Derivatives and Hedge Accounting - Derivatives not Designated as Hedging Instruments (Details) - Derivatives not designated as hedging instruments - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total	$ (62)	$ (152)	$ (266)	$ (220)
Net Investment Income - Fortitude Re Funds Withheld Assets
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total	$ 0	$ 0	$ (1)	$ 0
Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Net Investment Income	Net Investment Income	Net Investment Income	Net Investment Income
Net realized gains (losses) - Excluding Fortitude Re Funds Withheld Assets
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total	$ (10)	$ 7	$ (136)	$ (62)
Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Realized Investment Gains (Losses)	Realized Investment Gains (Losses)	Realized Investment Gains (Losses)	Realized Investment Gains (Losses)
Net Realized Gains (Losses) On Fortitude Re funds Withheld Assets
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total	$ (52)	$ (159)	$ (129)	$ (158)
Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Realized Investment Gains (Losses)	Realized Investment Gains (Losses)	Realized Investment Gains (Losses)	Realized Investment Gains (Losses)
Interest rate contracts
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total	$ 0	$ (1)	$ (5)	$ (3)
Foreign exchange contracts
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total	(8)	3	(152)	(62)
Credit contracts
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total	0	3	0	3
Embedded derivatives
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total	$ (54)	$ (157)	$ (109)	$ (158)