Intangible Assets, Goodwill, Acquisitions, and Divestitures - Summary of Goodwill (Details) $ in Millions	12 Months Ended
	Sep. 30, 2024 USD ($)
Goodwill [Line Items]
Beginning balance	$ 2,021.4
Acquisitions	0.1	[1]
Divestiture	(5.8)
Ending balance	2,015.7
Maintenance Services
Goodwill [Line Items]
Beginning balance	1,803.4
Acquisitions	0.1	[1]
Divestiture	(5.8)
Ending balance	1,797.7
Development Services
Goodwill [Line Items]
Beginning balance	218.0
Acquisitions	0.0	[1]
Divestiture	0.0
Ending balance	$ 218.0

[1] The acquisitions adjustment includes the immaterial impact of foreign currency adjustments during the period