Revenue - Schedule of Reportable Segment Revenues, Disaggregated by Revenue (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Disaggregation Of Revenue [Line Items]
Net service revenues	$ 626.7	$ 655.9
Operating Segments | Landscape Maintenance
Disaggregation Of Revenue [Line Items]
Net service revenues	402.6	421.4
Operating Segments | Snow Removal
Disaggregation Of Revenue [Line Items]
Net service revenues	39.7	61.8
Operating Segments | Maintenance Services
Disaggregation Of Revenue [Line Items]
Net service revenues	442.3	483.2
Operating Segments | Development Services
Disaggregation Of Revenue [Line Items]
Net service revenues	185.4	174.4
Eliminations
Disaggregation Of Revenue [Line Items]
Net service revenues	$ (1.0)	$ (1.7)