CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
ASSETS
Cash and cash equivalents	$ 27,841	$ 30,272
Accounts receivable:
Oil and gas sales	213,661	125,016
Joint interest operations	20,241	14,615
From affiliates	9,263	6,155
Derivative financial instruments	26,392	8,913
Other current assets	12,194	14,839
Total current assets	309,592	199,810
Oil and natural gas properties, successful efforts method:
Proved	5,180,782	4,647,188
Unproved	307,593	332,765
Other	6,630	6,858
Accumulated depreciation, depletion and amortization	(1,260,528)	(902,261)
Net property and equipment	4,234,477	4,084,550
Goodwill	335,897	335,897
Derivative financial instruments	342	661
Operating lease right-of-use assets	6,792	3,025
Other assets	37	40
Total assets	4,887,137	4,623,983
LIABILITIES AND STOCKHOLDERS' EQUITY
Accounts payable	324,811	259,284
Accrued costs	109,122	133,019
Operating leases	2,356	2,284
Derivative financial instruments	627,166	47,005
Total current liabilities	1,063,455	441,592
Long-term debt	2,801,312	2,517,149
Deferred income taxes	115,585	200,583
Derivative financial instruments	50,127	2,364
Long-term operating leases	4,486	740
Reserve for future abandonment costs	21,867	19,290
Other non-current liabilities	24	492
Total liabilities	4,056,856	3,182,210
Commitments and contingencies
Stockholders' equity:
Common stock—$0.50 par, 400,000,000 shares authorized, 232,924,646 and 232,414,718 shares issued and outstanding at September 30, 2021 and December 31, 2020, respectively	116,462	116,206
Additional paid-in capital	1,098,851	1,095,384
Accumulated earnings (deficit)	(560,032)	55,183
Total stockholders' equity	655,281	1,266,773
Total liabilities and stockholders' equity	4,887,137	4,623,983
Series B 10% Convertible Preferred Stock
Mezzanine equity:
Series B 10% Convertible Preferred stock — 5,000,000 shares authorized, 175,000 shares issued and outstanding at September 30, 2021 and December 31, 2020, respectively	$ 175,000	$ 175,000

Carrying value as of the balance sheet date of liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received that are used in an entity's business. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

Name:	us-gaap_AccountsPayableCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount, after allowance for credit loss, of right to consideration from customer for product sold and service rendered in normal course of business, classified as current.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=124259787&loc=d3e4428-111522

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-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=120391452&loc=d3e13212-122682

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section 45
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=124098289&loc=d3e6676-107765

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 9
-URI http://asc.fasb.org/extlink&oid=124259787&loc=d3e4531-111522