Long-Term Debt - Schedule of Interest Expense Related to Notes (Details) - 3.00% Convertible Senior Notes Due 2025 - USD ($) $ in Thousands	12 Months Ended
Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Debt Instrument [Line Items]
Contractual interest expense	$ 5,246	$ 5,246	$ 1,753
Amortization of debt discount	3,755	3,527	1,131
Amortization of issuance costs	944	887	285
Total interest expense related to the Notes	$ 9,945	$ 9,660	$ 3,169

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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