Commitments, Contingencies, And Guarantees (Narrative) (Detail) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Financial Instruments Owned and Pledged as Collateral [Line Items]
Securities lending collateral	$ 1,011	$ 1,330
Carrying value of limited partnerships and partially-owned investment companies included in other investments	2,200
Funding commitments relating to limited partnerships and partially-owned investment companies	916
Unrecognized tax benefits	22
Derivative liability subject to a master netting agreement	19	$ 34
Cash and Cash Equivalents [Member] \| Overnight and Continuous [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Securities lending collateral	492
Foreign [Member] \| Overnight and Continuous [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Securities lending collateral	385
U.S. Treasury And Agency [Member] \| Overnight and Continuous [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Securities lending collateral	77
Corporate Securities [Member] \| Overnight and Continuous [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Securities lending collateral	57
Securities Lending Program [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Secured Borrowings, Gross, Difference, Amount	$ 1

Carrying value of limited partnerships and partially-owned investment companies included in other investments.

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- Definition

Funding commitments relating to limited partnerships and partially-owned investment companies included in other investments.

+ References

No definition available.

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- Definition

Fair value, after effects of master netting arrangements, of financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset offset against the right to receive collateral. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 8

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=56946850&loc=d3e41678-113959

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 55

-Paragraph 13

-URI http://asc.fasb.org/extlink&oid=51825145&loc=SL20226016-175313

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 50

-Paragraph 3

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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.

+ References

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- Definition

Amount of secured borrowings in excess of (less than) the liability for repurchase agreements and securities lending transactions, before offset, included in offsetting disclosures.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 860

-SubTopic 30

-Section 50

-Paragraph 7

-Subparagraph (a)(1)

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- Definition

The carrying amount (fair value) as of the balance sheet date of securities held that had been pledged by counterparties under financing and lending arrangements, pursuant to which the entity has the right by agreement or custom to sell or re-pledge such securities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 5

-URI http://asc.fasb.org/extlink&oid=49124121&loc=d3e5086-111524

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- Definition

Amount of unrecognized tax benefits pertaining to uncertain tax positions taken in tax returns.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 50

-Paragraph 15A

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=6907707&loc=SL6600010-109319

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Unrecognized Tax Benefit

-URI http://asc.fasb.org/extlink&oid=6527854

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