CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Common Stock	Capital in Excess of Par Value	Retained Earnings	Accumulated Other Comprehensive (Loss) Income	Total
Balance at Dec. 31, 2021	$ 21,563		$ 640,936	$ (20,708)	$ 641,791
Balance (in shares) at Dec. 31, 2021	215,629,000
Increase (Decrease) in Stockholders' Equity
Stock issued for stock incentive plans, net	$ 104	$ 1,393			1,497
Stock issued for stock incentive plans, net (in shares)	1,037,000
Stock purchased and retired	$ (19)	(1,393)	502		(910)
Stock purchased and retired (in shares)	(190,000)
Net income			15,079		15,079
Pension adjustment, net of taxes				195	195
Foreign currency translation				116	116
Balance at Mar. 31, 2022	$ 21,648		656,517	(20,397)	657,768
Balance (in shares) at Mar. 31, 2022	216,476,000
Balance at Dec. 31, 2021	$ 21,563		640,936	(20,708)	641,791
Balance (in shares) at Dec. 31, 2021	215,629,000
Increase (Decrease) in Stockholders' Equity
Net income					131,358
Foreign currency translation					91
Balance at Sep. 30, 2022	$ 21,663		771,779	(20,032)	773,410
Balance (in shares) at Sep. 30, 2022	216,631,000
Balance at Mar. 31, 2022	$ 21,648		656,517	(20,397)	657,768
Balance (in shares) at Mar. 31, 2022	216,476,000
Increase (Decrease) in Stockholders' Equity
Stock issued for stock incentive plans, net	$ 18	1,677			1,695
Stock issued for stock incentive plans, net (in shares)	186,000
Stock purchased and retired		(1,677)	1,677
Net income			46,939		46,939
Pension adjustment, net of taxes				195	195
Foreign currency translation				65	65
Balance at Jun. 30, 2022	$ 21,666		705,133	(20,137)	706,662
Balance (in shares) at Jun. 30, 2022	216,662,000
Increase (Decrease) in Stockholders' Equity
Stock issued for stock incentive plans, net	$ (3)	1,575			1,572
Stock issued for stock incentive plans, net (in shares)	(31,000)
Stock purchased and retired		(1,575)	1,573		(2)
Net income			69,340		69,340
Dividends			(4,267)		(4,267)
Pension adjustment, net of taxes				195	195
Foreign currency translation				(90)	(90)
Balance at Sep. 30, 2022	$ 21,663		771,779	(20,032)	773,410
Balance (in shares) at Sep. 30, 2022	216,631,000
Balance at Dec. 31, 2022	$ 21,661		856,013	(19,939)	$ 857,735
Balance (in shares) at Dec. 31, 2022	216,609,000				216,609,191
Increase (Decrease) in Stockholders' Equity
Stock issued for stock incentive plans, net	$ 115	1,687			$ 1,802
Stock issued for stock incentive plans, net (in shares)	1,149,000
Stock purchased and retired	$ (139)	(1,687)	(9,523)		(11,349)
Stock purchased and retired (in shares)	(1,388,000)
Net income			71,524		71,524
Dividends			(8,679)		(8,679)
Pension adjustment, net of taxes				16,678	16,678
Foreign currency translation				(16)	(16)
Balance at Mar. 31, 2023	$ 21,637		909,335	(3,277)	927,695
Balance (in shares) at Mar. 31, 2023	216,370,000
Balance at Dec. 31, 2022	$ 21,661		856,013	(19,939)	$ 857,735
Balance (in shares) at Dec. 31, 2022	216,609,000				216,609,191
Increase (Decrease) in Stockholders' Equity
Net income					$ 154,854
Foreign currency translation					322
Balance at Sep. 30, 2023	$ 21,623		978,496	(2,363)	$ 997,756
Balance (in shares) at Sep. 30, 2023	216,228,000				216,228,372
Balance at Mar. 31, 2023	$ 21,637		909,335	(3,277)	$ 927,695
Balance (in shares) at Mar. 31, 2023	216,370,000
Increase (Decrease) in Stockholders' Equity
Stock issued for stock incentive plans, net	$ 4	2,312			2,316
Stock issued for stock incentive plans, net (in shares)	40,000
Stock purchased and retired		(2,312)	2,310		(2)
Stock purchased and retired (in shares)	(1,000)
Net income			65,013		65,013
Dividends			(8,635)		(8,635)
Pension adjustment, net of taxes				576	576
Foreign currency translation				439	439
Balance at Jun. 30, 2023	$ 21,641		968,023	(2,262)	987,402
Balance (in shares) at Jun. 30, 2023	216,409,000
Increase (Decrease) in Stockholders' Equity
Stock issued for stock incentive plans, net	$ (4)	1,919			1,915
Stock issued for stock incentive plans, net (in shares)	(44,000)
Stock purchased and retired	$ (14)	$ (1,919)	790		(1,143)
Stock purchased and retired (in shares)	(137,000)
Net income			18,317		18,317
Dividends			(8,634)		(8,634)
Foreign currency translation				(101)	(101)
Balance at Sep. 30, 2023	$ 21,623		$ 978,496	$ (2,363)	$ 997,756
Balance (in shares) at Sep. 30, 2023	216,228,000				216,228,372