Debt - Interest Expense (Details) - Senior Notes - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2022	Mar. 31, 2021
2024 Convertible Notes
Schedule of Contractual Maturities
Contractual interest expense	$ 1,033	$ 1,033	$ 2,066	$ 2,066
Amortization of deferred financing costs	142	111	309	223
Amortization of debt discount	0	1,461	0	2,891
Total interest expense	1,175	2,605	2,375	5,180
2025 Convertible Notes
Schedule of Contractual Maturities
Contractual interest expense	1,024	1,024	2,048	2,048
Amortization of deferred financing costs	182	141	389	281
Amortization of debt discount	0	1,712	0	3,391
Total interest expense	$ 1,206	$ 2,877	$ 2,437	$ 5,720