v3.26.3
Reserve for Property and Casualty Insurance Claims and Claims Expense - Schedule of Rollforward of the Reserve for Property and Casualty Insurance Claims and Claims Expense (Details) - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Sep. 30, 2026
Sep. 30, 2025
Sep. 30, 2026
Sep. 30, 2025
Dec. 31, 2025
Dec. 31, 2024
Property-liability insurance claims and claims expense            
Beginning balance     $ 41,079      
Incurred claims and claims expense related to:            
Prior years $ (753) $ (424) (2,398) $ (1,045)    
Claims and claims expense paid related to:            
Ending balance 40,796   40,796      
Property and casualty            
Property-liability insurance claims and claims expense            
Beginning balance     41,079 41,917    
Less: recoverables 7,301 8,993 7,301 8,993 $ 8,012 $ 8,602
Activity in the reserve for property-liability insurance claims and claims expense:            
Net beginning balance     33,067 33,315    
Incurred claims and claims expense related to:            
Current year     31,388 30,763    
Prior years     (2,398) (1,045)    
Total incurred     28,990 29,718    
Claims and claims expense paid related to:            
Current year     (16,587) (16,235)    
Prior years     (11,975) (12,688)    
Total paid     (28,562) (28,923)    
Net ending balance 33,495 34,110 33,495 34,110    
Plus: recoverables 7,301 8,993 7,301 8,993 $ 8,012 $ 8,602
Ending balance $ 40,796 $ 43,103 $ 40,796 $ 43,103