Leases - Assets and Liabilities - Operating Leases (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Sep. 30, 2020
Assets and Liabilities, Lessee [Abstract]
Operating lease right-of-use assets	$ 52,159	$ 39,071
Accrued expenses and other current liabilities	$ 7,489	$ 7,015
Operating Lease, Liability, Current, Statement of Financial Position	Accrued expenses and other current liabilities	Accrued expenses and other current liabilities
Long-term operating lease liabilities	$ 45,034	$ 31,855
Total lease liability balance	$ 52,523	$ 38,870