Investments (Details 37) (USD $) In Millions	3 Months Ended	9 Months Ended
Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Average investment and the related interest income in impaired mortgage loans held-for-investment
Average Investment	$ 576	$ 452	$ 592	$ 450
Interest Income Recognized - Cash Basis	1	0	4	7
Interest Income Recognized - Accrual Basis	0	1	1	2
Commercial mortgage loans portfolio segment [Member]
Average investment and the related interest income in impaired mortgage loans held-for-investment
Average Investment	330	148	308	147
Interest Income Recognized - Cash Basis	0	0	1	4
Interest Income Recognized - Accrual Basis	0	0	0	1
Agricultural mortgage loans portfolio segment [Member]
Average investment and the related interest income in impaired mortgage loans held-for-investment
Average Investment	229	286	258	288
Interest Income Recognized - Cash Basis	1	0	3	3
Interest Income Recognized - Accrual Basis	0	1	1	1
Residential mortgage loans portfolio segment [Member]
Average investment and the related interest income in impaired mortgage loans held-for-investment
Average Investment	17	18	26	15
Interest Income Recognized - Cash Basis	0	0	0	0
Interest Income Recognized - Accrual Basis	$ 0	$ 0	$ 0	$ 0

Represents the average investment and the related interest income in impaired mortgage loans held-for-investment.

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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)

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

-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

+ Details

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- Definition

The interest income recognized during the time within that period that the financing receivables were impaired.

+ References

+ Details

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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

+ Details

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