Investment in Piceance Energy (Details 1) (USD $) In Thousands, unless otherwise specified	4 Months Ended	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2013
Assets
Current assets	$ 59,926	$ 558,373
Current liabilities	(69,977)	(458,708)
Oil, natural gas and natural gas liquids revenues	2,144	7,739
Loss from operations	(5,021)	(39,313)
Net loss	(8,839)	(70,621)
Piceance Energy [Member]
Assets
Current assets	6,275	5,901
Non-current assets	460,991	454,402
Current liabilities	(11,826)	(13,040)
Non-current liabilities	(94,369)	(96,738)
Oil, natural gas and natural gas liquids revenues	19,391	61,091
Loss from operations	(2,095)	(6,765)
Net loss	$ (3,975)	$ (10,546)