Intangible Assets, Goodwill and Acquisitions - Additional Information (Details) $ in Millions	12 Months Ended
	Sep. 30, 2023 USD ($) Company	Sep. 30, 2022 USD ($) Company	Sep. 30, 2021 USD ($)
Finite Lived Intangible Assets [Line Items]
Amortization of intangible assets	$ 44.5	$ 51.5	$ 52.3
Number of unrelated maintenance services companies acquired | Company	3	8
Consideration paid, net of cash acquired	$ 13.8	$ 93.1	110.4
Net service revenues	$ 2,816.0	$ 2,774.6	$ 2,553.6
Unrelated Maintenance Services Companies
Finite Lived Intangible Assets [Line Items]
Acquisition of operations, Percentage	100.00%	100.00%
Consideration paid, net of cash acquired	$ 13.8
Business Acquisitions
Finite Lived Intangible Assets [Line Items]
Net service revenues	16.0	$ 65.5
Customer Relationships and Non-compete Agreements
Finite Lived Intangible Assets [Line Items]
Identifiable assets acquired related to intangible assets		$ 25.4
Customer Relationships
Finite Lived Intangible Assets [Line Items]
Identifiable assets acquired related to intangible assets	$ 4.0