Derivative Instruments - Additional Information (Detail) (Foreign Exchange Forward, Maximum)	9 Months Ended
Sep. 30, 2013
Foreign Exchange Forward \| Maximum
Derivative [Line Items]
Term of derivative contracts (in days)	90 days

Period the derivative contract is outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

No definition available.

Name:	us-gaap_DerivativeTermOfContract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration