Foreign Currency Sale Contracts (Detail) - Foreign Exchange Contract	3 Months Ended		9 Months Ended
	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Sep. 30, 2015 EUR (€)	Sep. 30, 2015 CAD
Euros
Derivative [Line Items]
Transaction Date Range			January 2013-September 2015
Total transaction amount	$ 124,000,000		$ 124,000,000		€ 100,000,000
Forward purchase date range			January 2016-September 2017
Change in fair value gain (loss)		$ 12,000,000	$ 10,000,000	$ 13,000,000
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			November 2016
Change in fair value gain (loss)	$ 2,000,000		$ 3,000,000