Debt - Schedule of Debt Instruments (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Sep. 30, 2023	Jun. 30, 2023
Debt Instrument [Line Items]
Gross Amount	$ 367,762	$ 367,762	$ 367,762
Less current portion, Gross Amount	137,762	34,389	0
Gross Amount, excluding current maturities	230,000	333,373	367,762
Debt Issuance Costs	(6,438)	(7,650)	(8,076)
Less current portion, Debt Issuance Costs	(436)	(124)	0
Debt Issuance Costs, excluding current	(6,002)	(7,526)	(8,076)
Carrying Amount	361,324	360,112	359,686
Less current portion, Carrying Amount	137,326	34,265	0
Carrying Amount, excluding current maturities	223,998	325,847	359,686
Senior Notes
Debt Instrument [Line Items]
Gross Amount	367,762
2029 Convertible Notes | Senior Notes
Debt Instrument [Line Items]
Gross Amount	230,000	230,000	230,000
Debt Issuance Costs	(6,002)	(6,716)	(6,970)
Carrying Amount	223,998	223,284	223,030
2025 Convertible Notes | Senior Notes
Debt Instrument [Line Items]
Gross Amount	103,373	103,373	103,373
Debt Issuance Costs	(433)	(810)	(940)
Carrying Amount	102,940	102,563	102,433
2024 Convertible Notes | Senior Notes
Debt Instrument [Line Items]
Gross Amount	34,389	34,389	34,389
Debt Issuance Costs	(3)	(124)	(166)
Carrying Amount	$ 34,386	$ 34,265	$ 34,223