Consolidated Statement of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Retained Earnings [Member]	Treasury stock, common	Total
Beginning Balance at Dec. 31, 2020	$ 533	$ 282,467		$ 1,594,708	$ (303,379)	$ 1,574,329
Beginning Balance, shares at Dec. 31, 2020	53,277
Beginning Balance, treasury shares at Dec. 31, 2020					6,628
Comprehensive income			$ (120)	78,112		77,992
Common stock purchased for treasury		(7,000)			$ (56,348)	(63,348)
Common stock acquired, shares					567
Share-based compensation	$ 1	3,018			$ (5,994)	(2,975)
Share-based compensation, shares	180				56
Exercise of stock options	$ 2	2,678				2,680
Exercise of stock options, shares	176
Ending Balance at Mar. 31, 2021	$ 536	281,163	(120)	1,672,820	$ (365,721)	1,588,678
Ending Balance, shares at Mar. 31, 2021	53,633
Ending Balance, treasury shares at Mar. 31, 2021					7,251
Beginning Balance at Dec. 31, 2020	$ 533	282,467		1,594,708	$ (303,379)	1,574,329
Beginning Balance, shares at Dec. 31, 2020	53,277
Beginning Balance, treasury shares at Dec. 31, 2020					6,628
Comprehensive income						175,231
Ending Balance at Sep. 30, 2021	$ 536	293,859		1,769,939	$ (663,558)	1,400,776
Ending Balance, shares at Sep. 30, 2021	53,637
Ending Balance, treasury shares at Sep. 30, 2021					10,583
Beginning Balance at Mar. 31, 2021	$ 536	281,163	(120)	1,672,820	$ (365,721)	1,588,678
Beginning Balance, shares at Mar. 31, 2021	53,633
Beginning Balance, treasury shares at Mar. 31, 2021					7,251
Comprehensive income			(65)	49,461		49,396
Common stock purchased for treasury		(3,000)			$ (95,331)	(98,331)
Common stock acquired, shares					982
Restricted shares forfeited, shares					8
Share-based compensation		2,940				2,940
Share-based compensation, shares	4
Ending Balance at Jun. 30, 2021	$ 536	281,103	(185)	1,722,281	$ (461,052)	1,542,683
Ending Balance, shares at Jun. 30, 2021	53,637
Ending Balance, treasury shares at Jun. 30, 2021					8,241
Comprehensive income			185	47,658		47,843
Common stock purchased for treasury		10,000			$ (202,506)	(192,506)
Common stock acquired, shares					2,324
Restricted shares forfeited, shares					18
Share-based compensation		2,756				2,756
Ending Balance at Sep. 30, 2021	$ 536	293,859		1,769,939	$ (663,558)	1,400,776
Ending Balance, shares at Sep. 30, 2021	53,637
Ending Balance, treasury shares at Sep. 30, 2021					10,583
Beginning Balance at Dec. 31, 2021	$ 536	296,670		1,855,052	$ (1,107,211)	$ 1,045,047
Beginning Balance, shares at Dec. 31, 2021	53,637
Beginning Balance, treasury shares at Dec. 31, 2021					15,915	15,915
Comprehensive income			(323)	58,078		$ 57,755
Common stock purchased for treasury					$ (394,930)	(394,930)
Common stock acquired, shares					4,575
Restricted shares forfeited, shares					6
Share-based compensation	$ 2	3,188			$ (4,625)	(1,435)
Share-based compensation, shares	189				52
Ending Balance at Mar. 31, 2022	$ 538	299,858	(323)	1,913,130	$ (1,506,766)	706,437
Ending Balance, shares at Mar. 31, 2022	53,826
Ending Balance, treasury shares at Mar. 31, 2022					20,548
Beginning Balance at Dec. 31, 2021	$ 536	296,670		1,855,052	$ (1,107,211)	$ 1,045,047
Beginning Balance, shares at Dec. 31, 2021	53,637
Beginning Balance, treasury shares at Dec. 31, 2021					15,915	15,915
Comprehensive income						$ 113,231
Ending Balance at Sep. 30, 2022	$ 538	306,152	(417)	1,968,700	$ (1,683,417)	$ 591,556
Ending Balance, shares at Sep. 30, 2022	53,830
Ending Balance, treasury shares at Sep. 30, 2022					22,453	22,453
Beginning Balance at Mar. 31, 2022	$ 538	299,858	(323)	1,913,130	$ (1,506,766)	$ 706,437
Beginning Balance, shares at Mar. 31, 2022	53,826
Beginning Balance, treasury shares at Mar. 31, 2022					20,548
Comprehensive income			(75)	25,562		25,487
Common stock purchased for treasury					$ (128,457)	(128,457)
Common stock acquired, shares					1,319
Share-based compensation		3,171				3,171
Share-based compensation, shares	4
Ending Balance at Jun. 30, 2022	$ 538	303,029	(398)	1,938,692	$ (1,635,223)	606,638
Ending Balance, shares at Jun. 30, 2022	53,830
Ending Balance, treasury shares at Jun. 30, 2022					21,867
Comprehensive income			(19)	30,008		29,989
Common stock purchased for treasury					$ (48,194)	(48,194)
Common stock acquired, shares					582
Restricted shares forfeited, shares					4
Share-based compensation		3,123				3,123
Ending Balance at Sep. 30, 2022	$ 538	$ 306,152	$ (417)	$ 1,968,700	$ (1,683,417)	$ 591,556
Ending Balance, shares at Sep. 30, 2022	53,830
Ending Balance, treasury shares at Sep. 30, 2022					22,453	22,453