Revenue - Schedule of Reportable Segment Revenues, Disaggregated by Revenue (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Disaggregation Of Revenue [Line Items]
Net service revenues	$ 766.0	$ 747.4	$ 2,072.3	$ 2,051.2
Operating Segments | Landscape Maintenance
Disaggregation Of Revenue [Line Items]
Net service revenues	555.3	548.9	1,335.8	1,296.3
Operating Segments | Snow Removal
Disaggregation Of Revenue [Line Items]
Net service revenues	9.3	12.9	209.9	257.1
Operating Segments | Maintenance Services
Disaggregation Of Revenue [Line Items]
Net service revenues	564.6	561.8	1,545.7	1,553.4
Operating Segments | Development Services
Disaggregation Of Revenue [Line Items]
Net service revenues	203.4	186.4	533.3	500.8
Eliminations
Disaggregation Of Revenue [Line Items]
Net service revenues	$ (2.0)	$ (0.8)	$ (6.7)	$ (3.0)