Investments (Details 6) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Other-than-temporary impairment losses by asset type
Gross	$ (9)	$ (84)	$ (51)	$ (207)
Included in OCI	(4)	(4)	(4)	(17)
Net	(13)	(88)	(55)	(224)
Fixed income securities
Other-than-temporary impairment losses by asset type
Gross	(5)	(50)	(51)	(156)
Included in OCI	(4)	(4)	(4)	(17)
Net	(9)	(54)	(55)	(173)
Municipal
Other-than-temporary impairment losses by asset type
Gross				(12)
Included in OCI				(3)
Net				(15)
Corporate
Other-than-temporary impairment losses by asset type
Gross		(14)	(14)	(18)
Included in OCI	(2)		(2)	1
Net	(2)	(14)	(16)	(17)
RMBS
Other-than-temporary impairment losses by asset type
Gross	(1)	(35)	(18)	(93)
Included in OCI	(5)	(1)	(8)	(7)
Net	(6)	(36)	(26)	(100)
CMBS
Other-than-temporary impairment losses by asset type
Gross	(4)	(1)	(19)	(27)
Included in OCI	3	(3)	6	(10)
Net	(1)	(4)	(13)	(37)
ABS
Other-than-temporary impairment losses by asset type
Gross				(6)
Included in OCI				2
Net				(4)
Equity securities
Other-than-temporary impairment losses by asset type
Gross	(1)		(1)	(5)
Net	(1)		(1)	(5)
Mortgage loans
Other-than-temporary impairment losses by asset type
Gross	(1)	(29)	3	(38)
Net	(1)	(29)	3	(38)
Limited partnership interests
Other-than-temporary impairment losses by asset type
Gross			(2)	(1)
Net			(2)	(1)
Other
Other-than-temporary impairment losses by asset type
Gross	(2)	(5)		(7)
Net	$ (2)	$ (5)		$ (7)

The amount by which the fair value of an investment is less than the amortized cost basis or carrying amount of that investment at the balance sheet date and the decline in fair value is deemed to be other than temporary, before considering whether or not such amount is recognized in earnings or other comprehensive income.

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

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number FAS115-1/124-1

-Paragraph 15C

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 35

-Paragraph 34

-URI http://asc.fasb.org/extlink&oid=16383099&loc=d3e25351-111560

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 16

-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.

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number FAS115-1/124-1

-Paragraph 16B

-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.

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number FAS115-1/124-1

-Paragraph 15D

-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.

Reference 6: 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=6943989&loc=d3e3602-108585

Reference 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number FAS115-2/124-2

-Paragraph 22

-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.

+ Details

- Definition

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.

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