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	$ 27,623	$ 54,545	$ 66,293	$ 147,617
Unrealized holding (losses) gains:
Before tax	(4,142)	13,636	54,683	78,625
Tax effect	1,138	(3,800)	(15,214)	(21,900)
Net of tax	(3,004)	9,836	39,469	56,725
Reclassification of net gains included in net income:
Before tax	14,328	0	13,323	0
Tax effect	(4,012)	0	(3,730)	0
Net of tax	10,316	0	9,593	0
Net unrealized holding (losses) gains	(13,320)	9,836	29,876	56,725
Unrealized holding gains (losses):
Before tax	28,614	(399)	11,274	3,500
Tax effect	(7,987)	111	(3,162)	(975)
Net of tax	20,627	(288)	8,112	2,525
Reclassification of net losses included in net income:
Before tax	(14,285)	0	(14,285)	0
Tax effect	4,000	0	4,000	0
Net of tax	(10,285)	0	(10,285)	0
Net unrealized holding gains (losses)	10,342	(288)	(2,173)	2,525
Total other comprehensive (loss) income	(2,978)	9,548	27,703	59,250
Total comprehensive income	$ 24,645	$ 64,093	$ 93,996	$ 206,867