Fair Value of Financial Instruments - Estimated Fair Value of Financial Instruments (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Dec. 31, 2015	Sep. 30, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Total derivative contracts, net	$ 1,612	$ 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	2,362	3,822
Deferred costs and other assets | Interest rate swap | Designated as Hedging Instrument
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Derivative assets designated as hedges	295	0
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	(1,045)	(1,326)
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	$ 0	$ (974)