Revenue - Schedule of Reportable Segment Revenues, Disaggregated by Revenue (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Disaggregation Of Revenue [Line Items]
Net service revenues	$ 614.7	$ 599.2
Operating Segments | Landscape Maintenance
Disaggregation Of Revenue [Line Items]
Net service revenues	368.0	376.9
Operating Segments | Snow Removal
Disaggregation Of Revenue [Line Items]
Net service revenues	68.4	32.4
Operating Segments | Maintenance Services
Disaggregation Of Revenue [Line Items]
Net service revenues	436.4	409.3
Operating Segments | Development Services
Disaggregation Of Revenue [Line Items]
Net service revenues	179.2	191.8
Eliminations
Disaggregation Of Revenue [Line Items]
Net service revenues	$ (0.9)	$ (1.9)