Investments (Net investment income) (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Net Investment Income [Line Items]
Gross investment income	$ 594	$ 450	$ 1,138	$ 915
Investment expense	(19)	(18)	(38)	(35)
Net investment income	575	432	1,100	880
Fixed maturity securities
Net Investment Income [Line Items]
Gross investment income	482	441	952	870
Equity securities
Net Investment Income [Line Items]
Gross investment income	21	(11)	33	(9)
Limited partnership investments
Net Investment Income [Line Items]
Gross investment income	55	6	80	24
Mortgage loans
Net Investment Income [Line Items]
Gross investment income	14	12	28	27
Short term investments
Net Investment Income [Line Items]
Gross investment income	13	2	28	2
Trading portfolio
Net Investment Income [Line Items]
Gross investment income	0	0	3	1
Other
Net Investment Income [Line Items]
Gross investment income	9	0	14	0
Common Stock
Net Investment Income [Line Items]
Net investment income (loss) recognized due to the change in fair value of common stock held as of June 30, 2023 and 2022	$ 10	$ (22)	$ 7	$ (23)

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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