Additional Insurance Benefits and Minimum Guarantees (Details) (USD $)	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011
Equity securities
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Aggregate fair value of securities supporting separate accounts	$ 9,300,000,000	$ 7,900,000,000
GMDBs
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Guaranteed minimum benefits	35,200,000,000	32,100,000,000
Additional liability recognized	$ 108,100,000	$ 226,400,000

Amount of expected guaranteed benefits in excess of the projected account balances for minimum guaranteed benefit contracts, net of reinsurance recoverables, as of the balance sheet date.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 20

-Section 55

-Paragraph 15

-URI http://asc.fasb.org/extlink&oid=6588021&loc=d3e7104-158389

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

-Publisher AICPA

-Name Statement of Position (SOP)

-Number 03-1

-Section Appendix C

-Paragraph 46

-Subparagraph C-1

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 80

-Section 50

-Paragraph 1

-Subparagraph (d)(3)

-URI http://asc.fasb.org/extlink&oid=6484115&loc=d3e19393-158473

Name:	us-gaap_LiabilitiesForGuaranteesOnLongDurationContractsGuaranteedBenefitLiabilityNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant