EMPLOYEE BENEFIT PLANS - Recognized in balance sheet and accumulated other comprehensive income (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Sep. 30, 2017
Amounts Recognized in the Consolidated Balance Sheets
Accrued liabilities	$ (58)	$ (45)
Noncurrent liabilities-other	(11,250)	(17,115)
Net amount recognized	(11,308)	(17,160)
Amounts recognized in accumulated other comprehensive income and not yet reflected in net periodic benefit cost
Net actuarial loss	(21,693)	$ (28,873)
Net actuarial loss, which is expected to be amortized in next year's periodic benefit cost	$ 1,200