Derivative Instruments - Additional Information (Detail)	9 Months Ended
Sep. 30, 2017
Forward Foreign Exchange Contracts [Member]
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Derivative contracts maturity	12 months

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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