GUARANTOR AND NON-GUARANTOR SUBSIDIARIES (Cash Flows) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Condensed consolidating statement of cash flows
Net cash from operating activities	$ 396,383	$ 297,366	$ 415,839
Cash flows used in investing activities:
Additions to property, plant and equipment	(257,196)	(257,613)	(280,207)
Proceeds from sales of fixed assets	6,195	8,164	4,699
Acquisitions, net of cash acquired	(94,345)	(16,187)	(63,264)
Additions to intangible assets including costs to obtain or renew permits	(5,296)	(6,519)	(6,740)
Intercompany	0	0
Intercompany debt	0	0	0
Proceeds from sale of long-term investments		13,861
Net cash used in investing activities	(350,642)	(258,294)	(345,512)
Cash flows (used in) from financing activities:
Change in uncashed checks	(14,630)	15,069	12,268
Proceeds from employee stock purchase plan	0	4,364	7,425
Proceeds from exercise of stock options	397	0	400
Remittance of shares, net	(2,159)	(2,793)	(731)
Repurchases of common stock	(73,347)	(104,341)	0
Excess tax benefit of stock-based compensation	71	878	1,409
Deferred financing costs paid	0	0	2,504
Payments on capital leases	(511)	(2,122)	(4,891)
Repayment of long-term obligations	0	(5,000)	0
Issuance costs related to issuances of common stock	0	0	(250)
Dividends paid		0	0
Intercompany	0	0
Intercompany debt	0	0	0
Net cash (used in) from financing activities	(90,179)	(93,945)	13,126
Effect of exchange rate change on cash	(17,733)	(8,321)	(3,216)
(Decrease) increase in cash and cash equivalents	(62,171)	(63,194)	80,237
Cash and cash equivalents, beginning of year	246,879	310,073	229,836
Cash and cash equivalents, end of year	184,708	246,879	310,073
Clean Harbors, Inc.
Condensed consolidating statement of cash flows
Net cash from operating activities	9,543	(5,242)	(33,932)
Cash flows used in investing activities:
Additions to property, plant and equipment	0	0	0
Proceeds from sales of fixed assets	0	0	0
Acquisitions, net of cash acquired	0	0	(6,025)
Additions to intangible assets including costs to obtain or renew permits	0	0	0
Intercompany	0	0
Intercompany debt	0	0	0
Proceeds from sale of long-term investments		0
Net cash used in investing activities	0	0	(6,025)
Cash flows (used in) from financing activities:
Change in uncashed checks	0	0	0
Proceeds from employee stock purchase plan		4,364	7,425
Proceeds from exercise of stock options	397		400
Remittance of shares, net	(2,159)	(2,793)	(731)
Repurchases of common stock	(73,347)	(104,341)
Excess tax benefit of stock-based compensation	71	878	1,409
Deferred financing costs paid			2,504
Payments on capital leases	0	0	0
Repayment of long-term obligations		(5,000)
Issuance costs related to issuances of common stock			(250)
Dividends paid		0	0
Intercompany	75,506	112,134
Intercompany debt	0	0	0
Net cash (used in) from financing activities	468	5,242	5,749
Effect of exchange rate change on cash	0	0	0
(Decrease) increase in cash and cash equivalents	10,011	0	(34,208)
Cash and cash equivalents, beginning of year	1,006	1,006	35,214
Cash and cash equivalents, end of year	11,017	1,006	1,006
U.S. Guarantor Subsidiaries
Condensed consolidating statement of cash flows
Net cash from operating activities	314,585	70,761	277,445
Cash flows used in investing activities:
Additions to property, plant and equipment	(220,789)	(172,525)	(145,075)
Proceeds from sales of fixed assets	1,447	3,956	1,078
Acquisitions, net of cash acquired	(94,345)	(6,550)	(57,239)
Additions to intangible assets including costs to obtain or renew permits	0	(623)	(5,247)
Intercompany	(75,506)	(112,134)
Intercompany debt	14,272	143,467	27,525
Proceeds from sale of long-term investments		0
Net cash used in investing activities	(374,921)	(144,409)	(178,958)
Cash flows (used in) from financing activities:
