Derivative Instruments and Hedging Activities Carrying Values of Derivative Instruments (Detail) - USD ($) $ in Thousands		Jun. 30, 2018	Dec. 31, 2017
Derivative [Line Items]
Derivative Net Carrying Value		$ 5,931	$ (426)
Designated as Hedging Instrument
Derivative [Line Items]
Derivative Net Carrying Value		5,931	(426)
Designated as Hedging Instrument | Foreign Exchange Contract
Derivative [Line Items]
Derivative Net Carrying Value	[1]	5,931	(426)
Prepaid Expenses And Other Current Assets
Derivative [Line Items]
Fair Value— Assets		6,422	621
Prepaid Expenses And Other Current Assets | Designated as Hedging Instrument
Derivative [Line Items]
Fair Value— Assets		6,422	621
Prepaid Expenses And Other Current Assets | Designated as Hedging Instrument | Foreign Exchange Contract
Derivative [Line Items]
Fair Value— Assets	[1]	6,422	621
Other Current Liabilities
Derivative [Line Items]
Fair Value— (Liabilities)		(491)	(1,047)
Other Current Liabilities | Designated as Hedging Instrument
Derivative [Line Items]
Fair Value— (Liabilities)		(491)	(1,047)
Other Current Liabilities | Designated as Hedging Instrument | Foreign Exchange Contract
Derivative [Line Items]
Fair Value— (Liabilities)	[1]	$ (491)	$ (1,047)

[1] Assets are included in prepaid expenses and other and liabilities are included in other accrued expenses on the accompanying consolidated balance sheets.