GUARANTOR AND NON-GUARANTOR SUBSIDIARIES (Cash Flows) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Condensed consolidating statement of cash flows
Net cash from operating activities	$ 259,624	$ 396,383	$ 297,366
Cash flows used in investing activities:
Additions to property, plant and equipment	(219,384)	(257,196)	(257,613)
Proceeds from sales of fixed assets	20,817	6,195	8,164
Acquisitions, net of cash acquired	(206,915)	(94,345)	(16,187)
Proceeds on sale of business, net of cash	47,134	0	0
Additions to intangible assets including costs to obtain or renew permits	(2,831)	(5,296)	(6,519)
Purchase of available-for-sale securities	(598)	0	0
Investment in subsidiaries	0
Intercompany	0	0	0
Intercompany debt	0	0	0
Proceeds from sale of long-term investments			13,861
Net cash used in investing activities	(361,777)	(350,642)	(258,294)
Cash flows from (used in) financing activities:
Change in uncashed checks	(3,177)	(14,630)	15,069
Proceeds from employee stock purchase plan	0	0	4,364
Proceeds from exercise of stock options	627	397	0
Issuance of restricted shares, net of shares remitted	(2,819)	(2,159)	(2,793)
Excess tax benefit of stock-based compensation	1,198	71	878
Deferred financing costs paid	(4,031)	0	0
Repurchases of common stock	(22,188)	(73,347)	(104,341)
Payments on capital leases	0	(511)	(2,122)
Repayment of long-term obligations	0	0	(5,000)
Issuance of senior secured notes, including premium	250,625
Dividends paid			0
Intercompany	0	0	0
Intercompany debt	0	0	0
Net cash from (used in) financing activities	220,235	(90,179)	(93,945)
Effect of exchange rate change on cash	4,207	(17,733)	(8,321)
Increase (decrease) in cash and cash equivalents	122,289	(62,171)	(63,194)
Cash and cash equivalents, beginning of year	184,708	246,879	310,073
Cash and cash equivalents, end of year	306,997	184,708	246,879
Reportable Legal Entities | Clean Harbors, Inc.
Condensed consolidating statement of cash flows
Net cash from operating activities	51,033	9,543	(5,242)
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
Proceeds on sale of business, net of cash	0
Additions to intangible assets including costs to obtain or renew permits	0	0	0
Purchase of available-for-sale securities	(102)
Investment in subsidiaries	(257,125)
Intercompany	0	0	0
Intercompany debt	0	0	0
Proceeds from sale of long-term investments			0
Net cash used in investing activities	(257,227)	0	0
Cash flows from (used in) financing activities:
Change in uncashed checks	0	0	0
Proceeds from employee stock purchase plan			4,364
Proceeds from exercise of stock options	627	397
Issuance of restricted shares, net of shares remitted	(2,819)	(2,159)	(2,793)
Excess tax benefit of stock-based compensation	1,198	71	878
Deferred financing costs paid	(4,031)
Repurchases of common stock	(22,188)	(73,347)	(104,341)
Payments on capital leases		0	0
Repayment of long-term obligations			(5,000)
Issuance of senior secured notes, including premium	250,625
Dividends paid			0
Intercompany	23,182	75,506	112,134
Intercompany debt	0	0	0
Net cash from (used in) financing activities	246,594	468	5,242
Effect of exchange rate change on cash	0	0	0
Increase (decrease) in cash and cash equivalents	40,400	10,011	0
Cash and cash equivalents, beginning of year	11,017	1,006	1,006
Cash and cash equivalents, end of year	51,417	11,017	1,006
Reportable Legal Entities | Guarantor Subsidiaries
Condensed consolidating statement of cash flows
Net cash from operating activities	125,591	314,585	70,761
Cash flows used in investing activities:
Additions to property, plant and equipment	(194,184)	(220,789)	(172,525)
Proceeds from sales of fixed assets	12,926	1,447	3,956
Acquisitions, net of cash acquired	(196,915)	(94,345)	(6,550)
Proceeds on sale of business, net of cash	18,885
Additions to intangible assets including costs to obtain or renew permits	(1,749)	0	(623)
Purchase of available-for-sale securities	0
Investment in subsidiaries	0
Intercompany	(23,182)	(75,506)	(112,134)
Intercompany debt	63,118	14,272	143,467
