Investments (Net investment income) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Net Investment Income [Line Items]
Gross investment income	$ 533	$ 503	$ 1,428	$ 1,621
Investment expense	(16)	(16)	(48)	(48)
Net investment income	517	487	1,380	1,573
Fixed maturity securities
Net Investment Income [Line Items]
Gross investment income	432	452	1,300	1,362
Equity securities
Net Investment Income [Line Items]
Gross investment income	18	16	24	62
Limited partnership investments
Net Investment Income [Line Items]
Gross investment income	64	12	38	125
Mortgage loans
Net Investment Income [Line Items]
Gross investment income	14	13	42	37
Short term investments
Net Investment Income [Line Items]
Gross investment income	1	8	9	27
Trading portfolio
Net Investment Income [Line Items]
Gross investment income	4	2	13	6
Other
Net Investment Income [Line Items]
Gross investment income	$ 0	$ 0	$ 2	$ 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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