UNAUDITED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Revenues:
Service revenues	$ 584,562	$ 801,347	$ 1,114,793	$ 1,397,677
Product revenues	112,948	134,881	218,800	271,050
Total revenues	697,510	936,228	1,333,593	1,668,727
Cost of revenues (exclusive of items shown separately below)
Service revenues	388,684	544,870	762,670	961,260
Product revenues	91,318	107,818	181,611	237,935
Total cost of revenues	480,002	652,688	944,281	1,199,195
Selling, general and administrative expenses	107,063	120,418	211,547	228,133
Accretion of environmental liabilities	2,548	2,599	5,053	5,218
Depreciation and amortization	73,393	67,773	142,295	136,129
Goodwill impairment charge	0	31,992	0	31,992
Income (loss) from operations	34,504	60,758	30,417	68,060
Other expense	(189)	(660)	(539)	(251)
Interest expense, net of interest income of $225, $188, $375 and $339, respectively	(21,647)	(19,249)	(40,627)	(38,687)
Income (loss) before provision for income taxes	12,668	40,849	(10,749)	29,122
Provision for income taxes	8,702	30,454	6,156	25,816
Net income (loss)	$ 3,966	$ 10,395	$ (16,905)	$ 3,306
Earnings (loss) per share:
Basic (in USD per share)	$ 0.07	$ 0.18	$ (0.29)	$ 0.06
Diluted (in USD per share)	$ 0.07	$ 0.18	$ (0.29)	$ 0.06
Shares used to compute earnings (loss) per share - Basic (in shares)	57,549	58,590	57,599	58,732
Shares used to compute earnings (loss) per share - Diluted (in shares)	57,678	58,710	57,599	58,832