DERIVATIVE FINANCIAL INSTRUMENTS - Effect of Derivative Instruments on Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	12 Months Ended
Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Interest rate swap contract
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) recognized in other comprehensive income	$ (23,161)	$ (23,667)	$ 430

Amount before tax and reclassification adjustments of other comprehensive income (loss) attributable to parent.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 14A
-URI http://asc.fasb.org/extlink&oid=121641772&loc=SL7669686-108580

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration