Amounts of Unrealized and Realized Net losses and Changes in Fair Value of Forward Contracts (Detail) (Interest and Other, net, USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Interest and Other, net
Derivative [Line Items]
Amount of Unrealized and Realized Net (Loss) Gains and Changes in the Fair Value of Forward Contracts	$ 1,146	$ (222)	$ 1,419	$ (54)