Deferred Policy Acquisition Costs, Value of Business Acquired and Other Policy-Related Intangibles (Deferred Sales Inducements) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
DSI
Balance at January 1,	$ 432	$ 515	$ 566
Capitalization	2	3	3
Amortization	(12)	(83)	(72)
Unrealized investment gains (losses)	(11)	(3)	18
Balance at December 31,	$ 411	$ 432	$ 515

Amount of addition in deferred sales inducement cost.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 30
-Section 50
-Paragraph 3
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6481800&loc=d3e11332-158416

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- Definition

Amount of increase (decrease) in deferred sales inducement cost, classified as other.

+ References

No definition available.

+ Details

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- Definition

Amount of amortization expense (reversal of expense) for deferred sales inducement cost.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 30
-Section 50
-Paragraph 3
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6481800&loc=d3e11332-158416

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- Definition

Amount, after accumulated amortization, of deferred sales inducement cost.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 30
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6481800&loc=d3e11332-158416

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

+ Details

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