v3.25.2
Insurance Claim Reserves (Details) - Reserve Detail for Claims and Claim Adjustment Expenses - USD ($)
$ in Millions
 6 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Reconciliation of beginning and ending reserve balances for claims and claim adjustment expenses [Roll Forward]    
Claims and claim adjustment expense reserves at beginning of year $ 64,093  
Claims and claim adjustment expense reserves at end of period 66,941  
Property-casualty [Member]    
Reconciliation of beginning and ending reserve balances for claims and claim adjustment expenses [Roll Forward]    
Claims and claim adjustment expense reserves at beginning of year 64,088 $ 61,621
Reinsurance recoverables on unpaid losses 7,669 7,817
Net reserves at beginning of year 56,419 53,804
Estimated claims and claim adjustment expenses for claims arising in the current year 15,392 14,213
Estimated decrease in claims and claim adjustment expenses for claims arising in prior years (650) (232)
Total increases 14,742 13,981
Claims and claim adjustment expense payments for claims arising in current year 4,504 3,953
Claims and claim adjustment expense payments for claims arising in prior years 7,763 7,750
Total payments 12,267 11,703
Unrealized foreign exchange (gain) loss 272 (75)
Net reserves at end of period 59,166 56,007
Reinsurance recoverables on unpaid losses 7,771 7,845
Claims and claim adjustment expense reserves at end of period 66,937 $ 63,852
Amount of increase in gross claims and claim adjustment expense reserves 2,850  
Accident and health [Member]    
Reconciliation of beginning and ending reserve balances for claims and claim adjustment expenses [Roll Forward]    
Claims and claim adjustment expense reserves at beginning of year 5  
Claims and claim adjustment expense reserves at end of period $ 4