Change in uncashed checks	(10,129)	11,046	9,922
Proceeds from employee stock purchase plan		0	0
Proceeds from exercise of stock options	0		0
Remittance of shares, net	0	0	0
Repurchases of common stock	0	0
Excess tax benefit of stock-based compensation	0	0	0
Deferred financing costs paid			0
Payments on capital leases	(203)	(170)	(227)
Repayment of long-term obligations		0
Issuance costs related to issuances of common stock			0
Dividends paid		(18,586)	(13,360)
Intercompany	0	0
Intercompany debt	0	0	0
Net cash (used in) from financing activities	(10,332)	(7,710)	(3,665)
Effect of exchange rate change on cash	0	0	0
(Decrease) increase in cash and cash equivalents	(70,668)	(81,358)	94,822
Cash and cash equivalents, beginning of year	154,147	235,505	140,683
Cash and cash equivalents, end of year	83,479	154,147	235,505
Foreign Non-Guarantor Subsidiaries
Condensed consolidating statement of cash flows
Net cash from operating activities	72,255	250,433	185,686
Cash flows used in investing activities:
Additions to property, plant and equipment	(36,407)	(85,088)	(135,132)
Proceeds from sales of fixed assets	4,748	4,208	3,621
Acquisitions, net of cash acquired	0	(9,637)	0
Additions to intangible assets including costs to obtain or renew permits	(5,296)	(5,896)	(1,493)
Intercompany	0	0
Intercompany debt	0	0	0
Proceeds from sale of long-term investments		13,861
Net cash used in investing activities	(36,955)	(82,552)	(133,004)
Cash flows (used in) from financing activities:
Change in uncashed checks	(4,501)	4,023	2,346
Proceeds from employee stock purchase plan		0	0
Proceeds from exercise of stock options	0		0
Remittance of shares, net	0	0	0
Repurchases of common stock	0	0
Excess tax benefit of stock-based compensation	0	0	0
Deferred financing costs paid			0
Payments on capital leases	(308)	(1,952)	(4,664)
Repayment of long-term obligations		0
Issuance costs related to issuances of common stock			0
Dividends paid		0	0
Intercompany	0	0
Intercompany debt	(14,272)	(143,467)	(27,525)
Net cash (used in) from financing activities	(19,081)	(141,396)	(29,843)
Effect of exchange rate change on cash	(17,733)	(8,321)	(3,216)
(Decrease) increase in cash and cash equivalents	(1,514)	18,164	19,623
Cash and cash equivalents, beginning of year	91,726	73,562	53,939
Cash and cash equivalents, end of year	90,212	91,726	73,562
Consolidating Adjustments
Condensed consolidating statement of cash flows
Net cash from operating activities	0	(18,586)	(13,360)
Cash flows used in investing activities:
Additions to property, plant and equipment	0	0	0
Proceeds from sales of fixed assets	0	0	0
Acquisitions, net of cash acquired	0	0	0
Additions to intangible assets including costs to obtain or renew permits	0	0	0
Intercompany	75,506	112,134
Intercompany debt	(14,272)	(143,467)	(27,525)
Proceeds from sale of long-term investments		0
Net cash used in investing activities	61,234	(31,333)	(27,525)
Cash flows (used in) from financing activities:
Change in uncashed checks	0	0	0
Proceeds from employee stock purchase plan		0	0
Proceeds from exercise of stock options	0		0
Remittance of shares, net	0	0	0
Repurchases of common stock	0	0
Excess tax benefit of stock-based compensation	0		0
Deferred financing costs paid			0
Payments on capital leases	0	0	0
Repayment of long-term obligations		0
Issuance costs related to issuances of common stock			0
Dividends paid		18,586	13,360
Intercompany	(75,506)	(112,134)
Intercompany debt	14,272	143,467	27,525
Net cash (used in) from financing activities	(61,234)	49,919	40,885
Effect of exchange rate change on cash	0	0	0
(Decrease) increase in cash and cash equivalents	0	0	0
Cash and cash equivalents, beginning of year	0	0	0
Cash and cash equivalents, end of year	$ 0	$ 0	$ 0