Accrued Expenses - Summary of accrued expenses reflected on the company's balance sheet (Detail) - USD ($) $ in Thousands	Mar. 31, 2020	Sep. 30, 2019
Accrued Liabilities, Current [Abstract]
Accrued bonus liabilities	$ 1,981	$ 3,888
Accrued sub-advisor fees	558	730
Other accrued expenses	563	920
Total accrued expenses	$ 3,102	$ 5,538