Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statement of Comprehensive Income [Abstract]
Net income	$ 65,898	$ 81,826	$ 201,936	$ 185,445
OTHER COMPREHENSIVE (LOSS) INCOME
Unrealized holding gains arising during the period on available-for-sale securities	4,975	18,736	82,703	79,547
Unrealized holding gain on the transfer of held-to-maturity securities to available-for-sale per ASU 2017-12	0	0	0	2,547
Less: Reclassification adjustment for realized gains included in net income	22,305	7,374	54,790	12,937
Other comprehensive (loss) income, before tax effect	(17,330)	11,362	27,913	69,157
Less: Tax effect of other comprehensive (loss) income	(4,529)	2,969	7,295	18,074
TOTAL OTHER COMPREHENSIVE (LOSS) INCOME	(12,801)	8,393	20,618	51,083
COMPREHENSIVE INCOME	$ 53,097	$ 90,219	$ 222,554	$ 236,528