Condensed 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
Stockholders' Equity Attributable to Parent, Beginning Balance at Dec. 31, 2021	$ 682	$ 343,742	$ 49,826		$ 1,228,110	$ 9,642	$ (402,641)		$ 1,229,361
Shares, Outstanding, Beginning Balance at Dec. 31, 2021	45,289,337
Increase Decrease In Stockholders Equity Roll Forward
Net Income (Loss)					47,923				47,923
Other comprehensive earnings (loss), net of tax			(115,581)						(115,581)
Deferred compensation						(973)	973
Share-based compensation		3,049							3,049
Share-based compensation (in shares)	26,605
Dividends and dividend equivalents					(11,330)				(11,330)
Stockholders' Equity Attributable to Parent, Ending Balance at Mar. 31, 2022	$ 682	346,791	(65,755)		1,264,703	8,669	(401,668)		1,153,422
Shares, Outstanding, Ending Balance at Mar. 31, 2022	45,315,942
Stockholders' Equity Attributable to Parent, Beginning Balance at Dec. 31, 2021	$ 682	343,742	49,826		1,228,110	9,642	(402,641)		1,229,361
Shares, Outstanding, Beginning Balance at Dec. 31, 2021	45,289,337
Increase Decrease In Stockholders Equity Roll Forward
Net Income (Loss)									485,577
Other comprehensive earnings (loss), net of tax									(294,392)
Stockholders' Equity Attributable to Parent, Ending Balance at Sep. 30, 2022	$ 683	352,129	(244,566)		1,678,746	9,047	(402,046)		1,393,993
Shares, Outstanding, Ending Balance at Sep. 30, 2022	45,378,171
Stockholders' Equity Attributable to Parent, Beginning Balance at Mar. 31, 2022	$ 682	346,791	(65,755)		1,264,703	8,669	(401,668)		1,153,422
Shares, Outstanding, Beginning Balance at Mar. 31, 2022	45,315,942
Increase Decrease In Stockholders Equity Roll Forward
Net Income (Loss)					(2,239)				(2,239)
Other comprehensive earnings (loss), net of tax			(97,563)						(97,563)
Deferred compensation						276	(276)
Share-based compensation	$ 1	2,370							2,371
Share-based compensation (in shares)	52,862
Dividends and dividend equivalents					(11,803)				(11,803)
Stockholders' Equity Attributable to Parent, Ending Balance at Jun. 30, 2022	$ 683	349,161	(163,318)		1,250,661	8,945	(401,944)		1,044,188
Shares, Outstanding, Ending Balance at Jun. 30, 2022	45,368,804
Increase Decrease In Stockholders Equity Roll Forward
Net Income (Loss)					439,893				439,893
Other comprehensive earnings (loss), net of tax			(81,248)						(81,248)
Deferred compensation						102	(102)
Share-based compensation		2,968							2,968
Share-based compensation (in shares)	9,367
Dividends and dividend equivalents					(11,808)				(11,808)
Stockholders' Equity Attributable to Parent, Ending Balance at Sep. 30, 2022	$ 683	352,129	(244,566)		1,678,746	9,047	(402,046)		1,393,993
Shares, Outstanding, Ending Balance at Sep. 30, 2022	45,378,171
Stockholders' Equity Attributable to Parent, Beginning Balance at Dec. 31, 2022	$ 684	352,391	(229,076)	$ (951)	1,446,341	12,015	(405,014)	$ (951)	1,177,341
Shares, Outstanding, Beginning Balance at Dec. 31, 2022	45,469,752
Increase Decrease In Stockholders Equity Roll Forward
Net Income (Loss)					98,811				98,811
Other comprehensive earnings (loss), net of tax			37,707						37,707
Deferred compensation						249	(249)
Share-based compensation	$ 1	2,863							2,864
Share-based compensation (in shares)	84,944
Dividends and dividend equivalents					(11,851)				(11,851)
Stockholders' Equity Attributable to Parent, Ending Balance at Mar. 31, 2023	$ 685	355,254	(191,369)		1,532,350	12,264	(405,263)		1,303,921
Shares, Outstanding, Ending Balance at Mar. 31, 2023	45,554,696
Stockholders' Equity Attributable to Parent, Beginning Balance at Dec. 31, 2022	$ 684	352,391	(229,076)	$ (951)	1,446,341	12,015	(405,014)	$ (951)	1,177,341
Shares, Outstanding, Beginning Balance at Dec. 31, 2022	45,469,752
Increase Decrease In Stockholders Equity Roll Forward
Net Income (Loss)									189,999
Other comprehensive earnings (loss), net of tax									(38,848)
Stockholders' Equity Attributable to Parent, Ending Balance at Sep. 30, 2023	$ 686	360,453	(267,924)		1,598,875	12,617	(405,616)		1,299,091
Shares, Outstanding, Ending Balance at Sep. 30, 2023	45,625,771
Stockholders' Equity Attributable to Parent, Beginning Balance at Mar. 31, 2023	$ 685	355,254	(191,369)		1,532,350	12,264	(405,263)		1,303,921
Shares, Outstanding, Beginning Balance at Mar. 31, 2023	45,554,696
Increase Decrease In Stockholders Equity Roll Forward
Net Income (Loss)					77,652				77,652
Other comprehensive earnings (loss), net of tax			(19,721)						(19,721)
Deferred compensation						243	(243)
Share-based compensation		2,402							2,402
Share-based compensation (in shares)	41,500
Dividends and dividend equivalents					(12,342)				(12,342)
Stockholders' Equity Attributable to Parent, Ending Balance at Jun. 30, 2023	$ 685	357,656	(211,090)		1,597,660	12,507	(405,506)		1,351,912
Shares, Outstanding, Ending Balance at Jun. 30, 2023	45,596,196
Increase Decrease In Stockholders Equity Roll Forward
Net Income (Loss)					13,536				13,536
Other comprehensive earnings (loss), net of tax			(56,834)						(56,834)
Deferred compensation						110	(110)
Share-based compensation	$ 1	2,797							2,798
Share-based compensation (in shares)	29,575
Dividends and dividend equivalents					(12,321)				(12,321)
Stockholders' Equity Attributable to Parent, Ending Balance at Sep. 30, 2023	$ 686	$ 360,453	$ (267,924)		$ 1,598,875	$ 12,617	$ (405,616)		$ 1,299,091
Shares, Outstanding, Ending Balance at Sep. 30, 2023	45,625,771