FAIR VALUE OF FINANCIAL INSTRUMENTS - Estimated Fair Value of Financial Instruments (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Mar. 31, 2017	Sep. 30, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Total derivative contracts, net	$ (33)	$ (1,794)
Prepaid expenses, deferred costs and other current assets | Interest rate swap | Designated as Hedging Instrument
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Derivative assets designated as cash flow hedges	66	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 cash flow hedges	0	(1,312)
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 cash flow hedges	$ (99)	$ (482)