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, 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
Balance at Dec. 31, 2022	36,796	1,149,899	2,197,918	(2,588,145)	2,247	798,715
Net income			182,456			182,456
Dividends paid			(17,446)			(17,446)
Stock awards and exercise of stock options	217	104,457		(21,386)		83,288
Purchases of treasury stock				(27,769)		(27,769)
Other				198	(199)	(1)
Balance at Sep. 30, 2023	37,013	1,254,356	2,362,928	(2,637,102)	2,048	1,019,243
Balance at Jun. 30, 2023	36,996	1,240,415	2,294,004	(2,621,657)	2,321	952,079
Net income			74,958			74,958
Dividends paid			(6,034)			(6,034)
Stock awards and exercise of stock options	17	14,462		(1,372)		13,107
Purchases of treasury stock				(14,344)		(14,344)
Other		(521)		271	(273)	(523)
Balance at Sep. 30, 2023	$ 37,013	$ 1,254,356	$ 2,362,928	$ (2,637,102)	$ 2,048	$ 1,019,243