v3.24.1.u1
Investments - Amortized cost or cost and fair value of available for sale securities (Details) - USD ($)
$ in Millions
Mar. 31, 2024
Dec. 31, 2023
Mar. 31, 2023
Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]        
Amortized Cost or Costs $ 188,403 $ 184,946    
Allowance for Credit Losses (97) (128) $ (96) $ (148)
Gross Unrealized Gains 2,009 2,186    
Gross Unrealized Losses (21,489) (20,477)    
Bonds available-for-sale [1] 168,826 166,527    
U.S. government and government sponsored entities        
Debt Securities, Available-for-sale [Line Items]        
Amortized Cost or Costs 1,626 1,436    
Allowance for Credit Losses 0 0    
Gross Unrealized Gains 10 17    
Gross Unrealized Losses (272) (233)    
Bonds available-for-sale 1,364 1,220    
Obligations of states, municipalities and political subdivisions        
Debt Securities, Available-for-sale [Line Items]        
Amortized Cost or Costs 6,130 6,466    
Allowance for Credit Losses 0 0    
Gross Unrealized Gains 41 58    
Gross Unrealized Losses (730) (693)    
Bonds available-for-sale 5,441 5,831    
Non-U.S. governments        
Debt Securities, Available-for-sale [Line Items]        
Amortized Cost or Costs 4,713 4,695    
Allowance for Credit Losses 0 (2)    
Gross Unrealized Gains 33 43    
Gross Unrealized Losses (759) (679)    
Bonds available-for-sale 3,987 4,057    
Corporate debt        
Debt Securities, Available-for-sale [Line Items]        
Amortized Cost or Costs 120,047 120,654    
Allowance for Credit Losses (61) (71)    
Gross Unrealized Gains 1,053 1,294    
Gross Unrealized Losses (16,868) (15,795)    
Bonds available-for-sale 104,171 106,082    
Mortgage-backed, asset-backed and collateralized        
Debt Securities, Available-for-sale [Line Items]        
Amortized Cost or Costs 55,887 51,695    
Allowance for Credit Losses (36) (55)    
Gross Unrealized Gains 872 774    
Gross Unrealized Losses (2,860) (3,077)    
Bonds available-for-sale 53,863 49,337    
RMBS        
Debt Securities, Available-for-sale [Line Items]        
Amortized Cost or Costs 15,807 14,491    
Allowance for Credit Losses (19) (25)    
Gross Unrealized Gains 625 599    
Gross Unrealized Losses (823) (788)    
Bonds available-for-sale 15,590 14,277    
RMBS | Affiliated Entity        
Debt Securities, Available-for-sale [Line Items]        
Amortized Cost or Costs 45 45    
Bonds available-for-sale 42 43    
CMBS        
Debt Securities, Available-for-sale [Line Items]        
Amortized Cost or Costs 11,215 11,045    
Allowance for Credit Losses (17) (30)    
Gross Unrealized Gains 43 22    
Gross Unrealized Losses (939) (1,056)    
Bonds available-for-sale 10,302 9,981    
CLO        
Debt Securities, Available-for-sale [Line Items]        
Amortized Cost or Costs 11,729 11,203    
Allowance for Credit Losses 0 0    
Gross Unrealized Gains 125 90    
Gross Unrealized Losses (86) (149)    
Bonds available-for-sale 11,768 11,144    
ABS        
Debt Securities, Available-for-sale [Line Items]        
Amortized Cost or Costs 17,136 14,956    
Allowance for Credit Losses 0 0    
Gross Unrealized Gains 79 63    
Gross Unrealized Losses (1,012) (1,084)    
Bonds available-for-sale $ 16,203 $ 13,935    
[1] See Note 9 for details of balances associated with variable interest entities