — 482,828 Total assets $ 851,852 $ 457,253 $ 1,477,660 $ 246,195 $ 773,322 $ 3,806,282 December 31, 2016 Technical Industrial and Field Safety-Kleen Oil, Gas and Lodging Corporate 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): June 30, 2017 December 31, 2016 United States $ 3,088,199 $ 2,960,337 Canada 718,083 721,583 Total $ 3,806,282 $ 3,681,920

GUARANTOR AND NON-GUARANTOR S44

GUARANTOR AND NON-GUARANTOR SUBSIDIARIES FINANCIAL INFORMATION (Tables)	6 Months Ended
	Jun. 30, 2017
Guarantor and Non-Guarantor Subsidiaries Financial Information [Abstract]
Schedule of condensed consolidating balance sheet	Following is the condensed consolidating balance sheet at June 30, 2017 (in thousands): Clean Harbors, Inc. Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating Adjustments Total Assets: Cash and cash equivalents $ 51,391 $ 303,996 $ 90,979 $ — $ 446,366 Intercompany receivables 220,885 314,705 38,312 (573,902 ) — Accounts receivables, net — 419,338 93,037 — 512,375 Other current assets 897 222,283 59,658 (6,845 ) 275,993 Property, plant and equipment, net — 1,198,630 403,823 — 1,602,453 Investments in subsidiaries 2,893,232 570,837 — (3,464,069 ) — Intercompany debt receivable — 89,441 24,701 (114,142 ) — Goodwill — 416,775 56,044 — 472,819 Permits and other intangibles, net — 421,793 61,035 — 482,828 Other long-term assets 2,363 7,555 4,598 (1,068 ) 13,448 Total assets $ 3,168,768 $ 3,965,353 $ 832,187 $ (4,160,026 ) $ 3,806,282 Liabilities and Stockholders’ Equity: Current liabilities $ 123,095 $ 375,919 $ 127,131 $ (6,845 ) $ 619,300 Intercompany payables 314,530 257,453 1,919 (573,902 ) — Closure, post-closure and remedial liabilities, net — 145,777 16,475 — 162,252 Long-term obligations 1,626,505 — — — 1,626,505 Intercompany debt payable 3,701 21,000 89,441 (114,142 ) — Other long-term liabilities — 278,833 19,523 (1,068 ) 297,288 Total liabilities 2,067,831 1,078,982 254,489 (695,957 ) 2,705,345 Stockholders’ equity 1,100,937 2,886,371 577,698 (3,464,069 ) 1,100,937 Total liabilities and stockholders’ equity $ 3,168,768 $ 3,965,353 $ 832,187 $ (4,160,026 ) $ 3,806,282 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 June 30, 2017 (in thousands): Clean Harbors, Inc. Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating Adjustments Total Revenues Service revenues $ — $ 474,801 $ 147,924 $ (11,785 ) $ 610,940 Product revenues — 125,859 18,730 (2,741 ) 141,848 Total revenues — 600,660 166,654 (14,526 ) 752,788 Cost of revenues (exclusive of items shown separately below) Service cost of revenues — 306,960 117,181 (11,785 ) 412,356 Product cost of revenues — 98,645 11,543 (2,741 ) 107,447 Total cost of revenues — 405,605 128,724 (14,526 ) 519,803 Selling, general and administrative expenses 27 92,504 19,763 — 112,294 Accretion of environmental liabilities — 2,181 235 — 2,416 Depreciation and amortization — 51,937 19,594 — 71,531 (Loss) income from operations (27 ) 48,433 (1,662 ) — 46,744 Other expense (76 ) (406 ) (351 ) — (833 ) Loss on early extinguishment of debt (6,045 ) — — — (6,045 ) Gain on sale of business — 31,722 — — 31,722 Interest (expense) income (22,614 ) 240 (118 ) — (22,492 ) Equity in earnings of subsidiaries, net of taxes 43,167 (5,332 ) — (37,835 ) — Intercompany interest income (expense) — 1,268 (1,268 ) — — Income (loss) before (benefit) provision for income taxes 14,405 75,925 (3,399 ) (37,835 ) 49,096 (Benefit) provision for income taxes (11,475 ) 31,981 2,710 — 23,216 Net income (loss) 25,880 43,944 (6,109 ) (37,835 ) 25,880 Other comprehensive income 15,098 15,098 12,837 (27,935 ) 15,098 Comprehensive income $ 40,978 $ 59,042 $ 6,728 $ (65,770 ) $ 40,978 Following is the consolidating statement of operations for the three months ended June 30, 2016 (in thousands): Clean Harbors, Inc. Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating Adjustments Total Revenues Service revenues $ — $ 456,013 $ 139,413 $ (10,864 ) $ 584,562 Product revenues — 95,648 19,391 (2,091 ) 112,948 Total revenues — 551,661 158,804 (12,955 ) 697,510 Cost of revenues (exclusive of items shown separately below) Service cost of revenues (587 ) 292,343 107,792 (10,864 ) 388,684 Product cost of revenues — 79,108 14,301 (2,091 ) 91,318 Total cost of revenues (587 ) 371,451 122,093 (12,955 ) 480,002 Selling, general and administrative expenses 37 83,882 23,144 — 107,063 Accretion of environmental liabilities — 2,313 235 — 2,548 Depreciation and amortization — 50,696 22,697 — 73,393 Income (loss) from operations 550 43,319 (9,365 ) — 34,504 Other income (expense) — 400 (589 ) — (189 ) Interest (expense) income (22,962 ) 1,284 31 — (21,647 ) Equity in earnings of subsidiaries, net of taxes 17,413 (9,195 ) — (8,218 ) — Intercompany interest income (expense) — 5,497 (5,497 ) — — (Loss) income before (benefit) provision for income taxes (4,999 ) 41,305 (15,420 ) (8,218 ) 12,668 (Benefit) provision for income taxes (8,965 ) 23,892 (6,225 ) — 8,702 Net income (loss) 3,966 17,413 (9,195 ) (8,218 ) 3,966 Other comprehensive loss (1,178 ) (1,178 ) (597 ) 1,775 (1,178 ) Comprehensive income (loss) $ 2,788 $ 16,235 $ (9,792 ) $ (6,443 ) $ 2,788 Following is the consolidating statement of operations for the six months ended June 30, 2017 (in thousands): Clean Harbors, Inc. Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating Adjustments Total Revenues Service revenues $ — $ 918,106 $ 278,995 $ (25,947 ) $ 1,171,154 Product revenues — 242,509 34,061 (5,995 ) 270,575 Total revenues — 1,160,615 313,056 (31,942 ) 1,441,729 Cost of revenues (exclusive of items shown separately below) Service cost of revenues — 601,105 228,285 (25,947 ) 803,443 Product cost of revenues — 195,150 23,790 (5,995 ) 212,945 Total cost of revenues — 796,255 252,075 (31,942 ) 1,016,388 Selling, general and administrative expenses 51 184,675 39,789 — 224,515 Accretion of environmental liabilities — 4,236 470 — 4,706 Depreciation and amortization — 103,837 40,106 — 143,943 (Loss) income from operations (51 ) 71,612 (19,384 ) — 52,177 Other expense (222 ) (1,795 ) (365 ) — (2,382 ) Loss on early extinguishment of debt (6,045 ) — — — (6,045 ) Gain on sale of business — 31,722 — — 31,722 Interest (expense) income (45,273 ) 359 (154 ) — (45,068 ) Equity in earnings of subsidiaries, net of taxes 35,530 (27,156 ) — (8,374 ) — Intercompany interest income (expense) — 2,565 (2,565 ) — — (Loss) income before (benefit) provision for income taxes (16,061 ) 77,307 (22,468 ) (8,374 ) 30,404 (Benefit) provision for income taxes (20,548 ) 41,618 4,847 — 25,917 Net income (loss) 4,487 35,689 (27,315 ) (8,374 ) 4,487 Other comprehensive income 21,149 21,149 17,869 (39,018 ) 21,149 Comprehensive income (loss) $ 25,636 $ 56,838 $ (9,446 ) $ (47,392 ) $ 25,636 Following is the consolidating statement of operations for the six months ended June 30, 2016 (in thousands): Clean Harbors, Inc. Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating Adjustments Total Revenues Service revenues $ — $ 884,490 $ 253,436 $ (23,133 ) $ 1,114,793 Product revenues — 185,236 38,104 (4,540 ) 218,800 Total revenues — 1,069,726 291,540 (27,673 ) 1,333,593 Cost of revenues (exclusive of items shown separately below) Service cost of revenues (587 ) 575,307 211,083 (23,133 ) 762,670 Product cost of revenues — 158,462 27,689 (4,540 ) 181,611 Total cost of revenues (587 ) 733,769 238,772 (27,673 ) 944,281 Selling, general and administrative expenses 61 164,537 46,949 — 211,547 Accretion of environmental liabilities — 4,603 450 — 5,053 Depreciation and amortization — 99,391 42,904 — 142,295 Income (loss) from operations 526 67,426 (37,535 ) — 30,417 Other income (expense) — 312 (851 ) — (539 ) Interest (expense) income (43,105 ) 2,395 83 — (40,627 ) Equity in earnings of subsidiaries, net of taxes 8,642 (35,690 ) — 27,048 — Intercompany interest income (expense) — 10,656 (10,656 ) — — (Loss) income before (benefit) provision for income taxes (33,937 ) 45,099 (48,959 ) 27,048 (10,749 ) (Benefit) provision for income taxes (17,032 ) 36,457 (13,269 ) — 6,156 Net (loss) income (16,905 ) 8,642 (35,690 ) 27,048 (16,905 ) Other comprehensive income 44,659 44,659 28,330 (72,989 ) 44,659 Comprehensive income (loss) $ 27,754 $ 53,301 $ (7,360 ) $ (45,941 ) $ 27,754
Schedule of condensed consolidating statement of cash flows	Following is the condensed consolidating statement of cash flows for the six months ended June 30, 2017 (in thousands): Clean Harbors, Inc. Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating Adjustments Total Net cash (used in) from operating activities $ (93,808 ) $ 206,496 $ 4,243 $ — $ 116,931 Cash flows from (used in) investing activities: Additions to property, plant and equipment — (75,152 ) (13,590 ) — (88,742 ) Proceeds from sales of fixed assets — 984 1,137 — 2,121 Acquisitions, net of cash acquired — (9,277 ) — — (9,277 ) Proceeds on sale of businesses, net of transactional costs — 46,210 181 — 46,391 Additions to intangible assets, including costs to obtain or renew permits — (888 ) (351 ) — (1,239 ) Proceeds from sale of investments 376 — — — 376 Intercompany — (14,343 ) — 14,343 — Net cash from (used in) investing activities 376 (52,466 ) (12,623 ) 14,343 (50,370 ) Cash flows from (used in) financing activities: Change in uncashed checks — (5,977 ) (2,384 ) — (8,361 ) Proceeds from exercise of stock options 46 — — — 46 Issuance of restricted shares, net of shares remitted (2,132 ) — — — (2,132 ) Repurchases of common stock (12,257 ) — — — (12,257 ) Deferred financing costs paid (4,727 ) — — — (4,727 ) Premiums paid on early extinguishment of debt (4,665 ) — — — (4,665 ) Principal payment on debt (296,202 ) — — — (296,202 ) Issuance of senior secured notes, net of discount 399,000 — — — 399,000 Intercompany 14,343 — — (14,343 ) — Net cash from (used in) financing activities 93,406 (5,977 ) (2,384 ) (14,343 ) 70,702 Effect of exchange rate change on cash — — 2,106 — 2,106 (Decrease) increase in cash and cash equivalents (26 ) 148,053 (8,658 ) — 139,369 Cash and cash equivalents, beginning of period 51,417 155,943 99,637 — 306,997 Cash and cash equivalents, end of period $ 51,391 $ 303,996 $ 90,979 $ — $ 446,366 Following is the condensed consolidating statement of cash flows for the six months ended June 30, 2016 (in thousands): Clean Harbors, Inc. Guarantor Subsidiaries Non-Guarantor Subsidiaries Consolidating Adjustments Total Net cash from operating activities $ 42,990 $ 65,860 $ 11,201 $ — $ 120,051 Cash flows used in investing activities: Additions to property, plant and equipment — (105,175 ) (18,354 ) — (123,529 ) Proceeds from sales of fixed assets — 694 1,974 — 2,668 Acquisitions, net of cash acquired — (48,989 ) (10,000 ) — (58,989 ) Additions to intangible assets, including costs to obtain or renew permits — (908 ) (65 ) — (973 ) Purchases of available-for-sale securities (102 ) — (496 ) — (598 ) Intercompany — (11,827 ) — 11,827 — Investment in subsidiaries (250,625 ) — — 250,625 — Net cash used in investing activities (250,727 ) (166,205 ) (26,941 ) 262,452 (181,421 ) Cash flows from (used in) financing activities: Change in uncashed checks — (9,266 ) (1,756 ) — (11,022 ) Proceeds from exercise of stock options 184 — — — 184 Issuance of restricted shares, net of shares remitted (1,879 ) — — — (1,879 ) Repurchases of common stock (10,134 ) — — — (10,134 ) Excess tax benefit of stock-based compensation 2 — — — 2 Deferred financing costs paid (2,614 ) — — — (2,614 ) Issuance of senior unsecured notes, including premium 250,625 250,625 — (250,625 ) 250,625 Intercompany 11,827 — — (11,827 ) — Net cash from (used in) financing activities 248,011 241,359 (1,756 ) (262,452 ) 225,162 Effect of exchange rate change on cash — — 4,423 — 4,423 Increase (decrease) in cash and cash equivalents 40,274 141,014 (13,073 ) — 168,215 Cash and cash equivalents, beginning of period 11,017 83,479 90,212 — 184,708 Cash and cash equivalents, end of period $ 51,291 $ 224,493 $ 77,139 $ — $ 352,923

