Income Taxes - Income Tax Expense Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Federal
Current income tax expense	$ 589	$ 1,074	$ 54
Deferred income tax expense	2,293	2,126	3,012
Total income tax expense	2,882	3,200	3,066
State
Current income tax expense	371	439	332
Deferred income tax expense	(65)	412	(308)
Total income tax expense	306	851	24
Total
Current income tax expense	960	1,513	386
Deferred income tax expense	2,228	2,538	2,704
Total income tax expense	$ 3,188	$ 4,051	$ 3,090