CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Income Statement [Abstract]
Revenues	$ 364,153	$ 415,858	$ 741,986	$ 892,526
Cost of revenues (exclusive of depreciation and amortization shown separately below)	262,284	265,786	538,893	571,036
Selling, general and administrative expenses	37,406	43,604	77,491	85,801
Pension settlement charges		911		18,286
Depreciation and amortization	32,333	26,203	62,337	50,328
Gain on disposition of assets, net	(3,338)	(3,015)	(4,552)	(5,951)
Operating income	35,468	82,369	67,817	173,026
Interest expense	(99)	(73)	(333)	(145)
Interest income	3,343	2,698	6,308	4,553
Other income, net	732	631	1,499	1,392
Income before income taxes	39,444	85,625	75,291	178,826
Income tax provision	7,025	20,612	15,405	42,289
Net income	$ 32,419	$ 65,013	$ 59,886	$ 136,537
Earnings per share
Basic (in dollars per share)	$ 0.15	$ 0.30	$ 0.28	$ 0.63
Diluted (in dollars per share)	0.15	0.30	0.28	0.63
Dividends paid per share	$ 0.04	$ 0.04	$ 0.08	$ 0.08