Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Accumulated Other Comprehensive Income
Balance, beginning			$ 1,989	$ 17,744
Other comprehensive income before reclassification			11,411	(12,105)
Amounts reclassified from accumulated other comprehensive income			3,438	2,368
Net current period other comprehensive income	$ (3,575)	$ 2,567	14,849	(9,737)
Balance, end	16,838	8,007	16,838	8,007
Available-For-Sale Securities
Accumulated Other Comprehensive Income
Balance, beginning			13,935	27,945
Other comprehensive income before reclassification			18,755	(5,524)
Amounts reclassified from accumulated other comprehensive income			399	58
Net current period other comprehensive income			19,154	(5,466)
Balance, end	33,089	22,479	33,089	22,479
Derivatives Used for Cash Flow Hedges
Accumulated Other Comprehensive Income
Balance, beginning			(11,946)	(10,201)
Other comprehensive income before reclassification			(7,344)	(6,581)
Amounts reclassified from accumulated other comprehensive income			3,039	2,310
Net current period other comprehensive income			(4,305)	(4,271)
Balance, end	$ (16,251)	$ (14,472)	$ (16,251)	$ (14,472)