Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Current assets
Cash and cash equivalents	$ 12,212	$ 23,153
Accrued production receivable	123,759	181,761
Trade and other receivables, net	118,457	156,955
Derivative assets	199,431	440,359
Other current assets	11,758	10,452
Total current assets	465,617	812,680
Oil and natural gas properties (using full cost accounting)
Proved properties	10,102,698	9,782,337
Unevaluated properties	917,463	918,406
CO2 properties	1,178,827	1,162,538
Pipelines and plants	2,285,152	2,269,564
Other property and equipment	450,053	468,051
Less accumulated depletion, depreciation, amortization and impairment	(8,252,335)	(4,248,652)
Net property and equipment	6,681,858	10,352,244
Derivative assets	0	66,187
Goodwill	0	1,283,590
Other assets	207,677	213,101
Total assets	7,355,152	12,727,802
Current liabilities
Accounts payable and accrued liabilities	250,514	394,758
Oil and gas production payable	101,692	128,170
Deferred tax liabilities	7,884	81,727
Current maturities of long-term debt	36,038	35,470
Total current liabilities	396,128	640,125
Long-term liabilities
Long-term debt, net of current portion	3,321,315	3,535,900
Asset retirement obligations	136,238	126,411
Deferred tax liabilities	1,336,247	2,694,842
Other liabilities	28,892	26,668
Total long-term liabilities	$ 4,822,692	$ 6,383,821
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; 414,322,723 and 411,779,911 shares issued, respectively	414	412
Paid-in capital in excess of par	3,235,266	3,230,418
Retained earnings (accumulated deficit)	(173,892)	3,392,465
Accumulated other comprehensive loss	(157)	(209)
Treasury stock, at cost, 61,373,201 and 58,415,507 shares, respectively	(925,299)	(919,230)
Total stockholders' equity	2,136,332	5,703,856
Total liabilities and stockholders' equity	$ 7,355,152	$ 12,727,802