Intangible Assets, Goodwill and Acquisitions - Schedule of Intangible Assets (Details) - USD ($) $ in Millions	Dec. 31, 2023	Sep. 30, 2023
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 732.0	$ 732.0
Accumulated Amortization	(609.9)	(599.7)
Customer Relationships
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	725.5	725.5
Accumulated Amortization	$ (604.2)	(594.1)
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	$ (3.0)	$ (2.9)