Fair Value of Derivative Instruments Not Designated as Hedging Instruments (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014 Commodity derivative contracts [Member]	Dec. 31, 2013 Nondesignated [Member] Commodity derivative contracts [Member] Accounts Receivable [Member]	Mar. 31, 2014 Nondesignated [Member] Commodity derivative contracts [Member] Accounts Payable [Member]	Mar. 31, 2014 Nondesignated [Member] Foreign exchange derivative contract [Member] Accounts Receivable [Member]	Dec. 31, 2013 Nondesignated [Member] Foreign exchange derivative contract [Member] Accounts Payable [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives		$ 1,970		$ 3,411
Liability Derivatives	$ (18,800)		$ (21,367)		$ (1,038)