SIGNIFICANT ACCOUNTING POLICI45

SIGNIFICANT ACCOUNTING POLICIES (Narrative) (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2017segment	Dec. 31, 2016USD ($)
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 (Narrativ

BUSINESS COMBINATIONS (Narrative) (Details) $ in Thousands	Jan. 31, 2017USD ($)	Jun. 30, 2017USD ($)	Dec. 31, 2016USD ($)rerefineryacquisition
Business Acquisition [Line Items]
Goodwill recognized		$ 4,916
2017 Acquisitions
Business Acquisition [Line Items]
Purchase price	$ 11,900
Goodwill recognized	$ 4,900
2016 Acquisitions
Business Acquisition [Line Items]
Purchase price			$ 204,800
Number of acquisitions | acquisition			7
Number of re-refineries acquired | rerefinery			3

BUSINESS COMBINATIONS (Assets A

BUSINESS COMBINATIONS (Assets Acquired and Liabilities Assumed) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Goodwill	$ 472,819	$ 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 As Reported December 31, 2016 | 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 BUSINESS (Narrat

DISPOSITION OF BUSINESS (Narrative) (Details) - Transformer Services $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2017USD ($)	Jun. 30, 2017USD ($)
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
Pre-tax gain		31.7
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	$ 46.5
Proceeds, net of transactional related costs	44.4
Transactional related costs	2.1
Pre-tax gain	$ 31.7

DISPOSITION OF BUSINESS (Summar

DISPOSITION OF BUSINESS (Summary of Carry Amounts of Transformer Services) (Details) - Transformer Services - Disposal Group, Disposed of by Sale, Not Discontinued Operations $ in Thousands	Jun. 30, 2017USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total current assets	$ 7,216
Property, plant and equipment, net	8,773
Total other assets	1,681
Total assets divested	17,670
Total current liabilities	3,849
Total other liabilities	1,170
Total liabilities divested	5,019
Net carrying value divested	$ 12,651

DISPOSITION OF BUSINESS (Income

DISPOSITION OF BUSINESS (Income (Loss) Attributable to Transformer Services) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 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	$ 1,873	$ 986	$ 2,771	$ 1,793

DISPOSITION OF BUSINESS (Inco51

DISPOSITION OF BUSINESS (Income (Loss) Attributable to Catalyst Services) (Details) - Catalyst Services - Disposal Group, Disposed of by Sale, Not Discontinued Operations - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2016	Jun. 30, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Final sale proceeds			$ 2,000
Income before provision for income taxes	$ 2,607	$ 1,508

INVENTORIES AND SUPPLIES (Detai

INVENTORIES AND SUPPLIES (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Inventory Disclosure [Abstract]
Oil and oil products	$ 57,554	$ 57,554		$ 52,158
Supplies and drums	92,995	92,995		90,610
Solvent and solutions	8,575	8,575		8,566
Modular camp accommodations	2,699	2,699		15,255
Other	10,717	10,717		11,839
Total inventories and supplies	172,540	172,540		$ 178,428
Transfer of inventory to property, plant and equipment	$ 12,600	$ 12,641	$ 0

PROPERTY, PLANT AND EQUIPMENT53

PROPERTY, PLANT AND EQUIPMENT (Schedule of Property, Plant and Equipment) (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	$ 3,083,169	$ 2,977,904
Less - accumulated depreciation and amortization	1,480,716	1,366,077
Total property, plant and equipment, net	1,602,453	1,611,827
Land
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	121,114	120,575
Asset retirement costs (non-landfill)
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	14,861	14,567
Landfill assets
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	141,878	139,708
Buildings and improvements
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	406,030	373,160
Camp equipment
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	168,524	152,740
Vehicles
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	564,723	541,022
Equipment
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	1,605,581	1,483,736
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	5,524	5,492
Construction in progress
Property, Plant and Equipment [Line Items]
Total property, plant and equipment, gross	$ 54,934	$ 146,904

PROPERTY, PLANT AND EQUIPMENT54

PROPERTY, PLANT AND EQUIPMENT (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Property, Plant and Equipment [Abstract]
Interest costs capitalized adjustment	$ 0.1	$ 1.3	$ 0.2	$ 2.5
Depreciation inclusive of amortization	$ 61.8	$ 63.5	$ 125.2	$ 122.8

GOODWILL AND OTHER INTANGIBLE55

GOODWILL AND OTHER INTANGIBLE ASSETS (Rollforward of Goodwill) (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2017USD ($)
Goodwill [Roll Forward]
Balance at beginning of year	$ 465,154
Increase from current period acquisitions	4,916
Measurement period adjustments from prior period acquisitions	2,186
Decrease from disposition of business	(1,300)
Foreign currency translation and other	1,863
Balance at end of year	472,819
Technical Services
Goodwill [Roll Forward]
Balance at beginning of year	61,116
Balance at end of year	59,973
Industrial and Field Services
Goodwill [Roll Forward]
Balance at beginning of year	107,968
Balance at end of year	108,583
Safety-Kleen
Goodwill [Roll Forward]
Balance at beginning of year	296,070
Balance at end of year	304,263
Oil, Gas and Lodging Services
Goodwill [Roll Forward]
Balance at beginning of year	0
Balance at end of year	0
Operating Segments | 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	157
Balance at end of year	59,973
Operating Segments | Industrial and Field Services
Goodwill [Roll Forward]
Balance at beginning of year	107,968
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	615
Balance at end of year	108,583
Operating Segments | Safety-Kleen
Goodwill [Roll Forward]
Balance at beginning of year	296,070
Increase from current period acquisitions	4,916
Measurement period adjustments from prior period acquisitions	2,186
Decrease from disposition of business	0
Foreign currency translation and other	1,091
Balance at end of year	304,263
Operating Segments | 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
Foreign currency translation and other	0
Balance at end of year	$ 0

GOODWILL AND OTHER INTANGIBLE56

GOODWILL AND OTHER INTANGIBLE ASSETS (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization of permits and other intangible assets	$ 9.7	$ 9.9	$ 18.8	$ 19.5

GOODWILL AND OTHER INTANGIBLE57

GOODWILL AND OTHER INTANGIBLE ASSETS (Amortizable Other Intangible Assets) (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2016
Schedule of Finite-lived and Indefinite-lived Intangible Assets [Line Items]
Cost	$ 603,758	$ 599,317
Accumulated Amortization	243,902	223,219
Net	$ 359,856	$ 376,098
Weighted Average Remaining Amortization Period (in years)	14 years 165 days	13 years 9 months 40 days
Total permits and other intangible assets, Cost	$ 726,730	$ 721,940
Total permits and other intangible assets, Net	482,828	498,721
Trademarks and trade names
Schedule of Finite-lived and Indefinite-lived Intangible Assets [Line Items]
Trademarks and trade names	122,972	122,623
Permits
Schedule of Finite-lived and Indefinite-lived Intangible Assets [Line Items]
Cost	173,174	171,637
Accumulated Amortization	70,698	67,301
Net	$ 102,476	$ 104,336
Weighted Average Remaining Amortization Period (in years)	21 years 130 days	18 years 9 months 40 days
Customer and supplier relationships
Schedule of Finite-lived and Indefinite-lived Intangible Assets [Line Items]
Cost	$ 395,911	$ 393,426
Accumulated Amortization	143,038	127,462
Net	$ 252,873	$ 265,964
Weighted Average Remaining Amortization Period (in years)	11 years 340 days	12 years 2 months
Other intangible assets
Schedule of Finite-lived and Indefinite-lived Intangible Assets [Line Items]
Cost	$ 34,673	$ 34,254
Accumulated Amortization	30,166	28,456
Net	$ 4,507	$ 5,798
Weighted Average Remaining Amortization Period (in years)	7 years 175 days	7 years 1 month

GOODWILL AND OTHER INTANGIBLE58

GOODWILL AND OTHER INTANGIBLE ASSETS (Expected Future Amortization) (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
2017 (six months)	$ 18,078
2,018	34,091
2,019	31,238
2,020	28,756
2,021	26,557
Thereafter	221,136
Net	$ 359,856	$ 376,098

