Consolidated Statements Of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Revenues and other income:
Oil and gas	$ 787,855	$ 718,956
Interest and other	19,315	21,908
Gains (Losses) on Sales of Assets	24,417	43,596
Total revenues and other income	831,587	784,460
Costs and expenses:
Oil and gas production	169,140	131,781
Production and ad valorem taxes	54,297	45,796
Depletion, depreciation and amortization	230,763	181,418
Exploration and abandonments	27,627	53,287
General and administrative	63,751	63,067
Accretion of discount on asset retirement obligations	3,153	2,430
Interest	50,735	46,858
Derivative (gains) losses, net	42,243	(91,750)
Other	21,349	23,607
Costs and expenses, Total	663,058	456,494
Income (loss) from continuing operations before income taxes	168,529	327,966
Income tax benefit (provision)	(59,329)	(117,703)
Income (loss) from continuing operations	109,200	210,263
Income (loss) from discontinued operations, net of tax	(465)	10,695
Net income (loss)	108,735	220,958
Net income attributable to noncontrolling interests	(8,072)	(6,339)
Net income (loss) attributable to common stockholders	100,663	214,619
Basic earnings per share:
Income (loss) from continuing operations attributable to common stockholders	$ 0.77	$ 1.65
Income (loss) from discontinued operations attributable to common stockholders	$ 0.00	$ 0.08
Net income (loss) attributable to common stockholders	$ 0.77	$ 1.73
Diluted earnings per share:
Income (loss) from continuing operations attributable to common stockholders	$ 0.75	$ 1.60
Income (loss) from discontinued operations attributable to common stockholders	$ 0.00	$ 0.08
Net income (loss) attributable to common stockholders	$ 0.75	$ 1.68
Weighted average shares outstanding:
Basic	128,940	122,480
Diluted	132,751	126,247
Dividends declared per share	$ 0.04	$ 0.04
Amounts attributable to common stockholders:
Income (loss) from continuing operations	101,128	203,924
Income (loss) from discontinued operations, net of tax	(465)	10,695
Net income (loss)	$ 100,663	$ 214,619