Investments (Net investment income) (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2025	Mar. 31, 2024
Net Investment Income [Line Items]
Gross investment income	$ 626	$ 630
Investment expense	(22)	(21)
Net investment income	604	609
Fixed maturity securities
Net Investment Income [Line Items]
Gross investment income	522	502
Equity securities
Net Investment Income [Line Items]
Gross investment income	6	22
Limited partnership investments
Net Investment Income [Line Items]
Gross investment income	56	54
Mortgage loans
Net Investment Income [Line Items]
Gross investment income	16	15
Short-term investments
Net Investment Income [Line Items]
Gross investment income	19	28
Trading portfolio
Net Investment Income [Line Items]
Gross investment income	1	1
Other
Net Investment Income [Line Items]
Gross investment income	6	8
Common Stock
Net Investment Income [Line Items]
Net investment income (loss) recognized due to the change in fair value of common stock held as of March 31, 2025 and 2024	$ (4)	$ 13

Amount of unrealized and realized gain (loss) on investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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Amount, before investment expense, of income earned from investments in securities and real estate. Includes, but is not limited to, real estate investment, policy loans, dividends, and interest. Excludes realized gain (loss) on investments.

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