Investments (Net investment income) (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Net Investment Income [Line Items]
Gross investment income	$ 607	$ 549	$ 1,128	$ 895
Investment expense	(16)	(15)	(33)	(32)
Net investment income	591	534	1,095	863
Fixed maturity securities
Net Investment Income [Line Items]
Gross investment income	425	430	853	868
Equity securities
Net Investment Income [Line Items]
Gross investment income	20	50	49	6
Limited partnership investments
Net Investment Income [Line Items]
Gross investment income	146	44	189	(26)
Mortgage loans
Net Investment Income [Line Items]
Gross investment income	15	14	29	28
Short term investments
Net Investment Income [Line Items]
Gross investment income	0	1	0	8
Trading portfolio
Net Investment Income [Line Items]
Gross investment income	2	8	7	9
Other
Net Investment Income [Line Items]
Gross investment income	$ (1)	$ 2	$ 1	$ 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.

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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.

+ References

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