Acquired Intangible Assets and Related Amortization (Detail) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Finite Lived Intangible Assets [Line Items]
Acquired intangible assets, net	$ 1,631.6	$ 296.4
Customer Relationships [Member]
Finite Lived Intangible Assets [Line Items]
Acquired intangible assets, gross	1,345.1	310.1
Accumulated amortization	(159.9)	(124.4)
Acquired intangible assets, net	1,185.2	185.7
Trade Secrets [Member]
Finite Lived Intangible Assets [Line Items]
Acquired intangible assets, gross	30.2	29.9
Accumulated amortization	(28.1)	(25.6)
Acquired intangible assets, net	2.1	4.3
Software [Member]
Finite Lived Intangible Assets [Line Items]
Acquired intangible assets, gross	358.6	87.7
Accumulated amortization	(78.0)	(54.9)
Acquired intangible assets, net	280.6	32.8
Trade Names [Member]
Finite Lived Intangible Assets [Line Items]
Acquired intangible assets, gross	161.6	75.3
Accumulated amortization	(26.7)	(19.9)
Acquired intangible assets, net	134.9	55.4
Other Intangible Assets [Member]
Finite Lived Intangible Assets [Line Items]
Acquired intangible assets, gross	57.4	43.5
Accumulated amortization	(28.6)	(25.3)
Acquired intangible assets, net	$ 28.8	$ 18.2