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			130,625			130,625
Dividends paid			(10,722)			(10,722)
Stock awards and exercise of stock options	137	44,877		(25,926)		19,088
Purchases of treasury stock				(77,214)		(77,214)
Other		(89)		(72)	71	(90)
Balance at Jun. 30, 2022	36,651	1,089,129	2,090,214	(2,533,306)	2,272	684,960
Balance at Mar. 31, 2022	36,579	1,064,448	2,029,158	(2,465,716)	2,236	666,705
Net income			66,456			66,456
Dividends paid			(5,400)			(5,400)
Stock awards and exercise of stock options	72	25,274		(17,693)		7,653
Purchases of treasury stock				(49,861)		(49,861)
Other		(593)		(36)	36	(593)
Balance at Jun. 30, 2022	36,651	1,089,129	2,090,214	(2,533,306)	2,272	684,960
Balance at Dec. 31, 2022	36,796	1,149,899	2,197,918	(2,588,145)	2,247	798,715
Net income			107,498			107,498
Dividends paid			(11,412)			(11,412)
Stock awards and exercise of stock options	200	89,995		(20,014)		70,181
Purchases of treasury stock				(13,425)		(13,425)
Other		521		(73)	74	522
Balance at Jun. 30, 2023	36,996	1,240,415	2,294,004	(2,621,657)	2,321	952,079
Balance at Mar. 31, 2023	36,884	1,186,119	2,246,354	(2,591,588)	2,284	880,053
Net income			53,377			53,377
Dividends paid			(5,727)			(5,727)
Stock awards and exercise of stock options	112	53,657		(16,608)		37,161
Purchases of treasury stock				(13,425)		(13,425)
Other		639		(36)	37	640
Balance at Jun. 30, 2023	$ 36,996	$ 1,240,415	$ 2,294,004	$ (2,621,657)	$ 2,321	$ 952,079