Intangible Assets, Goodwill and Acquisitions - Schedule of Intangible Assets (Details) - USD ($) $ in Millions	Sep. 30, 2023	Sep. 30, 2022
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 732.0	$ 729.6
Accumulated Amortization	(599.7)	(555.3)
Customer Relationships
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	725.5	723.1
Accumulated Amortization	$ (594.1)	(550.5)
Customer Relationships | Minimum
Finite Lived Intangible Assets [Line Items]
Useful Life	6 years
Customer Relationships | Maximum
Finite Lived Intangible Assets [Line Items]
Useful Life	21 years
Trademarks
Finite Lived Intangible Assets [Line Items]
Useful Life	12 years
Gross Carrying Amount	$ 3.8	3.8
Accumulated Amortization	$ (2.9)	(2.6)
Noncompete Agreements
Finite Lived Intangible Assets [Line Items]
Useful Life	5 years
Gross Carrying Amount	$ 2.7	2.7
Accumulated Amortization	$ (2.7)	$ (2.2)