Investments (Real Estate and Real Estate Joint Ventures) (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Real Estate [Line Items]
Leased real estate investments, Carrying Value	$ 5,129		$ 4,893
Other real estate investments, Carrying Value	419		420
Real estate joint ventures, Carrying Value	5,702		5,428
Real estate and real estate joint ventures (includes $144 and $127, respectively, under the fair value option)	11,250		$ 10,741
Real Estate and Real Estate Joint Ventures
Real Estate [Line Items]
Gross Investment Income, Operating	165	$ 130
Leased real estate investments
Real Estate [Line Items]
Operating Lease, Lease Income	106	92
Other real estate investments
Real Estate [Line Items]
Operating Lease, Lease Income	35	34
Real estate joint ventures
Real Estate [Line Items]
Income (Loss) from Equity Method Investments	$ 24	$ 4

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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