Goodwill and Other Intangible Assets - Components of Other Intangible Assets (Detail) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount, total other intangible assets	$ 489.9	$ 492.3
Accumulated Amortization, total other intangible assets	(401.8)	(392.6)
Net Book Value, total other intangible assets	88.1	99.7
Client Relationships
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount, total other intangible assets	431.9	433.9
Accumulated Amortization, total other intangible assets	(358.3)	(350.0)
Net Book Value, total other intangible assets	73.6	83.9
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	24.4	24.6
Accumulated Amortization, total other intangible assets	(24.4)	(24.5)
Net Book Value, total other intangible assets		0.1
Trade Names
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount, total other intangible assets	31.6	31.8
Accumulated Amortization, total other intangible assets	(17.1)	(16.1)
Net Book Value, total other intangible assets	$ 14.5	$ 15.7