Consolidated Statements Of Changes In Stockholders Equity - USD ($) $ in Thousands	Capital Stock [Member]	Paid-In Capital [Member]	Retained Earnings [Member]	Treasury Stock-At Cost [Member]	Deferred Compensation Payable In Company Stock [Member]	Total
Balance at Dec. 31, 2020	$ 36,259	$ 961,404	$ 1,723,777	$ (1,822,579)	$ 2,339	$ 901,200
Net income			193,925			193,925
Dividends paid			(16,457)			(16,457)
Stock awards and exercise of stock options	143	45,870		(14,681)		31,332
Purchases of treasury stock				(330,380)		(330,380)
Other		232			(133)	99
Balance at Sep. 30, 2021	36,402	1,007,506	1,901,245	(2,167,640)	2,206	779,719
Balance at Jun. 30, 2021	36,385	999,697	1,834,835	(2,002,326)	2,183	870,774
Net income			72,003			72,003
Dividends paid			(5,593)			(5,593)
Stock awards and exercise of stock options	17	8,233		(1,426)		6,824
Purchases of treasury stock				(163,731)		(163,731)
Other		(424)		(157)	23	(558)
Balance at Sep. 30, 2021	36,402	1,007,506	1,901,245	(2,167,640)	2,206	779,719
Balance at Dec. 31, 2021	36,514	1,044,341	1,970,311	(2,430,094)	2,201	623,273
Net income			187,498			187,498
Dividends paid			(16,391)			(16,391)
Stock awards and exercise of stock options	156	57,172		(27,842)		29,486
Purchases of treasury stock				(101,098)		(101,098)
Other		(1,352)		(107)	107	(1,352)
Balance at Sep. 30, 2022	36,670	1,100,161	2,141,418	(2,559,141)	2,308	721,416
Balance at Jun. 30, 2022	36,651	1,089,129	2,090,214	(2,533,306)	2,272	684,960
Net income			56,873			56,873
Dividends paid			(5,669)			(5,669)
Stock awards and exercise of stock options	19	12,295		(1,916)		10,398
Purchases of treasury stock				(23,884)		(23,884)
Other		(1,263)		(35)	36	(1,262)
Balance at Sep. 30, 2022	$ 36,670	$ 1,100,161	$ 2,141,418	$ (2,559,141)	$ 2,308	$ 721,416