v3.26.1
Investments - Additional Information (Details)
$ in Millions
3 Months Ended
Mar. 31, 2026
USD ($)
security
Mar. 31, 2025
USD ($)
Dec. 31, 2025
USD ($)
security
Schedule of Investments [Line Items]      
Fixed-maturity investments, non-investment grade, percent 7.00%   8.60%
Fixed-maturity securities, available for sale $ 6,875   $ 6,369
Alternative investment 965    
Accrued investment income $ 77   $ 70
Number of securities with unrealized losses greater than 10% of book value for 12 months or more | security 270   253
Total unrealized losses for securities having losses greater than 10% of book value for 12 months or more $ 152   $ 147
Assets held-in-trust 76   77
Fixed-maturity securities, trading 127   124
Securities purchased with credit deterioration 0 $ 0  
Asset Pledged as Collateral      
Schedule of Investments [Line Items]      
Fixed-maturity securities, available for sale 4    
Insured Financial Obligations, Loss Mitigation Securities      
Schedule of Investments [Line Items]      
Fixed-maturity securities, available for sale 135   140
Collateralized Loan Obligation Equity Tranches      
Schedule of Investments [Line Items]      
Fixed-maturity securities, available for sale 173   228
Contingent Value Instruments      
Schedule of Investments [Line Items]      
Fixed-maturity securities, trading 119   114
Financial Instrument, Other      
Schedule of Investments [Line Items]      
Investments, fair value disclosure 730    
Liquidity Bonds      
Schedule of Investments [Line Items]      
Fixed-maturity securities, available for sale 162   168
AGL Subsidiaries      
Schedule of Investments [Line Items]      
Assets held-in-trust 812   $ 813
Future Equity Investments      
Schedule of Investments [Line Items]      
Alternative investment 965    
Investments, unfunded commitment 554    
Alternative Investments, Authorized Amount To Invest 1,500    
Future Equity Investments | Sound Point Capital Management, LP      
Schedule of Investments [Line Items]      
Investments, authorized amount to invest $ 1,000