Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues:
Other	$ 137	$ 75	$ 62
Total Revenue	149,167	86,264	56,555
Operating costs and expenses
Lease operating	24,300	15,197	18,205
Production and ad valorem taxes	12,023	7,228	5,454
Rig expense			664
Depreciation, depletion, amortization and accretion	43,275	26,677	24,922
Proved property impairment			67,626
General and administrative (including stock-based compensation of $3,194, $3,238 and $2,366, respectively)	12,041	16,276	13,562
Total operating costs and expenses	91,639	65,378	130,433
Operating (loss) income	57,528	20,886	(73,878)
Other (income) expense:
Interest income	(1)	(1)	(1)
Interest expense	7,053	2,497	3,828
Amortization of deferred financing fees	440	423	1,019
Loss (gain) on derivative contracts	(8,060)	1,849	18,028
Loss (gain) on sale of non-oil and gas assets	181	(102)	(374)
Other	94	214
Total other (income) expense	(293)	4,880	22,500
Income (loss) before income tax	57,821	16,006	(96,378)
Income tax (expense) benefit
Net income (loss)	$ 57,821	$ 16,006	$ (96,378)
Net income (loss) per common share - basic (in dollars per share)	$ 0.35	$ 0.10	$ (0.79)
Net income (loss) per common share - diluted (in dollars per share)	$ 0.34	$ 0.10	$ (0.79)
Weighted average shares outstanding
Basic (in shares)	165,635	161,141	122,132
Diluted (in shares)	167,689	162,844	122,132
Oil Revenues [Member]
Revenues:
Revenues	$ 132,904	$ 73,584	$ 50,965
Gas Revenues [Member]
Revenues:
Revenues	7,854	6,898	3,978
Natural Gas Liquids Revenues [Member]
Revenues:
Revenues	$ 8,272	$ 5,707	$ 1,550