CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income:	$ 400,881	$ 359,440	$ 173,979
Other comprehensive income (loss), net of tax:
Changes in fair value on available-for-sale securities, net of tax	81,658	(51,464)	3,036
Changes in fair value of cash flow hedges, net of tax	(5,179)	2,660	2,487
Amortization of net unrealized gains on securities transferred from available-for-sale to held-to-maturity, net of tax	184	(73)	(208)
Gain on cash flow hedges reclassified from other comprehensive income into net income, net of tax	1,588	(657)	(347)
Net loss on sale of investment securities reclassified from other comprehensive income into net income, net of tax	(4,388)	(1,665)	(5,022)
Total other comprehensive income (loss), net of tax	82,639	(47,869)	9,990
Total comprehensive income	$ 483,520	$ 311,571	$ 183,969