Wexpro Acquisition of Producing Properties and Inclusion in Wexpro II Agreement (Details)	3 Months Ended	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2014
Business Acquisition [Line Items]
Business Acquisition, Effective Date of Acquisition	Sep. 04, 2013
Business Acquisition, Date of Acquisition Agreement	Jul. 25, 2013
Business Acquisition, Description of Acquired Entity	an additional interest in natural gas-producing properties in the Trail Unit of southwestern Wyoming's Vermillion Basin
Date of Acquisition's Inclusion under Wexpro II Agreement		Feb. 01, 2014