GUARANTOR AND NON-GUARANTOR SUBSIDIARIES (Balance Sheet) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Guarantor and Non-Guarantor Subsidiaries Financial Information [Abstract]
Guarantor, ownership interest by Clean Harbors, Inc.	100.00%
Assets:
Cash and cash equivalents	$ 319,399	$ 306,997	$ 184,708	$ 246,879
Short-term marketable securities	38,179	0
Intercompany receivables	0	0
Accounts receivable, net	528,924	496,226
Other current assets	267,554	289,648
Property, plant and equipment, net	1,587,365	1,611,827
Investments in subsidiaries	0	0
Intercompany debt receivable	0	0
Goodwill	478,523	465,154	453,105
Permits and other intangibles, net	469,128	498,721
Other long-term assets	17,498	13,347
Total assets	3,706,570	3,681,920	3,431,428
Liabilities and Stockholders' Equity:
Current liabilities	503,817	504,668
Intercompany payables	0	0
Closure, post-closure and remedial liabilities, net	165,723	166,322
Long-term obligations, less current portion	1,625,537	1,633,272
Intercompany debt payable	0	0
Other long-term liabilities	223,291	293,417
Total liabilities	2,518,368	2,597,679
Stockholders' equity	1,188,202	1,084,241	1,096,282	1,262,871
Total liabilities and stockholders' equity	3,706,570	3,681,920
Reportable Legal Entities | Clean Harbors, Inc.
Assets:
Cash and cash equivalents	51,638	51,417	11,017	1,006
Short-term marketable securities	0
Intercompany receivables	238,339	200,337
Accounts receivable, net	0	0
Other current assets	897	3,096
Property, plant and equipment, net	0	0
Investments in subsidiaries	3,112,547	2,851,571
Intercompany debt receivable	0	0
Goodwill	0	0
Permits and other intangibles, net	0	0
Other long-term assets	2,084	2,446
Total assets	3,405,505	3,108,867
Liabilities and Stockholders' Equity:
Current liabilities	16,954	21,805
Intercompany payables	574,812	365,848
Closure, post-closure and remedial liabilities, net	0	0
Long-term obligations, less current portion	1,625,537	1,633,272
Intercompany debt payable	0	3,701
Other long-term liabilities	0	0
Total liabilities	2,217,303	2,024,626
Stockholders' equity	1,188,202	1,084,241
Total liabilities and stockholders' equity	3,405,505	3,108,867
Reportable Legal Entities | Guarantor Subsidiaries
Assets:
Cash and cash equivalents	207,777	155,943	83,479	154,147
Short-term marketable securities	0
Intercompany receivables	590,100	354,836
Accounts receivable, net	433,042	417,029
Other current assets	233,602	234,408
Property, plant and equipment, net	1,174,975	1,211,210
Investments in subsidiaries	569,568	580,124
Intercompany debt receivable	92,530	86,409
Goodwill	415,641	412,638
Permits and other intangibles, net	408,655	435,594
Other long-term assets	12,064	7,582
Total assets	4,137,954	3,895,773
Liabilities and Stockholders' Equity:
Current liabilities	371,135	366,831
Intercompany payables	289,531	237,058
Closure, post-closure and remedial liabilities, net	148,872	150,682
Long-term obligations, less current portion	0	0
Intercompany debt payable	21,000	21,000
Other long-term liabilities	201,086	275,649
Total liabilities	1,031,624	1,051,220
Stockholders' equity	3,106,330	2,844,553
Total liabilities and stockholders' equity	4,137,954	3,895,773
Reportable Legal Entities | Non-Guarantor Subsidiaries
Assets:
Cash and cash equivalents	59,984	99,637	90,212	91,726
Short-term marketable securities	38,179
Intercompany receivables	52,909	49,055
Accounts receivable, net	95,882	79,197
Other current assets	52,947	69,257
Property, plant and equipment, net	412,390	400,617
Investments in subsidiaries	0	0
Intercompany debt receivable	21,000	24,701
Goodwill	62,882	52,516
Permits and other intangibles, net	60,473	63,127
Other long-term assets	3,350	4,387
Total assets	859,996	842,494
Liabilities and Stockholders' Equity:
Current liabilities	135,620	133,145
Intercompany payables	17,005	1,322
Closure, post-closure and remedial liabilities, net	16,851	15,640
Long-term obligations, less current portion	0	0
Intercompany debt payable	92,530	86,409
Other long-term liabilities	22,205	18,836
Total liabilities	284,211	255,352
Stockholders' equity	575,785	587,142
Total liabilities and stockholders' equity	859,996	842,494
Consolidating Adjustments
Assets:
Cash and cash equivalents	0	0	$ 0	$ 0
Short-term marketable securities	0
Intercompany receivables	(881,348)	(604,228)
Accounts receivable, net	0	0
Other current assets	(19,892)	(17,113)
Property, plant and equipment, net	0	0
Investments in subsidiaries	(3,682,115)	(3,431,695)
Intercompany debt receivable	(113,530)	(111,110)
Goodwill	0	0
Permits and other intangibles, net	0	0
Other long-term assets	0	(1,068)
Total assets	(4,696,885)	(4,165,214)
Liabilities and Stockholders' Equity:
Current liabilities	(19,892)	(17,113)
Intercompany payables	(881,348)	(604,228)
Closure, post-closure and remedial liabilities, net	0	0
Long-term obligations, less current portion	0	0
Intercompany debt payable	(113,530)	(111,110)
Other long-term liabilities	0	(1,068)
Total liabilities	(1,014,770)	(733,519)
Stockholders' equity	(3,682,115)	(3,431,695)
Total liabilities and stockholders' equity	$ (4,696,885)	$ (4,165,214)