Acquisitions and Dispositions of Oil and Gas Properties (Parenthetical) (Detail) (USD $)	0 Months Ended		1 Months Ended	3 Months Ended	4 Months Ended	12 Months Ended
	Aug. 23, 2011	Jul. 29, 2011	Dec. 31, 2013	Sep. 30, 2011	Jul. 29, 2011	Dec. 31, 2014	Dec. 31, 2013
Acquisitions And Dispositions Of Oil And Gas Properties [Line Items]
Additional consideration payable to sellers		Ten years after the closing date
Number of consecutive days for incremental purchase consideration		61 days
Maximum increase in purchase price		$ 25,000,000
Reduction in future consideration		(5,800,000)
Maximum future consideration		19,200,000			19,200,000
Accrual amount due to increase in oil price		500,000
Proceeds from sale of oil and gas properties	5,101,047		1,033,324		766,812	312,789	1,033,324
Recognized gain				2,479,934
Nymex Thresholds Price Per Barrel Oil Of Ninety
Acquisitions And Dispositions Of Oil And Gas Properties [Line Items]
Nymex thresholds per barrel of oil		90
Incremental purchase considerations payable to sellers		250,000
Nymex Thresholds Price Per Barrel Oil Of Hundred
Acquisitions And Dispositions Of Oil And Gas Properties [Line Items]
Nymex thresholds per barrel of oil		100
Incremental purchase considerations payable to sellers		250,000
Nymex Thresholds Price Per Barrel Oil Of One Hundred And Ten
Acquisitions And Dispositions Of Oil And Gas Properties [Line Items]
Nymex thresholds per barrel of oil		110
Incremental purchase considerations payable to sellers		500,000
Nymex Thresholds Price Per Barrel Oil Of One Hundred And Twenty Five
Acquisitions And Dispositions Of Oil And Gas Properties [Line Items]
Nymex thresholds per barrel of oil		125
Incremental purchase considerations payable to sellers		500,000
Nymex Thresholds Price Per Barrel Oil Of One Hundred And Fifty
Acquisitions And Dispositions Of Oil And Gas Properties [Line Items]
Nymex thresholds per barrel of oil		150
Incremental purchase considerations payable to sellers		2,000,000
Nymex Thresholds Price Per Mmbtu Of Five
Acquisitions And Dispositions Of Oil And Gas Properties [Line Items]
Incremental purchase considerations payable to sellers		50,000
Nymex thresholds per MMbtu		5.00
Nymex Thresholds Price Per Mmbtu Of Six
Acquisitions And Dispositions Of Oil And Gas Properties [Line Items]
Incremental purchase considerations payable to sellers		50,000
Nymex thresholds per MMbtu		6.00
Nymex Thresholds Price Per Mmbtu Of Seven Point Five
Acquisitions And Dispositions Of Oil And Gas Properties [Line Items]
Incremental purchase considerations payable to sellers		150,000
Nymex thresholds per MMbtu		7.50
Nymex Thresholds Price Per Mmbtu Of Ten
Acquisitions And Dispositions Of Oil And Gas Properties [Line Items]
Incremental purchase considerations payable to sellers		250,000
Nymex thresholds per MMbtu		10.00
Nymex Thresholds Price Per Mmbtu Of Twelve
Acquisitions And Dispositions Of Oil And Gas Properties [Line Items]
Incremental purchase considerations payable to sellers		250,000
Nymex thresholds per MMbtu		12.00
Wyoming
Acquisitions And Dispositions Of Oil And Gas Properties [Line Items]
Sellers retained interest		70.00%			70.00%
Percentage of recovery received		125.00%			125.00%
Colorado and Kansas
Acquisitions And Dispositions Of Oil And Gas Properties [Line Items]
Additional considerations for sellers on Oil reserves		250,000
Number of units required for additional consideration		20,000
Additional considerations for sellers on natural gas		150,000
Number of units required for additional consideration		150,000
Maximum increase in purchase price		$ 5,000,000
Maximum
Acquisitions And Dispositions Of Oil And Gas Properties [Line Items]
Reserve factor multiplier effect		5
Increase in oil price per barrel		100
Minimum
Acquisitions And Dispositions Of Oil And Gas Properties [Line Items]
Reserve factor multiplier effect		1
Increase in oil price per barrel		90