DERIVATIVE FINANCIAL INSTRUMENTS - Effect of Derivative Instruments on the Consolidated Statement of Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Derivatives designated as hedging instruments | Interest rate swap contract | Interest expense
Derivative, Gain (Loss) on Derivative, Net [Abstract]
Gain (Loss) Recognized in Consolidated Statements of Income	$ (9,360)	$ 524	$ 515
Derivatives not designated as hedging instruments | Foreign exchange contracts | Other income (expense), net
Derivative, Gain (Loss) on Derivative, Net [Abstract]
Gain (Loss) Recognized in Consolidated Statements of Income	$ (222)	$ 28	$ (1,569)