Loans Mortgages With Potential Concentration of Credit Risk (Details) $ in Millions		Jun. 30, 2015 USD ($)	Dec. 31, 2014 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair Value, Concentration of Risk, Loans Receivable		$ 10,838	$ 11,421
Current Weighted Average FICO Score on Mortgages With Potential Concentration of Credit Risk		738	738
Residential Mortgage Amortizing Loans [Member] | Mortgages With LTV Ratio Greater Than 80% and/or second liens [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair Value, Concentration of Risk, Loans Receivable	[1]	$ 7,810	$ 7,368
Residential Mortgage Interest Only Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair Value, Concentration of Risk, Loans Receivable	[2]	3,028	4,053
Residential Mortgage Interest Only Loans [Member] | Mortgages With Mortgage Insurance or With LTV Ratio Less Than or Equal to 80% [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair Value, Concentration of Risk, Loans Receivable	[2]	2,314	3,180
Residential Mortgage Interest Only Loans [Member] | Mortgages With No Mortgage Insurance and With LTV Ratio Greater Than 80% [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair Value, Concentration of Risk, Loans Receivable	[2]	$ 714	$ 873

[1] Comprised of loans with no MI

[2] Comprised of first and/or second liens, primarily with an initial 10 year interest only period.