Investments (Net Investment Income) (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
Net Investment Income [Line Items]
Less: Investment expenses	$ 237	$ 324
Net investment income	5,314	3,061
Securities Investment
Net Investment Income [Line Items]
Gross Investment Income, Operating	5,344	4,525
Net investment income	5,107	4,201
Fixed Maturity Securities
Net Investment Income [Line Items]
Gross Investment Income, Operating	2,753	2,875
Equity Securities
Net Investment Income [Line Items]
Gross Investment Income, Operating	11	14
FVO Securities (1)
Net Investment Income [Line Items]
Net investment income	36	(78)
Mortgage loans
Net Investment Income [Line Items]
Gross Investment Income, Operating	863	884
Policy loans
Net Investment Income [Line Items]
Gross Investment Income, Operating	121	126
Real Estate and Real Estate Joint Ventures
Net Investment Income [Line Items]
Gross Investment Income, Operating	176	165
Other limited partnership interests
Net Investment Income [Line Items]
Gross Investment Income, Operating	1,282	320
Cash, cash equivalents and short-term investments
Net Investment Income [Line Items]
Gross Investment Income, Operating	25	92
Operating joint ventures
Net Investment Income [Line Items]
Gross Investment Income, Operating	23	25
Other Investments
Net Investment Income [Line Items]
Gross Investment Income, Operating	54	102
Unit-linked investments
Net Investment Income [Line Items]
Net investment income	207	(1,140)
Trading Securities, Change in Unrealized Holding Gain (Loss)	$ 197	$ (1,100)

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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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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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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