Financial Instruments and Fair Value Measurements - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Derivatives Fair Value [Line Items]
Hedge ineffectiveness			$ 0	$ 0
Foreign currency translation gains (losses), net	$ (10,316,000)	$ 4,061,000	(153,359,000)	46,890,000
Forward Contracts [Member]
Derivatives Fair Value [Line Items]
Foreign currency translation gains (losses), net	$ 13,900,000	$ (8,000,000)	$ 54,200,000	$ (19,300,000)