Derivative Financial Instruments - Schedule of Location and Fair Value Amounts of All Derivative Instruments (Details) - Derivatives Not Designated as Hedging Contracts [Member] - Commodity Contracts [Member] - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Derivative Asset [Member]
Derivatives Fair Value [Line Items]
Gross Recognized Assets		$ 3,694
Net Recognized Assets		$ 3,694
Derivative Liability [Member]
Derivatives Fair Value [Line Items]
Gross Recognized Liabilities	$ 4,595
Net Recognized Liabilities	4,595
Derivative Liability [Member]
Derivatives Fair Value [Line Items]
Gross Recognized Liabilities	1,575
Net Recognized Liabilities	$ 1,575