XML 207 R87.htm IDEA: XBRL DOCUMENT v3.20.1
Investments - Investments in Funds that are Calculated Using Net Asset Value Per Share (Detail) - USD ($)
$ in Millions
Mar. 31, 2020
Dec. 31, 2019
Cash Instruments Assets [Member]    
Fair Value, Investments, Entities That Are Calculated Using Net Asset Value Per Share [Line Items]    
Fair Value of Investments $ 3,545 $ 4,206
Cash Instruments Liabilities [Member]    
Fair Value, Investments, Entities That Are Calculated Using Net Asset Value Per Share [Line Items]    
Unfunded Commitments 1,677 1,781
Private Equity Funds [Member] | Cash Instruments Assets [Member]    
Fair Value, Investments, Entities That Are Calculated Using Net Asset Value Per Share [Line Items]    
Fair Value of Investments 2,285 2,767
Private Equity Funds [Member] | Cash Instruments Liabilities [Member]    
Fair Value, Investments, Entities That Are Calculated Using Net Asset Value Per Share [Line Items]    
Unfunded Commitments 753 765
Credit Funds [Member] | Cash Instruments Assets [Member]    
Fair Value, Investments, Entities That Are Calculated Using Net Asset Value Per Share [Line Items]    
Fair Value of Investments 840 983
Credit Funds [Member] | Cash Instruments Liabilities [Member]    
Fair Value, Investments, Entities That Are Calculated Using Net Asset Value Per Share [Line Items]    
Unfunded Commitments 730 820
Hedge Funds [Member] | Cash Instruments Assets [Member]    
Fair Value, Investments, Entities That Are Calculated Using Net Asset Value Per Share [Line Items]    
Fair Value of Investments 106 125
Real Estate Funds [Member] | Cash Instruments Assets [Member]    
Fair Value, Investments, Entities That Are Calculated Using Net Asset Value Per Share [Line Items]    
Fair Value of Investments 314 331
Real Estate Funds [Member] | Cash Instruments Liabilities [Member]    
Fair Value, Investments, Entities That Are Calculated Using Net Asset Value Per Share [Line Items]    
Unfunded Commitments $ 194 $ 196