Fair Value of Financial Instruments - Estimated Fair Value of Financial Instruments (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Mar. 31, 2016	Sep. 30, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Total derivative contracts, net	$ (2,853)	$ 1,522
Prepaid expenses, deferred costs and other current assets | Foreign currency forwards | Designated as Hedging Instrument
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Derivative assets designated as hedges	0	3,822
Accrued liabilities | Interest rate swap | Designated as Hedging Instrument
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Derivative liabilities designated as hedges	(1,570)	(1,326)
Deferred credits and other liabilities | Foreign currency forwards | Designated as Hedging Instrument
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Derivative liabilities designated as hedges	(193)	0
Other long-term liabilities | Interest rate swap | Designated as Hedging Instrument
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Derivative liabilities designated as hedges	$ (1,090)	$ (974)