SEGMENT REPORTING (Assets by Reportable Segment) (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Jun. 30, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Property, plant and equipment, net	$ 1,531,548		$ 1,558,834
Goodwill	447,918		452,669
Permits and other intangible, net	518,995		530,080
Total assets	3,599,861		3,704,278
Technical Services
Segment Reporting Information [Line Items]
Property, plant and equipment, net	464,705		412,323
Goodwill	49,426		50,092
Permits and other intangible, net	74,885		74,870
Total assets	806,451		756,169
Industrial and Field Services
Segment Reporting Information [Line Items]
Property, plant and equipment, net	242,007		245,115
Goodwill	106,043		109,214
Permits and other intangible, net	15,375		17,801
Total assets	392,284		392,652
Kleen Performance Products
Segment Reporting Information [Line Items]
Property, plant and equipment, net	193,576		201,451
Goodwill	49,972		50,883
Permits and other intangible, net	142,898		151,041
Total assets	497,627		538,921
SK Environmental Services
Segment Reporting Information [Line Items]
Property, plant and equipment, net	258,178		240,078
Goodwill	209,089		173,873
Permits and other intangible, net	260,327		252,897
Total assets	793,163		731,072
Lodging Services
Segment Reporting Information [Line Items]
Property, plant and equipment, net	112,708		141,965
Goodwill	33,388		34,863
Permits and other intangible, net	7,791		10,744
Total assets	187,461		231,782
Oil and Gas Field Services
Segment Reporting Information [Line Items]
Property, plant and equipment, net	168,630		215,574
Goodwill	0	$ 0	33,744
Permits and other intangible, net	17,719		22,727
Total assets	264,910		361,223
Corporate Items
Segment Reporting Information [Line Items]
Property, plant and equipment, net	91,744		102,328
Goodwill	0		0
Permits and other intangible, net	0		0
Total assets	$ 657,965		$ 692,459