Intangible Assets (Acquired Intangible Assets) (Details) - USD ($) $ in Millions	Jun. 30, 2018	Sep. 30, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible assets, gross	$ 665.9	$ 578.7
Accumulated amortization and impairment	(216.9)	(210.4)
Intangible assets, net	449.0	368.3
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	603.2	510.9
Accumulated amortization	(203.3)	(189.5)
Finite-lived intangible assets, net	399.9	321.4
Trade names and trademarks
Acquired Indefinite-lived Intangible Assets [Line Items]
Indefinite-lived intangible assets, gross	62.7	67.8
Accumulated impairment	(13.6)	(20.9)
Indefinite-lived intangible assets, net	49.1	46.9
Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	497.6	424.1
Accumulated amortization	(158.2)	(142.3)
Finite-lived intangible assets, net	339.4	281.8
Patents and technology
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	34.1	13.4
Accumulated amortization	(11.3)	(10.6)
Finite-lived intangible assets, net	22.8	2.8
Other
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	71.5	73.4
Accumulated amortization	(33.8)	(36.6)
Finite-lived intangible assets, net	$ 37.7	$ 36.8