Investments (Mortgage Loans by Portfolio Segment) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Notes, Loans and Financing Receivable, Net, Current [Abstract]
Commercial mortgage loans	$ 8,502	$ 7,348
Percentage of loans receivable on commercial mortgage loans	62.60%	69.00%
Agricultural mortgage loans	$ 2,874	$ 2,200
Percentage of loans receivable on agricultural mortgage loans	21.10%	20.70%
Residential mortgage loans	$ 2,276	$ 1,138
Percentage of loans receivable on residential mortgage loans	16.70%	10.70%
Subtotal	$ 13,652	$ 10,686
Percentage of loans receivable on subtotal	100.40%	100.40%
Valuation allowances	$ (56)	$ (46)
Percentage of loans receivable on valuation allowances	0.40%	0.40%
Mortgage Loans on Real Estate, Commercial and Consumer, Net	$ 13,596	$ 10,640
Percentage of loans held for sale on total mortgage loans, net	100.00%	100.00%

The balance represents the amount of loans that are secured by real estate mortgages.

No definition available.

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- Definition

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

+ References

No definition available.

+ Details

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- Definition

Percentage of Consumer Mortgage Loans and Leases Receivable to total Mortgage Loans on Real Estate.

+ References

No definition available.

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- Definition

Percentage of Commercial Agricultural Loans Receivable to total Mortgage Loans on Real Estate.

+ References

No definition available.

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- Definition

Percentage of Commercial Mortgage Loans Receivable to total Mortgage Loans on Real Estate.

+ References

No definition available.

+ Details

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- Definition

Percentage of Mortgage Loans Held For Investment to total Mortgage Loans on Real Estate.

+ References

No definition available.

+ Details

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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=82921503&loc=d3e21338-158488

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- Definition

Amount before allowance of consumer mortgage. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes subordinated loans such as home equity lines of credit and loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=82891408&loc=d3e4428-111522

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.7(a)(3),(b))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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- Definition

Amount before allowance of loans issued to agricultural institutions. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans covered under loss sharing agreements.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.7(a)(1))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5066-111524

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- Definition

Amount before allowance of mortgage loans on existing land or building. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans covered under loss sharing agreements.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5066-111524

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
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-Subparagraph (SX 210.9-03.7(a)(3))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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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=6879938&loc=d3e572229-122910

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- References

No definition available.

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