ACCRUED EXPENSES (Details)

ACCRUED EXPENSES (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Payables and Accruals [Abstract]
Insurance	$ 58,816	$ 63,061
Interest	15,006	21,536
Accrued compensation and benefits	45,159	34,641
Income, real estate, sales and other taxes	37,474	35,083
Other	35,040	36,400
Total accrued expenses	191,495	190,721
Accrued legal matters	3,100	3,800
Accrued severance charges	$ 1,800	$ 2,900

CLOSURE AND POST-CLOSURE LIAB60

CLOSURE AND POST-CLOSURE LIABILITIES (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2017USD ($)
Changes to post-closure liabilities
Beginning balance	$ 58,331
Measurement period adjustments from prior period acquisitions	596
New asset retirement obligations	894
Adjustment related to disposition of business	(1,170)
Accretion	2,364
Changes in estimates recorded to statement of operations	(262)
Changes in estimates recorded to balance sheet	(287)
Expenditures	(810)
Currency translation and other	137
Ending balance	$ 59,793
Credit-adjusted risk-free rate	6.32%
Landfill Retirement Liability
Changes to post-closure liabilities
Beginning balance	$ 30,630
Measurement period adjustments from prior period acquisitions	0
New asset retirement obligations	894
Adjustment related to disposition of business	0
Accretion	1,094
Changes in estimates recorded to statement of operations	0
Changes in estimates recorded to balance sheet	0
Expenditures	(556)
Currency translation and other	82
Ending balance	32,144
Non-Landfill Retirement Liability
Changes to post-closure liabilities
Beginning balance	27,701
Measurement period adjustments from prior period acquisitions	596
New asset retirement obligations	0
Adjustment related to disposition of business	(1,170)
Accretion	1,270
Changes in estimates recorded to statement of operations	(262)
Changes in estimates recorded to balance sheet	(287)
Expenditures	(254)
Currency translation and other	55
Ending balance	$ 27,649

REMEDIAL LIABILITIES (Details)

REMEDIAL LIABILITIES (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2017USD ($)
Accrual for Environmental Loss Contingencies [Roll Forward]
Balance at beginning of year	$ 128,007
Measurement period adjustments from prior period acquisitions	504
Accretion	2,342
Changes in estimates recorded to statement of operations	133
Expenditures	(5,292)
Currency translation and other	465
Balance at end of year	126,159
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	43
Changes in estimates recorded to statement of operations	(36)
Expenditures	(19)
Currency translation and other	(1)
Balance at end of year	1,764
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	1,332
Changes in estimates recorded to statement of operations	(120)
Expenditures	(2,068)
Currency translation and other	2,712
Balance at end of year	66,007
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	967
Changes in estimates recorded to statement of operations	289
Expenditures	(3,205)
Currency translation and other	(2,246)
Balance at end of year	$ 58,388

FINANCING ARRANGEMENTS (Summary

FINANCING ARRANGEMENTS (Summary of Financing Arrangements) (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Current portion of long-term obligations	$ 107,798	$ 0
Long-term obligations	1,641,000	1,645,000
Unamortized debt issuance costs and debt discount/premium, net	(14,495)	(11,728)
Long-term obligations, at carrying value	1,626,505	1,633,272
Total current and long-term obligations, at carrying value	1,734,303	1,633,272
Secured debt | Term Loan Agreement
Debt Instrument [Line Items]
Current portion of long-term obligations	4,000	0
Long-term obligations	396,000	0
Unsecured debt | Senior unsecured notes, at 5.25%, due August 1, 2020
Debt Instrument [Line Items]
Current portion of long-term obligations	103,798	0
Long-term obligations	$ 400,000	800,000
Senior unsecured notes interest rate percentage	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
Senior unsecured notes interest rate percentage	5.125%

FINANCING ARRANGEMENTS (Narrati

FINANCING ARRANGEMENTS (Narrative) (Details) - USD ($)	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Debt Instrument [Line Items]
Premiums to repay debt early	$ 4,665,000	$ 0
Outstanding loan balances	0		$ 0
Available to borrow and outstanding letters of credit	225,300,000		195,200,000
Outstanding letters of credit	125,900,000		132,600,000
Secured debt | Term Loan Agreement
Debt Instrument [Line Items]
Senior secured credit agreement amount	$ 400,000,000
Prepayment premium	1.00%
Effective interest rate	3.23%
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	400,000,000
Unsecured debt | Senior unsecured notes, at 5.25%, due August 1, 2020
Debt Instrument [Line Items]
Senior secured credit agreement amount	503,800,000
Repurchased amount	$ 103,800,000
Redemption price percentage	101.313%
Debt fair value	$ 510,700,000		820,000,000
Unsecured debt | Senior unsecured notes, at 5.125%, due June 1, 2021 (2021 Notes)
Debt Instrument [Line Items]
Debt fair value	863,000,000		861,900,000
Revolving Credit Facility | Line of Credit
Debt Instrument [Line Items]
Revolving credit facility maximum borrowing capacity	$ 400,000,000		$ 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 (Comp

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		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Numerator for basic and diluted earnings (loss) per share:
Net income (loss)	$ 25,880	$ 3,966	$ 4,487	$ (16,905)
Denominator:
Basic shares outstanding (in shares)	57,190	57,549	57,226	57,599
Dilutive effect of equity-based compensation awards (in shares)	146	129	123	0
Dilutive shares outstanding (in shares)	57,336	57,678	57,349	57,599
Basic loss per share (in USD per share)	$ 0.45	$ 0.07	$ 0.08	$ (0.29)
Diluted loss per share (in USD per share)	$ 0.45	$ 0.07	$ 0.08	$ (0.29)

EARNINGS (LOSS) PER SHARE (Narr

EARNINGS (LOSS) PER SHARE (Narrative) (Details) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares excluded from computation of earning per share (in shares)				886,685
Performance Shares [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares excluded from computation of earning per share (in shares)	142,503	348,197	142,503
Restricted Stock Units (RSUs) [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares excluded from computation of earning per share (in shares)	14,699	9,537	21,013

ACCUMULATED OTHER COMPREHENSI66

ACCUMULATED OTHER COMPREHENSIVE LOSS (Changes in Accumulated Other Comprehensive Loss by Component) (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2017USD ($)
Components of Other Accumulated Income, Net of Tax [Roll Forward]
Balance at beginning of period	$ 1,084,241
Other comprehensive income before reclassifications	21,128
Amounts reclassified out of accumulated other comprehensive loss	222
Tax effects	(201)
Other comprehensive income	21,149
Balance at end of period	1,100,937
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	20,847
Amounts reclassified out of accumulated other comprehensive loss	0
Tax effects
Other comprehensive income	20,847
Balance at end of period	(191,364)
Unrealized 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	281
Amounts reclassified out of accumulated other comprehensive loss	222
Tax effects	(201)
Other comprehensive income	302
Balance at end of period	(19)
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	$ (193,177)

ACCUMULATED OTHER COMPREHENSI67

ACCUMULATED OTHER COMPREHENSIVE LOSS (Reclassified Out of Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Unrealized holding gains on available-for-sale investments	$ (833)	$ (189)	$ (2,382)	$ (539)
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	$ 76	$ 0	$ 222	$ 0

