Share-Based Compensation - Schedule of Restricted Stock Activity (Detail) - Restricted Stock [Member] - $ / shares	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Unvested, Beginning Balance	1,172,493	1,006,206	1,195,548
Number of Shares, Granted	495,087	718,959	346,123
Number of Shares, Vested	(585,755)	(455,303)	(492,465)
Number of Shares, Forfeited	(344,934)	(97,369)	(43,000)
Number of Shares, Unvested, Ending Balance	736,891	1,172,493	1,006,206
Weighted-Average Grant Date Fair Value, Unvested, Beginning Balance	$ 4.43	$ 6.22	$ 5.47
Weighted-Average Grant Date Fair Value, Granted	2.43	3.2	9.53
Weighted-Average Grant Date Fair Value, Vested	4.58	6.13	6.89
Weighted-Average Grant Date Fair Value, Forfeited	4.05	2.97	4.57
Weighted-Average Grant Date Fair Value, Unvested, Ending Balance	$ 3.35	$ 4.43	$ 6.22