Revenue - Schedule of Reportable Segment Revenues, Disaggregated by Revenue (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2023	Mar. 31, 2022
Disaggregation Of Revenue [Line Items]
Net service revenues	$ 650.4	$ 711.9	$ 1,306.3	$ 1,303.8
Operating Segments | Landscape Maintenance
Disaggregation Of Revenue [Line Items]
Net service revenues	359.0	345.2	780.5	747.4
Operating Segments | Snow Removal
Disaggregation Of Revenue [Line Items]
Net service revenues	138.8	208.2	200.6	244.2
Operating Segments | Maintenance Services
Disaggregation Of Revenue [Line Items]
Net service revenues	497.8	553.4	981.1	991.6
Operating Segments | Development Services
Disaggregation Of Revenue [Line Items]
Net service revenues	155.6	159.7	329.9	314.4
Eliminations
Disaggregation Of Revenue [Line Items]
Net service revenues	$ (3.0)	$ (1.2)	$ (4.7)	$ (2.2)