Supporting Financial Information - Accounts Payable, Accrued Expense and Other Current Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Sep. 30, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accounts payable	$ 11,827	$ 10,054
Accrued benefits	2,963	2,252
Accrued bonus and incentive compensation	1,819	1,951
Accrued workers' compensation insurance	4,888	4,007
Other accrued expenses	2,756	2,369
Accounts payable, accrued expenses, and other current liabilities	$ 24,253	$ 20,633