Investments (Details 12) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2011 loan	Dec. 31, 2010
Investments
Threshold percentage of mortgage loans to total carrying value	5.00%
Mortgage Loans on Real Estate
Percentage of mortgage portfolio carrying value	100.00%
Number of mortgage loans	629
Mortgage loans	$ 7,139	$ 6,679
Office buildings
Mortgage Loans on Real Estate
Percentage of mortgage portfolio carrying value	27.90%	32.10%
Retail
Mortgage Loans on Real Estate
Percentage of mortgage portfolio carrying value	24.80%	27.30%
Warehouse
Mortgage Loans on Real Estate
Percentage of mortgage portfolio carrying value	19.40%	21.90%
Apartment complex
Mortgage Loans on Real Estate
Percentage of mortgage portfolio carrying value	19.60%	12.80%
Other;
Mortgage Loans on Real Estate
Percentage of mortgage portfolio carrying value	8.30%	5.90%
Mortgage loans in the process of foreclosure	43
California
Mortgage Loans on Real Estate
Percentage of mortgage portfolio carrying value	22.60%	23.20%
Illinois
Mortgage Loans on Real Estate
Percentage of mortgage portfolio carrying value	9.10%	9.40%
New York
Mortgage Loans on Real Estate
Percentage of mortgage portfolio carrying value	5.80%	6.60%
New Jersey
Mortgage Loans on Real Estate
Percentage of mortgage portfolio carrying value	6.50%	6.50%
Pennsylvania
Mortgage Loans on Real Estate
Percentage of mortgage portfolio carrying value	5.30%	5.60%
Texas
Mortgage Loans on Real Estate
Percentage of mortgage portfolio carrying value	6.20%	5.30%
Mortgage loans, not in foreclosure
Mortgage Loans on Real Estate
Mortgage loans	7,096
Mortgage loans, not in foreclosure \| 2012
Mortgage Loans on Real Estate
Percentage of mortgage portfolio carrying value	8.20%
Number of mortgage loans	59
Mortgage loans	580
Mortgage loans, not in foreclosure \| 2013
Mortgage Loans on Real Estate
Percentage of mortgage portfolio carrying value	6.60%
Number of mortgage loans	59
Mortgage loans	473
Mortgage loans, not in foreclosure \| 2014
Mortgage Loans on Real Estate
Percentage of mortgage portfolio carrying value	13.20%
Number of mortgage loans	70
Mortgage loans	935
Mortgage loans, not in foreclosure \| 2015
Mortgage Loans on Real Estate
Percentage of mortgage portfolio carrying value	13.30%
Number of mortgage loans	64
Mortgage loans	942
Mortgage loans, not in foreclosure \| Thereafter
Mortgage Loans on Real Estate
Percentage of mortgage portfolio carrying value	58.70%
Number of mortgage loans	377
Mortgage loans	$ 4,166

This element represents the amount of mortgage loans as a percentage of total carrying value.

No definition available.

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- Definition

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

+ References

No definition available.

+ Details

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- Definition

The minimum percentage of mortgage loans to total carrying value that is used as a threshold for disclosure.

+ References

No definition available.

+ Details

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- Details

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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))

-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

+ Details

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- Details

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- Definition

Indicates the number of mortgages under each classification.

+ 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 210.12-29.3)

-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

-Article 12

-Section 29

-Paragraph 3

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)

-URI http://asc.fasb.org/extlink&oid=6882300&loc=d3e5864-122674

+ Details

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