CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Current assets
Cash and cash equivalents	$ 27,013	$ 99,143
Restricted cash - other	2,165	2,165
Accounts receivable, net	67,992	71,277
Derivative contracts	0	1,310
Prepaid expenses	4,241	5,248
Other current assets	11,288	15,954
Total current assets	112,699	195,097
Oil and natural gas properties, using full cost method of accounting
Proved	1,103,921	1,056,806
Unproved	91,793	100,884
Less: accumulated depreciation, depletion and impairment	(486,645)	(460,431)
Net oil and natural gas properties capitalized costs	709,069	697,259
Other property, plant and equipment, net	216,865	225,981
Other assets	1,343	1,290
Total assets	1,039,976	1,119,627
Current liabilities
Accounts payable and accrued expenses	118,866	139,155
Derivative contracts	19,952	10,627
Asset retirement obligations	40,943	41,017
Other current liabilities	425	8,115
Total current liabilities	180,186	198,914
Long-term debt	0	37,502
Derivative contracts	5,143	3,568
Asset retirement obligations	37,398	36,527
Other long-term obligations	3,809	3,176
Total liabilities	226,536	279,687
Commitments and contingencies (Note 10)
Stockholders’ Equity
Common stock, $0.001 par value; 250,000 shares authorized; 35,560 issued and outstanding at March 31, 2018 and 35,650 issued and outstanding at December 31, 2017	36	36
Warrants	88,500	88,500
Additional paid-in capital	1,052,718	1,038,324
Accumulated deficit	(327,814)	(286,920)
Total stockholders’ equity	813,440	839,940
Total liabilities and stockholders’ equity	$ 1,039,976	$ 1,119,627

Sum of the carrying values as of the balance sheet date of obligations incurred through that date and due within one year (or the operating cycle, if longer), including liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received, taxes, interest, rent and utilities, accrued salaries and bonuses, payroll taxes and fringe benefits.

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- Definition

Amount due from customers or clients, within one year of the balance sheet date (or the normal operating cycle, whichever is longer), for goods or services (including trade receivables) that have been delivered or sold in the normal course of business, reduced to the estimated net realizable fair value by an allowance established by the entity of the amount it deems uncertain of collection.