Condensed Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Common stock	Paid-in Capital	Accumulated Other Comprehensive Earnings (Loss)	Accumulated Other Comprehensive Earnings (Loss) Cumulative Effect, Period of Adoption, Adjustment	Retained Earnings	Retained Earnings Cumulative Effect, Period of Adoption, Adjustment	Deferred Compensation	Treasury Stock at Cost
Stockholders' Equity Attributable to Parent, Beginning Balance at Dec. 31, 2019	$ 995,388	$ 1,095	$ 678	$ 321,190	$ 52,473	$ 22	$ 1,014,046	$ 1,073	$ 7,980	$ (400,979)
Shares, Outstanding, Beginning Balance at Dec. 31, 2019			44,869,015
Accounting Standards Update [Extensible List]	ASU 2016-13
Increase Decrease In Stockholders Equity Roll Forward
Net earnings	$ (61,267)						(61,267)
Other comprehensive earnings (loss), net of tax	(13,031)				(13,031)
Deferred compensation									(1,010)	1,010
Share-based compensation	3,863		$ 1	3,862
Share-based compensation (in shares)			53,641
Dividends and dividend equivalents	(10,343)						(10,343)
Stockholders' Equity Attributable to Parent, Ending Balance at Mar. 31, 2020	915,705		$ 679	325,052	39,464		943,509		6,970	(399,969)
Shares, Outstanding, Ending Balance at Mar. 31, 2020			44,922,656
Stockholders' Equity Attributable to Parent, Beginning Balance at Dec. 31, 2019	995,388	$ 1,095	$ 678	321,190	52,473	$ 22	1,014,046	$ 1,073	7,980	(400,979)
Shares, Outstanding, Beginning Balance at Dec. 31, 2019			44,869,015
Increase Decrease In Stockholders Equity Roll Forward
Net earnings	30,899
Other comprehensive earnings (loss), net of tax	40,540
Stockholders' Equity Attributable to Parent, Ending Balance at Jun. 30, 2020	1,051,458		$ 679	325,862	93,035		1,024,881		7,600	(400,599)
Shares, Outstanding, Ending Balance at Jun. 30, 2020			44,952,602
Stockholders' Equity Attributable to Parent, Beginning Balance at Mar. 31, 2020	915,705		$ 679	325,052	39,464		943,509		6,970	(399,969)
Shares, Outstanding, Beginning Balance at Mar. 31, 2020			44,922,656
Increase Decrease In Stockholders Equity Roll Forward
Net earnings	92,166						92,166
Other comprehensive earnings (loss), net of tax	53,571				53,571
Deferred compensation									630	(630)
Share-based compensation	810			810
Share-based compensation (in shares)			29,946
Dividends and dividend equivalents	(10,794)						(10,794)
Stockholders' Equity Attributable to Parent, Ending Balance at Jun. 30, 2020	1,051,458		$ 679	325,862	93,035		1,024,881		7,600	(400,599)
Shares, Outstanding, Ending Balance at Jun. 30, 2020			44,952,602
Stockholders' Equity Attributable to Parent, Beginning Balance at Dec. 31, 2020	1,135,978		$ 681	335,365	108,714		1,084,217		8,292	(401,291)
Shares, Outstanding, Beginning Balance at Dec. 31, 2020			45,142,580
Increase Decrease In Stockholders Equity Roll Forward
Net earnings	73,012						73,012
Other comprehensive earnings (loss), net of tax	(44,747)				(44,747)
Deferred compensation									(366)	366
Share-based compensation	1,392			1,392
Share-based compensation (in shares)			60,858
Dividends and dividend equivalents	(10,849)						(10,849)
Stockholders' Equity Attributable to Parent, Ending Balance at Mar. 31, 2021	1,154,786		$ 681	336,757	63,967		1,146,380		7,926	(400,925)
Shares, Outstanding, Ending Balance at Mar. 31, 2021			45,203,438
Stockholders' Equity Attributable to Parent, Beginning Balance at Dec. 31, 2020	1,135,978		$ 681	335,365	108,714		1,084,217		8,292	(401,291)
Shares, Outstanding, Beginning Balance at Dec. 31, 2020			45,142,580
Increase Decrease In Stockholders Equity Roll Forward
Net earnings	154,827
Other comprehensive earnings (loss), net of tax	(29,570)
Stockholders' Equity Attributable to Parent, Ending Balance at Jun. 30, 2021	1,241,803		$ 682	338,099	79,144		1,216,877		8,251	(401,250)
Shares, Outstanding, Ending Balance at Jun. 30, 2021			45,223,343
Stockholders' Equity Attributable to Parent, Beginning Balance at Mar. 31, 2021	1,154,786		$ 681	336,757	63,967		1,146,380		7,926	(400,925)
Shares, Outstanding, Beginning Balance at Mar. 31, 2021			45,203,438
Increase Decrease In Stockholders Equity Roll Forward
Net earnings	81,815						81,815
Other comprehensive earnings (loss), net of tax	15,177				15,177
Deferred compensation									325	(325)
Share-based compensation	1,343		$ 1	1,342
Share-based compensation (in shares)			19,905
Dividends and dividend equivalents	(11,318)						(11,318)
Stockholders' Equity Attributable to Parent, Ending Balance at Jun. 30, 2021	$ 1,241,803		$ 682	$ 338,099	$ 79,144		$ 1,216,877		$ 8,251	$ (401,250)
Shares, Outstanding, Ending Balance at Jun. 30, 2021			45,223,343