STOCK-BASED COMPENSATION (Narra

STOCK-BASED COMPENSATION (Narrative) (Details) - USD ($) shares in Millions	3 Months Ended		6 Months Ended		28 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Mar. 13, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 2,900,000	$ 2,600,000	$ 5,200,000	$ 4,700,000
Income tax benefit	$ 800,000	$ 800,000	$ 1,500,000	$ 1,400,000
Share repurchase program authorized						$ 300,000,000
Repurchases of common stock (in shares)	0.1	0.1	0.2	0.2	4.1
Repurchases of common stock	$ 5,500,000	$ 5,100,000	$ 12,257,000	$ 10,100,000	$ 212,100,000
Stock repurchase program, remaining authorized repurchase amount	87,900,000		87,900,000		87,900,000
Restricted stock awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost	23,800,000		$ 23,800,000		23,800,000
Period for recognition (in years)			2 years 225 days
Fair value restricted stock	4,500,000	2,300,000	$ 6,000,000	6,100,000
Performance stock awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost	900,000		900,000		$ 900,000
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

STOCK-BASED COMPENSATION (Restr

STOCK-BASED COMPENSATION (Restricted Stock) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Restricted stock awards
Number of Shares
Beginning balance (in shares)			510,041
Granted (in shares)			161,250
Vested (in shares)			(105,064)
Forfeited (in shares)			(34,374)
Ending balance (in shares)	531,853		531,853
Weighted Average Grant-Date Fair Value
Beginning of period (in USD per share)			$ 52.65
Granted (in USD per share)			56.15
Vested (in USD per share)			54.17
Forfeited (in USD per share)			51.50
End of period (in USD per share)	$ 53.49		$ 53.49
Unrecognized compensation cost	$ 23.8		$ 23.8
Period for recognition (in years)			2 years 225 days
Fair value restricted stock	$ 4.5	$ 2.3	$ 6	$ 6.1
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 (Perfo

STOCK-BASED COMPENSATION (Performance Stock Awards (Details) - Performance stock awards - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Number of Shares
Beginning balance (in shares)			220,882
Granted (in shares)			588
Vested (in shares)			(25,168)
Forfeited (in shares)			(16,187)
Ending balance (in shares)	180,115		180,115
Weighted Average Grant-Date Fair Value
Beginning of period (in USD per share)			$ 54.69
Granted (in USD per share)			54.44
Vested (in USD per share)			54.84
Forfeited (in USD per share)			56.24
End of period (in USD per share)	$ 54.70		$ 54.70
Unrecognized compensation cost	$ 0.9		$ 0.9
Fair value restricted stock	$ 0	$ 0	$ 1.4	$ 0.4

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Details) CAD in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2017USD ($)siteproceedingclaim	Dec. 31, 2012CAD	Dec. 31, 1999municipality	Dec. 31, 1968permit	Dec. 31, 2016USD ($)
Contingencies [Line Items]
Recorded reserves for actual or probable liabilities | $	$ 20,800,000				$ 22,000,000
Number of pending personal injury claims allegedly resulting from the use of Safety-Kleen's products | proceeding	62
Number of product liability claims settled or dismissed | claim	17
Legal and Administrative Proceedings
Contingencies [Line Items]
Recorded reserves for actual or probable liabilities | $	$ 17,700,000				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
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 | $	$ 3,100,000				$ 3,800,000
Number of pending personal injury claims allegedly resulting from the use of Safety-Kleen's products | proceeding	5
Federal and State Enforcement Actions | Minimum
Contingencies [Line Items]
Minimum potential liability | $	$ 100,000

INCOME TAXES (Details)

INCOME TAXES (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Effective income tax rate	47.30%	68.70%	85.20%	(57.30%)
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) (

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

SEGMENT REPORTING (Third Party

SEGMENT REPORTING (Third Party Revenues to Direct Revenues) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Segment Reporting Information [Line Items]
Total revenues	$ 752,788	$ 697,510	$ 1,441,729	$ 1,333,593
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	752,788	697,510	1,441,729	1,333,593
Technical Services
Segment Reporting Information [Line Items]
Total revenues	254,487	229,130	484,705	448,235
Technical Services | Intersegment revenues, net
Segment Reporting Information [Line Items]
Total revenues	40,001	35,578	80,045	70,422
Technical Services | Corporate Items, net
Segment Reporting Information [Line Items]
Total revenues	408	667	1,130	1,055
Technical Services | Direct revenues
Segment Reporting Information [Line Items]
Total revenues	294,896	265,375	565,880	519,712
Industrial and Field Services
Segment Reporting Information [Line Items]
Total revenues	167,899	164,641	301,456	294,828
Industrial and Field Services | Intersegment revenues, net
Segment Reporting Information [Line Items]
Total revenues	(9,067)	(7,922)	(17,426)	(14,597)
Industrial and Field Services | Corporate Items, net
Segment Reporting Information [Line Items]
Total revenues	(133)	(303)	(29)	(316)
Industrial and Field Services | Direct revenues
Segment Reporting Information [Line Items]
Total revenues	158,699	156,416	284,001	279,915
Safety-Kleen
Segment Reporting Information [Line Items]
Total revenues	302,956	277,715	595,857	524,676
Safety-Kleen | Intersegment revenues, net
Segment Reporting Information [Line Items]
Total revenues	(31,639)	(29,092)	(63,708)	(57,613)
Safety-Kleen | Corporate Items, net
Segment Reporting Information [Line Items]
Total revenues	(2)	1	1	367
Safety-Kleen | Direct revenues
Segment Reporting Information [Line Items]
Total revenues	271,315	248,624	532,150	467,430
Oil, Gas and Lodging Services
Segment Reporting Information [Line Items]
Total revenues	27,245	24,860	59,377	63,911
Oil, Gas and Lodging Services | Intersegment revenues, net
Segment Reporting Information [Line Items]
Total revenues	705	1,436	1,089	1,788
Oil, Gas and Lodging Services | Corporate Items, net
Segment Reporting Information [Line Items]
Total revenues	45	79	139	183
Oil, Gas and Lodging Services | Direct revenues
Segment Reporting Information [Line Items]
Total revenues	27,995	26,375	60,605	65,882
Corporate Items
Segment Reporting Information [Line Items]
Total revenues	201	1,164	334	1,943
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	(318)	(444)	(1,241)	(1,289)
Corporate Items | Direct revenues
Segment Reporting Information [Line Items]
Total revenues	$ (117)	$ 720	$ (907)	$ 654

SEGMENT REPORTING (Adjusted EBI

SEGMENT REPORTING (Adjusted EBITDA Information) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Segment Reporting Information [Line Items]
Adjusted EBITDA	$ 120,691	$ 110,445	$ 200,826	$ 177,765
Reconciliation to Consolidated Statements of Operations:
Accretion of environmental liabilities	2,416	2,548	4,706	5,053
Depreciation and amortization	71,531	73,393	143,943	142,295
Income from operations	46,744	34,504	52,177	30,417
Other expense	833	189	2,382	539
Loss on early extinguishment of debt	6,045	0	6,045	0
Gain on sale of business	(31,722)	0	(31,722)	0
Interest expense, net of interest income	22,492	21,647	45,068	40,627
Income (loss) before (benefit) provision for income taxes	49,096	12,668	30,404	(10,749)
Technical Services
Segment Reporting Information [Line Items]
Adjusted EBITDA	73,080	68,891	131,567	129,289
Industrial and Field Services
Segment Reporting Information [Line Items]
Adjusted EBITDA	21,484	19,960	23,397	20,393
Safety-Kleen
Segment Reporting Information [Line Items]
Adjusted EBITDA	60,281	55,234	112,649	95,289
Oil, Gas and Lodging Services
Segment Reporting Information [Line Items]
Adjusted EBITDA	268	(1,199)	58	111
Corporate Items
Segment Reporting Information [Line Items]
Adjusted EBITDA	$ (34,422)	$ (32,441)	$ (66,845)	$ (67,317)

