CONSOLIDATED STATEMENTS OF INCOME (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Revenues:
Service revenues									$ 2,729,205	$ 2,063,160	$ 1,882,979
Product revenues									780,451	124,748	101,157
Total revenues	879,430	907,535	860,528	862,163	558,962	533,806	523,118	572,022	3,509,656	2,187,908	1,984,136
Cost of revenues: (exclusive of items shown separately below)
Service revenues									1,874,448	1,439,594	1,301,363
Product revenues									668,185	101,027	78,628
Total cost of revenues	645,164	647,119	614,326	636,024	399,743	372,940	367,623	400,315	2,542,633	1,540,621	1,379,991
Selling, general and administrative expenses									470,477	273,520	254,137
Accretion of environmental liabilities									11,541	9,917	9,680
Depreciation and amortization									264,449	161,646	122,663
Income from operations	58,877	73,608	53,243	34,828	36,231	56,739	47,533	61,701	220,556	202,204	217,665
Other income (expense)	(325)	(150)	1,655	525	(337)	(91)	(75)	(299)	1,705	(802)	6,402
Loss on early extinguishment of debt									0	(26,385)	0
Interest expense, net of interest income of $507, $846, and $798, respectively									(78,376)	(47,287)	(39,389)
Income before provision (benefit) for income taxes									143,885	127,730	184,678
Provision (benefit) for income taxes									48,319	(1,944)	57,426
Net income	$ 26,801	$ 35,361	$ 22,902	$ 10,502	$ 61,874	$ 12,359	$ 23,426	$ 32,015	$ 95,566	$ 129,674	$ 127,252
Earnings per share:
Basic (in dollars per share)	$ 0.44	$ 0.58	$ 0.38	$ 0.17	$ 1.11	$ 0.23	$ 0.44	$ 0.60	$ 1.58	$ 2.41	$ 2.40
Diluted (in dollars per share)	$ 0.44	$ 0.58	$ 0.38	$ 0.17	$ 1.11	$ 0.23	$ 0.44	$ 0.60	$ 1.57	$ 2.40	$ 2.39
Shares used to compute earnings per share — Basic									60,574	53,884	52,961
Shares used to compute earnings per share — Diluted									60,728	54,079	53,324