CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenues:
Service revenues									$ 2,280,809	$ 2,744,272	$ 2,639,796
Product revenues									474,417	530,865	761,840
Total revenues	$ 692,113	$ 729,520	$ 697,510	$ 636,083	$ 713,044	$ 893,366	$ 936,228	$ 732,499	2,755,226	3,275,137	3,401,636
Cost of revenues: (exclusive of items shown separately below)
Service revenues									1,543,210	1,898,907	1,790,377
Product revenues									389,647	457,899	651,419
Total cost of revenues	496,661	491,915	480,002	464,279	522,965	634,646	652,688	546,507	1,932,857	2,356,806	2,441,796
Selling, general and administrative expenses									422,015	414,164	437,921
Accretion of environmental liabilities									10,177	10,402	10,612
Depreciation and amortization									287,002	274,194	276,083
Goodwill impairment charges		34,000					32,000		34,013	31,992	123,414
Income (loss) from operations	21,943	16,802	34,504	(4,087)	25,549	93,970	60,758	7,302	69,162	187,579	111,810
Other income (expense), net	6,932	(198)	(189)	(350)	(990)	(139)	(660)	409	6,195	(1,380)	4,380
Gain on sale of business		16,400							16,884	0	0
Interest expense, net of interest income of $784, $626, and $819, respectively									(83,525)	(76,553)	(77,668)
(Loss) income before (benefit) provision for income taxes									8,716	109,646	38,522
Provision for income taxes									48,589	65,544	66,850
Net (loss) income	$ (12,713)	$ (10,255)	$ 3,966	$ (20,871)	$ 568	$ 40,228	$ 10,395	$ (7,089)	$ (39,873)	$ 44,102	$ (28,328)
(Loss) earnings per share:
Basic (in dollars per share)	$ (0.22)	$ (0.18)	$ 0.07	$ (0.36)	$ 0.01	$ 0.69	$ 0.18	$ (0.12)	$ (0.69)	$ 0.76	$ (0.47)
Diluted (in dollars per share)	$ (0.22)	$ (0.18)	$ 0.07	$ (0.36)	$ 0.01	$ 0.69	$ 0.18	$ (0.12)	$ (0.69)	$ 0.76	$ (0.47)
Shares used to compute (loss) earnings per share — Basic (in shares)									57,532	58,324	60,311
Shares used to compute (loss) earnings per share — Diluted (in shares)									57,532	58,434	60,311