Derivative Financial Instruments - Additional Information (Detail) (USD $)	3 Months Ended	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2013
Foreign Exchange Risk [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount of derivatives in contracts	$ 28,835,000	$ 28,835,000
Foreign Exchange Risk [Member] | Three months ended September 30, 2013 [Member] | Purchase contracts [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount of derivatives in contracts	15,900,000	15,900,000
Foreign Exchange Risk [Member] | Three months ended September 30, 2013 [Member] | Sales contracts [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount of derivatives in contracts	104,200,000	104,200,000
Foreign Exchange Risk [Member] | Nine months ended September 30, 2013 [Member] | Purchase contracts [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount of derivatives in contracts	45,300,000	45,300,000
Amount of outstanding derivatives in contracts	6,300,000	6,300,000
Foreign Exchange Risk [Member] | Nine months ended September 30, 2013 [Member] | Sales contracts [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount of derivatives in contracts	272,300,000	272,300,000
Amount of outstanding derivatives in contracts	35,200,000	35,200,000
Foreign Exchange Contracts [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Loss on Foreign exchange contract	$ 1,500,000	$ 400,000