Intangible Assets, Goodwill, Acquisitions, and Divestitures - Additional Information (Details) $ in Millions		3 Months Ended		6 Months Ended
	Jan. 12, 2024 USD ($) Subsidiary	Mar. 31, 2024 USD ($)	Mar. 31, 2023 USD ($) Company	Mar. 31, 2024 USD ($)	Mar. 31, 2023 USD ($) Company
Finite Lived Intangible Assets [Line Items]
Amortization of intangible assets		$ 8.7	$ 11.0	$ 18.8	$ 22.9
Weighted average amortization periods of intangible assets acquired					7 years
Number of unrelated maintenance services companies acquired | Company			3		3
Consideration paid, net of cash acquired				0.0	$ 13.8
Number of sale of fully owned subsidiaries | Subsidiary	1
Cash consideration	$ 51.6			51.6	0.0
Net Service Revenues		672.9	$ 650.4	1,299.6	$ 1,306.3
Selling, General and Administrative Expenses [Member]
Finite Lived Intangible Assets [Line Items]
Gain on sale of fully owned subsidiaries		$ 43.9		$ 43.9
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
Customer Relationships
Finite Lived Intangible Assets [Line Items]
Identifiable assets acquired related to intangible assets			$ 4.0		$ 4.0