Consolidated Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenues and other income
Oil, natural gas, and related product sales	$ 2,372,473	$ 2,466,234	$ 2,409,867
CO2 and helium sales and transportation fees	44,643	27,950	26,453
Interest income and other income	18,089	22,943	20,152
Total revenues and other income	2,435,205	2,517,127	2,456,472
Expenses
Lease operating expenses	647,559	730,574	532,359
Marketing and plant operating expenses	64,379	49,246	52,836
CO2 and helium discovery and operating expenses	25,222	16,916	14,694
Taxes other than income	169,701	176,231	160,016
General and administrative expenses	158,343	145,211	144,019
Interest, net of amounts capitalized of $24,202, $79,253 and $77,432, respectively	183,003	140,709	153,581
Depletion, depreciation, and amortization	592,972	509,943	507,538
Commodity derivatives expense (income)	(555,255)	41,024	(4,834)
Loss on early extinguishment of debt	113,908	44,651	0
Impairment of assets	0	0	17,515
Other expenses	12,816	20,242	21,891
Total expenses	1,412,648	1,874,747	1,599,615
Income before income taxes	1,022,557	642,380	856,857
Income tax provision	387,066	232,783	331,497
Net Income	$ 635,491	$ 409,597	$ 525,360
Net income per common share
Basic	$ 1.82	$ 1.12	$ 1.36
Diluted	$ 1.81	$ 1.11	$ 1.35
Dividends declared per common share	$ 0.25	$ 0	$ 0
Weighted average common shares outstanding
Basic	348,962	366,659	385,205
Diluted	351,167	369,877	388,938