Consolidated Statements of Comprehensive Earnings - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Statement Of Income And Comprehensive Income [Abstract]
NET EARNINGS	$ 227,562	$ 202,034	$ 164,812
OTHER ITEMS OF COMPREHENSIVE EARNINGS (LOSS):
Change in unrealized gain on investment securities available-for-sale, before income taxes	(89,238)	133,872	80,906
Reclassification adjustment for realized gains on investment securities included in net earnings, before income taxes	(815)	(3,633)	(733)
Minimum liability pension adjustment, before income taxes			1,676
Total other items of comprehensive earnings (losses)	(90,053)	130,239	81,849
Income tax benefit (expense) related to:
Change in unrealized gain on investment securities available-for-sale	18,740	(28,113)	(16,990)
Reclassification adjustment for realized gains on investment securities included in net earnings	171	763	154
Minimum liability pension adjustment			(352)
Total income tax benefit (expense)	18,911	(27,350)	(17,188)
COMPREHENSIVE EARNINGS	$ 118,598	$ 304,923	$ 229,473