Repurchase Agreements And Other Debt Federal Home Loan Bank Advances and Weighted Average Interest Rates (Details) $ in Millions	Sep. 30, 2015 USD ($) days years
Short-term Debt [Line Items]
Short-term Debt, Fair Value	$ 3,502
Short-term Debt, Percentage Bearing Fixed Interest Rate	0.27%
FHLB Weighted Average Days to Maturity | days	1,274
FHLB Weighted Average Years to Maturity | years	3.5
49 to 60 Months [Member]
Short-term Debt [Line Items]
Short-term Debt, Fair Value	$ 2,093
Short-term Debt, Percentage Bearing Fixed Interest Rate	0.26%
FHLB Weighted Average Days to Maturity | days	1,813
37 to 48 months [Member]
Short-term Debt [Line Items]
Short-term Debt, Fair Value	$ 411
Short-term Debt, Percentage Bearing Fixed Interest Rate	0.26%
FHLB Weighted Average Days to Maturity | days	1,419
Maturity Less than 30 Days [Member]
Short-term Debt [Line Items]
Short-term Debt, Fair Value	$ 753
Short-term Debt, Percentage Bearing Fixed Interest Rate	0.27%
FHLB Weighted Average Days to Maturity | days	6
10 to 12 Months [Member]
Short-term Debt [Line Items]
Short-term Debt, Fair Value	$ 245
Short-term Debt, Percentage Bearing Fixed Interest Rate	0.35%
FHLB Weighted Average Days to Maturity | days	322