v3.25.2
Claim and Claim Adjustment Expense Reserves (Narrative) (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Jun. 30, 2025
Jun. 30, 2024
Dec. 31, 2024
Dec. 31, 2011
Dec. 31, 2010
Liability for Claims and Claims Adjustment Expense [Line Items]              
Unusual or infrequent item, or both, net of insurance proceeds $ 62 $ 82 $ 159 $ 170      
Pretax (favorable) unfavorable premium development, excluding Life & Group 108 23 191 16      
Retroactive reinsurance benefit recognized 8 $ 13 25 $ 25      
Cumulative amounts ceded under AEP Loss Portfolio Transfer 3,700   3,700   $ 3,700    
Asbestos and Environmental Reserves              
Liability for Claims and Claims Adjustment Expense [Line Items]              
Net A&EP claim and allocated claim adjustment expense reserves ceded to NICO             $ 1,600
Aggregate limit under A&EP Loss Portfolio Transfer             4,000
A&EP claim and allocated claim adjustment expense reserves ceded under existing third party reinsurance contracts transferred to NICO under A&EP Loss Portfolio Transfer             1,200
Reinsurance premium paid to NICO under A&EP Loss Portfolio Transfer             2,000
Net reinsurance receivables transferred to NICO under A&EP Loss Portfolio Transfer             215
Total consideration paid to NICO under AEP Loss Portfolio Transfer           $ 2,200 $ 2,200
Deferred reinsurance benefit yet to be recognized 400   400   $ 425    
Fair value of collateral trust account established by NICO under A&EP Loss Portfolio Transfer 2,200   2,200        
Corporate & Other              
Liability for Claims and Claims Adjustment Expense [Line Items]              
Pretax (favorable) unfavorable premium development, excluding Life & Group $ 112   $ 134