Investments (Net investment income) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Net Investment Income [Line Items]
Gross investment income	$ 1,877	$ 2,223	$ 1,999
Investment expense	(72)	(64)	(64)
Net investment income	1,805	2,159	1,935
Fixed maturity securities
Net Investment Income [Line Items]
Gross investment income	1,787	1,707	1,728
Equity securities
Net Investment Income [Line Items]
Gross investment income	23	83	65
Limited partnership investments
Net Investment Income [Line Items]
Gross investment income	(12)	362	121
Mortgage loans
Net Investment Income [Line Items]
Gross investment income	54	61	57
Short term investments
Net Investment Income [Line Items]
Gross investment income	16	1	9
Trading portfolio
Net Investment Income [Line Items]
Gross investment income	4	9	18
Other
Net Investment Income [Line Items]
Gross investment income	5	0	1
Common Stock
Net Investment Income [Line Items]
Equity securities, FV-NI, gain (loss)	47	28	34
Non-redeemable preferred stock
Net Investment Income [Line Items]
Equity securities, FV-NI, gain (loss)	$ (75)	$ 2	$ (3)

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).

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 321
-SubTopic 10
-Section 50
-Paragraph 4
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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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-Topic 944
-SubTopic 220
-Section S99
-Paragraph 1
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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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