SEGMENT REPORTING (Assets by Re

SEGMENT REPORTING (Assets by Reportable Segment) (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Property, plant and equipment, net	$ 1,602,453	$ 1,611,827
Goodwill	472,819	465,154
Permits and other intangibles, net	482,828	498,721
Total assets	3,806,282	3,681,920
Technical Services
Segment Reporting Information [Line Items]
Property, plant and equipment, net	512,058	521,134
Goodwill	59,973	61,116
Permits and other intangibles, net	76,022	78,625
Total assets	851,852	862,957
Industrial and Field Services
Segment Reporting Information [Line Items]
Property, plant and equipment, net	243,195	245,143
Goodwill	108,583	107,968
Permits and other intangibles, net	17,135	17,817
Total assets	457,253	446,826
Safety-Kleen
Segment Reporting Information [Line Items]
Property, plant and equipment, net	590,282	584,647
Goodwill	304,263	296,070
Permits and other intangibles, net	381,020	391,390
Total assets	1,477,660	1,474,755
Oil, Gas and Lodging Services
Segment Reporting Information [Line Items]
Property, plant and equipment, net	181,001	182,038
Goodwill	0	0
Permits and other intangibles, net	8,651	10,889
Total assets	246,195	253,242
Corporate Items
Segment Reporting Information [Line Items]
Property, plant and equipment, net	75,917	78,865
Goodwill	0	0
Permits and other intangibles, net	0	0
Total assets	$ 773,322	$ 644,140

SEGMENT REPORTING (Total Assets

SEGMENT REPORTING (Total Assets by Geographical Area) (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Revenues from External Customers and Long-Lived Assets [Line Items]
Total assets	$ 3,806,282	$ 3,681,920
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Total assets	3,088,199	2,960,337
Canada
Revenues from External Customers and Long-Lived Assets [Line Items]
Total assets	$ 718,083	$ 721,583

GUARANTOR AND NON-GUARANTOR S78

GUARANTOR AND NON-GUARANTOR SUBSIDIARIES FINANCIAL INFORMATION (Narrative) (Details)	6 Months Ended
	Jun. 30, 2017
Guarantor and Non-Guarantor Subsidiaries Financial Information [Abstract]
Ownership percentage of U.S. guarantor subsidiaries	100.00%

GUARANTOR AND NON-GUARANTOR S79

GUARANTOR AND NON-GUARANTOR SUBSIDIARIES FINANCIAL INFORMATION (Condensed Consolidating Balance Sheets) (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016	Dec. 31, 2015
ASSETS
Cash and cash equivalents	$ 446,366	$ 306,997	$ 352,923	$ 184,708
Intercompany receivables	0	0
Accounts receivables, net	512,375	496,226
Other current assets	275,993	289,648
Property, plant and equipment, net	1,602,453	1,611,827
Investments in subsidiaries	0	0
Intercompany debt receivable	0	0
Goodwill	472,819	465,154
Permits and other intangibles, net	482,828	498,721
Other long-term assets	13,448	13,347
Total assets	3,806,282	3,681,920
LIABILITIES AND STOCKHOLDERS' EQUITY
Current liabilities	619,300	504,668
Intercompany payables	0	0
Closure, post-closure and remedial liabilities, net	162,252	166,322
Long-term obligations, less current portion	1,626,505	1,633,272
Intercompany debt payable	0	0
Other long-term liabilities	297,288	293,417
Total liabilities	2,705,345	2,597,679
Stockholders’ equity	1,100,937	1,084,241
Total liabilities and stockholders’ equity	3,806,282	3,681,920
Reportable Legal Entities | Clean Harbors, Inc.
ASSETS
Cash and cash equivalents	51,391	51,417	51,291	11,017
Intercompany receivables	220,885	200,337
Accounts receivables, net	0	0
Other current assets	897	3,096
Property, plant and equipment, net	0	0
Investments in subsidiaries	2,893,232	2,851,571
Intercompany debt receivable	0	0
Goodwill	0	0
Permits and other intangibles, net	0	0
Other long-term assets	2,363	2,446
Total assets	3,168,768	3,108,867
LIABILITIES AND STOCKHOLDERS' EQUITY
Current liabilities	123,095	21,805
Intercompany payables	314,530	365,848
Closure, post-closure and remedial liabilities, net	0	0
Long-term obligations, less current portion	1,626,505	1,633,272
Intercompany debt payable	3,701	3,701
Other long-term liabilities	0	0
Total liabilities	2,067,831	2,024,626
Stockholders’ equity	1,100,937	1,084,241
Total liabilities and stockholders’ equity	3,168,768	3,108,867
Reportable Legal Entities | Guarantor Subsidiaries
ASSETS
Cash and cash equivalents	303,996	155,943	224,493	83,479
Intercompany receivables	314,705	354,836
Accounts receivables, net	419,338	417,029
Other current assets	222,283	234,408
Property, plant and equipment, net	1,198,630	1,211,210
Investments in subsidiaries	570,837	580,124
Intercompany debt receivable	89,441	86,409
Goodwill	416,775	412,638
Permits and other intangibles, net	421,793	435,594
Other long-term assets	7,555	7,582
Total assets	3,965,353	3,895,773
LIABILITIES AND STOCKHOLDERS' EQUITY
Current liabilities	375,919	366,831
Intercompany payables	257,453	237,058
Closure, post-closure and remedial liabilities, net	145,777	150,682
Long-term obligations, less current portion	0	0
Intercompany debt payable	21,000	21,000
Other long-term liabilities	278,833	275,649
Total liabilities	1,078,982	1,051,220
Stockholders’ equity	2,886,371	2,844,553
Total liabilities and stockholders’ equity	3,965,353	3,895,773
Reportable Legal Entities | Non-Guarantor Subsidiaries
ASSETS
Cash and cash equivalents	90,979	99,637	77,139	90,212
Intercompany receivables	38,312	49,055
Accounts receivables, net	93,037	79,197
Other current assets	59,658	69,257
Property, plant and equipment, net	403,823	400,617
Investments in subsidiaries	0	0
Intercompany debt receivable	24,701	24,701
Goodwill	56,044	52,516
Permits and other intangibles, net	61,035	63,127
Other long-term assets	4,598	4,387
Total assets	832,187	842,494
LIABILITIES AND STOCKHOLDERS' EQUITY
Current liabilities	127,131	133,145
Intercompany payables	1,919	1,322
Closure, post-closure and remedial liabilities, net	16,475	15,640
Long-term obligations, less current portion	0	0
Intercompany debt payable	89,441	86,409
Other long-term liabilities	19,523	18,836
Total liabilities	254,489	255,352
Stockholders’ equity	577,698	587,142
Total liabilities and stockholders’ equity	832,187	842,494
Consolidating Adjustments
ASSETS
Cash and cash equivalents	0	0	$ 0	$ 0
Intercompany receivables	(573,902)	(604,228)
Accounts receivables, net	0	0
Other current assets	(6,845)	(17,113)
Property, plant and equipment, net	0	0
Investments in subsidiaries	(3,464,069)	(3,431,695)
Intercompany debt receivable	(114,142)	(111,110)
Goodwill	0	0
Permits and other intangibles, net	0	0
Other long-term assets	(1,068)	(1,068)
Total assets	(4,160,026)	(4,165,214)
LIABILITIES AND STOCKHOLDERS' EQUITY
Current liabilities	(6,845)	(17,113)
Intercompany payables	(573,902)	(604,228)
Closure, post-closure and remedial liabilities, net	0	0
Long-term obligations, less current portion	0	0
Intercompany debt payable	(114,142)	(111,110)
Other long-term liabilities	(1,068)	(1,068)
Total liabilities	(695,957)	(733,519)
Stockholders’ equity	(3,464,069)	(3,431,695)
Total liabilities and stockholders’ equity	$ (4,160,026)	$ (4,165,214)

