Segment Information - Schedule of Continuing Operations by Operating Segment (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Segment Reporting Information [Line Items]
Net Premiums Earned	$ 5,770	$ 5,871
Loss and Loss Adjustment Expenses Incurred	3,794	3,513
Amortization of DAC	825	838
General Operating Expense	1,115	1,238
Net Investment Income	1,105	979
Income from continuing operations before income tax expense	960	1,058
Interest expense	92	116
Changes in the fair values of equity securities and AIG's investment in Corebridge	217	88
Other income (expense) - net		1
Total net realized losses	(103)	(87)
Net realized gains (losses), net investment income	(2)	7
Net realized gains (losses), reconciliation to income (loss) from continuing operations before income tax expense	(66)	(55)
Net gain on divestitures and other	3	0
Non-operating litigation reserves and settlements, reconciliation to income (loss) from continuing operations before income tax expense	11
Unfavorable prior year development and related amortization changes ceded under retroactive reinsurance agreements	(9)	(2)
Net loss reserve discount charge	(17)	(76)
Non-operating pension expense	(5)
Net results of businesses in run-off, net investment income	5	3
Net results of businesses in run-off, net investment income, reconciliation to income (loss) from continuing operations before income tax expense	5	7
Integration and transaction costs associated with acquiring or divesting businesses	(5)	3
Restructuring and other costs	$ (76)	$ (67)
Restructuring Charges, Statement of Income or Comprehensive Income [Extensible Enumeration]	General Operating Expense	General Operating Expense
Non-recurring costs related to regulatory or accounting changes	$ (4)	$ (4)
Fortitude Re funds withheld assets
Segment Reporting Information [Line Items]
Net Investment Income	40	39
Total net realized losses	(2)	(19)
Fortitude Re funds withheld embedded derivative
Segment Reporting Information [Line Items]
Total net realized losses	(41)	(9)
Total
Segment Reporting Information [Line Items]
Net Investment Income	845	841
Income from continuing operations before income tax expense	909	1,153
Reportable Segments
Segment Reporting Information [Line Items]
Net Premiums Written	4,526	4,512
Net Premiums Earned	5,769	5,786
Loss and Loss Adjustment Expenses Incurred	3,766	3,353
Amortization of DAC	825	828
Other Acquisition Cost	232	275
General Operating Expense	703	734
Underwriting Income (Loss)	243	596
Net Investment Income	736	762
Income from continuing operations before income tax expense	979	1,358
Interest expense	(91)	(115)
Other Operations
Segment Reporting Information [Line Items]
Net Investment Income	108	76
Income from continuing operations before income tax expense	21	(89)
Elimination and consolidations
Segment Reporting Information [Line Items]
Net Investment Income	1	3
Income from continuing operations before income tax expense	0	(1)
North America Commercial | Reportable Segments
Segment Reporting Information [Line Items]
Net Premiums Written	1,174	1,033
Net Premiums Earned	2,124	1,983
Loss and Loss Adjustment Expenses Incurred	1,526	1,270
Amortization of DAC	227	220
Other Acquisition Cost	47	37
General Operating Expense	195	220
Underwriting Income (Loss)	129	236
International Commercial | Reportable Segments
Segment Reporting Information [Line Items]
Net Premiums Written	2,027	1,939
Net Premiums Earned	2,051	2,011
Loss and Loss Adjustment Expenses Incurred	1,178	1,088
Amortization of DAC	245	244
Other Acquisition Cost	94	89
General Operating Expense	294	260
Underwriting Income (Loss)	240	330
Global Personal | Reportable Segments
Segment Reporting Information [Line Items]
Net Premiums Written	1,325	1,540
Net Premiums Earned	1,594	1,792
Loss and Loss Adjustment Expenses Incurred	1,062	995
Amortization of DAC	353	364
Other Acquisition Cost	91	149
General Operating Expense	214	254
Underwriting Income (Loss)	$ (126)	$ 30