Financial Instruments and Fair Value Measurements - Foreign Currency Contracts Activity (Parenthetical) (Detail) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) Contracts	Sep. 30, 2016 USD ($) Contracts
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Number of forward and option contracts exercised \| Contracts			33	41
Gains (losses) from forward and option contracts exercised \| $	$ 1.6	$ (3.1)	$ 10.5	$ (1.2)

For each line item in the statement of financial position, the amounts of gains and losses from fair value changes included in earnings.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 30
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=75031198&loc=d3e14172-108612

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