v3.26.1
Transactions With Related Parties (Details) - USD ($)
$ in Millions
3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Mar. 31, 2026
Dec. 31, 2025
Mar. 31, 2025
Dec. 31, 2024
Related Party Transaction [Line Items]                
Net premiums written $ 4,049 $ 4,348 $ 8,397 $ 8,863        
Reinsurance recoverable on unpaid and paid losses and loss adjustment expenses 9,964 $ 9,044 9,964 9,044 $ 9,732 $ 9,526 $ 8,969 $ 8,260
Reinsurance balances payable 3,234   3,234     2,320    
Other assets 6,878   6,878     6,796    
Other liabilities 3,715   3,715     3,517    
Operating affiliates | Premia                
Related Party Transaction [Line Items]                
Funds held asset 28   28     124    
Operating affiliates | Somers                
Related Party Transaction [Line Items]                
Net premiums written     308 $ 419        
Reinsurance recoverable on unpaid and paid losses and loss adjustment expenses 2,000   2,000     2,000    
Reinsurance balances payable 580   580     $ 550    
Equity Method Investee | Greysbridge Holdings Ltd                
Related Party Transaction [Line Items]                
Other assets 163   163          
Other liabilities $ 163   $ 163