Debt - Interest Expense (Details) - Senior Notes - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
2029 Convertible Notes
Debt Instrument [Line Items]
Contractual interest expense	$ 431	$ 0
Amortization of deferred financing costs	52	0
Total interest expense	483	0
2025 Convertible Notes
Debt Instrument [Line Items]
Contractual interest expense	942	1,024
Amortization of deferred financing costs	188	207
Total interest expense	1,130	1,231
2024 Convertible Notes
Debt Instrument [Line Items]
Contractual interest expense	876	1,033
Amortization of deferred financing costs	138	167
Total interest expense	$ 1,014	$ 1,200