FAIR VALUE OF FINANCIAL INSTRUMENTS - Estimated Fair Value of Financial Instruments (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Jun. 30, 2017	Sep. 30, 2016
Derivative liabilities designated as cash flow hedging instruments:
Total derivative contracts, net	$ 113	$ (1,794)
Prepaid expenses, deferred costs and other current assets | Interest rate swap | Designated as Hedging Instrument
Derivative assets designated as cash flow hedging instruments:
Derivative assets designated as cash flow hedges	113	0
Accrued liabilities | Interest rate swap | Designated as Hedging Instrument
Derivative liabilities designated as cash flow hedging instruments:
Derivative liabilities designated as cash flow hedges	0	(1,312)
Other long-term liabilities | Interest rate swap | Designated as Hedging Instrument
Derivative liabilities designated as cash flow hedging instruments:
Derivative liabilities designated as cash flow hedges	$ 0	$ (482)