Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020
Statement of Comprehensive Income [Abstract]
Net earnings		$ 150,406	$ 116,830	$ (1,433,111)
Other comprehensive income (loss), net of tax:
Unrealized net holding gains (losses) on securities available-for-sale arising during the period		(91,523)	22,988	17,183
Income tax (expense) benefit related to unrealized holding gains (losses) arising during the period		25,454	(5,936)	(4,794)
Unrealized net holding gains (losses) on securities available-for-sale, net of tax		(66,069)	17,052	12,389
Reclassification adjustment for net (gains) losses included in net earnings	[1]	(101)	(4)	(182)
Income tax expense (benefit) related to reclassification adjustment		28	1	51
Reclassification adjustment for net (gains) losses included in net earnings, net of tax		(73)	(3)	(131)
Other comprehensive (loss) income, net of tax		(66,142)	17,049	12,258
Comprehensive income (loss)		$ 84,264	$ 133,879	$ (1,420,853)

[1] Entire amounts are recognized in "Gain on sale of securities" on the Condensed Consolidated Statements of Earnings (Loss).