Revenue - Schedule of Reportable Segment Revenues, Disaggregated by Revenue (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2024	Mar. 31, 2023
Disaggregation Of Revenue [Line Items]
Net service revenues	$ 672.9	$ 650.4	$ 1,299.6	$ 1,306.3
Operating Segments | Landscape Maintenance
Disaggregation Of Revenue [Line Items]
Net service revenues	337.4	359.0	740.1	780.5
Operating Segments | Snow Removal
Disaggregation Of Revenue [Line Items]
Net service revenues	173.1	138.8	212.7	200.6
Operating Segments | Maintenance Services
Disaggregation Of Revenue [Line Items]
Net service revenues	510.5	497.8	952.8	981.1
Operating Segments | Development Services
Disaggregation Of Revenue [Line Items]
Net service revenues	164.4	155.6	349.7	329.9
Eliminations
Disaggregation Of Revenue [Line Items]
Net service revenues	$ (2.0)	$ (3.0)	$ (2.9)	$ (4.7)