Fair Value and Balance Sheet Locations - (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Derivatives Fair Value [Line Items]
Derivative asset, fair value	$ 3,424	$ 9,366
Derivative liability, fair value	3,525	9,974
Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member] | Prepaid Expenses and Other Current Assets [Member]
Derivatives Fair Value [Line Items]
Derivative asset, fair value	394	262
Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member] | Accrued expenses [Member]
Derivatives Fair Value [Line Items]
Derivative liability, fair value	0	0
Not Designated as Hedging Instrument [Member] | 1.25% Call Option [Member] | Other Assets [Member]
Derivatives Fair Value [Line Items]
Derivative asset, fair value	3,030	9,104
Not Designated as Hedging Instrument [Member] | 1.25% Embedded Cash Conversion Option [Member] | Other Liabilities [Member]
Derivatives Fair Value [Line Items]
Derivative liability, fair value	$ 3,525	$ 9,974