Reinsurance (Funds Withheld) (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Reinsurance Liabilities Table [Line Items]
Funds Held under Reinsurance Agreements, Liability	$ 5,017	$ 4,483
Funds withheld at interest	5,436	5,683
Available-for-sale Securities [Member]
Reinsurance Liabilities Table [Line Items]
Funds withheld at interest	2,615	2,442
Equity Securities [Member]
Reinsurance Liabilities Table [Line Items]
Funds withheld at interest	2	2
Mortgage Loans on Real Estate [Member]
Reinsurance Liabilities Table [Line Items]
Funds withheld at interest	451	451
Funds Withheld At Interest [Member]
Reinsurance Liabilities Table [Line Items]
Funds withheld at interest	1,466	1,545
Partnership Interest [Member]
Reinsurance Liabilities Table [Line Items]
Funds withheld at interest	54	35
Short-term Investments [Member]
Reinsurance Liabilities Table [Line Items]
Funds withheld at interest	89	30
Accrued Income Receivable
Reinsurance Liabilities Table [Line Items]
Funds withheld at interest	31	28
Other Assets
Reinsurance Liabilities Table [Line Items]
Funds withheld at interest	0	1
Assets
Reinsurance Liabilities Table [Line Items]
Funds withheld at interest	$ 4,708	$ 4,534