Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Common Stock [Member]	Treasury Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Retained Earnings [Member]	Total
Beginning Balance at Dec. 31, 2020	$ 533	$ (303,379)	$ 282,467		$ 1,594,708	$ 1,574,329
Beginning Balance, shares at Dec. 31, 2020	53,277	6,628
Comprehensive income				$ (120)	78,112	77,992
Common stock purchased for treasury		$ (56,348)	(7,000)			(63,348)
Common stock acquired, shares		567
Share-based compensation	$ 1	$ (5,994)	3,018			(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	$ (365,721)	281,163	(120)	1,672,820	1,588,678
Ending Balance, shares at Mar. 31, 2021	53,633	7,251
Beginning Balance at Dec. 31, 2020	$ 533	$ (303,379)	282,467		1,594,708	1,574,329
Beginning Balance, shares at Dec. 31, 2020	53,277	6,628
Comprehensive income						127,388
Ending Balance at Jun. 30, 2021	$ 536	$ (461,052)	281,103	(185)	1,722,281	1,542,683
Ending Balance, shares at Jun. 30, 2021	53,637	8,241
Beginning Balance at Mar. 31, 2021	$ 536	$ (365,721)	281,163	(120)	1,672,820	1,588,678
Beginning Balance, shares at Mar. 31, 2021	53,633	7,251
Comprehensive income				(65)	49,461	49,396
Common stock purchased for treasury		$ (95,331)	(3,000)			(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	$ (461,052)	281,103	(185)	1,722,281	1,542,683
Ending Balance, shares at Jun. 30, 2021	53,637	8,241
Beginning Balance at Dec. 31, 2021	$ 536	$ (1,107,211)	296,670		1,855,052	1,045,047
Beginning Balance, shares at Dec. 31, 2021	53,637	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	$ (4,625)	3,188			(1,435)
Share-based compensation, shares	189	52
Ending Balance at Mar. 31, 2022	$ 538	$ (1,506,766)	299,858	(323)	1,913,130	706,437
Ending Balance, shares at Mar. 31, 2022	53,826	20,548
Beginning Balance at Dec. 31, 2021	$ 536	$ (1,107,211)	296,670		1,855,052	1,045,047
Beginning Balance, shares at Dec. 31, 2021	53,637	15,915
Comprehensive income						83,242
Ending Balance at Jun. 30, 2022	$ 538	$ (1,635,223)	303,029	(398)	1,938,692	606,638
Ending Balance, shares at Jun. 30, 2022	53,830	21,867
Beginning Balance at Mar. 31, 2022	$ 538	$ (1,506,766)	299,858	(323)	1,913,130	706,437
Beginning Balance, shares at Mar. 31, 2022	53,826	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	$ (1,635,223)	$ 303,029	$ (398)	$ 1,938,692	$ 606,638
Ending Balance, shares at Jun. 30, 2022	53,830	21,867