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LONG-TERM DEBT - Refinancing Transactions (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
	Jan. 26, 2021	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Debt Instrument [Line Items]
Loss on modification and early extinguishment of debt		$ (23,886)	$ 0	$ (23,958)	$ 0
Fourth Amendment To Credit Agreement \| Senior Secured Credit Facilities
Debt Instrument [Line Items]
Interest and debt expense	$ 24,000
Loss on modification and early extinguishment of debt	23,700
Debt discounts totaling	100
Debt issuance costs, net	4,500
Amortization of debt discount (premium)	$ 19,400