GUARANTOR AND NON-GUARANTOR S80

GUARANTOR AND NON-GUARANTOR SUBSIDIARIES FINANCIAL INFORMATION (Consolidating Statement of Operations) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Revenues:
Service revenues	$ 610,940	$ 584,562	$ 1,171,154	$ 1,114,793
Product revenues	141,848	112,948	270,575	218,800
Total revenues	752,788	697,510	1,441,729	1,333,593
Cost of revenues (exclusive of items shown separately below)
Service cost of revenues	412,356	388,684	803,443	762,670
Product cost of revenues	107,447	91,318	212,945	181,611
Total cost of revenues	519,803	480,002	1,016,388	944,281
Selling, general and administrative expenses	112,294	107,063	224,515	211,547
Accretion of environmental liabilities	2,416	2,548	4,706	5,053
Depreciation and amortization	71,531	73,393	143,943	142,295
(Loss) income from operations	46,744	34,504	52,177	30,417
Unrealized holding gains on available-for-sale investments	(833)	(189)	(2,382)	(539)
Loss on early extinguishment of debt	(6,045)	0	(6,045)	0
Gain on sale of business	31,722	0	31,722	0
Interest (expense) income	(22,492)	(21,647)	(45,068)	(40,627)
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	49,096	12,668	30,404	(10,749)
(Benefit) provision for income taxes	23,216	8,702	25,917	6,156
Net income (loss)	25,880	3,966	4,487	(16,905)
Other comprehensive income	15,098	(1,178)	21,149	44,659
Comprehensive income	40,978	2,788	25,636	27,754
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	(587)	0	(587)
Product cost of revenues	0	0	0	0
Total cost of revenues	0	(587)	0	(587)
Selling, general and administrative expenses	27	37	51	61
Accretion of environmental liabilities	0	0	0	0
Depreciation and amortization	0	0	0	0
(Loss) income from operations	(27)	550	(51)	526
Unrealized holding gains on available-for-sale investments	(76)	0	(222)	0
Loss on early extinguishment of debt	(6,045)		(6,045)
Gain on sale of business	0		0
Interest (expense) income	(22,614)	(22,962)	(45,273)	(43,105)
Equity in earnings of subsidiaries, net of taxes	43,167	17,413	35,530	8,642
Intercompany interest income (expense)	0	0	0	0
Income (loss) before (benefit) provision for income taxes	14,405	(4,999)	(16,061)	(33,937)
(Benefit) provision for income taxes	(11,475)	(8,965)	(20,548)	(17,032)
Net income (loss)	25,880	3,966	4,487	(16,905)
Other comprehensive income	15,098	(1,178)	21,149	44,659
Comprehensive income	40,978	2,788	25,636	27,754
Reportable Legal Entities | Guarantor Subsidiaries
Revenues:
Service revenues	474,801	456,013	918,106	884,490
Product revenues	125,859	95,648	242,509	185,236
Total revenues	600,660	551,661	1,160,615	1,069,726
Cost of revenues (exclusive of items shown separately below)
Service cost of revenues	306,960	292,343	601,105	575,307
Product cost of revenues	98,645	79,108	195,150	158,462
Total cost of revenues	405,605	371,451	796,255	733,769
Selling, general and administrative expenses	92,504	83,882	184,675	164,537
Accretion of environmental liabilities	2,181	2,313	4,236	4,603
Depreciation and amortization	51,937	50,696	103,837	99,391
(Loss) income from operations	48,433	43,319	71,612	67,426
Unrealized holding gains on available-for-sale investments	(406)	400	(1,795)	312
Loss on early extinguishment of debt	0		0
Gain on sale of business	31,722		31,722
Interest (expense) income	240	1,284	359	2,395
Equity in earnings of subsidiaries, net of taxes	(5,332)	(9,195)	(27,156)	(35,690)
Intercompany interest income (expense)	1,268	5,497	2,565	10,656
Income (loss) before (benefit) provision for income taxes	75,925	41,305	77,307	45,099
(Benefit) provision for income taxes	31,981	23,892	41,618	36,457
Net income (loss)	43,944	17,413	35,689	8,642
Other comprehensive income	15,098	(1,178)	21,149	44,659
Comprehensive income	59,042	16,235	56,838	53,301
Reportable Legal Entities | Non-Guarantor Subsidiaries
Revenues:
Service revenues	147,924	139,413	278,995	253,436
Product revenues	18,730	19,391	34,061	38,104
Total revenues	166,654	158,804	313,056	291,540
Cost of revenues (exclusive of items shown separately below)
Service cost of revenues	117,181	107,792	228,285	211,083
Product cost of revenues	11,543	14,301	23,790	27,689
Total cost of revenues	128,724	122,093	252,075	238,772
Selling, general and administrative expenses	19,763	23,144	39,789	46,949
Accretion of environmental liabilities	235	235	470	450
Depreciation and amortization	19,594	22,697	40,106	42,904
(Loss) income from operations	(1,662)	(9,365)	(19,384)	(37,535)
Unrealized holding gains on available-for-sale investments	(351)	(589)	(365)	(851)
Loss on early extinguishment of debt	0		0
Gain on sale of business	0		0
Interest (expense) income	(118)	31	(154)	83
Equity in earnings of subsidiaries, net of taxes	0	0	0	0
Intercompany interest income (expense)	(1,268)	(5,497)	(2,565)	(10,656)
Income (loss) before (benefit) provision for income taxes	(3,399)	(15,420)	(22,468)	(48,959)
(Benefit) provision for income taxes	2,710	(6,225)	4,847	(13,269)
Net income (loss)	(6,109)	(9,195)	(27,315)	(35,690)
Other comprehensive income	12,837	(597)	17,869	28,330
Comprehensive income	6,728	(9,792)	(9,446)	(7,360)
Consolidating Adjustments
Revenues:
Service revenues	(11,785)	(10,864)	(25,947)	(23,133)
Product revenues	(2,741)	(2,091)	(5,995)	(4,540)
Total revenues	(14,526)	(12,955)	(31,942)	(27,673)
Cost of revenues (exclusive of items shown separately below)
Service cost of revenues	(11,785)	(10,864)	(25,947)	(23,133)
Product cost of revenues	(2,741)	(2,091)	(5,995)	(4,540)
Total cost of revenues	(14,526)	(12,955)	(31,942)	(27,673)
Selling, general and administrative expenses	0	0	0	0
Accretion of environmental liabilities	0	0	0	0
Depreciation and amortization	0	0	0	0
(Loss) 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
Gain on sale of business	0		0
Interest (expense) income	0	0	0	0
Equity in earnings of subsidiaries, net of taxes	(37,835)	(8,218)	(8,374)	27,048
Intercompany interest income (expense)	0	0	0	0
Income (loss) before (benefit) provision for income taxes	(37,835)	(8,218)	(8,374)	27,048
(Benefit) provision for income taxes	0	0	0	0
Net income (loss)	(37,835)	(8,218)	(8,374)	27,048
Other comprehensive income	(27,935)	1,775	(39,018)	(72,989)
Comprehensive income	$ (65,770)	$ (6,443)	$ (47,392)	$ (45,941)

