v3.20.4
Fair Value Disclosures - Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($)
$ in Millions
Dec. 31, 2020
Dec. 31, 2019
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Trading securities $ 1,964 $ 1,249
Equity securities/mutual funds 2,317 1,926
Separate account assets 104,663 102,844
Total separate account collateral held under securities lending agreements 16,500 15,500
Separate account collateral liabilities under securities lending agreements 16,507 15,466
Investments Measured at NAV [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Other assets 69 68
Equity securities [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Equity securities/mutual funds 2,317 1,926
Fair Value, Measurements, Recurring [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Held-to-maturity investments 310 249
Total debt securities 2,274 1,498
Total equity method 1,081 943
Bank loans 248 204
Federal Reserve Bank Stock 94 93
Carried interest 627 528
Other investments 278 297
Total investments 6,919 5,489
Other assets 218 173
Separate account assets 104,663 102,844
Total separate account collateral held under securities lending agreements 16,507 15,466
Total 128,307 123,972
Separate account collateral liabilities under securities lending agreements 16,507 15,466
Other liabilities 340 398
Total liabilities measured at fair value 16,847 15,864
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Total equity method 235 169
Total investments 2,552 2,095
Other assets 205 173
Separate account assets 71,392 72,515
Total separate account collateral held under securities lending agreements 13,126 10,209
Total 87,275 84,992
Separate account collateral liabilities under securities lending agreements 13,126 10,209
Total liabilities measured at fair value 13,126 10,209
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Total debt securities 1,953 1,241
Bank loans 16 27
Total investments 1,969 1,268
Other assets 13  
Separate account assets 32,404 29,582
Total separate account collateral held under securities lending agreements 3,381 5,257
Total 37,767 36,107
Separate account collateral liabilities under securities lending agreements 3,381 5,257
Other liabilities 68 10
Total liabilities measured at fair value 3,449 5,267
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Total debt securities 11 8
Bank loans 232 177
Other investments 9 9
Total investments 252 194
Total 252 194
Other liabilities 272 388
Total liabilities measured at fair value 272 388
Fair Value, Measurements, Recurring [Member] | Debt Securities/ Fixed Income Mutual Funds [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Trading securities 1,964 1,249
Fair Value, Measurements, Recurring [Member] | Debt Securities/ Fixed Income Mutual Funds [Member] | Significant Other Observable Inputs (Level 2) [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Trading securities 1,953 1,241
Fair Value, Measurements, Recurring [Member] | Debt Securities/ Fixed Income Mutual Funds [Member] | Significant Unobservable Inputs (Level 3) [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Trading securities 11 8
Fair Value, Measurements, Recurring [Member] | Equity Securities/Mutual Funds [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Equity securities/mutual funds 2,317 1,926
Fair Value, Measurements, Recurring [Member] | Equity Securities/Mutual Funds [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Equity securities/mutual funds 2,317 1,926
Fair Value, Measurements, Recurring [Member] | Equity And Fixed Income Mutual Funds [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Total equity method 235 157
Fair Value, Measurements, Recurring [Member] | Equity And Fixed Income Mutual Funds [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Total equity method 235 157
Fair Value, Measurements, Recurring [Member] | Hedge Funds/Funds of Hedge Funds [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Total equity method 309 220
Fair Value, Measurements, Recurring [Member] | Private/ Public Equity [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Total equity method 315 248
Fair Value, Measurements, Recurring [Member] | Real Assets Funds [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Total equity method 218 296
Fair Value, Measurements, Recurring [Member] | Other Types Of Investments [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Total equity method 4 22
Fair Value, Measurements, Recurring [Member] | Other Types Of Investments [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Total equity method   12
Fair Value, Measurements, Recurring [Member] | Investments Measured at NAV [Member] | Investment in NAV [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Total equity method 846 774
Other investments 94 98
Total investments 940 872
Total 940 872
Fair Value, Measurements, Recurring [Member] | Investments Measured at NAV [Member] | Hedge Funds/Funds of Hedge Funds [Member] | Investment in NAV [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Total equity method 309 220
Fair Value, Measurements, Recurring [Member] | Investments Measured at NAV [Member] | Private/ Public Equity [Member] | Investment in NAV [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Total equity method 315 248
Fair Value, Measurements, Recurring [Member] | Investments Measured at NAV [Member] | Real Assets Funds [Member] | Investment in NAV [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Total equity method 218 296
Fair Value, Measurements, Recurring [Member] | Investments Measured at NAV [Member] | Other Types Of Investments [Member] | Investment in NAV [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Total equity method 4 10
Fair Value, Measurements, Recurring [Member] | Other [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Held-to-maturity investments 310 249
Total debt securities 310 249
Federal Reserve Bank Stock 94 93
Carried interest 627 528
Other investments 175 190
Total investments 1,206 1,060
Separate account assets 867 747
Total 2,073 1,807
Fair Value, Measurements, Recurring [Member] | Equity securities [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Total separate account collateral held under securities lending agreements 13,126 10,209
Fair Value, Measurements, Recurring [Member] | Equity securities [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Total separate account collateral held under securities lending agreements 13,126 10,209
Fair Value, Measurements, Recurring [Member] | Debt securities [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Total separate account collateral held under securities lending agreements 3,381 5,257
Fair Value, Measurements, Recurring [Member] | Debt securities [Member] | Significant Other Observable Inputs (Level 2) [Member]    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Total separate account collateral held under securities lending agreements $ 3,381 $ 5,257