Investments (Details Textual) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2011 Securities	Dec. 31, 2010	Dec. 31, 2009
Schedule of Available for Sale Securities [Line Items]
Percentage (based on amount of unrealized loss) of available for sale fixed maturities that are in an unrealized loss position and rated investment grade	38.00%
Percentage (based on fair value) of available for sale fixed maturities that are in an unrealized loss position and rated investment grade	62.00%
Other than temporary impairment charges	$ 52	$ 62	$ 203
Investments (Textual) [Abstract]
Number of available for sale fixed maturities in an unrealized loss position	850
Number of Residential MBS that have been in an unrealized loss position for 12 months or more	239
RMBS unrealized losses for 12 months or more as a percentage of total AFS fixed maturity unrealized losses for 12 months or more	87.00%
Average life of MBS	4 years
Realized gain (loss) from the mark-to-market of certain MBS	(1)	50	157
Residential Mortgage Backed Securities [Member]
Schedule of Available for Sale Securities [Line Items]
Non-credit related portion of other-than-temporary impairment charges taken for securities still owned	227	258
Percentage (based on amount of unrealized loss) of available for sale fixed maturities that are in an unrealized loss position for more than 12 months and rated investment grade	27.00%
Percentage (based on fair value) of available for sale fixed maturities that are in an unrealized loss position for more than 12 months and rated investment grade	49.00%
Percentage of gross unrealized losses on the available for sale fixed maturity portfolio	72.00%
Other than temporary impairment charges	52
Investments (Textual) [Abstract]
Gross unrealized losses on fixed maturities	180	128
Fixed Maturity Securities [Member]
Schedule of Available for Sale Securities [Line Items]
Other than temporary impairment charges	57	79	221
Investments (Textual) [Abstract]
Gross unrealized losses on fixed maturities	249	216
Other Corporate [Member]
Schedule of Available for Sale Securities [Line Items]
Other than temporary impairment charges	$ 6

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Mortgage backed securities average useful life.

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Non-credit related portion of other-than-temporary impairment charges taken for securities still owned.

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Number of Available For Sale Securities In An Unrealized Loss Position.

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Number Of Residential MBS That Have Been In Unrealized Loss Position For 12 Months Or More.

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Percentage (based on amount of unrealized loss) of available for sale fixed maturities that are in an unrealized loss position for more than 12 months and rated investment grade.

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Percentage (based on fair value) of available for sale fixed maturities that are in an unrealized loss position and rated investment grade.

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Percentage (based on fair value) of available for sale fixed maturities that are in an unrealized loss position for more than 12 months and rated investment grade.

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Percentage based on unrealized loss of available for sale fixed maturities that are in an unrealized loss position and rated investment grade.

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Percentage Of Gross Unrealized Loss On Available For Sale Fixed Maturity.

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Realized gain (loss) from mark to market of certain mortgage backed securities.

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RMBS Unrealized Losses For 12 Months Or More As Percentage Of Available For Sale Fixed Maturity Unrealized Losses For 12 Months Or More.

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This item represents the gross unrealized losses for securities, at a point in time, which are categorized neither as held-to-maturity nor trading securities.

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The amount of other than temporary impairment losses on investments in debt and equity securities categorized as Available-for-sale which have been recognized in earnings during the period. Such impairment losses consist of other than temporary impairments (OTTI) on equity securities, credit losses on investments in debt securities, and when the entity intends to sell an impaired debt security or it is more likely than not that the entity will be required to sell the impaired debt security before recovery of its amortized cost basis.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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