SEGMENT REPORTING (Third Party Revenues to Direct Revenues) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Segment Reporting Information [Line Items]
Total revenues	$ 688,941	$ 636,083
Intersegment revenues, net
Segment Reporting Information [Line Items]
Total revenues	0	0
Corporate Items, net
Segment Reporting Information [Line Items]
Total revenues	0	0
Direct revenues
Segment Reporting Information [Line Items]
Total revenues	688,941	636,083
Technical Services
Segment Reporting Information [Line Items]
Total revenues	230,218	219,105
Technical Services | Intersegment revenues, net
Segment Reporting Information [Line Items]
Total revenues	40,044	34,844
Technical Services | Corporate Items, net
Segment Reporting Information [Line Items]
Total revenues	722	388
Technical Services | Direct revenues
Segment Reporting Information [Line Items]
Total revenues	270,984	254,337
Industrial and Field Services
Segment Reporting Information [Line Items]
Total revenues	133,557	130,187
Industrial and Field Services | Intersegment revenues, net
Segment Reporting Information [Line Items]
Total revenues	(8,359)	(6,675)
Industrial and Field Services | Corporate Items, net
Segment Reporting Information [Line Items]
Total revenues	104	(13)
Industrial and Field Services | Direct revenues
Segment Reporting Information [Line Items]
Total revenues	125,302	123,499
Safety-Kleen
Segment Reporting Information [Line Items]
Total revenues	292,901	246,961
Safety-Kleen | Intersegment revenues, net
Segment Reporting Information [Line Items]
Total revenues	(32,069)	(28,521)
Safety-Kleen | Corporate Items, net
Segment Reporting Information [Line Items]
Total revenues	3	366
Safety-Kleen | Direct revenues
Segment Reporting Information [Line Items]
Total revenues	260,835	218,806
Oil, Gas and Lodging Services
Segment Reporting Information [Line Items]
Total revenues	32,132	39,051
Oil, Gas and Lodging Services | Intersegment revenues, net
Segment Reporting Information [Line Items]
Total revenues	384	352
Oil, Gas and Lodging Services | Corporate Items, net
Segment Reporting Information [Line Items]
Total revenues	94	104
Oil, Gas and Lodging Services | Direct revenues
Segment Reporting Information [Line Items]
Total revenues	32,610	39,507
Corporate Items
Segment Reporting Information [Line Items]
Total revenues	133	779
Corporate Items | Intersegment revenues, net
Segment Reporting Information [Line Items]
Total revenues	0	0
Corporate Items | Corporate Items, net
Segment Reporting Information [Line Items]
Total revenues	(923)	(845)
Corporate Items | Direct revenues
Segment Reporting Information [Line Items]
Total revenues	$ (790)	$ (66)