Revenue - Schedule of Reportable Segment Revenues, Disaggregated by Revenue (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Disaggregation Of Revenue [Line Items]
Net service revenues	$ 599.2	$ 626.7
Operating Segments | Landscape Maintenance
Disaggregation Of Revenue [Line Items]
Net service revenues	376.9	402.6
Operating Segments | Snow Removal
Disaggregation Of Revenue [Line Items]
Net service revenues	32.4	39.7
Operating Segments | Maintenance Services
Disaggregation Of Revenue [Line Items]
Net service revenues	409.3	442.3
Operating Segments | Development Services
Disaggregation Of Revenue [Line Items]
Net service revenues	191.8	185.4
Eliminations
Disaggregation Of Revenue [Line Items]
Net service revenues	$ (1.9)	$ (1.0)