GOODWILL AND INTANGIBLE ASSETS (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jun. 17, 2014
Changes in goodwill
Balance at the beginning of the period	$ 21,693	$ 23,105
USEM acquisition	197,163
Foreign Currency Translation	(1,684)	(1,412)
Balance at the end of the period	217,172	21,693	23,105
Intangible Assets
Total amortizing intangible assets	240,905	40,263
Accumulated amortization	(12,135)	(4,341)
Total intangible assets, cost	290,802	41,173
Total intangible assets, net	278,667	36,832
Net carrying amount of amortizing intangible assets	228,770	35,922
Amortization expense	8,207	1,461	1,469
Expected future amortization expense of amortizing intangible assets
2015	13,226
2016	12,545
2017	11,562
2018	10,689
2019	10,689
Thereafter	170,059
Permits and licenses
Intangible Assets
Nonamortizing intangible assets	49,750	750
Tradename
Intangible Assets
Nonamortizing intangible assets	147	160
Permits, licenses and lease
Intangible Assets
Total amortizing intangible assets	113,693	26,264
Accumulated amortization	(4,427)	(2,536)
Net carrying amount of amortizing intangible assets	109,266	23,728
Customer relationships
Intangible Assets
Total amortizing intangible assets	103,086	5,005
Accumulated amortization	(4,488)	(731)
Net carrying amount of amortizing intangible assets	98,598	4,274
Technology - Formulae and processes
Intangible Assets
Total amortizing intangible assets	7,844	8,551
Accumulated amortization	(1,009)	(826)
Net carrying amount of amortizing intangible assets	6,835	7,725
Customer backlog
Intangible Assets
Total amortizing intangible assets	4,600
Accumulated amortization	(246)
Net carrying amount of amortizing intangible assets	4,354
Tradename
Intangible Assets
Total amortizing intangible assets	5,481
Accumulated amortization	(979)
Net carrying amount of amortizing intangible assets	4,502
Developed software
Intangible Assets
Total amortizing intangible assets	3,745	329
Accumulated amortization	(428)	(185)
Net carrying amount of amortizing intangible assets	3,317	144
Non-compete agreements
Intangible Assets
Total amortizing intangible assets	920	20
Accumulated amortization	(462)	(20)
Net carrying amount of amortizing intangible assets	458
Internet domain and website
Intangible Assets
Total amortizing intangible assets	869
Accumulated amortization	(24)
Net carrying amount of amortizing intangible assets	845
Database
Intangible Assets
Total amortizing intangible assets	667	94
Accumulated amortization	(72)	(43)
Net carrying amount of amortizing intangible assets	595	51
Environmental Services
Changes in goodwill
Balance at the end of the period	152,100
Field & Industrial Services
Changes in goodwill
Balance at the end of the period	65,100
EQ
Changes in goodwill
Balance at the beginning of the period				197,163
Balance at the end of the period	197,163			197,163
Intangible Assets
Intangible assets	252,874			252,874
EQ | Customer relationships
Intangible Assets
Intangible assets				98,400
EQ | Customer backlog
Intangible Assets
Intangible assets				4,600
EQ | Tradename
Intangible Assets
Intangible assets				5,481
EQ | Developed software
Intangible Assets
Intangible assets				3,443
EQ | Non-compete agreements
Intangible Assets
Intangible assets				900
EQ | Internet domain and website
Intangible Assets
Intangible assets				869
EQ | Database
Intangible Assets
Intangible assets				581
EQ | Environmental Services
Changes in goodwill
Balance at the end of the period	$ 132,100