Quarterly report pursuant to Section 13 or 15(d)

Significant Accounting Policies (Details)

v3.22.2
Significant Accounting Policies (Details) - USD ($)
$ in Thousands
3 Months Ended 9 Months Ended
Jun. 30, 2022
Jun. 30, 2021
Jun. 30, 2022
Jun. 30, 2021
Sep. 30, 2021
Accounting Policies [Abstract]          
Restricted cash $ 105   $ 105   $ 0
Restricted investments $ 7,312   $ 7,312   $ 0
Revenues | Customer Concentration Risk | Various Departments Of Transportation          
Concentration Risk [Line Items]          
Concentration risk percentage 43.70% 35.90% 37.20% 30.70%  
Revenues | Customer Concentration Risk | Alabama Department of Transportation          
Concentration Risk [Line Items]          
Concentration risk percentage 14.40% 10.90% 10.90% 9.30%