Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Net Income	$ 107,898	$ 199,738	$ 157,870
Unrealized holding gains (losses):
Before tax	44,344	61,818	(16,294)
Tax effect	(12,231)	(17,218)	4,342
Net of tax	32,113	44,600	(11,952)
Reclassification of net gains included in net income:
Before tax	13,323	0	0
Tax effect	(3,730)	0	0
Net of tax	9,593	0	0
Net unrealized holding gains (losses)	22,520	44,600	(11,952)
Unrealized holding gains:
Before tax	44,774	4,670	2,786
Tax effect	(12,481)	(1,301)	(789)
Net of tax	32,293	3,369	1,997
Reclassification of net losses included in net income:
Before tax	(31,852)	0	0
Tax effect	8,919	0	0
Net of tax	(22,933)	0	0
Net unrealized holding gains	9,360	3,369	1,997
Net unrealized holding (losses) gains:
Before tax	(4,837)	3,624	(3,850)
Tax effect	1,290	(1,035)	1,018
Net of tax	(3,547)	2,589	(2,832)
Total other comprehensive income (loss)	28,333	50,558	(12,787)
Total comprehensive income	$ 136,231	$ 250,296	$ 145,083