Commitments and Contingencies (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Sep. 30, 2020
Commitments and Contingencies Disclosure [Abstract]
Accrued Insurance, Current	$ 6,136	$ 6,254
Liability for Claims and Claims Adjustment Expense	37	36
Loss Contingencies [Line Items]
Letters of Credit Outstanding, Amount	6,964
Estimated cost of completion of bonded projects	87,698
Purchase Commitment, Remaining Minimum Amount Committed	11,569
Insurance Related [Member]
Loss Contingencies [Line Items]
Letters of Credit Outstanding, Amount	6,764	5,464
Vendor Related [Member]
Loss Contingencies [Line Items]
Letters of Credit Outstanding, Amount	$ 200	$ 200