Commitments and Contingencies - Narrative (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($) Facility	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Commitment And Contingencies [Line Items]
Commitments for outsourced services	$ 74.1
Operating lease commitments	263.9
Minimum non-cancelable sublease rental commitments	20.3
Rent expense	$ 118.3	$ 117.6	$ 120.8
Number of sites cited as potentially responsible party | Facility	3
Number of previously and currently owned sites with potential remediation obligations | Facility	7
Purchase of Property, Plant and Equipment
Commitment And Contingencies [Line Items]
Commitments for the purchase of property, plant and equipment	$ 25.9