Financial Instruments - Additional Information (Detail) (USD $)			3 Months Ended	9 Months Ended
	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2013 Foreign Currency Forward Contracts [Member] Not Designated as Hedging Instrument [Member]	Sep. 30, 2013 Foreign Currency Forward Contracts [Member] Not Designated as Hedging Instrument [Member]
Financial Instruments And Fair Value Measurements [Line Items]
Net foreign currency loss			$ 1,300,000	$ 4,000,000
Net losses arising from the change in fair value			2,700,000	6,700,000
Notional amount of foreign currency forward contract	$ 231,300,000	$ 250,700,000