v3.26.1
Insurance Claim Reserves (Details) - Reserve Detail for Claims and Claim Adjustment Expenses - USD ($)
$ in Millions
 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
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 $ 65,737  
Claims and claim adjustment expense reserves at end of period 67,226  
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
Reinsurance recoverables on unpaid losses   7,669
Net reserves at beginning of year   56,419
Estimated claims and claim adjustment expenses for claims arising in the current year 13,192 15,392
Estimated decrease in claims and claim adjustment expenses for claims arising in prior years (939) (650)
Total increases 12,253 14,742
Claims and claim adjustment expense payments for claims arising in current year 3,501 4,504
Claims and claim adjustment expense payments for claims arising in prior years 7,487 7,763
Total payments 10,988 12,267
Net reserves disposed of related to the divestiture of the Canadian business (1,627)  
Unrealized foreign exchange (gain) loss (37) 272
Net reserves at end of period 59,447 59,166
Reinsurance recoverables on unpaid losses 7,775 7,771
Claims and claim adjustment expense reserves at end of period 67,222 $ 66,937
Amount of increase in gross claims and claim adjustment expense reserves 1,490  
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 3  
Claims and claim adjustment expense reserves at end of period 4  
Before Reclassifications of Held For Sale [Member] | 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 67,643  
Reinsurance recoverables on unpaid losses 7,797  
Net reserves at beginning of year 59,846  
Held for Sale Reclassification [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 $ (1,909)