GOODWILL AND OTHER INTANGIBLE ASSETS (Changes to Goodwill) (Details) - USD ($) $ in Thousands	3 Months Ended			12 Months Ended
	Sep. 30, 2016	Jun. 30, 2015	Sep. 30, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Goodwill [Roll Forward]
Goodwill, beginning of period				$ 453,105	$ 452,669
Increase from current period acquisitions				45,791	46,539
Measurement period adjustments from prior period acquisitions				2,095	3,574
Decrease from disposition of business				(4,994)
Goodwill impairment charge	$ (34,000)	$ (32,000)		(34,013)	(31,992)	$ (123,414)
Foreign currency translation and other				3,170	(17,685)
Goodwill, end of period				465,154	453,105	452,669
Technical Services
Goodwill [Roll Forward]
Goodwill, beginning of period				49,267	50,092
Increase from current period acquisitions				12,572	0
Measurement period adjustments from prior period acquisitions				0	0
Decrease from disposition of business				0
Goodwill impairment charge				0	0
Foreign currency translation and other				(723)	(825)
Goodwill, end of period				61,116	49,267	50,092
Industrial and Field Services
Goodwill [Roll Forward]
Goodwill, beginning of period				105,286	109,214
Increase from current period acquisitions				6,953	0
Measurement period adjustments from prior period acquisitions				0	0
Decrease from disposition of business				(4,994)
Goodwill impairment charge				0	0
Foreign currency translation and other				723	(3,928)
Goodwill, end of period				107,968	105,286	109,214
Safety-Kleen
Goodwill [Roll Forward]
Goodwill, beginning of period				266,344	224,756
Increase from current period acquisitions				26,266	46,539
Measurement period adjustments from prior period acquisitions				2,095	0
Decrease from disposition of business				0
Goodwill impairment charge			$ (123,400)	0	0
Foreign currency translation and other				1,365	(4,951)
Goodwill, end of period				296,070	266,344	224,756
Oil, Gas and Lodging Services
Goodwill [Roll Forward]
Goodwill, beginning of period				32,208	68,607
Increase from current period acquisitions				0	0
Measurement period adjustments from prior period acquisitions				0	3,574
Decrease from disposition of business				0
Goodwill impairment charge				(34,013)	(31,992)
Foreign currency translation and other				1,805	(7,981)
Goodwill, end of period				$ 0	$ 32,208	$ 68,607