v3.22.0.1
Investments - Fair Value Measurement Inputs (Detail)
$ in Millions
Dec. 31, 2021
USD ($)
yr
Dec. 31, 2020
USD ($)
yr
Level 3 assets | $ $ 715,812 $ 627,073
Level 3 assets [Member]    
Level 3 assets | $ 24,083 26,305
Corporate debt securities [Member] | Level 3 assets [Member] | Investments [Member]    
Level 3 assets | $ $ 4,527 $ 5,286
Corporate debt securities [Member] | Level 3 assets [Member] | Yield [Member] | Investments [Member] | Minimum [Member]    
Investments measurement input 2.00% 4.50%
Corporate debt securities [Member] | Level 3 assets [Member] | Yield [Member] | Investments [Member] | Maximum [Member]    
Investments measurement input 29.00% 19.50%
Corporate debt securities [Member] | Level 3 assets [Member] | Yield [Member] | Investments [Member] | Weighted Average [Member]    
Investments measurement input 10.80% 10.20%
Corporate debt securities [Member] | Level 3 assets [Member] | Recovery rate [Member] | Investments [Member] | Minimum [Member]    
Investments measurement input 9.10% 10.00%
Corporate debt securities [Member] | Level 3 assets [Member] | Recovery rate [Member] | Investments [Member] | Maximum [Member]    
Investments measurement input 76.00% 70.00%
Corporate debt securities [Member] | Level 3 assets [Member] | Recovery rate [Member] | Investments [Member] | Weighted Average [Member]    
Investments measurement input 59.10% 50.70%
Corporate debt securities [Member] | Level 3 assets [Member] | Duration [Member] | Investments [Member] | Minimum [Member]    
Investments measurement input 1.4 3.0
Corporate debt securities [Member] | Level 3 assets [Member] | Duration [Member] | Investments [Member] | Maximum [Member]    
Investments measurement input 6.4 7.7
Corporate debt securities [Member] | Level 3 assets [Member] | Duration [Member] | Investments [Member] | Weighted Average [Member]    
Investments measurement input 3.8 4.2
Corporate debt securities [Member] | Level 3 assets [Member] | Multiples [Member] | Investments [Member] | Minimum [Member]    
Investments measurement input 0.5 0.6
Corporate debt securities [Member] | Level 3 assets [Member] | Multiples [Member] | Investments [Member] | Maximum [Member]    
Investments measurement input 28.2 29.3
Corporate debt securities [Member] | Level 3 assets [Member] | Multiples [Member] | Investments [Member] | Weighted Average [Member]    
Investments measurement input 6.9 6.9
Securities backed by real estate [Member] | Level 3 assets [Member] | Investments [Member]    
Level 3 assets | $ $ 1,078 $ 998
Securities backed by real estate [Member] | Level 3 assets [Member] | Yield [Member] | Investments [Member] | Minimum [Member]    
Investments measurement input 8.30% 8.20%
Securities backed by real estate [Member] | Level 3 assets [Member] | Yield [Member] | Investments [Member] | Maximum [Member]    
Investments measurement input 20.30% 52.40%
Securities backed by real estate [Member] | Level 3 assets [Member] | Yield [Member] | Investments [Member] | Weighted Average [Member]    
Investments measurement input 13.10% 17.50%
Securities backed by real estate [Member] | Level 3 assets [Member] | Recovery rate [Member] | Investments [Member] | Minimum [Member]    
Investments measurement input 55.10% 21.60%
Securities backed by real estate [Member] | Level 3 assets [Member] | Recovery rate [Member] | Investments [Member] | Maximum [Member]    
Investments measurement input 61.00% 57.80%
Securities backed by real estate [Member] | Level 3 assets [Member] | Recovery rate [Member] | Investments [Member] | Weighted Average [Member]    
Investments measurement input 56.40% 33.70%
Securities backed by real estate [Member] | Level 3 assets [Member] | Duration [Member] | Investments [Member] | Minimum [Member]    
Investments measurement input 0.1 0.4
Securities backed by real estate [Member] | Level 3 assets [Member] | Duration [Member] | Investments [Member] | Maximum [Member]    
Investments measurement input 2.6 3.6
Securities backed by real estate [Member] | Level 3 assets [Member] | Duration [Member] | Investments [Member] | Weighted Average [Member]    
Investments measurement input 1.2 2.7
Equity Securities [Member] | Level 3 assets [Member] | Investments [Member]    
Level 3 assets | $ $ 7,915 $ 9,642
Equity Securities [Member] | Level 3 assets [Member] | Multiples [Member] | Investments [Member] | Minimum [Member]    
Investments measurement input 0.4 0.6
Equity Securities [Member] | Level 3 assets [Member] | Multiples [Member] | Investments [Member] | Maximum [Member]    
Investments measurement input 30.5 27.9
Equity Securities [Member] | Level 3 assets [Member] | Multiples [Member] | Investments [Member] | Weighted Average [Member]    
Investments measurement input 10.1 9.0
Equity Securities [Member] | Level 3 assets [Member] | Discount rate/yield [Member] | Investments [Member] | Minimum [Member]    
Investments measurement input 2.00% 4.00%
Equity Securities [Member] | Level 3 assets [Member] | Discount rate/yield [Member] | Investments [Member] | Maximum [Member]    
Investments measurement input 35.00% 38.50%
Equity Securities [Member] | Level 3 assets [Member] | Discount rate/yield [Member] | Investments [Member] | Weighted Average [Member]    
Investments measurement input 14.10% 13.50%
Equity Securities [Member] | Level 3 assets [Member] | Capitalization rate [Member] | Investments [Member] | Minimum [Member]    
Investments measurement input 3.50% 3.70%
Equity Securities [Member] | Level 3 assets [Member] | Capitalization rate [Member] | Investments [Member] | Maximum [Member]    
Investments measurement input 14.00% 14.10%
Equity Securities [Member] | Level 3 assets [Member] | Capitalization rate [Member] | Investments [Member] | Weighted Average [Member]    
Investments measurement input 5.70% 6.30%
Other debt obligations [Member] | Level 3 assets [Member] | Investments [Member]    
Level 3 assets | $ $ 382 $ 497
Other debt obligations [Member] | Level 3 assets [Member] | Yield [Member] | Investments [Member] | Minimum [Member]    
Investments measurement input 2.30% 1.70%
Other debt obligations [Member] | Level 3 assets [Member] | Yield [Member] | Investments [Member] | Maximum [Member]    
Investments measurement input 10.60% 6.20%
Other debt obligations [Member] | Level 3 assets [Member] | Yield [Member] | Investments [Member] | Weighted Average [Member]    
Investments measurement input 3.20% 3.50%
Other debt obligations [Member] | Level 3 assets [Member] | Duration [Member] | Investments [Member] | Minimum [Member]    
Investments measurement input 0.9 0.2
Other debt obligations [Member] | Level 3 assets [Member] | Duration [Member] | Investments [Member] | Maximum [Member]    
Investments measurement input 9.3 10.3
Other debt obligations [Member] | Level 3 assets [Member] | Duration [Member] | Investments [Member] | Weighted Average [Member]    
Investments measurement input 4.8 6.4