Investments - Net Investment Income (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2026	Mar. 31, 2025
Net Investment Income [Line Items]
Investment income, operating	$ 639	$ 632
Investment expenses	(26)	(24)
Net investment income	613	608
Aggregate income (loss) recognized due to the change in fair value of equity and trading portfolio securities held	(74)	(49)
Fixed maturity securities
Net Investment Income [Line Items]
Investment income, operating	543	521
Limited partnership investments
Net Investment Income [Line Items]
Gain (losses) on investments, before investment expenses	55	56
Short-term investments
Net Investment Income [Line Items]
Investment income, operating	20	19
Equity securities
Net Investment Income [Line Items]
Gain (losses) on investments, before investment expenses	(4)	6
Income (loss) from trading portfolio
Net Investment Income [Line Items]
Gain (losses) on investments, before investment expenses	(2)	4
Other
Net Investment Income [Line Items]
Investment income, operating	$ 27	$ 26

Amount, before investment expenses, of gains (losses) on investments.

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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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Amount of expenses related to the generation of investment income.

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Amount, after 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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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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