Fair Value Measurements - Assets Categorized on Basis of Various Levels (Detail) - USD ($) $ in Thousands	Mar. 31, 2020	Sep. 30, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market fund deposits	$ 4,553	$ 21,816
Mutual fund investments	8	9
Total	4,561	21,825
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market fund deposits	4,553	21,816
Mutual fund investments	8	9
Total	$ 4,561	$ 21,825