UNAUDITED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Revenues:
Service revenues	$ 619,719	$ 560,214
Product revenues	130,059	128,727
Total revenues	749,778	688,941
Cost of revenues: (exclusive of items shown separately below)
Service revenues	447,649	391,087
Product revenues	98,776	105,498
Total cost of revenues	546,425	496,585
Selling, general and administrative expenses	115,088	112,221
Accretion of environmental liabilities	2,430	2,290
Depreciation and amortization	74,844	72,412
Income from operations	10,991	5,433
Other expense, net	(299)	(1,549)
Interest expense, net of interest income of $764 and $215, respectively	(20,270)	(22,576)
(Loss) income before (benefit) provision for income taxes	(9,578)	(18,692)
Provision for income taxes	3,053	2,701
Net loss	$ (12,631)	$ (21,393)
Loss per share:
Basic (in USD per share)	$ (0.22)	$ (0.37)
Diluted (in USD per share)	$ (0.22)	$ (0.37)
Shares used to compute loss per share - Basic (in shares)	56,457	57,262
Shares used to compute loss per share - Diluted (in shares)	56,457	57,262