Investments (Sales or Disposals and Impairments of Fixed Maturity and Equity Securities) (Details) - Fixed maturity securities - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Debt Securities, Available-for-sale [Line Items]
Proceeds from Sale of Insurance Investments	$ 2,450	$ 2,403	$ 5,288	$ 4,363
Available-for-sale Securities, Gross Realized Gains	9	11	12	20
Available-for-sale Securities, Realized Losses, Excluding Other than Temporary Impairments	(74)	(10)	(115)	(56)
Total OTTI losses recognized in earnings [Abstract]
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net	0	(1)	0	(1)
Components of Sales or Disposals of Fixed Maturity and Equity Securities [Abstract]
Net investment gains (losses)	$ (65)	$ 0	$ (103)	$ (37)

No definition available.

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- Definition

This item represents the gross profit realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities.

+ References

No definition available.

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Amount of loss realized on the sale of debt or equity securities classified as available-for-sale. Excludes other than temporary impairments (OTTI).

+ References

No definition available.

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- References

No definition available.

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The amount of other than temporary impairment (OTTI) losses on equity securities, OTTI related to credit losses on debt securities, and OTTI losses on debt securities when the entity intends to sell the securities or it is more likely than not that the entity will be required to sell the securities before recovery of its amortized cost basis. Additionally, this item includes OTTI losses recognized during the period on investments accounted for under the cost method of accounting.

+ References

No definition available.

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- Definition

The cash inflow associated with the sale of insurance policy investment assets during the period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3179-108585

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- Definition

The net realized gains or losses on investments during the period, not including gains or losses on securities separately or otherwise categorized as trading, available-for-sale, or held-to-maturity.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04.3(a))
-URI http://asc.fasb.org/extlink&oid=114873790&loc=SL114874131-224263

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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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