Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019
Statement of Comprehensive Income [Abstract]
Net earnings		$ (1,433,111)	$ 117,881	$ 112,604
Other comprehensive income (loss), net of tax:
Unrealized net holding gains (losses) on securities available-for-sale arising during the period		17,183	(24,547)	62,639
Income tax (expense) benefit related to unrealized holding gains (losses) arising during the period		(4,794)	7,446	(17,758)
Unrealized net holding gains (losses) on securities available-for-sale, net of tax		12,389	(17,101)	44,881
Reclassification adjustment for net (gains) losses included in net earnings	[1]	(182)	(184)	(2,161)
Income tax expense (benefit) related to reclassification adjustment		51	56	613
Reclassification adjustment for net (gains) losses included in net earnings, net of tax		(131)	(128)	(1,548)
Other comprehensive income (loss), net of tax		12,258	(17,229)	43,333
Comprehensive income (loss)		$ (1,420,853)	$ 100,652	$ 155,937

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