Goodwill and Other Intangible Assets - Components of Other Intangible Assets (Detail) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount, total other intangible assets	$ 574.0	$ 582.6
Accumulated Amortization, total other intangible assets	(473.0)	(469.3)
Net Book Value, total other intangible assets	101.0	113.3
Client Relationships
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount, total other intangible assets	512.5	520.3
Accumulated Amortization, total other intangible assets	(428.5)	(425.5)
Net Book Value, total other intangible assets	84.0	94.8
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	25.2	25.7
Accumulated Amortization, total other intangible assets	(24.9)	(25.2)
Net Book Value, total other intangible assets	0.3	0.5
Trade Names
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount, total other intangible assets	34.3	34.6
Accumulated Amortization, total other intangible assets	(17.6)	(16.6)
Net Book Value, total other intangible assets	$ 16.7	$ 18.0