Revenue - Schedule of Reportable Segment Revenues, Disaggregated by Revenue (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Disaggregation Of Revenue [Line Items]
Net service revenues	$ 655.9	$ 591.8
Operating Segments | Landscape Maintenance
Disaggregation Of Revenue [Line Items]
Net service revenues	421.4	402.2
Operating Segments | Snow Removal
Disaggregation Of Revenue [Line Items]
Net service revenues	61.8	36.0
Operating Segments | Maintenance Services
Disaggregation Of Revenue [Line Items]
Net service revenues	483.2	438.2
Operating Segments | Development Services
Disaggregation Of Revenue [Line Items]
Net service revenues	174.4	154.7
Eliminations
Disaggregation Of Revenue [Line Items]
Net service revenues	$ (1.7)	$ (1.1)