v3.26.1
Segment Information - Reconciliation of Other Items from Segments to Consolidated (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Segment Reporting [Line Items]        
Deferred Policy Acquisition Costs, Amortization Expense $ 669 $ 625 $ 1,325 $ 1,232
Insurance operating costs and other expense 1,215 1,138 2,443 2,285
Amortization of other intangible assets 17 17 35 35
Benefits, Losses and Expenses 6,032 5,542 11,982 11,364
Policyholder Benefits and Claims Incurred, Net 4,081 3,712 8,079 7,712
Operating Segments [Member]        
Segment Reporting [Line Items]        
Deferred Policy Acquisition Costs, Amortization Expense 669 625 1,325 1,232
Amortization of other intangible assets 17 17 35 35
Benefits, Losses and Expenses 5,910 5,453 11,772 11,188
Operating Segments [Member] | P&C Business Insurance        
Segment Reporting [Line Items]        
Prior accident year development [1] (52) (146) (22) (229)
Deferred Policy Acquisition Costs, Amortization Expense 590 546 1,167 1,077
Insurance operating costs and other expense 539 507 1,097 1,019
Amortization of other intangible assets 7 7 14 14
Policyholder Dividends, Expense 12 11 24 21
Benefits, Losses and Expenses 3,359 2,991 6,758 6,139
Operating Segments [Member] | P&C Personal Insurance        
Segment Reporting [Line Items]        
Prior accident year development [1] (59) (41) (94) (80)
Deferred Policy Acquisition Costs, Amortization Expense 70 70 141 138
Insurance operating costs and other expense 175 172 355 354
Amortization of other intangible assets 0 0 1 1
Benefits, Losses and Expenses 822 884 1,624 1,846
Operating Segments [Member] | Property & Casualty Other Operations [Member]        
Segment Reporting [Line Items]        
Prior accident year development [1] 0 0 (36) 0
Deferred Policy Acquisition Costs, Amortization Expense 0 0 0 0
Insurance operating costs and other expense 2 2 4 4
Amortization of other intangible assets 0 0 0 0
Benefits, Losses and Expenses 2 2 (32) 4
Operating Segments [Member] | Employee Benefits [Member]        
Segment Reporting [Line Items]        
Deferred Policy Acquisition Costs, Amortization Expense 9 9 17 17
Insurance operating costs and other expense 417 407 856 813
Amortization of other intangible assets 10 10 20 20
Benefits, Losses and Expenses 1,727 1,576 3,422 3,199
Operating Segments [Member] | Employee Benefits [Member] | Disability Insurance Policy [Member]        
Segment Reporting [Line Items]        
Policyholder Benefits and Claims Incurred, Net 741 617 1,415 1,238
Operating Segments [Member] | Employee Benefits [Member] | Life Insurance Product Line [Member]        
Segment Reporting [Line Items]        
Policyholder Benefits and Claims Incurred, Net 484 478 972 997
Operating Segments [Member] | Employee Benefits [Member] | Insurance, Other [Member]        
Segment Reporting [Line Items]        
Policyholder Benefits and Claims Incurred, Net 66 55 142 114
Non-Catastrophe [Member] | Operating Segments [Member] | P&C Business Insurance        
Segment Reporting [Line Items]        
Current accident year 2,134 1,952 4,178 3,843
Non-Catastrophe [Member] | Operating Segments [Member] | P&C Personal Insurance        
Segment Reporting [Line Items]        
Current accident year 543 585 1,069 1,148
Catastrophe | Operating Segments [Member] | P&C Business Insurance        
Segment Reporting [Line Items]        
Current accident year 129 114 300 394
Catastrophe | Operating Segments [Member] | P&C Personal Insurance        
Segment Reporting [Line Items]        
Current accident year $ 93 $ 98 $ 152 $ 285