Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Capital in Excess of Par Value	Retained Earnings	Accumulated Other Comprehensive (Loss) Income
Beginning balance at Dec. 31, 2021	$ 672,813	$ 345	$ 646,945	$ 280,960	$ (255,437)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	466,979			466,979
Actuarially Determined Long-Term Liability Adjustments, (Net of Tax)	105,396				105,396
Investments in Available-for-Sale Securities (Net of Tax)	0
Interest Rate Hedge, Net of Tax	401				401
Comprehensive Income	572,776			466,979	105,797
Issuance of Common Stock	0	4	(4)
Repurchases of Common Stock	(7,988)	(2)	(2,333)	(5,653)
Employee Stock-Based Compensation	7,890		7,890
Shares Withheld for Taxes	(6,261)		(6,261)
Dividends on Common Shares	(71,486)			(71,486)
Dividend Equivalents Earned on Stock-Based Compensation Awards	(1,918)
Dividend Equivalents Earned on Stock-Based Compensation Awards				(1,918)
Ending balance at Dec. 31, 2022	1,165,826	347	646,237	668,882	(149,640)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	655,892			655,892	0
Actuarially Determined Long-Term Liability Adjustments, (Net of Tax)	500				500
Investments in Available-for-Sale Securities (Net of Tax)	80				80
Interest Rate Hedge, Net of Tax	0
Comprehensive Income	656,472			655,892	580
Issuance of Common Stock	0	4	(4)
Repurchases of Common Stock	(395,392)	(52)	(95,587)	(299,753)
Excise Tax on Repurchases of Common Stock	(3,729)			(3,729)
Employee Stock-Based Compensation	10,046		10,046
Shares Withheld for Taxes	(12,831)		(12,831)
Dividends on Common Shares	(75,474)			(75,474)
Dividend Equivalents Earned on Stock-Based Compensation Awards	(1,476)			(1,476)
Ending balance at Dec. 31, 2023	1,343,442	299	547,861	944,342	(149,060)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	286,405			286,405
Actuarially Determined Long-Term Liability Adjustments, (Net of Tax)	14,528				14,528
Investments in Available-for-Sale Securities (Net of Tax)	(41)				(41)
Interest Rate Hedge, Net of Tax	0
Comprehensive Income	300,892	0	0	286,405	14,487
Issuance of Common Stock	0	2	(2)
Repurchases of Common Stock	(66,878)	(7)	(13,671)	(53,200)
Excise Tax on Repurchases of Common Stock	(537)			(537)
Employee Stock-Based Compensation	11,366		11,350	16
Shares Withheld for Taxes	(5,126)		(5,126)
Dividends on Common Shares	(14,697)			(14,697)
Dividend Equivalents Earned on Stock-Based Compensation Awards	(215)			(215)
Ending balance at Dec. 31, 2024	$ 1,568,247	$ 294	$ 540,412	$ 1,162,114	$ (134,573)