Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Accumulated Other Comprehensive Loss
Balance, beginning	$ (9,427)	$ (1,979)
Other comprehensive income (loss) before reclassification	33,312	(15,927)
Reclassification adjustments for (gains) losses included in net income	2	883
Total other comprehensive income (loss), net of tax	33,314	(15,044)
Balance, end	23,887	(17,023)
Available-For-Sale Debt Securities
Accumulated Other Comprehensive Loss
Balance, beginning	(6,613)	5,031
Other comprehensive income (loss) before reclassification	34,681	(19,196)
Reclassification adjustments for (gains) losses included in net income	(165)	211
Total other comprehensive income (loss), net of tax	34,516	(18,985)
Balance, end	27,903	(13,954)
Derivatives Used for Cash Flow Hedges
Accumulated Other Comprehensive Loss
Balance, beginning	(2,814)	(7,010)
Other comprehensive income (loss) before reclassification	(1,369)	3,269
Reclassification adjustments for (gains) losses included in net income	167	672
Total other comprehensive income (loss), net of tax	(1,202)	3,941
Balance, end	$ (4,016)	$ (3,069)