UNAUDITED CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 24,876	$ 49,704
Restricted cash	325	325
Accounts receivable	25,086	29,514
Short-term derivative instruments	276	18,813
Prepaid expenses and other current assets	9,738	7,241
Total current assets	60,301	105,597
Property and equipment, at cost:
Oil and natural gas properties, successful efforts method	609,414	598,331
Support equipment and facilities	110,725	108,760
Other	6,687	6,625
Accumulated depreciation, depletion and impairment	(96,701)	(85,535)
Property and equipment, net	630,125	628,181
Long-term derivative instruments	288	2,469
Restricted investments	94,536	94,467
Operating lease - long term right-of-use asset	5,011	0
Other long-term assets	5,922	6,129
Total assets	796,183	836,843
Current liabilities:
Accounts payable	4,580	2,345
Revenues payable	24,136	24,779
Accrued liabilities (see Note 13)	21,199	23,155
Short-term derivative instruments	9,108	139
Total current liabilities	59,023	50,418
Long-term debt (see Note 8)	270,000	294,000
Asset retirement obligations	77,082	75,867
Long-term derivative instruments	1,429	0
Operating lease liability	3,090	0
Other long-term liabilities	62	0
Total liabilities	410,686	420,285
Commitments and contingencies (see Note 15)
Stockholders' equity:
Preferred stock, $0.0001 par value: 45,000,000 shares authorized; no shares issued and outstanding at March 31, 2019 and December 31, 2018, respectively	0	0
Warrants, 2,173,913 warrants issued and outstanding at March 31, 2019 and December 31, 2018, respectively	4,788	4,788
Common stock, $0.0001 par value: 300,000,000 shares authorized; 22,258,450 and 22,181,881 shares issued and outstanding at March 31, 2019 and December 31, 2018, respectively	3	3
Additional paid-in capital	356,288	355,872
Accumulated earnings (deficit)	24,418	55,895
Total stockholders' equity	385,497	416,558
Total liabilities and equity	$ 796,183	$ 836,843