Assumed life reinsurance programs involving minimum benefits guarantees under annuity contracts (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010	Mar. 31, 2010	Dec. 31, 2009
Guaranteed Minimum Benefits [Line Items]
Net premiums earned	$ 3,757	$ 3,233	$ 7,066	$ 6,510
Policy benefits	108	87	199	174
Total net realized gains (losses) including OTTI	(73)	9	(118)	177
Guaranteed Minimum Death Benefit [Member]
Guaranteed Minimum Benefits [Line Items]
Net premiums earned	25	27	51	56
Policy benefits	21	22	43	46
Reported liabilities	181		181		185
Net amount at risk	3,100		3,100		2,900
Discounting assumptions used in the calculation of the benefit reserve aging - lower range	1.00%		1.00%
Discounting assumptions used in the calculation of the benefits reserve aging - upper range	2.00%		2.00%
Percent of Annuity 2000 mortality table used for mortality assumption	100.00%		100.00%
Total claim amount payable if all of the Company's cedants' policyholders covered were to die immediately	1,500		1,500
Guaranteed Living Benefit [Member]
Guaranteed Minimum Benefits [Line Items]
Net premiums earned	41	40	82	81
Policy benefits	6	6	12	13
Total net realized gains (losses) including OTTI	(75)	(301)	(17)	(205)
Gain (loss) recognized in income	(40)	(267)	53	(137)
Net cash received (disbursed)	40	40	81	80
Net (increase) decrease in liability	(80)	(307)	(28)	(217)
Reported liabilities	676	776	676	776	648	469	559
Fair value derivative adjustment in liability	524	648	524	648	507	347	443
Net amount at risk	$ 789		$ 789		$ 719
Discounting assumptions used in the calculation of the benefits reserve aging - upper range	1.00%		1.00%
Average attained age of all policyholders under all benefits reinsured			67

Guaranteed minimum benefit the portion of reported liabilities derived from a fair value derivative adjustment

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Guaranteed Minimum Benefits total gain (loss) recognized in income

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For guaranteed minimum benefits, the line items associated with this table

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Guaranteed Minimum Benefits net cash received (disbursed)

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The percent of the Annuity 2000 mortality table used for the mortality assumption

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The net realized gains or losses on investments, derivative instruments, and foreign exchange recognized during the period.

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- Definition

Total net amount of increases and decreases to the liability for guaranteed minimum benefits on long-duration contracts occurring during the period, for all guaranteed benefit types.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Statement of Position (SOP)
-Number 03-1
-Paragraph 38

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Statement of Position (SOP)
-Number 03-1
-Section Appendix C
-Paragraph 46
-Subparagraph C-1

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Sum of the amount of expected guaranteed benefits in excess of the projected account balances for minimum guaranteed benefit contracts, as of the balance sheet date, net of reinsurance recoverables, for all guaranteed benefit types.

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- Definition

Increases and decreases to the future policy benefit reserve based on changes in actuarial calculations, catastrophes, historical results and any other factors that influence the present value of future benefits to be paid to or on behalf of policyholders.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Financial Reporting Release (FRR)
-Number 403
-Paragraph 04
-Subparagraph b

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Audit and Accounting Guide (AAG)
-Number AAG-LHI
-Chapter 9
-Paragraph 27, 28
-IssueDate 2006-05-01

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Percentage discount rate at the high end of a range of reasonable estimates used to calculate present value of an expected stream of future payments, which is included in the calculation of the amount of the specified guaranteed benefit obligation as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 60
-Paragraph 60
-Subparagraph b

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Statement of Position (SOP)
-Number 03-1
-Paragraph 38
-Subparagraph c

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Percentage discount rate at the low end of a range of reasonable estimates used to calculate present value of an expected stream of future payments, which is included in the calculation of the amount of the specified guaranteed benefit obligation as of the balance sheet date.

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- Definition

Net amount at risk, representing the guaranteed benefit in excess of the current account balance corresponding to the specified product, guarantee type and subset of the guarantee.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Statement of Position (SOP)
-Number 03-1
-Section Appendix C
-Paragraph 46
-Subparagraph C-1

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Statement of Position (SOP)
-Number 03-1
-Paragraph 38
-Subparagraph d(2), d(3)

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The portion of the specified guaranteed benefit amount in excess of the sum of the current account balance amounts assuming death of the insureds, corresponding to the specified guarantee or subset of the guarantee.

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- Definition

Weighted average attained age of all policyholders or contract holders in the specified guarantee type and subset of guarantee class.

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- Definition

Premiums earned on the income statement for all insurance and reinsurance contracts after subtracting any amounts ceded to another insurer and adding premiums assumed from other insurers.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 04
-Paragraph 1
-Article 7

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 113
-Paragraph 27
-Subparagraph a, b

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