Accrued Expenses and Other Liabilities -Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Sep. 30, 2019
Accrued Liabilities And Other Liabilities [Abstract]
Compensation	$ 19,876	$ 13,031
Cost of revenue related liabilities	4,000	1,668
Sales and other taxes payable	13,443	219
Professional fees	4,948	3,863
Facilities related liabilities	59	273
Other	8,707	5,140
Total	$ 51,033	$ 24,194