DEBT - Carrying Value of 2026 Notes (Details) - USD ($)	Sep. 30, 2024	Sep. 30, 2023	Feb. 28, 2021	Feb. 05, 2021
Debt Instrument [Line Items]
Carrying amount	$ 2,697,000
Convertible Debt | 2026 Notes
Debt Instrument [Line Items]
Debt interest rate (as a percent)	0.75%			0.75%
Debt issued	$ 155,300,000		$ 155,300,000
Principal amount	155,250,000	$ 155,250,000
Less: unamortized discount and issuance costs, net of amortization	(11,649,000)	(19,734,000)
Carrying amount	$ 143,601,000	$ 135,516,000