Derivatives - Schedule of Pre-Tax Gain (Loss) Recognized in the Statement of Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Commodity derivatives | Cost of revenues
Derivative Instruments, Gain (Loss) [Line Items]
Cost of revenues	$ (1,338)	$ 14,367	$ 8,228
J. Aron repurchase obligation derivative | Cost of revenues
Derivative Instruments, Gain (Loss) [Line Items]
Cost of revenues	(29,810)	12,654	0
J. Aron repurchase obligation derivative | Interest Expense
Derivative Instruments, Gain (Loss) [Line Items]
Cost of revenues	$ 2,729	$ 0	$ 0