Organization (Details)	3 Months Ended	9 Months Ended
	Sep. 30, 2015 a	Sep. 30, 2015 a segment
Organization
Number of business segments | segment		2
O & G Lease
Organization
Area of land (in acres)	3,800	3,800
U.S. Lime O & G | O & G Lease
Organization
Percentage of non-operating working interest		20.00%
Overall average revenue interest (as a percent)		34.70%
Number of wells		33
U.S. Lime O & G | O & G Lease | Minimum
Organization
Percentage of royalty interest		15.40%
U.S. Lime O & G | O & G Lease | Maximum
Organization
Percentage of royalty interest		20.00%
U.S. Lime O & G | Drillsite Agreement
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 under a lease (in acres)	538