Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net Income	$ 181,878	$ 116,377	$ 121,131
Other Comprehensive (Loss) Income, Net of Tax
Unrealized (losses) gains on available-for-sale securities	(15,608)	3,428	(21,407)
Reclassification adjustment for losses included in net income	12	636	1,335
Net unrealized (losses) gains on available-for-sale securities	(15,596)	4,064	(20,072)
Tax effect	3,952	(1,563)	7,776
Net of tax amount	(11,644)	2,501	(12,296)
Unrealized gains (losses) on derivatives used for cash flow hedges	3,286	444	(1,643)
Reclassification adjustment for losses included in net income	2,334	4,892	6,417
Net unrealized gains on derivatives used for cash flow hedges	5,620	5,336	4,774
Tax effect	(1,424)	(2,083)	(1,849)
Net of tax amount	4,196	3,253	2,925
Total other comprehensive (loss) income, net of tax	(7,448)	5,754	(9,371)
Total Comprehensive Income	$ 174,430	$ 122,131	$ 111,760