Investments (Details 37) (USD $) In Millions	3 Months Ended	6 Months Ended
Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Average investment and the related interest income in impaired mortgage loans held-for-investment
Average Investment	$ 579	$ 467	$ 560	$ 452
Interest Income Recognized - Cash Basis	0	4	5	7
Interest Income Recognized - Accrual Basis	1	0	2	1
Commercial mortgage loans portfolio segment [Member]
Average investment and the related interest income in impaired mortgage loans held-for-investment
Average Investment	292	182	264	156
Interest Income Recognized - Cash Basis	0	2	3	4
Interest Income Recognized - Accrual Basis	0	0	1	1
Agricultural mortgage loans portfolio segment [Member]
Average investment and the related interest income in impaired mortgage loans held-for-investment
Average Investment	255	278	268	289
Interest Income Recognized - Cash Basis	0	2	2	3
Interest Income Recognized - Accrual Basis	1	0	1	0
Residential mortgage loans portfolio segment [Member]
Average investment and the related interest income in impaired mortgage loans held-for-investment
Average Investment	32	7	28	7
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

Reflects the average recorded investment in impaired loans during each period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 114
-Paragraph 20
-Subparagraph c

+ Details

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- Definition

Reflects the amount of interest income recognized using a cash-basis method during the period that loans were deemed to be impaired.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher OTS
-Name Federal Regulation (FR)
-Number Title 12
-Chapter V
-Section 563c.102
-Paragraph 8
-Subparagraph j(ii)
-Subsection I

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 114
-Paragraph 20
-Subparagraph c

+ Details

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- Definition

Reflects the amount of interest income on impaired and nonperforming loans that was recognized as income during the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 114
-Paragraph 20

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher OTS
-Name Federal Regulation (FR)
-Number Title 12
-Chapter V
-Section 563c.102
-Paragraph 8
-Subparagraph j(ii)
-Subsection I

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 15
-Paragraph 40

+ Details

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