Employee Benefits - Summary of Nonvested Options (Detail) - $ / shares shares in Thousands	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Nonvested beginning of period, Options	209
Granted, Options	367
Vested, Options	(145)
Forfeitures, Options	(2)
Nonvested end of period, Options	429	209
Nonvested beginning of period, Weighted Average Grant Date Fair Value	$ 3.24
Granted, Weighted Average Grant Date Fair Value	3.54	$ 3.61	$ 3.27
Vested, Weighted Average Grant Date Fair Value	3.64
Forfeitures, Weighted Average Grant Date Fair Value	3.11
Nonvested end of period, Weighted Average Grant Date Fair Value	$ 3.36