Condensed Consolidated Income Statements - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Condensed Consolidated Income Statements
Revenues	$ 608,751	$ 757,294	$ 1,288,941	$ 1,627,225
Costs, expenses and other operating
Cost of sales (exclusive of items shown separately below)	528,684	606,127	1,096,407	1,177,864
Depreciation, depletion and amortization	38,439	36,077	77,259	71,556
Accretion on asset retirement obligations	5,870	5,293	11,739	10,585
Selling, general and administrative expenses	22,518	22,791	48,105	48,813
Other operating income, net	(2,410)	(2,010)	(18,393)	(7,179)
Costs, expenses and other operating	593,101	668,278	1,215,117	1,301,639
Income from operations	15,650	89,016	73,824	325,586
Interest expense, net
Interest expense	(3,933)	(3,537)	(8,249)	(7,663)
Interest and investment income	5,403	4,201	11,503	7,537
Interest expense, net	1,470	664	3,254	(126)
Income before nonoperating expenses	17,120	89,680	77,078	325,460
Nonoperating expense
Non-service related pension and postretirement benefit (costs) credits	(285)	593	(571)	1,185
Net loss resulting from early retirement of debt				(1,126)
Nonoperating expenses	(285)	593	(571)	59
Income before income taxes	16,835	90,273	76,507	325,519
Provision for income taxes	2,002	12,920	5,721	50,058
Net income	$ 14,833	$ 77,353	$ 70,786	$ 275,461
Net income per common share
Basic earnings per share (in dollars per share)	$ 0.82	$ 4.20	$ 3.88	$ 15.16
Diluted earnings per share (in dollars per share)	$ 0.81	$ 4.04	$ 3.82	$ 14.16
Weighted average shares outstanding
Basic weighted average shares outstanding (in shares)	18,097	18,406	18,222	18,165
Diluted weighted average shares outstanding (in shares)	18,295	19,135	18,535	19,459
Dividends declared per common share (in dollars per share)	$ 1.11	$ 2.45	$ 2.76	$ 5.56