Derivative Financial Instruments and Fair Value Measurements - Derivatives Recorded at Fair Value in Consolidated Balance Sheets (Detail) - Not Designated As Hedging Instruments - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Derivatives, Fair Value [Line Items]
Derivative Assets	$ 2,276	$ 317
Derivative Liabilities	5,431	10,713
Current | Commodities Contracts
Derivatives, Fair Value [Line Items]
Derivative Assets	2,276	317
Derivative Liabilities	5,431	10,023
Non-current | Commodities Contracts
Derivatives, Fair Value [Line Items]
Derivative Assets	0	0
Derivative Liabilities	$ 0	$ 690