Income Tax Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Current:
Federal	$ (6,067)	$ 7,578	$ 18,724
State	(1,016)	2,664	5,344
Deferred
Federal	11,052	8,775	7,485
State	3,633	1,359	2,185
Income tax expense	$ 7,602	$ 20,376	$ 33,738