Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2019		Dec. 31, 2018
Current assets
Cash and cash equivalents	$ 516		$ 38,560
Accrued production receivable	139,407		125,788
Trade and other receivables, net	18,318		26,970
Derivative assets	11,936		93,080
Other current assets	10,434		11,896
Total current assets	180,611		296,294
Oil and natural gas properties (using full cost accounting)
Proved properties	11,447,680		11,072,209
Unevaluated properties	872,910		996,700
CO2 properties	1,198,846		1,196,795
Pipelines and plants	2,329,078		2,302,817
Other property and equipment	212,334		250,279
Less accumulated depletion, depreciation, amortization and impairment	(11,688,020)		(11,500,190)
Net property and equipment	4,372,828		4,318,610
Operating lease right-of-use assets	34,099		0
Derivative assets	0		4,195
Other assets	104,329		104,123
Total assets	4,691,867		4,723,222
Current liabilities
Accounts payable and accrued liabilities	183,832		198,380
Oil and gas production payable	62,869		61,288
Derivative liabilities	8,346		0
Current maturities of long-term debt (including future interest payable of $86,054 and $85,303, respectively – see Note 6)	102,294	[1]	105,125
Operating lease liabilities	6,901		0
Total current liabilities	364,242		364,793
Long-term liabilities
Long-term debt, net of current portion (including future interest payable of $78,860 and $164,914, respectively – see Note 6)	2,232,570		2,664,211
Asset retirement obligations	177,108		174,470
Deferred tax liabilities, net	410,230		309,758
Operating lease liabilities	41,932		0
Other liabilities	53,526		68,213
Total long-term liabilities	2,915,366		3,216,652
Commitments and contingencies (Note 12)
Stockholders' equity
Preferred stock, $.001 par value, 25,000,000 shares authorized, none issued and outstanding	0		0
Common stock, $.001 par value, 750,000,000 shares authorized; 508,065,495 and 462,355,725 shares issued, respectively	508		462
Paid-in capital in excess of par	2,739,099		2,685,211
Accumulated deficit	(1,321,314)		(1,533,112)
Treasury stock, at cost, 1,652,771 and 1,941,749 shares, respectively	(6,034)		(10,784)
Total stockholders' equity	1,412,259		1,141,777
Total liabilities and stockholders' equity	$ 4,691,867		$ 4,723,222

[1] Our current maturities of long-term debt as of December 31, 2019 include $86.1 million of future interest payable related to the 2021 Senior Secured Notes and 2022 Senior Secured Notes that is due within the next twelve months.