Derivative Instruments - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013
Derivative [Line Items]
Outstanding option contracts	$ 11,150
Fair value of derivative assets	542
Fair value of derivative liabilities	24
Other accounts receivable and prepaid expenses	518
Hedging transactions, research and development expenses	111
Hedging transactions, sales and marketing expenses	11
Hedging transactions, general and administrative expenses	$ 19
Minimum
Derivative [Line Items]
Hedging period	1 month
Maximum
Derivative [Line Items]
Hedging period	12 months