Derivative Instruments - Gains (Losses) on Derivative Instruments and Classification on Consolidated Statement of Operations (Parenthetical) (Detail) (Unrealized gain (loss) on cash flow hedges [Member], Designated as hedging instrument [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013
Operating expenses [Member]
Derivatives, Fair Value [Line Items]
Cash flow hedge loss reclassified	$ 206
Cost of revenues [Member]
Derivatives, Fair Value [Line Items]
Cash flow hedge loss reclassified	$ 17