Quarterly report pursuant to Section 13 or 15(d)

Significant Accounting Policies (Details)

v3.22.1
Significant Accounting Policies (Details) - USD ($)
$ in Thousands
3 Months Ended 6 Months Ended
Mar. 31, 2022
Mar. 31, 2021
Mar. 31, 2022
Mar. 31, 2021
Sep. 30, 2021
Concentration Risk [Line Items]          
Restricted cash $ 1,721   $ 1,721   $ 0
Restricted investments $ 6,203   $ 6,203   $ 0
Revenues | Customer Concentration Risk | Various Departments Of Transportation          
Concentration Risk [Line Items]          
Concentration risk percentage 30.80% 26.10% 32.30% 27.00%  
Revenues | Customer Concentration Risk | Florida Department of Transportation          
Concentration Risk [Line Items]          
Concentration risk percentage 12.50% 9.50% 11.20% 9.10%  
Private | Revenues | Customer Concentration Risk          
Concentration Risk [Line Items]          
Concentration risk percentage 42.10% 41.80% 40.50% 41.20%  
Public | Revenues | Customer Concentration Risk          
Concentration Risk [Line Items]          
Concentration risk percentage 57.90% 58.20% 59.50% 58.80%