Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Accumulated Other Comprehensive Income (Loss)
Balance, beginning	$ 17,744	$ 9,645	$ 47,962
Other comprehensive income (loss) before reclassification	(18,791)	7,366	(38,500)
Amounts reclassified from accumulated other comprehensive income	3,036	733	183
Net current period other comprehensive income (loss)	(15,755)	8,099	(38,317)
Balance, end	1,989	17,744	9,645
Available-For-Sale Securities
Accumulated Other Comprehensive Income (Loss)
Balance, beginning	27,945	8,485	58,245
Other comprehensive income (loss) before reclassification	(13,968)	19,335	(49,943)
Amounts reclassified from accumulated other comprehensive income	(42)	125	183
Net current period other comprehensive income (loss)	(14,010)	19,460	(49,760)
Balance, end	13,935	27,945	8,485
Derivatives Used for Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss)
Balance, beginning	(10,201)	1,160	(10,283)
Other comprehensive income (loss) before reclassification	(4,823)	(11,969)	11,443
Amounts reclassified from accumulated other comprehensive income	3,078	608	0
Net current period other comprehensive income (loss)	(1,745)	(11,361)	11,443
Balance, end	$ (11,946)	$ (10,201)	$ 1,160