Investments (Net investment income) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Net Investment Income [Line Items]
Gross investment income	$ 647	$ 573	$ 1,916	$ 1,711
Investment expense	(21)	(20)	(63)	(58)
Net investment income	626	553	1,853	1,653
Fixed maturity securities
Net Investment Income [Line Items]
Gross investment income	517	491	1,530	1,443
Equity securities
Net Investment Income [Line Items]
Gross investment income	21	9	56	42
Limited partnership investments
Net Investment Income [Line Items]
Gross investment income	67	28	195	108
Mortgage loans
Net Investment Income [Line Items]
Gross investment income	14	15	43	43
Short-term investments
Net Investment Income [Line Items]
Gross investment income	20	23	68	51
Trading portfolio
Net Investment Income [Line Items]
Gross investment income	0	1	1	4
Other
Net Investment Income [Line Items]
Gross investment income	8	6	23	20
Common Stock
Net Investment Income [Line Items]
Net investment income (loss) recognized due to change in fair value of stock held	11	(3)	20	2
Non-redeemable preferred stock
Net Investment Income [Line Items]
Net investment income (loss) recognized due to change in fair value of stock held	$ 13	$ 2	$ 24	$ 2

Amount of unrealized and realized gain (loss) on investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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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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