Consolidated Statements of Comprehensive Income - Unaudited - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 23,663	$ 23,722	$ 47,804	$ 49,469
Unrealized (losses) gains on available-for-sale debt securities:
Unrealized (losses) gains arising during the period	(12,190)	19,885	(46,288)	18,762
Income tax effect	3,170	(7,755)	12,035	(7,317)
Reclassification adjustments for gains on securities included in net income	0	(3,183)	0	(3,183)
Income tax effect	0	(1,241)	0	(1,241)
Net unrealized (losses) gains on available-for-sale debt securities	(9,020)	10,188	(34,253)	9,503
Unrealized gains on cash flow hedges:
Unrealized gains (losses) arising during the period	1,895	(689)	2,768	(360)
Income tax effect	(492)	269	(719)	141
Reclassification adjustment for (gains) losses included in net income	(259)	767	(128)	1,594
Income tax effect	67	(299)	33	(622)
Net unrealized gains on cash flow hedges	1,211	48	1,954	753
Other comprehensive (loss) income, net of income tax effect	(7,809)	10,236	(32,299)	10,256
Comprehensive income	$ 15,854	$ 33,958	$ 15,505	$ 59,725