v2.4.0.6
Fair Value, Investments in Entities That Calculate Net Asset Value Per Share (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2011
Dec. 31, 2010
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]    
Fair value $ 1,434 $ 3,669
Unfunded commitments 268 705
Offshore Funds [Member]
   
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]    
Fair value 352 1,665
Unfunded commitments 0 0
Redemption frequency Daily - Annually Daily - Annually
Redemption notice period 1 - 180 days 1 - 180 days
Funds of funds [Member]
   
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]    
Fair value 1 63
Unfunded commitments 0 0
Redemption frequency Quarterly Monthly - Quarterly
Redemption notice period 90 days 10 - 90 days
Hedge Funds [Member]
   
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]    
Fair value 22 23
Unfunded commitments 0 0
Redemption frequency Daily - Annually Monthly - Annually
Redemption notice period 5 - 95 days 30 - 120 days
Private equity [Member]
   
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]    
Fair value 976 1,830
Unfunded commitments 240 669
Redemption frequency N/A N/A
Redemption notice period N/A N/A
Venture Capital Funds [Member]
   
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]    
Fair value 83 88
Unfunded commitments $ 28 $ 36
Redemption frequency N/A N/A
Redemption notice period N/A N/A