Accrued Expenses - Summary of accrued expenses reflected on the company's balance sheet (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Sep. 30, 2019
Accrued Liabilities, Current [Abstract]
Accrued bonus liabilities	$ 2,571	$ 3,888
Accrued sub-advisor fees	552	730
Other accrued expenses	690	920
Total accrued expenses	$ 3,813	$ 5,538