Investments (Mortgage Loans by Portfolio Segment) (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value	$ 15,333	$ 13,652
Mortgage loans, gross as a percentage of total mortgage loans, net	100.40%	100.40%
Mortgage loans valuation allowances	$ (64)	$ (56)
Mortgage loans valuation allowances as a percentage of total mortgage loans, net	(0.40%)	(0.40%)
Total mortgage loans, net	$ 15,269	$ 13,596
Total mortgage loans, net as a percentage of total mortgage loans, net	100.00%	100.00%
Mortgage Loans \| Commercial
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value	$ 9,446	$ 8,502
Mortgage loans, gross as a percentage of total mortgage loans, net	61.90%	62.60%
Mortgage Loans \| Agricultural
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value	$ 3,228	$ 2,874
Mortgage loans, gross as a percentage of total mortgage loans, net	21.10%	21.10%
Mortgage Loans \| Residential
Loans and Leases Receivable Disclosure [Line Items]
Carrying Value	$ 2,659	$ 2,276
Mortgage loans, gross as a percentage of total mortgage loans, net	17.40%	16.70%

Percentage of Allowance For Loan And Lease Losses on Real Estate to total Mortgage Loans on Real Estate.

No definition available.

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- Definition

Percentage of loans receivable to total mortgage loans on real estate, net of valuation allowances.

+ References

No definition available.

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- Definition

Percentage of Mortgage Loans On Real Estate to total Mortgage Loans on Real Estate.

+ References

No definition available.

+ Details

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- Definition

The reserve to cover probable credit losses related to specifically identified fixed maturity real estate loans as well as probable credit losses inherent in the remainder of that loan portfolio.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 310
-Section 45
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=118959141&loc=d3e21338-158488

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

The balance represents the amount of loans that are secured by real estate mortgages, offset by the reserve to cover probable credit losses on the loan portfolio.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.1(c))
-URI http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910

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- Definition

Amount, before allowance for credit loss, of financing receivable.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 5
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=119407570&loc=SL82919230-210447

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