Investments (Real Estate and Real Estate Joint Ventures) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Real Estate [Line Items]
Leased real estate investments, Carrying Value	$ 5,450	$ 4,893
Other real estate investments, Carrying Value	419	420
Real estate joint ventures, Carrying Value	6,064	5,428
Real Estate Investments, Net	11,933	10,741
Income (Loss) from Equity Method Investments	829	795	$ 592
Real estate and real estate joint ventures
Real Estate [Line Items]
Gross Investment Income, Operating	532	676	694
Leased real estate investments
Real Estate [Line Items]
Operating Lease, Lease Income	435	380	399
Other real estate investments
Real Estate [Line Items]
Operating Lease, Lease Income	133	192	188
Real estate joint ventures
Real Estate [Line Items]
Income (Loss) from Equity Method Investments	$ (36)	$ 104	$ 107

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 operating lease income from lease payments and variable lease payments paid and payable to lessor. Includes, but is not limited to, variable lease payments not included in measurement of lease receivable.

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Amount of real estate investments, net of accumulated depreciation, which may include the following: (1) land available-for-sale; (2) land available-for-development; (3) investments in building and building improvements; (4) tenant allowances; (5) developments in-process; (6) rental properties; (7) other real estate investments; (8) real estate joint ventures; and (9) unconsolidated real estate and other joint ventures not separately presented.

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The book value of investments in real estate joint ventures including direct and indirect investments.

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Amount of real estate owned for income production and capital accretion potential, not otherwise specified in the existing taxonomy. Such real estate excludes that which is occupied or used in the business, for entertainment purposes, or held in inventory for specific purposes.

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Carrying amount of income producing properties held for rental.

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