Gains Losses on Derivative Financial Instruments Recorded in Consolidated Statements of Income (Detail) (Foreign currency forward contracts, USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended
Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015	Mar. 31, 2014
Foreign currency forward contracts
Derivative [Line Items]
Gains (losses) on Foreign currency forward contracts	$ (10)	$ 194	$ (339)	$ 532

Aggregate net gain (loss) on all derivative instruments recognized in earnings during the period, before tax effects.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4A

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5618551-113959

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration