Summary of Significant Accounting Policies and Select Balance Sheet Information - Schedule of Other Long-term Liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Sep. 30, 2020
Other Liabilities Disclosure [Abstract]
Deferred consideration	$ 5,106	$ 2,216
Contingent consideration	817
Unrecognized tax benefits	2,538	2,464
Operating lease liabilities	3,188	3,340
Other long-term liabilities	$ 11,649	$ 8,020