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