Condensed Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Revenues and other income
Oil, natural gas, and related product sales	$ 246,668	$ 366,891	$ 434,471	$ 664,361
CO2 sales and transportation fees	6,622	7,152	12,894	14,124
Interest income and other income	1,858	2,651	2,627	5,858
Total revenues and other income	255,148	376,694	449,992	684,343
Expenses
Lease operating expenses	100,019	132,170	202,466	273,254
Marketing and plant operating expenses	12,999	14,215	26,193	25,900
CO2 discovery and operating expenses	1,071	945	1,678	1,892
Taxes other than income	19,504	33,555	39,596	60,234
General and administrative expenses	22,545	37,947	56,446	84,227
Interest, net of amounts capitalized of $6,289, $8,738, $12,069, and $17,147, respectively	36,058	39,863	78,229	79,962
Depletion, depreciation, and amortization	66,541	147,940	143,907	297,898
Commodity derivatives expense (income)	98,209	48,926	121,035	(34,150)
Gain on debt extinguishment	(12,278)	0	(107,269)	0
Write-down of oil and natural gas properties	479,400	1,705,800	735,400	1,852,000
Other expenses	34,688	0	36,232	0
Total expenses	858,756	2,161,361	1,333,913	2,641,217
Loss before income taxes	(603,608)	(1,784,667)	(883,921)	(1,956,874)
Income tax benefit	(222,940)	(636,168)	(318,060)	(700,629)
Net loss	$ (380,668)	$ (1,148,499)	$ (565,861)	$ (1,256,245)
Net loss per common share
Basic	$ (1.03)	$ (3.28)	$ (1.58)	$ (3.59)
Diluted	(1.03)	(3.28)	(1.58)	(3.59)
Dividends declared per common share	$ 0	$ 0.0625	$ 0	$ 0.1250
Weighted average common shares outstanding
Basic	370,566	350,039	358,901	349,653
Diluted	370,566	350,039	358,901	349,653