Schedule III (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Deferred Policy Acquisition Costs	$ 2,106	$ 2,065
Liability for Unpaid Losses and Loss Adjustment Expenses, Future Policy Benefits	72,051	70,485
Unearned Premiums	17,991	17,232
Policy and Contract Claims	0	31
Premiums	23,751	23,537	$ 25,564
Net Investment Income	4,215	4,255	3,446
Losses and Loss Expenses Incurred	14,162	14,567	15,393
Amortization of Deferred Policy Acquisition Costs	3,371	3,425	3,771
Other Operating Expenses	5,053	5,529	5,399
Net Premiums Written	23,673	23,902	27,206
Net Investment Income	4,215	4,255	3,446
Reportable Segments
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Net Investment Income	3,433	3,060	3,022
Corporate Reconciling Items And Eliminations
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Deferred Policy Acquisition Costs	1	(95)
Liability for Unpaid Losses and Loss Adjustment Expenses, Future Policy Benefits	6,764	6,759
Unearned Premiums	143	183
Policy and Contract Claims	0	31
Premiums	73	80	473
Net Investment Income	782	1,195	424
Losses and Loss Expenses Incurred	194	529	618
Amortization of Deferred Policy Acquisition Costs	14	12	148
Other Operating Expenses	1,032	1,440	1,055
Net Premiums Written	(2)	0	487
North America Commercial | Reportable Segments
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Deferred Policy Acquisition Costs	454	379
Liability for Unpaid Losses and Loss Adjustment Expenses, Future Policy Benefits	39,171	39,619
Unearned Premiums	6,185	5,936
Policy and Contract Claims	0	0
Premiums	8,626	8,172	10,233
Losses and Loss Expenses Incurred	5,466	5,713	6,323
Amortization of Deferred Policy Acquisition Costs	862	824	1,371
Other Operating Expenses	1,154	1,087	1,184
Net Premiums Written	8,759	8,452	11,432
International Commercial | Reportable Segments
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Deferred Policy Acquisition Costs	582	718
Liability for Unpaid Losses and Loss Adjustment Expenses, Future Policy Benefits	18,208	16,208
Unearned Premiums	6,313	5,773
Policy and Contract Claims	0	0
Premiums	8,580	8,145	7,964
Losses and Loss Expenses Incurred	4,781	4,463	4,641
Amortization of Deferred Policy Acquisition Costs	1,088	1,018	943
Other Operating Expenses	1,593	1,437	1,378
Net Premiums Written	8,663	8,364	8,168
Global Personal | Reportable Segments
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Deferred Policy Acquisition Costs	1,069	1,063
Liability for Unpaid Losses and Loss Adjustment Expenses, Future Policy Benefits	7,908	7,899
Unearned Premiums	5,350	5,340
Policy and Contract Claims	0	0
Premiums	6,472	7,140	6,894
Losses and Loss Expenses Incurred	3,721	3,862	3,811
Amortization of Deferred Policy Acquisition Costs	1,407	1,571	1,309
Other Operating Expenses	1,274	1,565	1,782
Net Premiums Written	$ 6,253	$ 7,086	$ 7,119