Investments (Details) - Net Investment Income - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Net investment income
Gross investment income	$ 2,264	$ 2,508	$ 2,513
Investment expenses	37	40	39
Net investment income	2,227	2,468	2,474
Fixed maturities [Member]
Net investment income
Gross investment income	2,011	2,070	1,980
Equity securities [Member]
Net investment income
Gross investment income	15	15	16
Short-term securities [Member]
Net investment income
Gross investment income	44	105	92
Real estate [Member]
Net investment income
Gross investment income	48	55	48
Other investments [Member]
Net investment income
Gross investment income	$ 146	$ 263	$ 377

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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