Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands		Mar. 31, 2018	Dec. 31, 2017
Current assets
Cash and cash equivalents		$ 85	$ 58
Accrued production receivable		157,845	146,334
Trade and other receivables, net		43,553	45,193
Derivative assets		1,859	0
Other current assets		11,512	10,670
Total current assets		214,854	202,255
Oil and natural gas properties (using full cost accounting)
Proved properties		10,824,027	10,775,792
Unevaluated properties		960,039	951,397
CO2 properties		1,191,107	1,191,058
Pipelines and plants		2,286,346	2,286,047
Other property and equipment		334,808	339,218
Less accumulated depletion, depreciation, amortization and impairment		(11,424,173)	(11,376,646)
Net property and equipment		4,172,154	4,166,866
Other assets		99,774	102,178
Total assets		4,486,782	4,471,299
Current liabilities
Accounts payable and accrued liabilities		149,676	177,220
Oil and gas production payable		75,915	76,588
Derivative liabilities		114,512	99,061
Current maturities of long-term debt (including future interest payable of $100,083 and $75,347, respectively - see Note 4)	[1]	129,667	105,188
Total current liabilities		469,770	458,057
Long-term liabilities
Long-term debt, net of current portion (including future interest payable of $256,140 and $241,472, respectively - see Note 4)		2,923,378	2,979,086
Asset retirement obligations		167,763	165,756
Derivative liabilities		1,876	0
Deferred tax liabilities, net		213,151	198,099
Other liabilities		20,626	22,136
Total long-term liabilities		3,326,794	3,365,077
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, 600,000,000 shares authorized; 402,927,941 and 402,549,346 shares issued, respectively		403	403
Paid-in capital in excess of par		2,511,131	2,507,828
Accumulated deficit		(1,816,232)	(1,855,810)
Treasury stock, at cost, 787,867 and 457,041 shares, respectively		(5,084)	(4,256)
Total stockholders' equity		690,218	648,165
Total liabilities and stockholders' equity		$ 4,486,782	$ 4,471,299

[1] Future interest payable represents most of the interest due over the terms of our 9% Senior Secured Second Lien Notes due 2021, 9¼% Senior Secured Second Lien Notes due 2022 (the “2022 Senior Secured Notes”), 5% Convertible Senior Notes due 2023 (the “2023 Convertible Senior Notes”), and 2024 Convertible Senior Notes and has been accounted for as debt in accordance with FASC 470-60, Troubled Debt Restructuring by Debtors. Our current maturities of long-term debt as of March 31, 2018 include $100.1 million of future interest payable related to these notes that is due within the next twelve months. See January 2018 Note Exchanges below for further discussion.