Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands		Jun. 30, 2019	Dec. 31, 2018
Current assets
Cash and cash equivalents		$ 341	$ 38,560
Accrued production receivable		135,697	125,788
Trade and other receivables, net		28,469	26,970
Derivative assets		24,447	93,080
Other current assets		14,989	11,896
Total current assets		203,943	296,294
Oil and natural gas properties (using full cost accounting)
Proved properties		11,275,255	11,072,209
Unevaluated properties		941,336	996,700
CO2 properties		1,198,657	1,196,795
Pipelines and plants		2,324,265	2,302,817
Other property and equipment		223,666	250,279
Less accumulated depletion, depreciation, amortization and impairment		(11,583,497)	(11,500,190)
Net property and equipment		4,379,682	4,318,610
Operating lease right-of-use assets		36,421	0
Derivative assets		9,488	4,195
Other assets		102,500	104,123
Total assets		4,732,034	4,723,222
Current liabilities
Accounts payable and accrued liabilities		180,283	198,380
Oil and gas production payable		63,034	61,288
Derivative liabilities		1,912	0
Current maturities of long-term debt (including future interest payable of $85,677 and $85,303, respectively - see Note 4)	[1]	101,829	105,125
Operating lease liabilities		6,739	0
Total current liabilities		353,797	364,793
Long-term liabilities
Long-term debt, net of current portion (including future interest payable of $121,982 and $164,914, respectively - see Note 4)		2,466,127	2,664,211
Asset retirement obligations		181,491	174,470
Derivative liabilities		22	0
Deferred tax liabilities, net		362,303	309,758
Operating lease liabilities		45,391	0
Other liabilities		52,227	68,213
Total long-term liabilities		3,107,561	3,216,652
Commitments and contingencies (Note 7)
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; 464,166,479 and 462,355,725 shares issued, respectively		464	462
Paid-in capital in excess of par		2,694,184	2,685,211
Accumulated deficit		(1,412,094)	(1,533,112)
Treasury stock, at cost, 2,474,904 and 1,941,749 shares, respectively		(11,878)	(10,784)
Total stockholders' equity		1,270,676	1,141,777
Total liabilities and stockholders' equity		$ 4,732,034	$ 4,723,222

[1] Our current maturities of long-term debt as of June 30, 2019 include $85.7 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.