Fair Value of Company's Short-term Investments and Foreign Currency Forward Contracts (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term investment fair value disclosure	$ 19,861
Net Derivatives	795	351
Fair Value, Measurements, Recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total	20,656	(351)
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total	19,861
Fair Value, Measurements, Recurring | Significant Other Observable (Level 2)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total	795	(351)
Fair Value, Measurements, Recurring | Corporate bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term investment fair value disclosure	14,235
Fair Value, Measurements, Recurring | Corporate bonds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term investment fair value disclosure	14,235
Fair Value, Measurements, Recurring | Government bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term investment fair value disclosure	5,626
Fair Value, Measurements, Recurring | Government bonds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term investment fair value disclosure	5,626
Fair Value, Measurements, Recurring | Foreign Currency Forward Contract
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Net Derivatives	795	(351)
Fair Value, Measurements, Recurring | Foreign Currency Forward Contract | Significant Other Observable (Level 2)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Net Derivatives	$ 795	$ (351)