BUSINESS COMBINATIONS (Assets Acquired and Liabilities Assumed) (Details) - USD ($) $ in Thousands	6 Months Ended	15 Months Ended
	Jun. 30, 2016	Jun. 30, 2016	Dec. 31, 2015	Apr. 11, 2015
Business Acquisition [Line Items]
Goodwill	$ 461,491	$ 461,491	$ 453,105
2016 Acquisitions
Business Acquisition [Line Items]
Accounts receivable	9,186	9,186
Measurement period adjustments, accounts receivable	0
Inventories and supplies	9,431	9,431
Measurement period adjustment, inventories and supplies	0
Prepaid and other current assets	433	433
Measurement period adjustment, prepaid and other current assets	0
Property, plant and equipment	44,304	44,304
Measurement period adjustments, property, plant and equipment	(1,477)
Permits and other intangibles	2,105	2,105
Measurement period adjustments, permits and other intangibles	900
Current liabilities	(7,119)	(7,119)
Measurement period adjustments, current liabilities	0
Deferred taxes, unrecognized tax benefits and other long-term liabilities	(548)	(548)
Measurement period adjustments, deferred taxes, unrecognized tax benefits and other long-term liabilities	0
Total identifiable net assets	57,792	57,792
Measurement period adjustments, total identifiable net assets	(577)
Goodwill	1,197	1,197
Measurement period adjustments, goodwill	577
Total	58,989	58,989
Measurement period adjustments, total	0
Thermo Fluids Inc.
Business Acquisition [Line Items]
Accounts receivable	7,301	7,301
Measurement period adjustments, accounts receivable		192
Inventories and supplies	1,791	1,791
Measurement period adjustment, inventories and supplies		0
Prepaid and other current assets	665	665
Measurement period adjustment, prepaid and other current assets		(1,084)
Property, plant and equipment	27,641	27,641
Measurement period adjustments, property, plant and equipment		(2,827)
Permits and other intangibles	18,100	18,100
Measurement period adjustments, permits and other intangibles		(1,900)
Current liabilities	(5,884)	(5,884)
Measurement period adjustments, current liabilities		(25)
Closure and post-closure liabilities	(2,333)	(2,333)
Measurement period adjustments, closure and post-closure liabilities		(657)
Deferred taxes, unrecognized tax benefits and other long-term liabilities	(9,174)	(9,174)
Measurement period adjustments, deferred taxes, unrecognized tax benefits and other long-term liabilities		3,907
Total identifiable net assets	38,107	38,107
Measurement period adjustments, total identifiable net assets		(2,394)
Goodwill	41,229	41,229
Measurement period adjustments, goodwill		4,638
Total	79,336	79,336
Measurement period adjustments, total		2,244
At Acquisition Dates | 2016 Acquisitions
Business Acquisition [Line Items]
Accounts receivable	9,186	9,186
Inventories and supplies	9,431	9,431
Prepaid and other current assets	433	433
Property, plant and equipment	45,781	45,781
Permits and other intangibles	1,205	1,205
Current liabilities	(7,119)	(7,119)
Deferred taxes, unrecognized tax benefits and other long-term liabilities	(548)	(548)
Total identifiable net assets	58,369	58,369
Goodwill	620	620
Total	$ 58,989	$ 58,989
At Acquisition Dates | Thermo Fluids Inc.
Business Acquisition [Line Items]
Accounts receivable				$ 7,109
Inventories and supplies				1,791
Prepaid and other current assets				1,749
Property, plant and equipment				30,468
Permits and other intangibles				20,000
Current liabilities				(5,859)
Closure and post-closure liabilities				(1,676)
Deferred taxes, unrecognized tax benefits and other long-term liabilities				(13,081)
Total identifiable net assets				40,501
Goodwill				36,591
Total				$ 77,092