Derivative Instruments and Hedging Activities - Fair Value of Derivative Instruments on Gross Basis (Detail) - Designated as Hedging Instrument [Member] - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Derivative Assets	$ 87.7	$ 23.8
Derivative Liabilities	19.6	68.6
Foreign Exchange Forward Contracts [Member] | Other Current Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets	31.3	14.5
Foreign Exchange Forward Contracts [Member] | Other Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets	21.1	4.8
Foreign Exchange Forward Contracts [Member] | Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liabilities	13.0	45.8
Foreign Exchange Forward Contracts [Member] | Other Long-term Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liabilities	2.6	22.8
Interest Rate Swaps [Member] | Other Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets	3.9	$ 4.5
Cross-currency Interest Rate Swaps [Member] | Other Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets	31.4
Cross-currency Interest Rate Swaps [Member] | Other Long-term Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liabilities	$ 4.0