Proceeds from sale of long-term investments			0
Net cash used in investing activities	(321,101)	(374,921)	(144,409)
Cash flows from (used in) financing activities:
Change in uncashed checks	(3,651)	(10,129)	11,046
Proceeds from employee stock purchase plan			0
Proceeds from exercise of stock options	0	0
Issuance of restricted shares, net of shares remitted	0	0	0
Excess tax benefit of stock-based compensation	0	0	0
Deferred financing costs paid	0
Repurchases of common stock	0	0	0
Payments on capital leases		(203)	(170)
Repayment of long-term obligations			0
Issuance of senior secured notes, including premium	250,625
Dividends paid			(18,586)
Intercompany	0	0	0
Intercompany debt	21,000	0	0
Net cash from (used in) financing activities	267,974	(10,332)	(7,710)
Effect of exchange rate change on cash	0	0	0
Increase (decrease) in cash and cash equivalents	72,464	(70,668)	(81,358)
Cash and cash equivalents, beginning of year	83,479	154,147	235,505
Cash and cash equivalents, end of year	155,943	83,479	154,147
Reportable Legal Entities | Non-Guarantor Subsidiaries
Condensed consolidating statement of cash flows
Net cash from operating activities	83,000	72,255	250,433
Cash flows used in investing activities:
Additions to property, plant and equipment	(25,200)	(36,407)	(85,088)
Proceeds from sales of fixed assets	7,891	4,748	4,208
Acquisitions, net of cash acquired	(10,000)	0	(9,637)
Proceeds on sale of business, net of cash	28,249
Additions to intangible assets including costs to obtain or renew permits	(1,082)	(5,296)	(5,896)
Purchase of available-for-sale securities	(496)
Intercompany	0	0	0
Intercompany debt	(21,000)	0	0
Proceeds from sale of long-term investments			13,861
Net cash used in investing activities	(21,638)	(36,955)	(82,552)
Cash flows from (used in) financing activities:
Change in uncashed checks	474	(4,501)	4,023
Proceeds from employee stock purchase plan			0
Proceeds from exercise of stock options	0	0
Issuance of restricted shares, net of shares remitted	0	0	0
Excess tax benefit of stock-based compensation	0	0	0
Deferred financing costs paid	0
Repurchases of common stock	0	0	0
Payments on capital leases		(308)	(1,952)
Repayment of long-term obligations			0
Issuance of senior secured notes, including premium	0
Dividends paid			0
Intercompany	6,500	0	0
Intercompany debt	(63,118)	(14,272)	(143,467)
Net cash from (used in) financing activities	(56,144)	(19,081)	(141,396)
Effect of exchange rate change on cash	4,207	(17,733)	(8,321)
Increase (decrease) in cash and cash equivalents	9,425	(1,514)	18,164
Cash and cash equivalents, beginning of year	90,212	91,726	73,562
Cash and cash equivalents, end of year	99,637	90,212	91,726
Consolidating Adjustments
Condensed consolidating statement of cash flows
Net cash from operating activities	0	0	(18,586)
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
Proceeds on sale of business, net of cash	0
Additions to intangible assets including costs to obtain or renew permits	0	0	0
Purchase of available-for-sale securities	0
Investment in subsidiaries	257,125
Intercompany	23,182	75,506	112,134
Intercompany debt	(42,118)	(14,272)	(143,467)
Proceeds from sale of long-term investments			0
Net cash used in investing activities	238,189	61,234	(31,333)
Cash flows from (used in) financing activities:
Change in uncashed checks	0	0	0
Proceeds from employee stock purchase plan			0
Proceeds from exercise of stock options	0	0
Issuance of restricted shares, net of shares remitted	0	0	0
Excess tax benefit of stock-based compensation	0	0	0
Deferred financing costs paid	0
Repurchases of common stock	0	0	0
Payments on capital leases		0	0
Repayment of long-term obligations			0
Issuance of senior secured notes, including premium	(250,625)
Dividends paid			18,586
Intercompany	(29,682)	(75,506)	(112,134)
Intercompany debt	42,118	14,272	143,467
Net cash from (used in) financing activities	(238,189)	(61,234)	49,919
Effect of exchange rate change on cash	0	0	0
Increase (decrease) 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