CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating Revenues:
Total operating revenues	$ 453,017	$ 252,839	$ 178,819
Operating Expenses:
Production tax expense	36,762	14,476	10,638
Exploration expense	70	83	83
Impairment, dry hole costs and abandonment expense	719	49,553	4,249
(Gain) loss on sale of properties	1,046	(92)	1,078
Depreciation, depletion and amortization	228,480	159,964	171,641
Unused commitments	18,187	18,231	18,272
General and administrative expense	45,130	42,476	42,169
Merger transaction expense	7,991	8,749	0
Other operating expenses, net	1,273	(1,514)	(316)
Total operating expenses	372,152	318,764	278,065
Operating Income (Loss)	80,865	(65,925)	(99,246)
Other Income and Expense:
Interest and other income	1,793	1,359	235
Interest expense	(52,703)	(57,710)	(59,373)
Commodity derivative gain (loss)	93,349	(9,112)	(20,720)
Gain (loss) on extinguishment of debt	(257)	(8,239)	8,726
Total other income (expense)	42,182	(73,702)	(71,132)
Income (Loss) before Income Taxes	123,047	(139,627)	(170,378)
(Provision for) Benefit from Income Taxes	(1,827)	1,402	0
Net income (loss)	$ 121,220	$ (138,225)	$ (170,378)
Net Income (Loss) Per Common Share, Basic (in dollars per share)	$ 0.64	$ (1.80)	$ (3.08)
Net Income (Loss) Per Common Share, Diluted (in dollars per share)	$ 0.64	$ (1.80)	$ (3.08)
Weighted Average Common Shares Outstanding, Basic (in shares)	188,299,074	76,858,815	55,384,020
Weighted Average Common Shares Outstanding, Diluted (in shares)	189,241,036	76,858,815	55,384,020
Oil, gas and NGL production
Operating Revenues:
Production and other revenues	$ 452,917	$ 251,215	$ 178,328
Other operating revenues, net
Operating Revenues:
Production and other revenues	100	1,624	491
Lease operating expense
Operating Expenses:
Cost of goods and services	27,850	24,223	27,886
Gathering, transportation and processing expense
Operating Expenses:
Cost of goods and services	$ 4,644	$ 2,615	$ 2,365