Debt - Schedule of Interest Expense (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Dec. 31, 2022	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
Debt Instrument [Line Items]
(Gain) loss on extinguishment	$ 3,500	$ 0	$ 0	$ 3,545
Senior Notes | 2032 Senior Notes
Debt Instrument [Line Items]
Contractual interest expense		11,247	0	0
Amortization of deferred financing costs		423	0	0
Total interest expense		11,670	0	0
Senior Notes | 2029 Convertible Notes
Debt Instrument [Line Items]
Contractual interest expense		8,624	8,625	6,900
Amortization of deferred financing costs		1,002	972	742
Total interest expense		9,626	9,597	7,642
Senior Notes | 2025 Convertible Notes
Debt Instrument [Line Items]
Contractual interest expense		1,432	2,455	2,779
Amortization of deferred financing costs		301	509	559
(Gain) loss on extinguishment		0	0	(5,389)
Total interest expense		1,733	2,964	(2,051)
Senior Notes | 2024 Convertible Notes
Debt Instrument [Line Items]
Contractual interest expense		0	742	1,609
Amortization of deferred financing costs		0	124	260
(Gain) loss on extinguishment		0	0	8,935
Total interest expense		$ 0	$ 866	$ 10,804