UNAUDITED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Revenues:
Service revenues	$ 612,352	$ 594,225	$ 1,783,506	$ 1,709,018
Product revenues	143,494	135,295	414,069	354,095
Total revenues	755,846	729,520	2,197,575	2,063,113
Cost of revenues (exclusive of items shown separately below)
Service revenues	412,369	385,542	1,215,812	1,148,212
Product revenues	107,226	106,373	320,171	287,984
Total cost of revenues	519,595	491,915	1,535,983	1,436,196
Selling, general and administrative expenses	113,252	110,954	337,767	322,501
Accretion of environmental liabilities	2,347	2,476	7,053	7,529
Depreciation and amortization	72,989	73,360	216,932	215,655
Goodwill impairment charge	0	34,013	0	34,013
Income from operations	47,663	16,802	99,840	47,219
Other expense	(432)	(198)	(2,814)	(737)
Loss on early extinguishment of debt	(1,846)	0	(7,891)	0
(Loss) gain on sale of businesses	(77)	16,431	31,645	16,431
Interest expense, net of interest income of $573, $196, $1,098 and $571, respectively	(20,675)	(21,565)	(65,743)	(62,192)
Income (loss) before (benefit) provision for income taxes	24,633	11,470	55,037	721
Provision for income taxes	12,575	21,725	38,492	27,881
Net income (loss)	$ 12,058	$ (10,255)	$ 16,545	$ (27,160)
Earnings (loss) per share:
Basic (in USD per share)	$ 0.21	$ (0.18)	$ 0.29	$ (0.47)
Diluted (in USD per share)	$ 0.21	$ (0.18)	$ 0.29	$ (0.47)
Shares used to compute loss per share - Basic (in shares)	57,033	57,487	57,149	57,575
Shares used to compute loss per share - Diluted (in shares)	57,195	57,487	57,280	57,575