Accrued Expenses and Other Liabilities -Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Sep. 30, 2020
Accrued Liabilities And Other Liabilities [Abstract]
Compensation	$ 22,065	$ 37,960
Cost of revenue related liabilities	4,011	3,683
Sales and other taxes payable	18,031	14,688
Professional fees	3,223	2,458
Interest Payable	1,444	2,703
Other	3,426	6,365
Total	$ 52,200	$ 67,857