Derivatives and Hedging - Schedule of Balance Sheet Hedges Cover Currency Exposures in Notional Amounts (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Derivatives and their notional amounts	$ 243,486	$ 235,454
Accounts Receivable [Member]
Derivatives, Fair Value [Line Items]
Derivatives and their notional amounts	52,130	44,427
Other Assets And Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivatives and their notional amounts	34,109	46,550
Intercompany [Member]
Derivatives, Fair Value [Line Items]
Derivatives and their notional amounts	$ 157,247	$ 144,477