SEGMENT REPORTING (Assets by Reportable Segment) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Property, plant and equipment, net	$ 1,502,497us-gaap_PropertyPlantAndEquipmentNet	$ 1,558,834us-gaap_PropertyPlantAndEquipmentNet
Goodwill	445,412us-gaap_Goodwill	452,669us-gaap_Goodwill
Permits and other intangible, net	520,045	530,080
Total assets	3,546,042us-gaap_Assets	3,704,278us-gaap_Assets
Technical Services
Segment Reporting Information [Line Items]
Property, plant and equipment, net	423,520	412,323
Goodwill	49,667	50,092
Permits and other intangible, net	77,280	74,870
Total assets	764,557	756,169
Industrial and Field Services
Segment Reporting Information [Line Items]
Property, plant and equipment, net	247,136	245,115
Goodwill	107,193	109,214
Permits and other intangible, net	16,814	17,801
Total assets	394,345	392,652
Oil Re-refining and Recycling
Segment Reporting Information [Line Items]
Property, plant and equipment, net	194,767	201,451
Goodwill	50,303	50,883
Permits and other intangible, net	147,598	151,041
Total assets	503,987	538,921
SK Environmental Services
Segment Reporting Information [Line Items]
Property, plant and equipment, net	232,072	240,078
Goodwill	171,906	173,873
Permits and other intangible, net	249,003	252,897
Total assets	711,062	731,072
Lodging Services
Segment Reporting Information [Line Items]
Property, plant and equipment, net	125,281	141,965
Goodwill	35,030	34,863
Permits and other intangible, net	9,389	10,744
Total assets	206,871	231,782
Oil and Gas Field Services
Segment Reporting Information [Line Items]
Property, plant and equipment, net	190,301	215,574
Goodwill	31,313	33,744
Permits and other intangible, net	19,961	22,727
Total assets	323,265	361,223
Corporate Items
Segment Reporting Information [Line Items]
Property, plant and equipment, net	89,420	102,328
Goodwill	0	0
Permits and other intangible, net	0	0
Total assets	$ 641,955	$ 692,459

Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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