Debt - Schedule of Debt Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2025	Sep. 30, 2024	Mar. 31, 2024
Debt Instrument [Line Items]
Gross Amount	$ 633,373	$ 333,373	$ 367,762
Gross Amount, current portion	103,373	103,373	34,389
Gross Amount, excluding current portion	530,000	230,000	333,373
Deferred Financing Costs	(12,860)	(6,045)	(6,842)
Deferred Financing Costs, current portion	(48)	(301)	(42)
Deferred Financing Costs, excluding current portion	(12,812)	(5,744)	(6,800)
Carrying Amount	620,513	327,328	360,920
Carrying Amount, current portion	103,325	103,072	34,347
Carrying Amount, excluding current portion	517,188	224,256	326,573
Senior Notes
Debt Instrument [Line Items]
Gross Amount	633,373
2032 Senior Notes | Senior Notes
Debt Instrument [Line Items]
Gross Amount	300,000	0	0
Deferred Financing Costs	(7,535)	0	0
Carrying Amount	292,465	0	0
2029 Convertible Notes | Senior Notes
Debt Instrument [Line Items]
Gross Amount	230,000	230,000	230,000
Deferred Financing Costs	(5,277)	(5,744)	(6,244)
Carrying Amount	224,723	224,256	223,756
2025 Convertible Notes | Senior Notes
Debt Instrument [Line Items]
Gross Amount	103,373	103,373	103,373
Deferred Financing Costs	(48)	(301)	(556)
Carrying Amount	103,325	103,072	102,817
2024 Convertible Notes | Senior Notes
Debt Instrument [Line Items]
Gross Amount	0	0	34,389
Deferred Financing Costs	0	0	(42)
Carrying Amount	$ 0	$ 0	$ 34,347