Identified Intangible Assets and Goodwill - Additional Information (Detail) (USD $) In Billions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Goodwill And Other Intangible Asset [Line Items]
Accumulated impairment losses	$ 2.4	$ 2.4

The accumulated impairment losses related to goodwill as of the balance sheet date.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (a,h)

-URI http://asc.fasb.org/extlink&oid=14024403&loc=d3e13816-109267

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