Revenue - Schedule of Reportable Segment Revenues, Disaggregated by Revenue (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Mar. 31, 2026	Mar. 31, 2025	Mar. 31, 2026	Mar. 31, 2025
Disaggregation Of Revenue [Line Items]
Net service revenues	$ 702.9	$ 662.6	$ 1,317.7	$ 1,261.8
Operating Segments \| Landscape Maintenance
Disaggregation Of Revenue [Line Items]
Net service revenues	333.0	320.3	701.0	697.3
Operating Segments \| Snow Removal
Disaggregation Of Revenue [Line Items]
Net service revenues	221.6	172.5	290.0	204.8
Operating Segments \| Maintenance Services
Disaggregation Of Revenue [Line Items]
Net service revenues	554.6	492.8	991.0	902.1
Operating Segments \| Development Services
Disaggregation Of Revenue [Line Items]
Net service revenues	149.6	171.9	328.8	363.7
Eliminations
Disaggregation Of Revenue [Line Items]
Net service revenues	$ (1.3)	$ (2.1)	$ (2.1)	$ (4.0)

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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- Definition

Amount, including tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value-added and excise.

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