Fair Value Measurements (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012
Principal Investments [Member]
Fair Values of Direct and Indirect Funds and Direct and Indirect Unfunded Commitments for Funds [Abstract]
Fair Value	$ 482
Unfunded Commitments	106
Principal Investments [Member] | Hedge funds [Member]
Fair Values of Direct and Indirect Funds and Direct and Indirect Unfunded Commitments for Funds [Abstract]
Fair Value	4
Principal Investments [Member] | Private equity funds [Member]
Fair Values of Direct and Indirect Funds and Direct and Indirect Unfunded Commitments for Funds [Abstract]
Fair Value	478
Unfunded Commitments	106
Private Equity and Mezzanine Investments [Member]
Fair Values of Direct and Indirect Funds and Direct and Indirect Unfunded Commitments for Funds [Abstract]
Fair Value	43
Unfunded Commitments	6
Private Equity and Mezzanine Investments [Member] | Passive Funds [Member]
Fair Values of Direct and Indirect Funds and Direct and Indirect Unfunded Commitments for Funds [Abstract]
Fair Value	18
Unfunded Commitments	3
Private Equity and Mezzanine Investments [Member] | Co Managed Funds [Member]
Fair Values of Direct and Indirect Funds and Direct and Indirect Unfunded Commitments for Funds [Abstract]
Fair Value	25
Unfunded Commitments	$ 3