Accounts Receivable (Detail) (USD $)
In Thousands, unless otherwise specified
Dec. 31, 2013
Dec. 31, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Trade receivables $ 92,959 $ 76,395
Derivative receivables 866 162
Other receivables 533 1,799
Total accounts receivable $ 94,358 $ 78,356