Derivatives - Summary of Gains (Losses) on Derivatives Designated as Hedging Instruments (Detail) (Forward exchange contracts [Member], Cash Flow Hedging [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Forward exchange contracts [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net gain recognized in OCI	$ 1,779	$ 1,334
Net gain (loss) reclassified from OCI into income	$ 203	$ (513)