Effects of Derivative Instruments on Financial Statements (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Amount of gain (loss) recognized in other comprehensive income (loss)	$ 19,324	$ (6,536)	$ (4,880)	$ 4,842
Cost of operations
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Income (loss) reclassified from AOCI into income: effective portion	2,867	468	4,837	426
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	$ 3,546	$ (1,437)	$ 15,011	$ (3,260)