DERIVATIVE FINANCIAL INSTRUMENTS - Fair Value of Derivative Instruments in the Consolidated Balance Sheet (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Sep. 30, 2019
Derivatives designated as hedging instruments | Interest rate swap contract | Accrued expenses, income taxes payable and other current liabilities
Derivative Asset [Abstract]
Derivative Assets	$ 0	$ 0
Derivative Liability [Abstract]
Derivative Liabilities	11,992	5,351
Derivatives designated as hedging instruments | Interest rate swap contract | Other long-term liabilities
Derivative Asset [Abstract]
Derivative Assets	0	0
Derivative Liability [Abstract]
Derivative Liabilities	26,000	18,841
Derivatives not designated as hedging instruments | Foreign exchange contracts | Accrued expenses, income taxes payable and other current liabilities
Derivative Asset [Abstract]
Derivative Assets	0	0
Derivative Liability [Abstract]
Derivative Liabilities	165	52
Derivatives not designated as hedging instruments | Foreign exchange contracts | Prepaid expenses and other current assets
Derivative Asset [Abstract]
Derivative Assets	27	0
Derivative Liability [Abstract]
Derivative Liabilities	$ 0	$ 0