GUARANTOR AND NON-GUARANTOR S81

GUARANTOR AND NON-GUARANTOR SUBSIDIARIES FINANCIAL INFORMATION (Condensed Consolidating Statements of Cash Flows) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Condensed consolidating statement of cash flows
Net cash (used in) from operating activities	$ 116,931	$ 120,051
Cash flows from (used in) investing activities:
Additions to property, plant and equipment	(88,742)	(123,529)
Proceeds from sales of fixed assets	2,121	2,668
Acquisitions, net of cash acquired	(9,277)	(58,989)
Proceeds on sale of businesses, net of transactional costs	46,391	0
Additions to intangible assets, including costs to obtain or renew permits	(1,239)	(973)
Purchases of available-for-sale securities	0	(598)
Proceeds from sale of investments	376	0
Intercompany	0	0
Investment in subsidiaries		0
Net cash used in investing activities	(50,370)	(181,421)
Cash flows from (used in) financing activities:
Change in uncashed checks	(8,361)	(11,022)
Proceeds from exercise of stock options	46	184
Issuance of restricted shares, net of shares remitted	(2,132)	(1,879)
Repurchases of common stock	(12,257)	(10,134)
Deferred financing costs paid	(4,727)	(2,614)
Excess tax benefit of stock-based compensation	0	2
Premiums paid on early extinguishment of debt	(4,665)	0
Principal payment on debt	(296,202)	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
Net cash from financing activities	70,702	225,162
Effect of exchange rate change on cash	2,106	4,423
(Decrease) increase in cash and cash equivalents	139,369	168,215
Cash and cash equivalents, beginning of period	306,997	184,708
Cash and cash equivalents, end of period	446,366	352,923
Consolidating Adjustments
Condensed consolidating statement of cash flows
Net cash (used in) from operating activities	0	0
Cash flows from (used in) investing activities:
Additions to property, plant and equipment	0	0
Proceeds from sales of fixed assets	0	0
Acquisitions, net of cash acquired	0	0
Proceeds on sale of businesses, net of transactional costs	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	14,343	11,827
Investment in subsidiaries		250,625
Net cash used in investing activities	14,343	262,452
Cash flows from (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	(14,343)	(11,827)
Net cash from financing activities	(14,343)	(262,452)
Effect of exchange rate change on cash	0	0
(Decrease) increase 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. | Reportable Legal Entities
Condensed consolidating statement of cash flows
Net cash (used in) from operating activities	(93,808)	42,990
Cash flows from (used in) investing activities:
Additions to property, plant and equipment	0	0
Proceeds from sales of fixed assets	0	0
Acquisitions, net of cash acquired	0	0
Proceeds on sale of businesses, net of transactional costs	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
Investment in subsidiaries		(250,625)
Net cash used in investing activities	376	(250,727)
Cash flows from (used in) financing activities:
Change in uncashed checks	0	0
Proceeds from exercise of stock options	46	184
Issuance of restricted shares, net of shares remitted	(2,132)	(1,879)
Repurchases of common stock	(12,257)	(10,134)
Deferred financing costs paid	(4,727)	(2,614)
Excess tax benefit of stock-based compensation		2
Premiums paid on early extinguishment of debt	(4,665)
Principal payment on debt	(296,202)
Issuance of senior secured notes, net of discount	399,000
Issuance of senior unsecured notes, including premium		250,625
Intercompany	14,343	11,827
Net cash from financing activities	93,406	248,011
Effect of exchange rate change on cash	0	0
(Decrease) increase in cash and cash equivalents	(26)	40,274
Cash and cash equivalents, beginning of period	51,417	11,017
Cash and cash equivalents, end of period	51,391	51,291
Guarantor Subsidiaries | Reportable Legal Entities
Condensed consolidating statement of cash flows
Net cash (used in) from operating activities	206,496	65,860
Cash flows from (used in) investing activities:
Additions to property, plant and equipment	(75,152)	(105,175)
Proceeds from sales of fixed assets	984	694
Acquisitions, net of cash acquired	(9,277)	(48,989)
Proceeds on sale of businesses, net of transactional costs	46,210
Additions to intangible assets, including costs to obtain or renew permits	(888)	(908)
Purchases of available-for-sale securities		0
Proceeds from sale of investments	0
Intercompany	(14,343)	(11,827)
Investment in subsidiaries		0
Net cash used in investing activities	(52,466)	(166,205)
Cash flows from (used in) financing activities:
Change in uncashed checks	(5,977)	(9,266)
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
Net cash from financing activities	(5,977)	241,359
Effect of exchange rate change on cash	0	0
(Decrease) increase in cash and cash equivalents	148,053	141,014
Cash and cash equivalents, beginning of period	155,943	83,479
Cash and cash equivalents, end of period	303,996	224,493
Non-Guarantor Subsidiaries | Reportable Legal Entities
Condensed consolidating statement of cash flows
Net cash (used in) from operating activities	4,243	11,201
Cash flows from (used in) investing activities:
Additions to property, plant and equipment	(13,590)	(18,354)
Proceeds from sales of fixed assets	1,137	1,974
Acquisitions, net of cash acquired	0	(10,000)
Proceeds on sale of businesses, net of transactional costs	181
Additions to intangible assets, including costs to obtain or renew permits	(351)	(65)
Purchases of available-for-sale securities		(496)
Proceeds from sale of investments	0
Intercompany	0	0
Investment in subsidiaries		0
Net cash used in investing activities	(12,623)	(26,941)
Cash flows from (used in) financing activities:
Change in uncashed checks	(2,384)	(1,756)
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
Net cash from financing activities	(2,384)	(1,756)
Effect of exchange rate change on cash	2,106	4,423
(Decrease) increase in cash and cash equivalents	(8,658)	(13,073)
Cash and cash equivalents, beginning of period	99,637	90,212
Cash and cash equivalents, end of period	$ 90,979	$ 77,139

SUBSEQUENT EVENTS (Details)

SUBSEQUENT EVENTS (Details) - Jul. 14, 2017 - Subsequent event - Lonestar CAD / shares in Millions, CAD in Millions, $ in Millions	USD ($)	CAD	CADCAD / shares
Business Acquisition [Line Items]
Cash paid to acquire Lonestar	$ 34	CAD 43
Equity payout (in CAD per share)			CAD 0
Debt outstanding assumed	$ 17.4		CAD 22