Fair Value Measurements Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Sep. 30, 2014
Assets
Available-for-sale securities	$ 133,928us-gaap_AvailableForSaleSecurities	$ 151,342us-gaap_AvailableForSaleSecurities
Fair Value, Measurements, Recurring
Assets
Cash equivalents	10,404	6,404
Available-for-sale securities	133,928	151,342
Foreign exchange contracts	31
Convertible debt securities	5,207
Stock warrants	70
Total Assets	149,640	157,746
Liabilities
Foreign exchange contracts		58
Quoted Prices in Active Markets for Identical Assets (Level 1) \| Fair Value, Measurements, Recurring
Assets
Cash equivalents	10,154	5,166
Available-for-sale securities	0	0
Foreign exchange contracts	0
Convertible debt securities	0
Stock warrants	0
Total Assets	10,154	5,166
Liabilities
Foreign exchange contracts	0	0
Significant Other Observable Inputs (Level 2) \| Fair Value, Measurements, Recurring
Assets
Cash equivalents	250	1,238
Available-for-sale securities	133,928	151,342
Foreign exchange contracts	31
Convertible debt securities	0
Stock warrants	0
Total Assets	134,209	152,580
Liabilities
Foreign exchange contracts	15	58
Significant Unobservable Inputs (Level 3) \| Fair Value, Measurements, Recurring
Assets
Cash equivalents	0	0
Available-for-sale securities	0	0
Foreign exchange contracts	0
Convertible debt securities	5,207
Stock warrants	70
Total Assets	5,277	0
Liabilities
Foreign exchange contracts	$ 0	$ 0

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

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-Name Accounting Standards Codification

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Fair value portion of borrowing which can be exchanged for a specified number of another security at the option of the issuer or the holder, for example, but not limited to, the entity's common stock.

+ References

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Fair value portion of asset contracts related to the exchange of different currencies, including, but not limited to, foreign currency options, forward contracts, and swaps.

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Fair value portion of liability contracts related to the exchange of different currencies, including, but not limited to, foreign currency options, forward (delivery or nondelivery) contracts, and swaps entered into.

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Fair value portion of warrants not settleable in cash classified as equity.

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