Subsequent Event (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended
	Oct. 31, 2015	Dec. 31, 2015	Sep. 30, 2015	Dec. 31, 2014
Subsequent Event [Line Items]
Amount of new funding from brokered deposits and repurchase agreements			$ 302,941	$ 146,781
Subsequent Event | Brokered Money Market Deposits and Repurchase Agreements
Subsequent Event [Line Items]
Amount of new funding from brokered deposits and repurchase agreements	$ 800,000
Weighted average duration of brokered deposits and repurchase agreements	0.56%
Subsequent Event | Long-term Debt
Subsequent Event [Line Items]
Prepayment of long-term borrowings	$ 795,000
Average cost of prepayment	3.78%
Subsequent Event | Long-term Debt | Forecast
Subsequent Event [Line Items]
Prepayment penalty charges		$ 50,300