OPERATING SEGMENTS (Details 2) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Reconciliation of adjusted EBITDA to Net Income
Adjusted EBITDA	$ 31,424	$ 17,094	$ 58,653	$ 37,370
Reconciliation to Net Income
Income tax expense	(5,055)	(4,247)	(7,957)	(9,474)
Interest expense	(5,433)	(858)	(11,127)	(944)
Interest income	6	39	47	83
Foreign currency gain (loss)	292	743	(775)	(197)
Other income	233	170	769	256
Impairment charges	(6,700)		(6,700)
Depreciation and amortization of plant and equipment	(7,656)	(4,573)	(15,135)	(8,412)
Amortization of intangibles	(3,304)	(862)	(6,606)	(1,215)
Stock-based Compensation	(627)	(255)	(1,089)	(525)
Accretion and non-cash adjustment of closure & post-closure liabilities	(1,042)	(386)	(2,077)	(716)
Net income	2,138	6,865	8,003	16,226
Field & Industrial Services
Reconciliation to Net Income
Impairment charges	(6,700)		(6,700)
Operating Segment | Environmental Services
Reconciliation of adjusted EBITDA to Net Income
Adjusted EBITDA	36,450	24,723	73,616	48,767
Operating Segment | Field & Industrial Services
Reconciliation of adjusted EBITDA to Net Income
Adjusted EBITDA	5,026	1,836	8,098	1,836
Corporate
Reconciliation of adjusted EBITDA to Net Income
Adjusted EBITDA	$ (10,052)	$ (9,465)	$ (23,061)	$ (13,233)