Condensed Consolidated Income Statements - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Condensed Consolidated Income Statements
Revenues	$ 869,931	$ 867,936
Costs, expenses and other operating
Cost of sales (exclusive of items shown separately below)	571,737	508,225
Depreciation, depletion and amortization	35,479	32,210
Accretion on asset retirement obligations	5,292	4,430
Change in fair value of coal derivatives, net	(1,462)	15,519
Selling, general and administrative expenses	26,022	26,648
Other operating income, net	(3,707)	(3,439)
Costs, expenses and other operating	633,361	583,593
Income from operations	236,570	284,343
Interest expense, net
Interest expense	(4,126)	(7,047)
Interest and investment income	3,336	24
Interest expense, net	(790)	(7,023)
Income before nonoperating expenses	235,780	277,320
Nonoperating expense
Non-service related pension and postretirement benefit credits (costs)	592	(873)
Net loss resulting from early retirement of debt	(1,126)	(4,120)
Nonoperating expenses	(534)	(4,993)
Income before income taxes	235,246	272,327
Provision for income taxes	37,138	455
Net income	$ 198,108	$ 271,872
Net income per common share
Basic earnings per share (in dollars per share)	$ 11.05	$ 17.60
Diluted earnings per share (in dollars per share)	$ 10.02	$ 12.89
Weighted average shares outstanding
Basic weighted average shares outstanding (in shares)	17,924	15,448
Diluted weighted average shares outstanding (in shares)	19,784	21,271
Dividends declared per common share (in dollars per share)	$ 3.11	$ 0.25