Acquisitions and Divestitures - Additional Information (Details)	1 Months Ended					3 Months Ended		9 Months Ended
	Jun. 30, 2016 shares	May 31, 2016 USD ($) shares	Aug. 31, 2015 USD ($) a	Jun. 30, 2015 USD ($) a Boe Well	Apr. 30, 2015 USD ($)	Sep. 30, 2016 USD ($) a	Sep. 30, 2015 USD ($)	Sep. 30, 2016 USD ($) a	Sep. 30, 2015 USD ($)
Business Acquisition [Line Items]
Common stock issued, net of offering costs, shares | shares	4,753,770
Sales of oil, natural gas and natural gas liquids recognized						$ 10,530,000	$ 13,033,000	$ 27,117,000	$ 39,233,000
Total consideration								45,698,000
Cash consideration					$ 3,400,000
Gain (loss) on sale of properties					$ 1,600,000	$ 8,000	$ (13,000)	$ 8,000	$ 1,667,000
Effective date of transaction					Mar. 01, 2015
Southern Gonzales County [Member]
Business Acquisition [Line Items]
Acquisition of operating interests			33.00%	50.00%
Company acquired gross acres | a			1,650	1,000
Number of wells acquired | Well				2
Percentage of acres held for production				100.00%
Gross production, barrels of oil equivalents per day | Boe				44
Working interest acquired			$ 3,300,000
Northern Kames County [Member]
Business Acquisition [Line Items]
Company acquired gross acres | a				400		350		350
Net acres | a						117		117
Banks Field of McKenzie County [Member]
Business Acquisition [Line Items]
Number of wells acquired | Well				41
Total consideration				$ 1,400,000
Purchase price adjustment for revenues, net for production taxes, operating expenses and capital costs				$ 2,000,000
Net acres acquired | a				164
Number of drilling wells acquired | Well				21
Lynden Arrangement [Member]
Business Acquisition [Line Items]
Common stock issued, net of offering costs, shares | shares		3,700,279
Sales of oil, natural gas and natural gas liquids recognized						$ 2,800,000		$ 4,300,000
Operating expenses inclusive of depletion						2,200,000		3,100,000
Material non-recurring transaction costs						$ 0		$ 700,000
Total consideration		$ 45,698,000