Long-Term Debt - Schedule of Interest Expense Related to Notes (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2022	Mar. 31, 2021
Debt Instrument [Line Items]
Total interest expense related to the Notes			$ 1,800	$ 2,400
3.00% Convertible Senior Notes Due 2025
Debt Instrument [Line Items]
Contractual interest expense	$ 1,294	$ 1,294	2,616	2,616
Amortization of debt discount	919	863	1,843	1,731
Amortization of issuance costs	231	217	463	435
Total interest expense related to the Notes	$ 2,444	$ 2,374	$ 4,922	$ 4,782

Amount of noncash expense included in interest expense to amortize debt discount and premium associated with the related debt instruments. Excludes amortization of financing costs. Alternate captions include noncash interest expense.

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