Effects of Derivative Instruments on Financial Statements (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Amount of loss recognized in other comprehensive income	$ (15,450)	$ (6,040)
Cost of operations
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Income reclassified from AOCI into income: effective portion	2,014	1,294
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	$ (2,849)	$ 2,350