Contingencies, Commitments and Guarantees (Commitments and Guarantees - Narrative) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Mortgage Loan Commitments
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Fair Value Disclosure, Off-balance Sheet Risks, Face Amount, Liability	$ 372	$ 36
Commitments to Fund Partnership Investments and Private Corporate Bond Investments
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Fair Value Disclosure, Off-balance Sheet Risks, Face Amount, Liability	1,100	918
Secured Demand Notes | Affiliated Entity
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Fair Value Disclosure, Off-balance Sheet Risks, Face Amount, Liability	32	32
Securities Pledged as Collateral, at Fair Value	$ 60	$ 57