Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Accumulated Other Comprehensive Income
Balance, beginning			$ 17,744	$ 9,645
Other comprehensive income before reclassification			(13,868)	14,487
Amounts reclassified from accumulated other comprehensive income			1,564	74
Net current period other comprehensive income	$ (12,587)	$ 8,918	(12,304)	14,561
Balance, end	5,440	24,206	5,440	24,206
Available-For-Sale Securities
Accumulated Other Comprehensive Income
Balance, beginning			27,945	8,485
Other comprehensive income before reclassification			(12,574)	21,628
Amounts reclassified from accumulated other comprehensive income			28	74
Net current period other comprehensive income			(12,546)	21,702
Balance, end	15,399	30,187	15,399	30,187
Derivatives Used for Cash Flow Hedges
Accumulated Other Comprehensive Income
Balance, beginning			(10,201)	1,160
Other comprehensive income before reclassification			(1,294)	(7,141)
Amounts reclassified from accumulated other comprehensive income			1,536	0
Net current period other comprehensive income			242	(7,141)
Balance, end	$ (9,959)	$ (5,981)	$ (9,959)	$ (5,981)