Guarantees Repurchased Mortgage Loan (Details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Repurchased mortgage loans, carrying value	$ 293	$ 312
Loans Held For Investment [Member]
Repurchased mortgage loans, carrying value	265	271
Nonperforming Financing Receivable [Member] | Loans Held For Investment [Member]
Repurchased mortgage loans, carrying value	15	29
Nonperforming Financing Receivable [Member] | Residential Mortgage, Loans Held For Sale [Member]
Repurchased mortgage loans, carrying value	$ 13	$ 12