Derivative Financial Instruments - Additional Information (Detail) (USD $)	Jun. 30, 2012	Dec. 31, 2011
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Net gain (loss) on derivative financial instruments	$ (18,714,000)	$ 3,089,000
Net deferred gains expected to be reclassified out of AOCI over the next 12 months	(2,500,000)
Notional value of outstanding derivative contracts	1,000,000,000
Notional value of foreign currency forward-exchange contracts, maturity date	2017
Notional value of foreign currency forward-exchange contracts	750,000,000
Foreign currency cash flow hedge contracts, fair value	$ (11,800,000)