v3.25.2
Investments - Additional Information (Details)
£ in Millions, $ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2025
USD ($)
security
Jun. 30, 2024
USD ($)
Jun. 30, 2025
USD ($)
security
Jun. 30, 2024
USD ($)
Jun. 30, 2025
GBP (£)
security
Dec. 31, 2024
USD ($)
security
Schedule of Investments [Line Items]            
Fixed-maturity investments, non-investment grade, percent 13.40%   13.40%   13.40% 12.60%
Estimated Fair Value $ 6,498   $ 6,498     $ 6,369
Alternative investment 923   923      
Accrued investment income $ 67   $ 67     $ 64
Number of securities with unrealized losses greater than 10% of book value for 12 months or more | security 321   321   321 438
Total unrealized losses for securities having losses greater than 10% of book value for 12 months or more $ 169   $ 169     $ 223
Assets held-in-trust 79   79     79
Fixed-maturity securities, trading 137   137     147
Proceeds from sale and maturity of debt securities, available-for-sale     427 $ 488    
Securities purchased with credit deterioration 0 $ 0 0 $ 0    
Insured Financial Obligations, Loss Mitigation Securities            
Schedule of Investments [Line Items]            
Estimated Fair Value 503   503     479
Insured Financial Obligations, Loss Mitigation Securities Paid Down            
Schedule of Investments [Line Items]            
Estimated Fair Value 408   408      
Collateralized Loan Obligation Equity Tranches            
Schedule of Investments [Line Items]            
Estimated Fair Value 238   238     277
Consolidated Investment Vehicles            
Schedule of Investments [Line Items]            
Equity method investments 40   40     33
Contingent Value Instruments            
Schedule of Investments [Line Items]            
Fixed-maturity securities, trading 117   117      
Financial Instrument, Other            
Schedule of Investments [Line Items]            
Investments, fair value disclosure 583   583      
Sound Point Capital Management, LP            
Schedule of Investments [Line Items]            
Equity method investments 412   412     418
AGL Subsidiaries            
Schedule of Investments [Line Items]            
Assets held-in-trust 1,092   1,092     $ 1,135
Future Equity Investments            
Schedule of Investments [Line Items]            
Alternative investment 923   923      
Investments, unfunded commitment 567   567      
Investments, authorized amount to invest 1,500   1,500      
Future Equity Investments | Sound Point Capital Management, LP            
Schedule of Investments [Line Items]            
Investments, authorized amount to invest 1,000   1,000      
Debt Securities Through A Facility            
Schedule of Investments [Line Items]            
Liquidity bonds purchased 75   75   £ 55  
Purchase commitment, debt securities $ 75   $ 75   £ 55