v3.26.1
Investments - Value of other securities measured at fair value based on election of the fair value option (Details) - USD ($)
$ in Millions
3 Months Ended 12 Months Ended
Mar. 31, 2026
Dec. 31, 2025
Debt and Equity Securities, FV-NI [Line Items]    
Total fixed maturity securities [1] $ 5,386 $ 5,407
Equity securities [1] 1,157 79
Total    
Debt and Equity Securities, FV-NI [Line Items]    
Total $ 6,543 $ 5,486
Total | Investment Concentration Risk | Investments    
Debt and Equity Securities, FV-NI [Line Items]    
Concentration risk (as a percent) 100.00% 100.00%
Fixed maturity securities    
Debt and Equity Securities, FV-NI [Line Items]    
Total fixed maturity securities $ 5,386 $ 5,407
Fixed maturity securities | Investment Concentration Risk | Investments    
Debt and Equity Securities, FV-NI [Line Items]    
Concentration risk (as a percent) 82.00% 99.00%
Fixed maturity securities | U.S. government and government sponsored entities    
Debt and Equity Securities, FV-NI [Line Items]    
Total fixed maturity securities $ 191 $ 192
Fixed maturity securities | U.S. government and government sponsored entities | Investment Concentration Risk | Investments    
Debt and Equity Securities, FV-NI [Line Items]    
Concentration risk (as a percent) 3.00% 4.00%
Fixed maturity securities | Obligations of states, municipalities and political subdivisions    
Debt and Equity Securities, FV-NI [Line Items]    
Total fixed maturity securities $ 34 $ 34
Fixed maturity securities | Obligations of states, municipalities and political subdivisions | Investment Concentration Risk | Investments    
Debt and Equity Securities, FV-NI [Line Items]    
Concentration risk (as a percent) 1.00% 1.00%
Fixed maturity securities | Non-U.S. governments    
Debt and Equity Securities, FV-NI [Line Items]    
Total fixed maturity securities $ 72 $ 75
Fixed maturity securities | Non-U.S. governments | Investment Concentration Risk | Investments    
Debt and Equity Securities, FV-NI [Line Items]    
Concentration risk (as a percent) 1.00% 1.00%
Fixed maturity securities | Corporate debt    
Debt and Equity Securities, FV-NI [Line Items]    
Total fixed maturity securities $ 2,966 $ 2,914
Fixed maturity securities | Corporate debt | Investment Concentration Risk | Investments    
Debt and Equity Securities, FV-NI [Line Items]    
Concentration risk (as a percent) 45.00% 53.00%
Fixed maturity securities | Mortgage-backed, asset-backed and collateralized:    
Debt and Equity Securities, FV-NI [Line Items]    
Total fixed maturity securities $ 2,123 $ 2,192
Fixed maturity securities | Mortgage-backed, asset-backed and collateralized: | Investment Concentration Risk | Investments    
Debt and Equity Securities, FV-NI [Line Items]    
Concentration risk (as a percent) 32.00% 40.00%
Fixed maturity securities | RMBS    
Debt and Equity Securities, FV-NI [Line Items]    
Total fixed maturity securities $ 134 $ 137
Fixed maturity securities | RMBS | Investment Concentration Risk | Investments    
Debt and Equity Securities, FV-NI [Line Items]    
Concentration risk (as a percent) 2.00% 2.00%
Fixed maturity securities | CMBS    
Debt and Equity Securities, FV-NI [Line Items]    
Total fixed maturity securities $ 203 $ 217
Fixed maturity securities | CMBS | Investment Concentration Risk | Investments    
Debt and Equity Securities, FV-NI [Line Items]    
Concentration risk (as a percent) 3.00% 4.00%
Fixed maturity securities | CLO    
Debt and Equity Securities, FV-NI [Line Items]    
Total fixed maturity securities $ 591 $ 585
Fixed maturity securities | CLO | Investment Concentration Risk | Investments    
Debt and Equity Securities, FV-NI [Line Items]    
Concentration risk (as a percent) 9.00% 11.00%
Fixed maturity securities | ABS    
Debt and Equity Securities, FV-NI [Line Items]    
Total fixed maturity securities $ 1,195 $ 1,253
Fixed maturity securities | ABS | Investment Concentration Risk | Investments    
Debt and Equity Securities, FV-NI [Line Items]    
Concentration risk (as a percent) 18.00% 23.00%
Equity securities    
Debt and Equity Securities, FV-NI [Line Items]    
Equity securities $ 1,157 $ 79
Equity securities | Investment Concentration Risk | Investments    
Debt and Equity Securities, FV-NI [Line Items]    
Concentration risk (as a percent) 18.00% 1.00%
[1] See Note 8 for details of balances associated with variable interest entities