Goodwill and Other Intangible Assets - Components of Other Intangible Assets (Detail) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount, total other intangible assets	$ 582.6	$ 599.1
Accumulated Amortization, total other intangible assets	(469.3)	(455.8)
Net Book Value, total other intangible assets	113.3	143.3
Client Relationships
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount, total other intangible assets	520.3	534.1
Accumulated Amortization, total other intangible assets	(425.5)	(412.4)
Net Book Value, total other intangible assets	94.8	121.7
Patents
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount, total other intangible assets	2.0	2.0
Accumulated Amortization, total other intangible assets	(2.0)	(2.0)
Trademarks, Licenses and Agreements
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount, total other intangible assets	25.7	26.2
Accumulated Amortization, total other intangible assets	(25.2)	(25.2)
Net Book Value, total other intangible assets	0.5	1.0
Trade Names
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount, total other intangible assets	34.6	36.8
Accumulated Amortization, total other intangible assets	(16.6)	(16.2)
Net Book Value, total other intangible assets	$ 18.0	$ 20.6