Derivatives (Embedded Derivatives) (Details) - USD ($) $ in Millions	Jun. 30, 2026	Dec. 31, 2025
Derivatives, Fair Value [Line Items]
Embedded derivatives within asset host contracts (2)	$ (56)	$ (53)
Embedded derivatives within liability host contracts (2)	7	(166)
Assumed affiliated reinsurance \| StatementOfFinancialPositionLocationBalance [Axis]: us-gaap:OtherAssetsNoncurrent
Derivatives, Fair Value [Line Items]
Embedded derivatives within asset host contracts (2)	(62)	(22)
Assumed affiliated reinsurance \| StatementOfFinancialPositionLocationBalance [Axis]: us-gaap:OtherLiabilitiesNoncurrent
Derivatives, Fair Value [Line Items]
Embedded derivatives within liability host contracts (2)	0	53
Funds withheld on affiliated reinsurance \| StatementOfFinancialPositionLocationBalance [Axis]: us-gaap:OtherAssetsNoncurrent
Derivatives, Fair Value [Line Items]
Embedded derivatives within asset host contracts (2)	6	(31)
Funds withheld and guarantees on reinsurance (including affiliated) \| StatementOfFinancialPositionLocationBalance [Axis]: us-gaap:OtherLiabilitiesNoncurrent
Derivatives, Fair Value [Line Items]
Embedded derivatives within liability host contracts (2)	(356)	(281)
Fixed annuities with equity indexed returns [Member] \| StatementOfFinancialPositionLocationBalance [Axis]: us-gaap:PolicyholderFunds
Derivatives, Fair Value [Line Items]
Embedded derivatives within liability host contracts (2)	396	67
Funds withheld on unaffiliated reinsurance \| StatementOfFinancialPositionLocationBalance [Axis]: us-gaap:OtherLiabilitiesNoncurrent
Derivatives, Fair Value [Line Items]
Embedded derivatives within liability host contracts (2)	$ (33)	$ (5)