Fair Value, Investments in Entities That Calculate Net Asset Value Per Share (Details) (USD $) In Millions	3 Months Ended	12 Months Ended
Jun. 30, 2011	Dec. 31, 2010
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair value	$ 2,918	$ 3,669
Unfunded commitments	317	705
Offshore Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair value	1,739	1,665
Unfunded commitments	0	0
Redemption frequency	Daily-Annually	Daily-Annually
Redemption notice period	1-180 days	1-180 days
Funds of funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair value	4	63
Unfunded commitments	0	0
Redemption frequency	Monthly-Quarterly	Monthly-Quarterly
Redemption notice period	10-90 days	10-90 days
Hedge funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair value	26	23
Unfunded commitments	0	0
Redemption frequency	Quarterly-Annually	Monthly-Annually
Redemption notice period	60 - 90 days	30 - 120 days
Private Equity Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair value	1,060	1,830
Unfunded commitments	285	669
Venture Capital Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Fair value	89	88
Unfunded commitments	$ 32	$ 36

This element represents the total fair market value of investments in certain entities that calculate net asset value per share (including by unit, membership interest, or other equity (ownership interest) unit measure) (alternative investments). This element is intended to be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements, but may also be used in both the balance sheet and disclosure in the same submission. This item represents alternative investments as of the balance sheet date which may include investments in certain hedge funds, venture capital funds, private equity funds, real estate partnerships or funds, and any other investment in which investee management calculates net asset value per share as the primary metric for investment value.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph a
-URI http://asc.fasb.org/extlink&oid=6925170&loc=d3e19207-110258

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph a
-URI http://asc.fasb.org/extlink&oid=6925170&loc=d3e19296-110258

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Subparagraph (a)
-Paragraph 6A
-URI http://asc.fasb.org/extlink&oid=6925170&loc=SL6742756-110258

+ Details

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Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

States the frequency (for example, annually, semi-annually, quarterly) with which the entity can redeem its investment, or portion thereof, for each of those certain investments for which net asset value per share is calculated (including by unit, membership interest, or other equity (ownership interest) unit measure) (alternative investments), by major category.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 6A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=6925170&loc=SL6742756-110258

+ Details

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Namespace Prefix:	us-gaap
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

States the notice requirement (for example, 30 to 60 days) the entity is required to deliver before it can redeem its investment, or portion thereof, for each of those certain investments for which net asset value per share is calculated (including by unit, membership interest, or other equity (ownership interest) unit measure) (alternative investments), by major category.

+ References

+ Details

Name:	us-gaap_FairValueInvestmentsEntitiesThatCalculateNetAssetValuePerShareInvestmentRedemptionNoticePeriod
Namespace Prefix:	us-gaap
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ Details

Name:	us-gaap_FairValueInvestmentsEntitiesThatCalculateNetAssetValuePerShareLineItems
Namespace Prefix:	us-gaap
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount of unfunded commitments for which the entity is obligated, to those certain investments for which net asset value per share is calculated (including by unit, membership interest, or other equity (ownership interest) unit measure) (alternative investments).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 6A
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6925170&loc=SL6742756-110258

+ Details

Name:	us-gaap_FairValueInvestmentsEntitiesThatCalculateNetAssetValuePerShareUnfundedCommittments
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant