Acquisitions and Divestitures - Additional Information (Detail) (USD $)	3 Months Ended		1 Months Ended				1 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2011 Eagle Ford	Mar. 31, 2012 Eagle Ford Well	Dec. 31, 2011 Eagle Ford Maximum Well	Dec. 31, 2011 Eagle Ford Partner Well	Jan. 31, 2012 Counties of Butler and Armstrong in Pennsylvania
Business Acquisition [Line Items]
Working interest			57.00%
Number of wells to be drilled					6	3
Number of wells drilled				2
Proceeds from the sale of oil and gas property, net	$ 778,000	$ 360,000					$ 1,000,000
Gain on sale of undeveloped acres							$ 600,000