DEBT - Schedule of Debt (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Sep. 30, 2022
Debt Instrument [Line Items]
Deferred financing costs	$ (9,446)	$ (10,844)
Long-term debt	762,149	760,537
Secured Debt | Senior Secured Term Loan Facility due May 26, 2028
Debt Instrument [Line Items]
Long-term debt, gross	371,595	371,381
Secured Debt | Senior Notes due June 2031
Debt Instrument [Line Items]
Long-term debt, gross	$ 400,000	$ 400,000