Investments (Mortgage loans on real estate aging) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Mortgage Loans Aging [Abstract]
Current	$ 7,011	$ 6,858
Sixty to ninety days past due	8	26
Greater than ninety days past due	24	76
Valuation allowance associated with impaired mortgage loans on real estate	(21)	(31)
Unamortized premium (discount)	7	13
Total carrying value	7,029	6,942
Information About Impaired Mortgage Loans [Abstract]
Number Of Impaired Mortgage Loans	10	12
Principal balance of impaired mortgage loans on real estate	75	100
Valuation allowance associated with impaired mortgage loans	21	31
Carrying value of impaired mortgage loans on real estate	54	69
Impaired Financing Receivable, Average Recorded Investment	51	57	54
Interest income recognized on impaired mortgage loans on real estate	1	2	3
Amount of interest income collected on impaired mortgage loans on real estate	$ 1	$ 2	$ 3

Mortgage loans that are greater than 90 days past due.

No definition available.

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- Definition

Mortgage loans that are current.

+ References

No definition available.

+ Details

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- Definition

Total number of impaired mortgage loans as of the balance sheet date.

+ References

No definition available.

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- Definition

Mortgage loans that are less than 90 days past due but more than 60 days past due.

+ References

No definition available.

+ Details

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- Definition

The amount of premium (net of discount) that was originally recognized at the issuance of the mortgage loan that has yet to be amortized.

+ References

No definition available.

+ Details

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- Definition

The reserve to cover probable credit losses related to specifically identified fixed maturity real estate loans as well as probable credit losses inherent in the remainder of that loan portfolio.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 60

-Paragraph 47

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 944

-SubTopic 310

-Section 45

-Paragraph 4

-URI http://asc.fasb.org/extlink&oid=6873192&loc=d3e21338-158488

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- Definition

The average recorded investment related to impaired financing receivables.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 15

-URI http://asc.fasb.org/extlink&oid=6965416&loc=d3e5212-111524

-Subparagraph (c)(1)

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 17

-URI http://asc.fasb.org/extlink&oid=6965416&loc=d3e5258-111524

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- Definition

The interest income recognized on a cash-basis method of accounting during the time within that period that the financing receivables were impaired.

+ References

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- Definition

The recorded investment related to impaired financing receivables.

+ References

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 14A

-URI http://asc.fasb.org/extlink&oid=6965416&loc=SL6953550-111524

-Subparagraph (b)

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- Definition

The gross interest income that would have been recorded in the period on troubled debt restructurings, if the loans had been current in accordance with their original terms and had been outstanding throughout the period or since origination, if held for part of the period.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 114

-Paragraph 20

-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 OTS

-Name Federal Regulation (FR)

-Number Title 12

-Chapter V

-Section 563c.102

-Subsection I

-Paragraph 8

-Subparagraph j(ii)

-LegacyDoc This is a non-GAAP reference that was included in the 2009 taxonomy. It will be removed from future versions of this taxonomy.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 15

-Paragraph 40

-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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- Definition

The carrying amount of the outstanding balance due under the mortgage loan.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 948

-SubTopic 310

-Section S99

-Paragraph 1

-Subparagraph (SX 210.12-29)

-URI http://asc.fasb.org/extlink&oid=6589523&loc=d3e617274-123014

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph c

-Subparagraph Schedule IV

-Article 5

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 29

-Article 12

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 205

-SubTopic 10

-Section S99

-Paragraph 6

-Subparagraph (SX 210.5-04.(c) Schedule IV)

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- Definition

The balance represents the amount of loans that are secured by real estate mortgages, offset by the reserve to cover probable credit losses on the loan portfolio.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 60

-Paragraph 47

-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 SEC

-Name Regulation S-X (SX)

-Number 210

-Article 7

-Section 03

-Paragraph 1

-Subparagraph c

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-03.1(c))

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