Income Tax Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Current:
Federal	$ 17,083	$ 7,921	$ (6,067)
State	7,086	4,722	(1,016)
Deferred
Federal	(2,643)	(3,168)	11,052
State	(901)	(1,958)	3,633
Income tax expense	$ 20,625	$ 7,517	$ 7,602