Investments (Net Investment Income) (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Net Investment Income [Line Items]
Gross investment income	$ 675	$ 966	$ 1,622	$ 1,808
Less: Investment expenses	40	48	91	102
Net investment income	635	918	1,531	1,706
Fixed maturity securities
Net Investment Income [Line Items]
Gross investment income	667	666	1,325	1,308
Equity securities
Net Investment Income [Line Items]
Gross investment income	1	2	3	5
Mortgage loans
Net Investment Income [Line Items]
Gross investment income	166	175	332	333
Policy loans
Net Investment Income [Line Items]
Gross investment income	8	12	14	22
Limited partnerships and LLCs
Net Investment Income [Line Items]
Gross investment income	(190)	87	(108)	95
Cash, cash equivalents and short-term investments
Net Investment Income [Line Items]
Gross investment income	12	17	32	27
Other
Net Investment Income [Line Items]
Gross investment income	$ 11	$ 7	$ 24	$ 18

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, 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.

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