Provision for Income Taxes - Schedule of Deferred Tax Asset and Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Sep. 30, 2020
Deferred tax assets
Allowance for bad debt	$ 413	$ 527
Amortization of finite-lived intangible assets	586	405
State net operating loss	488	664
Employee benefits	736	37
Accrued insurance claims	1,610	1,583
Other	335	556
Total deferred tax assets	4,168	3,772
Deferred tax liabilities
Amortization of goodwill	(6,541)	(5,048)
Property, plant and equipment	(14,530)	(12,341)
Other	(459)	0
Total deferred tax liabilities,	(21,530)	(17,389)
Net deferred tax liabilities	$ (17,362)	$ (13,617)