Investments in Piceance Energy: Summary of Income Statement of Equity Investment (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Schedule of Equity Method Investments [Line Items]
Oil, natural gas and natural gas liquids revenues	$ 1,577	$ 1,560
Income (loss) from operations	(14,802)	2,601
Net loss	(14,568)	(4,816)
Piceance Energy
Schedule of Equity Method Investments [Line Items]
Oil, natural gas and natural gas liquids revenues	20,243	13,987
Income (loss) from operations	3,609	(3,504)
Net loss	$ (1,091)	$ (7,079)