GOODWILL AND OTHER INTANGIBLE ASSETS (Rollforward of Goodwill) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Goodwill [Roll Forward]
Balance at beginning of year			$ 453,105
Acquired from current period acquisitions			50,067
Measurement period adjustment from prior period acquisitions			2,095
Decrease from disposition of business			(4,994)
Goodwill impairment charge	$ (34,013)	$ 0	(34,013)	$ (31,992)
Foreign currency translation and other			4,373
Balance at end of year	470,633		470,633
Technical Services
Goodwill [Roll Forward]
Balance at beginning of year			49,267
Balance at end of year	57,637		57,637
Industrial and Field Services
Goodwill [Roll Forward]
Balance at beginning of year			105,286
Balance at end of year	106,349		106,349
Kleen Performance Products
Goodwill [Roll Forward]
Balance at beginning of year			49,755
Balance at end of year	68,482		68,482
SK Environmental Services
Goodwill [Roll Forward]
Balance at beginning of year			216,589
Balance at end of year	238,165		238,165
Lodging Services
Goodwill [Roll Forward]
Balance at beginning of year			32,208
Goodwill impairment charge	(34,000)
Balance at end of year	0		0
Oil and Gas Field Services
Goodwill [Roll Forward]
Balance at beginning of year			0
Balance at end of year	0		0
Operating Segments | Technical Services
Goodwill [Roll Forward]
Balance at beginning of year			49,267
Acquired from current period acquisitions			8,989
Measurement period adjustment from prior period acquisitions			0
Decrease from disposition of business			0
Goodwill impairment charge
Foreign currency translation and other			(619)
Balance at end of year	57,637		57,637
Operating Segments | Industrial and Field Services
Goodwill [Roll Forward]
Balance at beginning of year			105,286
Acquired from current period acquisitions			4,925
Measurement period adjustment from prior period acquisitions			0
Decrease from disposition of business			(4,994)
Goodwill impairment charge
Foreign currency translation and other			1,132
Balance at end of year	106,349		106,349
Operating Segments | Kleen Performance Products
Goodwill [Roll Forward]
Balance at beginning of year			49,755
Acquired from current period acquisitions			18,629
Measurement period adjustment from prior period acquisitions			0
Decrease from disposition of business			0
Goodwill impairment charge
Foreign currency translation and other			98
Balance at end of year	68,482		68,482
Operating Segments | SK Environmental Services
Goodwill [Roll Forward]
Balance at beginning of year			216,589
Acquired from current period acquisitions			17,524
Measurement period adjustment from prior period acquisitions			2,095
Decrease from disposition of business
Goodwill impairment charge
Foreign currency translation and other			1,957
Balance at end of year	238,165		238,165
Operating Segments | Lodging Services
Goodwill [Roll Forward]
Balance at beginning of year			32,208
Acquired from current period acquisitions			0
Measurement period adjustment from prior period acquisitions			0
Decrease from disposition of business
Goodwill impairment charge			(34,013)
Foreign currency translation and other			1,805
Balance at end of year	0		0
Operating Segments | Oil and Gas Field Services
Goodwill [Roll Forward]
Balance at beginning of year			0
Acquired from current period acquisitions			0
Measurement period adjustment from prior period acquisitions			0
Decrease from disposition of business
Goodwill impairment charge
Foreign currency translation and other			0
Balance at end of year	$ 0		$ 0