Consolidated balance sheets - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 37,446	$ 27,732
Accounts receivable, net	66,087	60,363
Inventories, net	4,059	5,138
Prepaid expenses	2,814	2,661
Derivative instruments	24,025	0
Total current assets	134,431	95,894
Property and equipment, net	43,096	50,641
Oil and natural gas properties, using the full cost method:
Proved	915,333	634,294
Unevaluated (excluded from the amortization base)	466,616	482,239
Accumulated depreciation, depletion, amortization and impairment	(221,431)	(124,180)
Total oil and natural gas properties	1,160,518	992,353
Derivative instruments	2,199	0
Other assets	425	418
Total assets	1,340,669	1,139,306
Current liabilities:
Accounts payable and accrued liabilities	73,779	75,414
Accrued payroll and benefits payable	10,976	11,276
Accrued interest payable	13,359	187
Revenue distribution payable	26,225	17,966
Long-term debt and capital leases, classified as current	3,479	3,273
Derivative instruments	0	8,959
Total current liabilities	127,818	117,075
Long-term debt and capital leases, less current maturities	303,992	141,386
Derivative instruments	1,542	4,167
Deferred compensation	540	696
Asset retirement obligations	22,090	33,216
Commitments and contingencies (Note 17)
Stockholders’ equity:
Preferred stock, 5,000,000 shares authorized, none issued and outstanding as of December 31, 2018 and 2017	0	0
Additional paid in capital	974,616	961,200
Treasury stock, at cost, 261,103 and nil shares at December 31, 2018 and 2017	(4,936)	0
Accumulated deficit	(85,460)	(118,902)
Total stockholders' equity	884,687	842,766
Total liabilities and stockholders' equity	1,340,669	1,139,306
Class A
Stockholders’ equity:
Common stock	467	389
Common Class B
Stockholders’ equity:
Common stock	$ 0	$ 79