Foreign Currency Sale Contracts (Detail) - Foreign Exchange Contract	3 Months Ended		6 Months Ended
	Jun. 30, 2015 USD ($)	Mar. 31, 2014 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)	Jun. 30, 2015 EUR (€)	Jun. 30, 2015 CAD
Euros
Derivative [Line Items]
Transaction Date Range			July 2011-May 2014
Total transaction amount	$ 135,000,000		$ 135,000,000		€ 100,000,000
Forward purchase date range			August 2015-May 2017
Change in fair value gain (loss)	(4,000,000)	$ 1,000,000	$ 10,000,000	$ 1,000,000
Canadian Dollars
Derivative [Line Items]
Transaction Date Range			November 2014
Total transaction amount	$ 22,000,000		$ 22,000,000			CAD 25,000,000
Forward purchase date range
Change in fair value gain (loss)			$ 1,000,000