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