Intangible Assets, Goodwill, Acquisitions and Divestitures - Schedule of Intangible Assets (Details) - USD ($) $ in Millions	Dec. 31, 2025	Sep. 30, 2025
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 689.3	$ 715.9
Accumulated Amortization	(629.0)	(649.4)
Customer Relationships
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	689.3	715.9
Accumulated Amortization	$ (629.0)	$ (649.4)
Customer Relationships | Minimum
Finite Lived Intangible Assets [Line Items]
Estimated Useful Life	6 years
Customer Relationships | Maximum
Finite Lived Intangible Assets [Line Items]
Estimated Useful Life	21 years