Intangible Assets, Goodwill and Acquisitions - Schedule of Intangible Assets (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2019	Sep. 30, 2019
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 651.3	$ 647.1
Accumulated Amortization	(409.1)	(395.6)
Customer Relationships
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	643.8	639.6
Accumulated Amortization	$ (406.6)	(393.3)
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]
Gross Carrying Amount	$ 4.8	4.8
Accumulated Amortization	$ (1.7)	(1.7)
Trademarks | Minimum
Finite Lived Intangible Assets [Line Items]
Useful Life	4 years
Trademarks | Maximum
Finite Lived Intangible Assets [Line Items]
Useful Life	12 years
Noncompete Agreements
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 2.7	2.7
Accumulated Amortization	$ (0.8)	$ (0.6)
Noncompete Agreements | Minimum
Finite Lived Intangible Assets [Line Items]
Useful Life	5 years