Debt - Outstanding Obligations (Details) - USD ($)	Mar. 31, 2022	Oct. 01, 2021	Sep. 30, 2021	Mar. 31, 2021
Gross Amount
Total long-term debt	$ 316,250,000		$ 316,250,000	$ 316,250,000
Debt Discount and Issuance Costs
Total long-term debt	(4,082,000)		(52,064,000)	(59,107,000)
Carrying Amount
Total		$ 311,471,000
Total long-term debt	312,168,000		264,186,000	257,143,000
Senior Notes | 2024 Convertible Notes
Gross Amount
Total	143,750,000		143,750,000	143,750,000
Debt Discount and Issuance Costs
Total	(1,502,000)		(20,207,000)	(23,443,000)
Carrying Amount
Total	142,248,000		123,543,000	120,307,000
Senior Notes | 2025 Convertible Notes
Gross Amount
Total	172,500,000		172,500,000	172,500,000
Debt Discount and Issuance Costs
Total	(2,580,000)		(31,857,000)	(35,664,000)
Carrying Amount
Total	$ 169,920,000		$ 140,643,000	$ 136,836,000