Commitments and Contingencies (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Sep. 30, 2020
Commitments and Contingencies Disclosure [Abstract]
Accrued Insurance, Current	$ 6,537	$ 6,254
Liability for Claims and Claims Adjustment Expense	38	36
Loss Contingencies [Line Items]
Letters of Credit Outstanding, Amount	6,314
Estimated cost of completion of bonded projects	90,149
Purchase Commitment, Remaining Minimum Amount Committed	10,467
Insurance Related [Member]
Loss Contingencies [Line Items]
Letters of Credit Outstanding, Amount	$ 6,114	5,464
Vendor Related [Member]
Loss Contingencies [Line Items]
Letters of Credit Outstanding, Amount		$ 200