Investments - Net Investment Income (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Net Investment Income [Line Items]
Investment income, operating	$ 790	$ 740	$ 1,429	$ 1,372
Investment expenses	(29)	(26)	(55)	(50)
Net investment income	761	714	1,374	1,322
Aggregate income (loss) recognized due to the change in fair value of equity and trading portfolio securities held	22	30	(13)	(10)
Fixed maturity securities
Net Investment Income [Line Items]
Investment income, operating	552	536	1,095	1,057
Limited partnership investments
Net Investment Income [Line Items]
Gain (losses) on investments, before investment expenses	99	81	154	137
Short-term investments
Net Investment Income [Line Items]
Investment income, operating	11	16	31	35
Equity securities
Net Investment Income [Line Items]
Gain (losses) on investments, before investment expenses	41	27	37	33
Income from trading portfolio
Net Investment Income [Line Items]
Gain (losses) on investments, before investment expenses	61	52	59	56
Other
Net Investment Income [Line Items]
Investment income, operating	$ 26	$ 28	$ 53	$ 54

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

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Trading Securities, Change in Unrealized Holding Gain (Loss), Net Investment Income Recognized

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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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