Investments (Net investment income) (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2022	Mar. 31, 2021
Net Investment Income [Line Items]
Gross investment income	$ 465	$ 521
Investment expense	(17)	(17)
Net investment income	448	504
Fixed maturity securities
Net Investment Income [Line Items]
Gross investment income	429	428
Equity securities
Net Investment Income [Line Items]
Gross investment income	2	29
Limited partnership investments
Net Investment Income [Line Items]
Gross investment income	18	43
Mortgage loans
Net Investment Income [Line Items]
Gross investment income	15	14
Trading portfolio
Net Investment Income [Line Items]
Gross investment income	1	5
Other
Net Investment Income [Line Items]
Gross investment income	$ 0	$ 2

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.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
-Topic 944
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04.2)
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Amount of expenses related to the generation of investment income.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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-Topic 944
-SubTopic 220
-Section S99
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-Subparagraph (SX 210.7-04.2)
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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.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
-Topic 944
-SubTopic 220
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-Paragraph 1
-Subparagraph (SX 210.7-04(2))
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