Intangible Assets (Acquired Intangible Assets) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Sep. 30, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible assets, gross	$ 706.9	$ 658.1
Accumulated amortization and impairment	(271.1)	(238.6)
Intangible assets, net	435.8	419.5
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	654.7	601.9
Accumulated amortization	(259.9)	(226.5)
Finite-lived intangible assets, net	394.8	375.4
Trade names and trademarks
Acquired Indefinite-lived Intangible Assets [Line Items]
Indefinite-lived intangible assets, gross	52.2	56.2
Accumulated impairment	(11.2)	(12.1)
Indefinite-lived intangible assets, net	41.0	44.1
Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	538.0	487.9
Accumulated amortization	(209.9)	(179.8)
Finite-lived intangible assets, net	328.1	308.1
Patents and technology
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	39.1	39.0
Accumulated amortization	(16.3)	(13.3)
Finite-lived intangible assets, net	22.8	25.7
Other
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	77.6	75.0
Accumulated amortization	(33.7)	(33.4)
Finite-lived intangible assets, net	$ 43.9	$ 41.6