v3.8.0.1
Financial Instruments and Fair Value Measurements - Schedule of Fair Value and Classification of Derivative Instruments (Parenthetical) (Detail) - USD ($)
$ in Millions
3 Months Ended 9 Months Ended
Sep. 30, 2017
Sep. 30, 2016
Sep. 30, 2017
Sep. 30, 2016
Foreign Currency Options [Member]        
Derivatives Fair Value [Line Items]        
Unrealized gains (losses) on foreign exchange transactions $ (12.3) $ 3.1 $ (44.8) $ (10.4)