GOODWILL AND OTHER INTANGIBLE ASSETS (Rollforward of Goodwill) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2016 USD ($)
Goodwill [Roll Forward]
Balance at beginning of year	$ 453,105
Measurement period adjustment from prior acquisitions	2,095
Foreign currency translation and other	5,442
Balance at end of year	460,642
Technical Services
Goodwill [Roll Forward]
Balance at beginning of year	49,267
Balance at end of year	48,694
Industrial and Field Services
Goodwill [Roll Forward]
Balance at beginning of year	105,286
Balance at end of year	106,637
SK Environmental Services
Goodwill [Roll Forward]
Balance at beginning of year	216,589
Balance at end of year	220,854
Lodging Services
Goodwill [Roll Forward]
Balance at beginning of year	32,208
Balance at end of year	34,314
Oil and Gas Field Services
Goodwill [Roll Forward]
Balance at beginning of year	0
Balance at end of year	0
Operating Segments | Technical Services
Goodwill [Roll Forward]
Balance at beginning of year	49,267
Measurement period adjustment from prior acquisitions	0
Foreign currency translation and other	(573)
Balance at end of year	48,694
Operating Segments | Industrial and Field Services
Goodwill [Roll Forward]
Balance at beginning of year	105,286
Measurement period adjustment from prior acquisitions	0
Foreign currency translation and other	1,351
Balance at end of year	106,637
Operating Segments | Kleen Performance Products
Goodwill [Roll Forward]
Balance at beginning of year	49,755
Measurement period adjustment from prior acquisitions	0
Foreign currency translation and other	388
Balance at end of year	50,143
Operating Segments | SK Environmental Services
Goodwill [Roll Forward]
Balance at beginning of year	216,589
Measurement period adjustment from prior acquisitions	2,095
Foreign currency translation and other	2,170
Balance at end of year	220,854
Operating Segments | Lodging Services
Goodwill [Roll Forward]
Balance at beginning of year	32,208
Measurement period adjustment from prior acquisitions	0
Foreign currency translation and other	2,106
Balance at end of year	34,314
Operating Segments | Oil and Gas Field Services
Goodwill [Roll Forward]
Balance at beginning of year	0
Measurement period adjustment from prior acquisitions	0
Foreign currency translation and other	0
Balance at end of year	$ 0