Contingencies, Commitments and Guarantees (Commitments and Guarantees - Narrative) (Details) (USD $)	6 Months Ended
	Jun. 30, 2013	Dec. 31, 2012
Contingencies, Commitments and Guarantees (Textuals) [Abstract]
Commitments to fund partnership investments	$ 1,000,000,000	$ 1,000,000,000
Number of years over which commitments will be invested in partnerships	5 years
Commitments to Fund Bank Credit Facilities and Private Corporate Bond Investments [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Fair Value Disclosure, Off-balance Sheet Risks, Amount, Liability	104,000,000	144,000,000
Mortgage Loan Commitments [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Fair Value Disclosure, Off-balance Sheet Risks, Amount, Liability	271,000,000	181,000,000
Secured Demand Notes [Member] | Affiliated Entity [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Fair Value Disclosure, Off-balance Sheet Risks, Amount, Liability	74,000,000	86,000,000
Securities Pledged as Collateral, at Fair Value	$ 84,000,000	$ 106,000,000