Investments (Repurchase Agreements - Narrative) (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Securities Financing Transaction [Line Items]
Federal Home Loan Bank, Advances, General Debt Obligations, Disclosures, Collateral Pledged	$ 1,300	$ 564
Federal Home Loan Bank, Advances, Branch of FHLB Bank, Amount of Advances	$ 800	300
Repurchase Agreements [Member]
Securities Financing Transaction [Line Items]
Percentage of Reinvestment Portfolio in Fixed Maturity Securities	64.00%
U.S. government and agency
Securities Financing Transaction [Line Items]
Federal Home Loan Bank, Advances, Branch of FHLB Bank, Amount of Advances	$ 804	$ 300

The percentage of the reinvestment portfolio acquired with the cash collateral consists mainly of Fixed maturities.

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- Definition

Amount of advances from the Federal Home Loan Bank (FHLB).

+ References

+ Details

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- Definition

Amount of the collateral pledged in support of federal home loan bank advances outstanding.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6479118&loc=d3e64650-112822

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823

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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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