Significant Accounting Policies - Concentration of Risks (Details) - Revenues - Customer Concentration Risk	3 Months Ended		6 Months Ended
	Mar. 31, 2026	Mar. 31, 2025	Mar. 31, 2026	Mar. 31, 2025
Private
Concentration Risk [Line Items]
Concentration risk percentage	30.90%	37.90%	32.80%	40.10%
Public
Concentration Risk [Line Items]
Concentration risk percentage	69.10%	62.10%	67.20%	59.90%
Florida Department of Transportation
Concentration Risk [Line Items]
Concentration risk percentage	12.50%	11.40%	11.80%