Repurchase Agreements And Other Debt Federal Home Loan Bank Advances and Weighted Average Interest Rates (Details) $ in Millions	Sep. 30, 2016 USD ($) days	Dec. 31, 2015 USD ($) days
Short-term Debt [Line Items]
Short-term Debt, Percentage Bearing Fixed Interest Rate	0.63%	0.53%
FHLB Weighted Average Days to Maturity | days	123	141
Advances from Federal Home Loan Banks | $	$ 3,037	$ 3,753
Maturity Less than 30 Days [Member]
Short-term Debt [Line Items]
Short-term Debt, Percentage Bearing Fixed Interest Rate	0.00%	0.47%
FHLB Weighted Average Days to Maturity | days	0	14
Advances from Federal Home Loan Banks | $	$ 0	$ 1,952
thirty one to ninety [Member]
Short-term Debt [Line Items]
Short-term Debt, Percentage Bearing Fixed Interest Rate	0.00%	0.60%
FHLB Weighted Average Days to Maturity | days	0	84
Advances from Federal Home Loan Banks | $	$ 0	$ 681
4 to 6 Months [Member]
Short-term Debt [Line Items]
Short-term Debt, Percentage Bearing Fixed Interest Rate	0.63%	0.00%
FHLB Weighted Average Days to Maturity | days	123	0
Advances from Federal Home Loan Banks | $	$ 3,037	$ 0
13 Months [Member]
Short-term Debt [Line Items]
Short-term Debt, Percentage Bearing Fixed Interest Rate	0.00%	0.58%
FHLB Weighted Average Days to Maturity | days	0	397
Advances from Federal Home Loan Banks | $	$ 0	$ 1,120