Derivative Financial Instruments - Schedule of Location and Fair Value Amounts of All Derivative Instruments (Details) - Derivatives Not Designated as Hedging Contracts - Commodity Contracts - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Derivative asset - current
Derivative Asset [Abstract]
Gross Recognized Assets	$ 213	$ 184
Gross Amounts Offset, Assets	0	0
Total financial assets	213	184
Derivative asset - noncurrent
Derivative Asset [Abstract]
Gross Recognized Assets	103	0
Gross Amounts Offset, Assets	0	0
Total financial assets	103	0
Derivative liability - current
Derivative Liability [Abstract]
Gross Recognized Liabilities	14,241	11,805
Gross Amounts Offset, Liabilities	(1,758)	0
Total financial liabilities	12,483	11,805
Derivative liability - noncurrent
Derivative Liability [Abstract]
Gross Recognized Liabilities	2,280	1,826
Gross Amounts Offset, Liabilities	0	0
Total financial liabilities	$ 2,280	$ 1,826