Goodwill and Identifiable Assets - Summary of Identifiable Intangible Assets with Definite and Indefinite Useful Lives (Detail) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Finite And Infinite Lived Intangible Assets [Line Items]
Intangible assets with definite life, Gross Carrying Value	$ 116.2	$ 113.2
Intangible assets with definite life, Accumulated Amortization	(85.8)	(82.0)
Intangible assets with definite life, Net	30.4	31.2
Gross Carrying Value	125.1	122.1
Net	39.3	40.1
Trademarks and tradenames with indefinite lives [Member]
Finite And Infinite Lived Intangible Assets [Line Items]
Intangible assets with definite life, Accumulated Amortization	0.0
Intangible assets with indefinite life, Gross Carrying Value	8.9	8.9
Intangible assets with indefinite life, Net	8.9	8.9
Customer relationships [Member]
Finite And Infinite Lived Intangible Assets [Line Items]
Intangible assets with definite life, Gross Carrying Value	25.2	25.0
Intangible assets with definite life, Accumulated Amortization	(18.0)	(17.5)
Intangible assets with definite life, Net	7.2	7.5
Trademarks and tradenames [Member]
Finite And Infinite Lived Intangible Assets [Line Items]
Intangible assets with definite life, Gross Carrying Value	0.6	0.6
Intangible assets with definite life, Accumulated Amortization	(0.2)	(0.2)
Intangible assets with definite life, Net	0.4	0.4
Capitalized Software [Member]
Finite And Infinite Lived Intangible Assets [Line Items]
Intangible assets with definite life, Gross Carrying Value	45.3	42.6
Intangible assets with definite life, Accumulated Amortization	(33.3)	(31.2)
Intangible assets with definite life, Net	12.0	11.4
Technology [Member]
Finite And Infinite Lived Intangible Assets [Line Items]
Intangible assets with definite life, Gross Carrying Value	34.6	34.4
Intangible assets with definite life, Accumulated Amortization	(24.9)	(24.2)
Intangible assets with definite life, Net	9.7	10.2
Customer Contracts [Member]
Finite And Infinite Lived Intangible Assets [Line Items]
Intangible assets with definite life, Gross Carrying Value	10.5	10.6
Intangible assets with definite life, Accumulated Amortization	(9.4)	(8.9)
Intangible assets with definite life, Net	$ 1.1	$ 1.7