Investments - Components of 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]
Gross investment income	$ 1,035	$ 924	$ 2,931	$ 2,609
Investment expenses	(10)	(10)	(28)	(26)
Net Investment Income	1,025	914	2,903	2,583
Available-for-sale Securities
Net Investment Income [Line Items]
Gross investment income	1,020	907	2,886	2,553
Total equity securities
Net Investment Income [Line Items]
Gross investment income	15	17	45	56
Total equity securities \| Nonredeemable preferred stocks
Net Investment Income [Line Items]
Gross investment income	2	6	8	19
Total equity securities \| Common equities
Net Investment Income [Line Items]
Gross investment income	13	11	37	37
Total fixed maturities
Net Investment Income [Line Items]
Gross investment income	1,001	887	2,807	2,487
Total fixed maturities \| U.S. government
Net Investment Income [Line Items]
Gross investment income	429	470	1,262	1,314
Total fixed maturities \| State and local government
Net Investment Income [Line Items]
Gross investment income	32	24	83	64
Total fixed maturities \| Corporate and other debt
Net Investment Income [Line Items]
Gross investment income	273	214	761	593
Total fixed maturities \| Residential mortgage-backed
Net Investment Income [Line Items]
Gross investment income	59	38	152	95
Total fixed maturities \| Commercial mortgage-backed
Net Investment Income [Line Items]
Gross investment income	90	63	244	175
Total fixed maturities \| Other asset-backed
Net Investment Income [Line Items]
Gross investment income	118	78	305	246
Short-term investments
Net Investment Income [Line Items]
Gross investment income	$ 19	$ 20	$ 79	$ 66

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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