Goodwill and Other Identifiable Intangible Assets - Detail of Identifiable Intangible Assets (Detail) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Acquired Intangible Assets By Major Class [Line Items]
Cost	$ 441.7	$ 479.4
Accumulated amortization	(314.1)	(320.6)
Net	127.6	158.8
Net, indefinite-life intangibles	161.8	163.0
Cost	603.5	642.4
Net	289.4	321.8
Customer relationships
Acquired Intangible Assets By Major Class [Line Items]
Cost	353.3	360.9
Accumulated amortization	(245.5)	(229.9)
Net	107.8	131.0
Trade names intangibles
Acquired Intangible Assets By Major Class [Line Items]
Cost	0.4	1.5
Accumulated amortization	(0.4)	(1.4)
Net	0.0	0.1
Patented Technology [Member]
Acquired Intangible Assets By Major Class [Line Items]
Cost	88.0	117.0
Accumulated amortization	(68.2)	(89.3)
Net	$ 19.8	$ 27.7