Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Common stock	Paid-in Capital	Accumulated Other Comprehensive Earnings (Loss)	Retained Earnings Cumulative Effect, Period of Adoption, Adjustment	Retained Earnings	Deferred Compensation	Treasury Stock at Cost	Cumulative Effect, Period of Adoption, Adjustment	Total
Shareholders' Equity Attributable to Parent, Beginning Balance at Dec. 31, 2020	$ 681	$ 335,365	$ 108,714		$ 1,084,217	$ 8,292	$ (401,291)		$ 1,135,978
Shares, Outstanding, Beginning Balance at Dec. 31, 2020	45,142,580
Increase Decrease In Shareholders Equity Roll Forward
Net Income (Loss)					279,354				279,354
Other comprehensive earnings (loss), net of tax			(58,888)						(58,888)
Deferred compensation						1,350	(1,350)
Share-based compensation	$ 1	8,377							8,378
Share-based compensation (in shares)	146,757
Dividends and dividend equivalents					(135,461)				(135,461)
Shareholders' Equity Attributable to Parent, Ending Balance at Dec. 31, 2021	$ 682	343,742	49,826		1,228,110	9,642	(402,641)		1,229,361
Shares, Outstanding, Ending Balance at Dec. 31, 2021	45,289,337
Increase Decrease In Shareholders Equity Roll Forward
Net Income (Loss)					583,411				583,411
Other comprehensive earnings (loss), net of tax			(278,902)						(278,902)
Deferred compensation						2,373	(2,373)
Share-based compensation	$ 2	8,649							8,651
Share-based compensation (in shares)	180,415
Dividends and dividend equivalents					(365,180)				(365,180)
Shareholders' Equity Attributable to Parent, Ending Balance at Dec. 31, 2022	$ 684	352,391	(229,076)	$ (951)	1,446,341	12,015	(405,014)	$ (951)	1,177,341
Shares, Outstanding, Ending Balance at Dec. 31, 2022	45,469,752
Increase Decrease In Shareholders Equity Roll Forward
Net Income (Loss)					304,611				304,611
Other comprehensive earnings (loss), net of tax			62,773						62,773
Deferred compensation						1,524	(1,524)
Share-based compensation	$ 2	9,954							9,956
Share-based compensation (in shares)	170,295
Dividends and dividend equivalents					(140,216)				(140,216)
Shareholders' Equity Attributable to Parent, Ending Balance at Dec. 31, 2023	$ 686	$ 362,345	$ (166,303)		$ 1,609,785	$ 13,539	$ (406,538)		$ 1,413,514
Shares, Outstanding, Ending Balance at Dec. 31, 2023	45,640,047