Reinsurance (Funds Withheld) (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Reinsurance Funds Withheld Assets [Line Items]
Funds withheld at interest	$ 8,268	$ 5,436
Fixed Maturities [Member]
Reinsurance Funds Withheld Assets [Line Items]
Funds withheld at interest	2,930	2,615
Equity securities
Reinsurance Funds Withheld Assets [Line Items]
Funds withheld at interest	2	2
Mortgage Loans on Real Estate [Member]
Reinsurance Funds Withheld Assets [Line Items]
Funds withheld at interest	549	451
Funds withheld at interest
Reinsurance Funds Withheld Assets [Line Items]
Funds withheld at interest	1,401	1,466
Partnership
Reinsurance Funds Withheld Assets [Line Items]
Funds withheld at interest	52	54
Short-term Investments [Member]
Reinsurance Funds Withheld Assets [Line Items]
Funds withheld at interest	67	89
Accrued Income Receivable
Reinsurance Funds Withheld Assets [Line Items]
Funds withheld at interest	37	31
Other Assets
Reinsurance Funds Withheld Assets [Line Items]
Funds withheld at interest	1	0
Assets
Reinsurance Funds Withheld Assets [Line Items]
Funds withheld at interest	$ 5,039	$ 4,708