UNAUDITED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Revenues:
Total revenues	$ 1,397,900	$ 1,356,312	$ 2,705,287	$ 2,525,421
Cost of revenues: (exclusive of items shown separately below)
Total cost of revenues	947,512	898,469	1,879,026	1,741,858
Selling, general and administrative expenses	167,382	155,608	334,135	306,781
Accretion of environmental liabilities	3,486	3,197	6,893	6,353
Depreciation and amortization	89,697	87,868	174,455	172,166
Income from operations	189,823	211,170	310,778	298,263
Other (expense) income, net	(1,283)	1,265	(1,167)	1,969
Loss on early extinguishment of debt	0	0	(2,362)	0
Gain on sale of business	0	8,864	0	8,864
Interest expense, net of interest income of $2,001, $563, $4,956 and $1,056, respectively	(30,072)	(26,256)	(50,704)	(51,273)
Income before provision for income taxes	158,468	195,043	256,545	257,823
Provision for income taxes	42,702	46,886	68,378	64,352
Net income	$ 115,766	$ 148,157	$ 188,167	$ 193,471
Earnings per share:
Basic (in dollars per share)	$ 2.14	$ 2.73	$ 3.48	$ 3.56
Diluted (in dollars per share)	$ 2.13	$ 2.71	$ 3.46	$ 3.54
Shares used to compute earnings per share - Basic (in shares)	54,092	54,318	54,084	54,362
Shares used to compute earnings per share - Diluted (in shares)	54,448	54,597	54,422	54,639
Service revenues
Revenues:
Total revenues	$ 1,159,090	$ 1,085,043	$ 2,212,323	$ 2,027,104
Cost of revenues: (exclusive of items shown separately below)
Total cost of revenues	771,600	736,560	1,523,195	1,429,984
Product revenues
Revenues:
Total revenues	238,810	271,269	492,964	498,317
Cost of revenues: (exclusive of items shown separately below)
Total cost of revenues	$ 175,912	$ 161,909	$ 355,831	$ 311,874