Geographic, Financial and Other Information - Additional Information (Detail)	9 Months Ended
Sep. 30, 2012 Country
Segment Reporting Information [Line Items]
Number of reportable operating segments	1
Number of countries in which entity operates	14

Additional information about the entity or its reportable segments that may contribute to an understanding of the enterprise.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 131

-Paragraph 8

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration