Income Taxes - Income Tax Expense Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Federal
Current income tax expense	$ 424	$ 589	$ 1,074
Deferred income tax benefit	(145)	2,293	2,126
Total income tax expense	279	2,882	3,200
State
Current income tax expense	263	371	439
Deferred income tax benefit	(223)	(65)	412
Total income tax expense	40	306	851
Total
Current income tax expense	687	960	1,513
Deferred income tax benefit	(368)	2,228	2,538
Total income tax expense	$ 319	$ 3,188	$ 4,051