Intangible Assets, Goodwill and Acquisitions - Schedule of Intangible Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 729.6	$ 701.4
Accumulated Amortization	(555.3)	(503.8)
Customer Relationships
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	723.1	694.9
Accumulated Amortization	$ (550.5)	(499.8)
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	$ (2.6)	(2.3)
Noncompete Agreements
Finite Lived Intangible Assets [Line Items]
Useful Life	5 years
Gross Carrying Amount	$ 2.7	2.7
Accumulated Amortization	$ (2.2)	$ (1.7)