Investments (Details 6) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2013	Mar. 31, 2012
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses	$ (1)	$ (33)
Portion of loss recognized in other comprehensive income	(8)	(3)
Net other-than-temporary impairment losses recognized in earnings	(9)	(36)
Fixed income securities
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses	(25)	(31)
Portion of loss recognized in other comprehensive income	(8)	(3)
Net other-than-temporary impairment losses recognized in earnings	(33)	(34)
Municipal
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses	(7)
Net other-than-temporary impairment losses recognized in earnings	(7)
Corporate
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses		(13)
Net other-than-temporary impairment losses recognized in earnings		(13)
RMBS
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses	1	(12)
Portion of loss recognized in other comprehensive income	(1)	(3)
Net other-than-temporary impairment losses recognized in earnings		(15)
CMBS
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses	(19)	(6)
Portion of loss recognized in other comprehensive income	(7)
Net other-than-temporary impairment losses recognized in earnings	(26)	(6)
Mortgage loans
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses	26	(3)
Net other-than-temporary impairment losses recognized in earnings	26	(3)
Limited partnership interests
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses		(1)
Net other-than-temporary impairment losses recognized in earnings		(1)
Other
Other-than-temporary impairment losses by asset type
Total other-than-temporary impairment losses	(2)	2
Net other-than-temporary impairment losses recognized in earnings	$ (2)	$ 2

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

Before tax amount of other than temporary impairment (OTTI) on a debt security, categorized as either available-for-sale or held-to-maturity, recognized in other comprehensive income (loss), attributable to the parent entity.

+ References+ 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.

+ References+ Details