Investments (Details 38) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011
Financing Receivable, Modifications [Line Items]
Number of Mortgage Loans	15
Carrying Value after Specific Valuation Allowance, Pre-Modification	$ 189
Carrying Value after Specific Valuation Allowance, Post-Modification	153
Commercial
Financing Receivable, Modifications [Line Items]
Number of Mortgage Loans	5
Carrying Value after Specific Valuation Allowance, Pre-Modification	147
Carrying Value after Specific Valuation Allowance, Post-Modification	111
Agricultural
Financing Receivable, Modifications [Line Items]
Number of Mortgage Loans	10
Carrying Value after Specific Valuation Allowance, Pre-Modification	42
Carrying Value after Specific Valuation Allowance, Post-Modification	42
Residential
Financing Receivable, Modifications [Line Items]
Number of Mortgage Loans	0
Carrying Value after Specific Valuation Allowance, Pre-Modification	0
Carrying Value after Specific Valuation Allowance, Post-Modification	$ 0

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The number of financing receivables that have been modified by troubled debt restructurings.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 32

-URI http://asc.fasb.org/extlink&oid=6965416&loc=SL6953670-111524

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 33

-URI http://asc.fasb.org/extlink&oid=6965416&loc=SL6953676-111524

+ Details

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- Definition

The amount of the outstanding recorded investment related to financing receivables that have been modified by troubled debt restructurings after the financing receivable has been modified.

+ References

+ Details

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- Definition

The amount of the outstanding recorded investment related to financing receivables that have been modified by troubled debt restructurings before the financing receivable has been modified.

+ References

+ Details

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