v3.22.0.1
Investments - Cash Instruments by Level (Detail) - USD ($)
$ in Millions
Dec. 31, 2021
Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments in funds at NAV $ 3,470  
Investment at fair value 83,427 $ 82,778
Investments [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments in funds at NAV 3,469 3,664
Investment at fair value 79,958 79,114
Level 1 [Member] | Investments [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investment at fair value 51,175 47,392
Level 2 [Member] | Investments [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investment at fair value 14,881 15,299
Level 3 [Member] | Investments [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investment at fair value 13,902 16,423
U.S. [Member] | Investments [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investment at fair value 46,322 43,915
U.S. [Member] | Level 1 [Member] | Investments [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investment at fair value 46,322 43,915
Non-U.S. [Member] | Investments [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investment at fair value 2,612 2,157
Non-U.S. [Member] | Level 1 [Member] | Investments [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investment at fair value 2,612 2,109
Non-U.S. [Member] | Level 2 [Member] | Investments [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investment at fair value   48
Corporate debt securities [Member] | Investments [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investment at fair value 9,793 10,991
Corporate debt securities [Member] | Level 1 [Member] | Investments [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investment at fair value 65 70
Corporate debt securities [Member] | Level 2 [Member] | Investments [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investment at fair value 5,201 5,635
Corporate debt securities [Member] | Level 3 [Member] | Investments [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investment at fair value 4,527 5,286
Securities backed by real estate [Member] | Investments [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investment at fair value 2,280 1,940
Securities backed by real estate [Member] | Level 2 [Member] | Investments [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investment at fair value 1,202 942
Securities backed by real estate [Member] | Level 3 [Member] | Investments [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investment at fair value 1,078 998
Money Market Instruments [Member] | Investments [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investment at fair value 1,396 2,185
Money Market Instruments [Member] | Level 1 [Member] | Investments [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investment at fair value 41 781
Money Market Instruments [Member] | Level 2 [Member] | Investments [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investment at fair value 1,355 1,404
Other debt obligations [Member] | Investments [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investment at fair value 417 497
Other debt obligations [Member] | Level 2 [Member] | Investments [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investment at fair value 35  
Other debt obligations [Member] | Level 3 [Member] | Investments [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investment at fair value 382 497
Equity Securities [Member] | Investments [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investment at fair value 17,138 17,429
Equity Securities [Member] | Level 1 [Member] | Investments [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investment at fair value 2,135 517
Equity Securities [Member] | Level 2 [Member] | Investments [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investment at fair value 7,088 7,270
Equity Securities [Member] | Level 3 [Member] | Investments [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investment at fair value $ 7,915 $ 9,642