UNAUDITED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Revenues:
Total revenues	$ 1,365,696	$ 1,363,086	$ 4,070,983	$ 3,888,507
Cost of revenues: (exclusive of items shown separately below)
Total cost of revenues	943,951	910,648	2,822,977	2,652,506
Selling, general and administrative expenses	171,019	151,711	505,154	458,492
Accretion of environmental liabilities	3,388	3,246	10,281	9,599
Depreciation and amortization	92,970	88,394	267,425	260,560
Income from operations	154,368	209,087	465,146	507,350
Other income (expense), net	334	104	(833)	2,073
Loss on early extinguishment of debt	0	0	(2,362)	0
Gain on sale of business	0	0	0	8,864
Interest expense, net of interest income of $2,877, $1,103, $7,833 and $2,159, respectively	(29,696)	(28,081)	(80,400)	(79,354)
Income before provision for income taxes	125,006	181,110	381,551	438,933
Provision for income taxes	33,666	45,311	102,044	109,663
Net income	$ 91,340	$ 135,799	$ 279,507	$ 329,270
Earnings per share:
Basic (in dollars per share)	$ 1.69	$ 2.51	$ 5.17	$ 6.07
Diluted (in dollars per share)	$ 1.68	$ 2.50	$ 5.14	$ 6.04
Shares used to compute earnings per share - Basic (in shares)	54,122	54,111	54,097	54,278
Shares used to compute earnings per share - Diluted (in shares)	54,419	54,381	54,411	54,542
Service revenues
Revenues:
Total revenues	$ 1,129,216	$ 1,073,810	$ 3,341,539	$ 3,100,914
Cost of revenues: (exclusive of items shown separately below)
Total cost of revenues	765,004	738,041	2,288,199	2,168,025
Product revenues
Revenues:
Total revenues	236,480	289,276	729,444	787,593
Cost of revenues: (exclusive of items shown separately below)
Total cost of revenues	$ 178,947	$ 172,607	$ 534,778	$ 484,481