Unaudited Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 49,132	$ 38,559
Other Comprehensive Income (Loss), Net of Tax
Unrealized gains (losses) on available-for-sale securities	46,452	(25,711)
Reclassification adjustment for (gains) losses included in net income	(221)	282
Net unrealized gains (losses) on available-for-sale securities	46,231	(25,429)
Tax effect	(11,715)	6,444
Net of tax amount	34,516	(18,985)
Unrealized (losses) gains on derivatives used for cash flow hedges	(1,834)	4,379
Reclassification adjustment for losses included in net income	223	900
Net unrealized (losses) gains on derivatives used for cash flow hedges	(1,611)	5,279
Tax effect	409	(1,338)
Net of tax amount	(1,202)	3,941
Total other comprehensive income (loss), net of tax	33,314	(15,044)
Total Comprehensive Income	$ 82,446	$ 23,515