Fair Value Measurements (Details 3) (Level 3, Recurring, Discounted cash flow)	3 Months Ended
	Mar. 31, 2015
Trading securities. | Weighted average
Significant unobservable inputs used in the fair value measurements
Discount rates (as a percent)	10.00%
Trading securities. | Minimum
Significant unobservable inputs used in the fair value measurements
Discount rates (as a percent)	8.00%
Trading securities. | Maximum
Significant unobservable inputs used in the fair value measurements
Discount rates (as a percent)	17.00%
Loans held for sale | Weighted average
Significant unobservable inputs used in the fair value measurements
Discount rates (as a percent)	93.00%
Loans held for sale | Minimum
Significant unobservable inputs used in the fair value measurements
Discount rates (as a percent)	90.00%
Loans held for sale | Maximum
Significant unobservable inputs used in the fair value measurements
Discount rates (as a percent)	94.00%
MSR | Weighted average
Significant unobservable inputs used in the fair value measurements
Discount rates (as a percent)	10.98%
Constant prepayment rate (as a percent)	14.95%