EMPLOYEE BENEFIT PLANS - Amounts Recognized in the Consolidated Balance Sheets and Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Sep. 30, 2019
Amounts Recognized in the Consolidated Balance Sheets
Accrued liabilities	$ (18)	$ (50)
Noncurrent liabilities-other	(30,025)	(28,653)
Net amount recognized	(30,043)	(28,703)
Amounts recognized in accumulated other comprehensive income and not yet reflected in net periodic benefit cost
Net actuarial loss	$ (33,923)	$ (37,084)