Derivatives And Hedging (Derivative Instruments Not Designated As Hedging Instruments) (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Derivative [Line Items]
Assets fair value	$ 29	$ 1,495
Liabilities fair value	33	1,498
Other Liabilities [Member] \| Credit Default Swap [Member]
Derivative [Line Items]
Liabilities fair value	4	3
Separate Account Liabilities [Member] \| Separate Account Derivatives [Member]
Derivative [Line Items]
Liabilities fair value	29	1,495
Separate Account Assets [Member] \| Separate Account Derivatives [Member]
Derivative [Line Items]
Assets fair value	$ 29	$ 1,495

Fair value as of the balance sheet date of derivative instrument not designated as hedging instrument and classified as a liability.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 107

-Paragraph 10

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4B

-Subparagraph (c)(2)

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5624163-113959

Name:	us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsLiabilityAtFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant