Revenue - Schedule of Reportable Segment Revenues, Disaggregated by Revenue (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Mar. 31, 2025	Mar. 31, 2024
Disaggregation Of Revenue [Line Items]
Net service revenues	$ 662.6	$ 672.9	$ 1,261.8	$ 1,299.6
Operating Segments | Landscape Maintenance
Disaggregation Of Revenue [Line Items]
Net service revenues	320.3	337.4	697.3	740.1
Operating Segments | Snow Removal
Disaggregation Of Revenue [Line Items]
Net service revenues	172.5	173.1	204.8	212.7
Operating Segments | Maintenance Services
Disaggregation Of Revenue [Line Items]
Net service revenues	492.8	510.5	902.1	952.8
Operating Segments | Development Services
Disaggregation Of Revenue [Line Items]
Net service revenues	171.9	164.4	363.7	349.7
Eliminations
Disaggregation Of Revenue [Line Items]
Net service revenues	$ (2.1)	$ (2.0)	$ (4.0)	$ (2.9)