DERIVATIVE FINANCIAL INSTRUMENTS (Details) ₩ in Thousands, $ in Thousands	Jun. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2017 KRW (₩)	Dec. 31, 2014 USD ($)
Interest Rate Swap [Member]
Derivative Instruments [Abstract]
Outstanding variable rate debt				$ 86,406
Foreign Exchange Contracts [Member] | Buy [Member]
Derivative Instruments [Abstract]
Derivative notional amount	$ 7,907	$ 8,176
Foreign Exchange Contracts [Member] | Sell [Member]
Derivative Instruments [Abstract]
Derivative notional amount	$ 20,825	$ 24,295
Net Investment Hedging [Member]
Derivative Instruments [Abstract]
Derivative notional amount | ₩			₩ 100,000,000