CONSOLIDATED STATEMENTS OF (LOSS) INCOME (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended																12 Months Ended
	Dec. 31, 2014		Sep. 30, 2014		Jun. 30, 2014		Mar. 31, 2014		Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenues:
Service revenues																	$ 2,639,796	$ 2,729,205	$ 2,063,160
Product revenues																	761,840	780,451	124,748
Total revenues	845,024		851,465		858,480		846,667		879,430		907,535		860,528		862,163		3,401,636	3,509,656	2,187,908
Cost of revenues: (exclusive of items shown separately below)
Service revenues																	1,790,377	1,874,448	1,439,594
Product revenues																	651,419	668,185	101,027
Total cost of revenues	610,720	[1]	598,407	[1]	606,950	[1]	625,719	[1]	645,164	[1]	647,119	[1]	614,326	[1]	636,024	[1]	2,441,796	2,542,633	1,540,621
Selling, general and administrative expenses																	437,921	470,477	273,520
Accretion of environmental liabilities																	10,612	11,541	9,917
Depreciation and amortization																	276,083	264,449	161,646
Goodwill impairment charge																	123,414	0	0
Income from operations	57,537		(42,748)		67,115		29,906		58,877		73,608		53,243		34,828		111,810	220,556	202,204
Other income (expense)	244		613		(655)		4,178		(325)		(150)		1,655		525		4,380	1,705	(802)
Loss on early extinguishment of debt																	0	0	(26,385)
Interest expense, net of interest income of $820, $507, and $846, respectively																	(77,668)	(78,376)	(47,287)
Income before provision (benefit) for income taxes																	38,522	143,885	127,730
Provision (benefit) for income taxes																	66,850	48,319	(1,944)
Net (loss) income	$ 27,377		$ (93,337)		$ 28,672		$ 8,960		$ 26,801		$ 35,361		$ 22,902		$ 10,502		$ (28,328)	$ 95,566	$ 129,674
(Loss) earnings per share:
Basic (in dollars per share)	$ 0.46	[2]	$ (1.55)	[2]	$ 0.47	[2]	$ 0.15	[2]	$ 0.44	[2]	$ 0.58	[2]	$ 0.38	[2]	$ 0.17	[2]	$ (0.47)	$ 1.58	$ 2.41
Diluted (in dollars per share)	$ 0.46	[2]	$ (1.55)	[2]	$ 0.47	[2]	$ 0.15	[2]	$ 0.44	[2]	$ 0.58	[2]	$ 0.38	[2]	$ 0.17	[2]	$ (0.47)	$ 1.57	$ 2.40
Shares used to compute (loss) earnings per share — Basic																	60,311	60,574	53,884
Shares used to compute (loss) earnings per share — Diluted																	60,311	60,728	54,079

[1] (1)Items shown separately on the statements of income consist of (i) accretion of environmental liabilities and (ii) depreciation and amortization.

[2] (2)Earnings per share are computed independently for each of the quarters presented. Accordingly, the quarterly basic and diluted earnings per share may not equal the total computed for the year. (3)In the fourth quarter of 2014 an adjustment was recorded to correct income tax expense that was recorded in the third quarter of 2014 resulting in a benefit of approximately $5.4 million in the fourth quarter.