Derivative Financial Instruments and Fair Value Measurements - Summary of Derivative Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - Commodities Contracts - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Derivatives, Fair Value [Line Items]
Assets - Fair Value	$ 317	$ 2
Liabilities - Fair Value	10,713	4,392
Level 2
Derivatives, Fair Value [Line Items]
Assets - Fair Value	317	2
Liabilities - Fair Value	$ 10,713	$ 4,392