Other Operating Revenues and Expenses (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Other Operating Revenues [Abstract]
Gain on sales of assets	$ 5,142	$ 495
Marketing revenue	382	1,795
Total other operating revenues	5,524	2,290
Other operating expenses:
Loss on sales of assets	(492)	(127)
Impairment of inventory	(10)	(6)
Total other operating expenses	$ (502)	$ (133)