Line of Credit (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Oct. 04, 2017	May 26, 2016
Line of Credit Facility [Line Items]
Deferred finance costs	$ 400	$ 700
Letter of Credit
Line of Credit Facility [Line Items]
Line of credit, expiration date	Oct. 04, 2022
Letter of Credit | Minimum
Line of Credit Facility [Line Items]
Line of credit, expiration period	90 days
Line of Credit | Credit Agreement | Revolving Credit Facility
Line of Credit Facility [Line Items]
Line of credit, maximum borrowing capacity			$ 75,000	$ 75,000
Outstanding line of credit	$ 0	0
Deferred finance costs	$ 100	$ 200
Line of Credit | Credit Agreement | Swing Loan
Line of Credit Facility [Line Items]
Line of credit, maximum borrowing capacity			7,500
Secured Debt | Senior Secured Term Loan Facility
Line of Credit Facility [Line Items]
Face amount			$ 200,000