Derivative Instruments - Gains (Losses) on Derivative Instruments and Classification on Consolidated Statement of Operations (Parenthetical) (Detail) (Designated As Hedging Instrument [Member], Unrealized Gain (Loss) on Cash Flow Hedges [Member], USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Operating Expenses [Member]
Derivatives, Fair Value [Line Items]
Cash flow hedge loss reclassified	$ (581)	$ 1,712	$ (553)
Cost of revenues [Member]
Derivatives, Fair Value [Line Items]
Cash flow hedge loss reclassified	$ (72)	$ 117	$ (45)