Investments - Net Investment Income (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Net Investment Income [Line Items]
Investment income, operating	$ 768	$ 800	$ 2,140	$ 2,156
Investment expenses	(25)	(24)	(75)	(72)
Net investment income	743	776	2,065	2,084
Aggregate income (loss) recognized due to the change in fair value of equity and trading portfolio securities held	72	108	42	123
Fixed maturity securities
Net Investment Income [Line Items]
Investment income, operating	540	517	1,597	1,530
Limited partnership investments
Net Investment Income [Line Items]
Gain (losses) on investments, before investment expenses	68	67	205	195
Short-term investments
Net Investment Income [Line Items]
Investment income, operating	19	21	54	70
Equity securities
Net Investment Income [Line Items]
Gain (losses) on investments, before investment expenses	12	21	45	56
Income from trading portfolio
Net Investment Income [Line Items]
Gain (losses) on investments, before investment expenses	99	141	155	210
Other
Net Investment Income [Line Items]
Investment income, operating	$ 30	$ 33	$ 84	$ 95

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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