Derivative Financial Instruments - Additional Information (Detail) (USD $)	3 Months Ended	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2013
Foreign Exchange Risk [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount of derivatives in contracts	$ 25,255,000	$ 25,255,000
Foreign Exchange Risk [Member] | Three months ended June 30, 2013 [Member] | Purchase contracts [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount of derivatives in contracts	12,400,000	12,400,000
Foreign Exchange Risk [Member] | Three months ended June 30, 2013 [Member] | Sales contracts [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount of derivatives in contracts	92,800,000	92,800,000
Foreign Exchange Risk [Member] | Six months ended June 30, 2013 [Member] | Purchase contracts [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount of derivatives in contracts	29,400,000	29,400,000
Amount of outstanding derivatives in contracts	4,900,000	4,900,000
Foreign Exchange Risk [Member] | Six months ended June 30, 2013 [Member] | Sales contracts [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount of derivatives in contracts	168,100,000	168,100,000
Amount of outstanding derivatives in contracts	30,200,000	30,200,000
Foreign Exchange Contracts [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gain on Foreign exchange contract	$ 800,000	$ 1,100,000