Organization (Details)	6 Months Ended
	Jun. 30, 2014 segment
Organization
Number of business segments	2
Subsidiaries [Member] | Lease Agreements [Member]
Organization
Percentage of non-operating working interest	20.00%
Overall average revenue interest (as a percent)	34.70%
Number of wells	33
Subsidiaries [Member] | Lease Agreements [Member] | Minimum [Member]
Organization
Percentage of royalty interest	15.40%
Subsidiaries [Member] | Lease Agreements [Member] | Maximum [Member]
Organization
Percentage of royalty interest	20.00%
Subsidiaries [Member] | Drillsite Agreement [Member]
Organization
Percentage of royalty interest	3.00%
Percentage of non-operating working interest	12.50%
Overall average revenue interest (as a percent)	12.40%
Number of wells	6
Area of land (in acres)	538