Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Current assets
Cash and cash equivalents	$ 17,660	$ 99,143
Restricted cash - other	1,985	2,165
Accounts receivable, net	45,503	71,277
Derivative contracts	5,286	1,310
Prepaid expenses	2,628	5,248
Other current assets	265	15,954
Total current assets	73,327	195,097
Oil and natural gas properties, using full cost method of accounting
Proved	1,269,091	1,056,806
Unproved	60,152	100,884
Less: accumulated depreciation, depletion and impairment	(580,132)	(460,431)
Net oil and natural gas properties capitalized costs	749,111	697,259
Other property, plant and equipment, net	200,838	225,981
Other assets	1,062	1,290
Total assets	1,024,338	1,119,627
Current liabilities
Accounts payable and accrued expenses	111,797	139,155
Derivative contracts	0	10,627
Asset retirement obligations	25,393	41,017
Other current liabilities	0	8,115
Total current liabilities	137,190	198,914
Long-term debt	0	37,502
Derivative contracts	0	3,568
Asset retirement obligations	34,671	36,527
Other long-term obligations	4,756	3,176
Total liabilities	176,617	279,687
Commitments and contingencies (Note 13)
Stockholders’ Equity
Common stock, $0.001 par value; 250,000 shares authorized; 35,687 issued and outstanding at December 31, 2018 and 35,650 issued and outstanding at December 31, 2017	36	36
Warrants	88,516	88,500
Additional paid-in capital	1,055,164	1,038,324
Accumulated deficit	(295,995)	(286,920)
Total stockholders’ equity	847,721	839,940
Total liabilities and stockholders’ equity	$ 1,024,338	$ 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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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- 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.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130549-203045

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(3))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682