Acquired Intangible Assets and Related Amortization (Detail) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Finite Lived Intangible Assets [Line Items]
Acquired intangible assets, net	$ 1,633.1	$ 296.4
Customer Relationships [Member]
Finite Lived Intangible Assets [Line Items]
Acquired intangible assets, gross	1,325.4	310.1
Accumulated amortization	(144.4)	(124.4)
Acquired intangible assets, net	1,181.0	185.7
Trade Secrets [Member]
Finite Lived Intangible Assets [Line Items]
Acquired intangible assets, gross	30.2	29.9
Accumulated amortization	(27.6)	(25.6)
Acquired intangible assets, net	2.6	4.3
Computer Software Intangible Asset [Member]
Finite Lived Intangible Assets [Line Items]
Acquired intangible assets, gross	354.1	87.7
Accumulated amortization	(70.6)	(54.9)
Acquired intangible assets, net	283.5	32.8
Trade Names [Member]
Finite Lived Intangible Assets [Line Items]
Acquired intangible assets, gross	160.7	75.3
Accumulated amortization	(24.4)	(19.9)
Acquired intangible assets, net	136.3	55.4
Other Intangible Assets [Member]
Finite Lived Intangible Assets [Line Items]
Acquired intangible assets, gross	57.6	43.5
Accumulated amortization	(27.9)	(25.3)
Acquired intangible assets, net	$ 29.7	$ 18.2