v3.26.1
Allowance for Expected Credit Losses (Details) - Narrative - Reinsurer Concentration Risk [Member]
$ in Millions
3 Months Ended
Mar. 31, 2026
USD ($)
Reinsurance Recoverables [Member] | Reinsurer Group Rated by A.M. Best [Member] | A.M. Best, Rating Provided [Member]  
Reinsurance recoverables, credit quality indicator  
Reinsurance recoverables, after deducting mandatory pools and associations and before allowances for expected credit losses $ 5,970
Concentration risk percentage 90.00%
Reinsurance Recoverables [Member] | Reinsurer Group Not Rated by A.M. Best [Member]  
Reinsurance recoverables, credit quality indicator  
Concentration risk percentage 10.00%
Reinsurance Recoverables [Member] | Captive Insurance Companies [Member]  
Reinsurance recoverables, credit quality indicator  
Concentration risk percentage 5.00%
Reinsurance Recoverables [Member] | Voluntary Pools [Member]  
Reinsurance recoverables, credit quality indicator  
Concentration risk percentage 1.00%
Reinsurance Recoverables [Member] | Other Companies [Member]  
Reinsurance recoverables, credit quality indicator  
Concentration risk percentage 4.00%
Reinsurance Recoverables Rated by A.M. Best [Member] | Reinsurer Group Rated by A.M. Best [Member] | A.M. Best, A- Rating Or Better [Member]  
Reinsurance recoverables, credit quality indicator  
Concentration risk percentage 94.00%