GUARANTOR AND NON-GUARANTOR SUBSIDIARIES FINANCIAL INFORMATION (Condensed Consolidating Statements of Cash Flows) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Condensed consolidating statement of cash flows
Net cash from (used in) operating activities	$ 178,827	$ 309,593
Cash flows used in investing activities:
Additions to property, plant and equipment	(175,348)	(189,999)
Proceeds from sales of fixed assets	3,982	3,740
Acquisitions, net of cash acquired	(207,089)	(79,610)
Proceeds on sale of business, net of cash	47,134	0
Costs to obtain or renew permits	(1,920)	(4,633)
Purchases of available-for-sale securities	(598)	0
Investment in subsidiaries	0
Intercompany	0	0
Net cash used in investing activities	(333,839)	(270,502)
Cash flows from (used in) financing activities:
Change in uncashed checks	(7,084)	(21,882)
Exercise of stock options	230	397
Issuance of restricted shares, net of shares remitted	(2,500)	(2,027)
Repurchases of common stock	(15,869)	(69,155)
Excess tax benefit of stock-based compensation	21	102
Deferred financing costs paid	(2,614)	0
Payments of capital leases	0	(500)
Issuance of senior secured notes, including premium	250,625
Intercompany	0	0
Intercompany debt	0
Net cash from (used in) financing activities	222,809	(93,065)
Effect of exchange rate change on cash	5,352	(13,714)
Increase (decrease) in cash and cash equivalents	73,149	(67,688)
Cash and cash equivalents, beginning of period	184,708	246,879
Cash and cash equivalents, end of period	257,857	179,191
Consolidating Adjustments
Condensed consolidating statement of cash flows
Net cash from (used in) operating activities	0	0
Cash flows 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 business, net of cash	0
Costs to obtain or renew permits	0	0
Purchases of available-for-sale securities	0
Investment in subsidiaries	250,625
Intercompany	18,118	71,182
Net cash used in investing activities	268,743	71,182
Cash flows from (used in) financing activities:
Change in uncashed checks	0	0
Exercise of stock options	0	0
Issuance of restricted shares, net of shares remitted	0	0
Repurchases of common stock	0	0
Excess tax benefit of stock-based compensation	0	0
Deferred financing costs paid	0
Payments of capital leases		0
Issuance of senior secured notes, including premium	(250,625)
Intercompany	(18,118)	(71,182)
Intercompany debt	0
Net cash from (used in) financing activities	(268,743)	(71,182)
Effect of exchange rate change on cash	0	0
Increase (decrease) in cash and cash equivalents	0	0
Cash and cash equivalents, beginning of period	0	0
Cash and cash equivalents, end of period	0	0
Clean Harbors, Inc. | Reportable Legal Entities
Condensed consolidating statement of cash flows
Net cash from (used in) operating activities	43,033	9,503
Cash flows 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 business, net of cash	0
Costs to obtain or renew permits	0	0
Purchases of available-for-sale securities	(102)
Investment in subsidiaries	(250,625)
Intercompany	0	0
Net cash used in investing activities	(250,727)	0
Cash flows from (used in) financing activities:
Change in uncashed checks	0	0
Exercise of stock options	230	397
Issuance of restricted shares, net of shares remitted	(2,500)	(2,027)
Repurchases of common stock	(15,869)	(69,155)
Excess tax benefit of stock-based compensation	21	102
Deferred financing costs paid	(2,614)
Payments of capital leases		0
Issuance of senior secured notes, including premium	250,625
Intercompany	18,118	71,182
Intercompany debt	0
Net cash from (used in) financing activities	248,011	499
Effect of exchange rate change on cash	0	0
Increase (decrease) in cash and cash equivalents	40,317	10,002
Cash and cash equivalents, beginning of period	11,017	1,006
Cash and cash equivalents, end of period	51,334	11,008
U.S. Guarantor Subsidiaries | Reportable Legal Entities
Condensed consolidating statement of cash flows
Net cash from (used in) operating activities	128,182	240,713
Cash flows used in investing activities:
Additions to property, plant and equipment	(152,836)	(162,329)
Proceeds from sales of fixed assets	950	1,177
Acquisitions, net of cash acquired	(197,089)	(79,610)
Proceeds on sale of business, net of cash	18,885
Costs to obtain or renew permits	(949)	(4)
Purchases of available-for-sale securities	0
Investment in subsidiaries	0
Intercompany	(18,118)	(71,182)
Net cash used in investing activities	(349,157)	(311,948)
Cash flows from (used in) financing activities:
Change in uncashed checks	(6,064)	(16,635)
Exercise of stock options	0	0
Issuance of restricted shares, net of shares remitted	0	0
Repurchases of common stock	0	0
Excess tax benefit of stock-based compensation	0	0
Deferred financing costs paid	0
Payments of capital leases		(203)
Issuance of senior secured notes, including premium	250,625
Intercompany	0	0
Intercompany debt	63,118
Net cash from (used in) financing activities	307,679	(16,838)
Effect of exchange rate change on cash	0	0
Increase (decrease) in cash and cash equivalents	86,704	(88,073)
Cash and cash equivalents, beginning of period	83,479	154,147
Cash and cash equivalents, end of period	170,183	66,074
Foreign Non-Guarantor Subsidiaries | Reportable Legal Entities
Condensed consolidating statement of cash flows
Net cash from (used in) operating activities	7,612	59,377
Cash flows used in investing activities:
Additions to property, plant and equipment	(22,512)	(27,670)
Proceeds from sales of fixed assets	3,032	2,563
Acquisitions, net of cash acquired	(10,000)	0
Proceeds on sale of business, net of cash	28,249
Costs to obtain or renew permits	(971)	(4,629)
Purchases of available-for-sale securities	(496)
Investment in subsidiaries	0
Intercompany	0	0
Net cash used in investing activities	(2,698)	(29,736)
Cash flows from (used in) financing activities:
Change in uncashed checks	(1,020)	(5,247)
Exercise of stock options	0	0
Issuance of restricted shares, net of shares remitted	0	0
Repurchases of common stock	0	0
Excess tax benefit of stock-based compensation	0	0
Deferred financing costs paid	0
Payments of capital leases		(297)
Issuance of senior secured notes, including premium	0
Intercompany	0	0
Intercompany debt	(63,118)
Net cash from (used in) financing activities	(64,138)	(5,544)
Effect of exchange rate change on cash	5,352	(13,714)
Increase (decrease) in cash and cash equivalents	(53,872)	10,383
Cash and cash equivalents, beginning of period	90,212	91,726
Cash and cash equivalents, end of period	$ 36,340	$ 102,109