Investments (Net Investment Income) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Net Investment Income [Line Items]
Gross investment income	$ 1,320	$ 1,034	$ 3,789	$ 2,694
Less: Investment expenses	39	38	109	130
Net investment income	1,281	996	3,680	2,564
Fixed maturity securities
Net Investment Income [Line Items]
Gross investment income	716	676	2,109	2,021
Equity securities
Net Investment Income [Line Items]
Gross investment income	1	1	3	4
Mortgage loans
Net Investment Income [Line Items]
Gross investment income	171	166	502	498
Policy loans
Net Investment Income [Line Items]
Gross investment income	16	15	49	40
Limited partnerships and LLCs
Net Investment Income [Line Items]
Gross investment income	402	155	1,090	48
Cash, cash equivalents and short-term investments
Net Investment Income [Line Items]
Gross investment income	1	7	4	44
Other
Net Investment Income [Line Items]
Gross investment income	$ 13	$ 14	$ 32	$ 39

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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