Organization (Details)	3 Months Ended
	Mar. 31, 2013 segment
Organization
Number of business segments	2
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 drilled	33
Area of land (in acres)	3,800
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 drilled	6
Area of land (in acres)	538