Investments - Net Investment Income (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2026	Sep. 30, 2025	Sep. 30, 2026	Sep. 30, 2025
Net Investment Income [Line Items]
Investment income, operating	$ 740	$ 768	$ 2,169	$ 2,140
Investment expenses	(27)	(25)	(82)	(75)
Net investment income	713	743	2,087	2,065
Aggregate income (loss) recognized due to the change in fair value of equity and trading portfolio securities held	(21)	72	(27)	42
Fixed maturity securities
Net Investment Income [Line Items]
Investment income, operating	565	540	1,660	1,597
Limited partnership investments
Net Investment Income [Line Items]
Gain (losses) on investments, before investment expenses	35	68	189	205
Short-term investments
Net Investment Income [Line Items]
Investment income, operating	14	19	45	54
Equity securities
Net Investment Income [Line Items]
Gain (losses) on investments, before investment expenses	22	12	59	45
Income from trading portfolio
Net Investment Income [Line Items]
Gain (losses) on investments, before investment expenses	77	99	136	155
Other
Net Investment Income [Line Items]
Investment income, operating	$ 27	$ 30	$ 80	$ 84

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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