SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - IMPACT OF ASC 740 ON THE UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Depreciation and amortization	$ 27,362	$ 24,637
Deferred income taxes	$ 17,667	19,976
As Previously Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Depreciation and amortization		27,758
Deferred income taxes		3,246
Effect of Change
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Depreciation and amortization		(3,121)
Deferred income taxes		$ 16,730