v3.22.0.1
Investments - Investments in Funds that are Calculated Using Net Asset Value Per Share (Detail) - USD ($)
$ in Millions
Dec. 31, 2021
Dec. 31, 2020
Fair Value, Investments, Entities That Are Calculated Using Net Asset Value Per Share [Line Items]    
Fair Value of Investments $ 3,470  
Cash Instruments Assets [Member]    
Fair Value, Investments, Entities That Are Calculated Using Net Asset Value Per Share [Line Items]    
Fair Value of Investments 3,469 $ 3,664
Cash Instruments Liabilities [Member]    
Fair Value, Investments, Entities That Are Calculated Using Net Asset Value Per Share [Line Items]    
Unfunded Commitments 1,322 1,450
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 1,411 2,042
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 619 557
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 1,686 1,312
Credit Funds [Member] | Cash Instruments Liabilities [Member]    
Fair Value, Investments, Entities That Are Calculated Using Net Asset Value Per Share [Line Items]    
Unfunded Commitments 556 680
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 84 102
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 288 208
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 $ 147 $ 213