Unaudited Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Statement of Comprehensive Income [Abstract]
Net income	$ 75,619	$ 77,757	$ 234,048	$ 184,540
Available-For-Sale and Transferred Securities:
Unrealized (losses) gains on available-for-sale securities	(15,259)	1,693	(84,929)	123,262
Reclassification adjustment for gains included in net income	(498)	(24)	(870)	(1,014)
Reclassification adjustment for securities transferred from available-for-sale to held-to-maturity	(1,379)	0	(2,237)	0
Tax effect	4,330	(424)	22,246	(30,979)
Net of tax amount	(12,806)	1,245	(65,790)	91,269
Cash Flow Hedge:
Unrealized gains (losses) on derivatives used for cash flow hedges	30	(76)	479	(532)
Tax effect	(7)	20	(120)	135
Net of tax amount	23	(56)	359	(397)
Total other comprehensive (loss) income, net of tax	(12,783)	1,189	(65,431)	90,872
Total Comprehensive Income	$ 62,836	$ 78,946	$ 168,617	$ 275,412