Contingencies and Commitments - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012 judge
India
Other Commitments And Contingencies [Line Items]
Judges deciding potential precedent case	2
Favorable Regulatory Action \| India
Other Commitments And Contingencies [Line Items]
Judges deciding potential precedent case	1
Unfavorable Regulatory Action \| India
Other Commitments And Contingencies [Line Items]
Judges deciding potential precedent case	1
Maximum [Member]
Other Commitments And Contingencies [Line Items]
Tax charges and related liabilities if the ruling is unfavorable	6

Reflects the estimated amount of loss from the specified contingency as of the balance sheet date.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 5

-Paragraph 9, 10, 11, 12

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 450

-SubTopic 20

-Section 50

-Paragraph 4

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6952336&loc=d3e14435-108349

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section 50

-Paragraph 9

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6952336&loc=d3e14557-108349

Name:	us-gaap_LossContingencyEstimateOfPossibleLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant