Effects of Derivative Instruments on Financial Statements (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Amount of gain (loss) recognized in other comprehensive income	$ (6,040)	$ 6,948
Cost of operations
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Income (loss) reclassified from AOCI into income: effective portion	1,294	(135)
Gain (loss) on foreign currency-net
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Gain (loss) recognized in income: ineffective portion and amount excluded from effectiveness testing	$ 2,350	$ (1,970)