Notes Payable (NPI Agreement) - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Jun. 30, 2014
Line of Credit Facility [Line Items]
Accretion of discount related to the NPI	$ 4,431,400	$ 3,429,500
Net Profits Interest Agreement [Member]
Line of Credit Facility [Line Items]
Percentage of net profit	6.50%
Percentage of net profit for subsequent borrowing	2.50%
Percentage of NPI earned	1.00%
Net Profits Interest Agreement [Member] | Minimum [Member]
Line of Credit Facility [Line Items]
Minimum amount of NPI earned	1,500,000
Net Profits Interest Agreement [Member] | Morgan Stanley Credit Agreement - Morgan Stanley Npi [Member]
Line of Credit Facility [Line Items]
Discount related to NPI			4,072,410
Accretion of discount related to the NPI	518,307
Net Profits Interest Agreement [Member] | Morgan Stanley Credit Agreement - Morgan Stanley Npi [Member] | Proved Property [Member]
Line of Credit Facility [Line Items]
Discount related to NPI			3,339,376
Net Profits Interest Agreement [Member] | Morgan Stanley Credit Agreement - Morgan Stanley Npi [Member] | Unproved Property [Member]
Line of Credit Facility [Line Items]
Discount related to NPI			$ 733,034