Fair Value Measurements (Fair Value And Maximum Future Funding Commitments Related To Investments) (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014
Fair Value And Maximum Future Funding Commitments Related To Investments [Line Items]
Maximum future funding commitment	$ 824	$ 1,010
Fair Value	2,477	2,561
Financial
Fair Value And Maximum Future Funding Commitments Related To Investments [Line Items]
Maximum future funding commitment	105	145
Fair Value	300	282
Real Assets
Fair Value And Maximum Future Funding Commitments Related To Investments [Line Items]
Maximum future funding commitment	140	210
Fair Value	474	451
Distressed
Fair Value And Maximum Future Funding Commitments Related To Investments [Line Items]
Maximum future funding commitment	218	175
Fair Value	261	232
Private Credit
Fair Value And Maximum Future Funding Commitments Related To Investments [Line Items]
Maximum future funding commitment	209	190
Fair Value	265	299
Traditional
Fair Value And Maximum Future Funding Commitments Related To Investments [Line Items]
Maximum future funding commitment	152	285
Fair Value	895	895
Vintage
Fair Value And Maximum Future Funding Commitments Related To Investments [Line Items]
Maximum future funding commitment		5
Fair Value	13	24
Investment Funds
Fair Value And Maximum Future Funding Commitments Related To Investments [Line Items]
Fair Value	$ 269	$ 378
Minimum \| Financial
Fair Value And Maximum Future Funding Commitments Related To Investments [Line Items]
Expected liquidation period	5 years	5 years
Minimum \| Real Assets
Fair Value And Maximum Future Funding Commitments Related To Investments [Line Items]
Expected liquidation period	3 years	3 years
Minimum \| Distressed
Fair Value And Maximum Future Funding Commitments Related To Investments [Line Items]
Expected liquidation period	5 years	5 years
Minimum \| Private Credit
Fair Value And Maximum Future Funding Commitments Related To Investments [Line Items]
Expected liquidation period	3 years	3 years
Minimum \| Traditional
Fair Value And Maximum Future Funding Commitments Related To Investments [Line Items]
Expected liquidation period	3 years	3 years
Minimum \| Vintage
Fair Value And Maximum Future Funding Commitments Related To Investments [Line Items]
Expected liquidation period	1 year	1 year
Maximum \| Financial
Fair Value And Maximum Future Funding Commitments Related To Investments [Line Items]
Expected liquidation period	9 years	9 years
Maximum \| Real Assets
Fair Value And Maximum Future Funding Commitments Related To Investments [Line Items]
Expected liquidation period	7 years	7 years
Maximum \| Distressed
Fair Value And Maximum Future Funding Commitments Related To Investments [Line Items]
Expected liquidation period	9 years	9 years
Maximum \| Private Credit
Fair Value And Maximum Future Funding Commitments Related To Investments [Line Items]
Expected liquidation period	7 years	7 years
Maximum \| Traditional
Fair Value And Maximum Future Funding Commitments Related To Investments [Line Items]
Expected liquidation period	9 years	9 years
Maximum \| Vintage
Fair Value And Maximum Future Funding Commitments Related To Investments [Line Items]
Expected liquidation period	2 years	2 years

Fair Value And Maximum Future Funding Commitments Related To Investments [Line Items]

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- Definition

Fair value of investments in certain entities that calculate net asset value per share, including, but not limited to, by unit, membership interest, or other ownership interest. Investments include, but are not limited to, investments in certain hedge funds, venture capital funds, private equity funds, real estate partnerships or funds.

+ References

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=36462937&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 6A
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=36462937&loc=SL6742756-110258

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- Definition

Estimate remaining period the underlying assets are expected to be liquidated by the investees for investments for which net asset value per share is calculated (including by unit, membership interest, or other ownership interest unit measure), in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ 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 (b)
-URI http://asc.fasb.org/extlink&oid=36462937&loc=SL6742756-110258

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- 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=36462937&loc=SL6742756-110258

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