Condensed Consolidated Statements of Operations (Unaudited) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Revenues and other income
Oil, natural gas, and related product sales	$ 592,141,000	$ 591,099,000	$ 1,225,642,000	$ 1,097,291,000
CO2 sales and transportation fees	5,301,000	5,343,000	12,096,000	10,267,000
Interest income and other income	4,339,000	4,955,000	9,159,000	8,004,000
Total revenues and other income	601,781,000	601,397,000	1,246,897,000	1,115,562,000
Expenses
Lease operating expenses	124,511,000	126,085,000	262,475,000	249,882,000
Marketing expenses	12,218,000	6,270,000	23,048,000	11,573,000
CO2 discovery and operating expenses	1,062,000	1,693,000	7,267,000	3,639,000
Taxes other than income	38,812,000	39,632,000	82,506,000	72,115,000
General and administrative	34,826,000	28,709,000	71,433,000	71,028,000
Interest, net of amounts capitalized of $18,475, $13,194, $37,920 and $24,151, respectively	41,604,000	42,249,000	77,918,000	91,026,000
Depletion, depreciation, and amortization	132,289,000	103,495,000	253,184,000	197,089,000
Derivatives income	(139,109,000)	(172,904,000)	(93,834,000)	(2,154,000)
Loss on early extinguishment of debt	0	348,000	0	16,131,000
Impairment of assets	215,000	0	17,515,000	0
Other expenses	12,552,000	2,018,000	23,272,000	4,377,000
Total expenses	258,980,000	177,595,000	724,784,000	714,706,000
Income before income taxes	342,801,000	423,802,000	522,113,000	400,856,000
Income tax provision
Current income taxes	784,000	12,028,000	29,492,000	11,180,000
Deferred income taxes	130,152,000	152,528,000	167,289,000	144,620,000
Net income	$ 211,865,000	$ 259,246,000	$ 325,332,000	$ 245,056,000
Net income per common share - basic	$ 0.55	$ 0.65	$ 0.84	$ 0.62
Net income per common share - diluted	$ 0.54	$ 0.64	$ 0.83	$ 0.61
Weighted average common shares outstanding
Basic	387,159,000	398,631,000	386,764,000	398,032,000
Diluted	390,702,000	403,919,000	390,823,000	403,703,000