DEBT - Interest Costs Recognized on 2026 Notes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Debt Instrument [Line Items]
Total interest expense recognized	$ 2,469	$ 2,329	$ 7,274	$ 6,895
Convertible Debt | 2026 Notes
Debt Instrument [Line Items]
Contractual interest expense	290	289	871	880
Amortization of debt discount and issuance costs	2,179	2,040	6,403	6,015
Total interest expense recognized	$ 2,469	$ 2,329	$ 7,274	$ 6,895