Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands		12 Months Ended
		Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Revenues		$ 1,337,435	$ 1,040,930	$ 827,098
Costs and expenses:
Cost of goods sold		715,846	687,781	682,066
Selling, general and administrative expenses		73,432	72,519	57,925
Net gain on fire damage		(3,361)
Gain on sale of facility				(9,176)
Total costs and expenses		785,917	760,300	730,815
Operating income		551,518	280,630	96,283
Interest expense, net	[1]	(29,275)	(29,463)	(30,361)
Pension settlement charge			(42,988)
Loss on the extinguishment of debt				(5,512)
Non-operating pension and other postretirement employee benefit costs		(13,227)	(14,226)	(3,739)
Income before income taxes		509,016	193,953	56,671
Income taxes		(85,156)	(27,123)	(1,010)
Net income		$ 423,860	$ 166,830	$ 55,661
Net income per share:
Basic (in dollars per share)		$ 6.29	$ 2.48	$ 0.82
Diluted (in dollars per share)		6.26	2.47	0.82
Dividends/Special distribution per share		$ 5.67	$ 1.61	$ 1.60
Weighted-average shares outstanding (in thousands)
Basic (in shares)		67,352	67,237	67,608
Diluted (in shares)		67,719	67,568	67,743

[1] Includes amortization of bond discounts and deferred loan fees.