Other Operating Revenues and Expenses (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Other operating revenues:
Gain on sales of assets	$ 123,392	$ 8,718	$ 11,685
Marketing revenue	0	24	3,708
Total other operating revenues	123,392	8,742	15,393
Other operating expenses:
Loss on sales of assets	3,152	1,355	2,511
Marketing expense	440	849	0
Impairment of inventory	1,454	10,381	36
Other operating expenses	$ 5,046	$ 12,585	$ 2,547