Long-Term Debt - Summary of Maturities of Borrowing Obligations (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Sep. 30, 2023
Debt Instrument [Line Items]
2025	$ 87,500
2028	210,000
Total before unamortized discount and issuance costs and current portion	297,500
Less: unamortized discount and issuance costs	(15,594)
Less: current portion of long-term debt	(87,094)
Total long-term debt	194,812	$ 275,951
2028 Notes
Debt Instrument [Line Items]
2028	122,500
Total before unamortized discount and issuance costs and current portion	122,500
Less: unamortized discount and issuance costs	(1,809)
Total long-term debt	120,691
2025 Modified Notes
Debt Instrument [Line Items]
2025	87,500
2028	87,500
Total before unamortized discount and issuance costs and current portion	175,000
Less: unamortized discount and issuance costs	(13,785)
Less: current portion of long-term debt	(87,094)
Total long-term debt	$ 74,121