CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenues
Sales and other operating revenues	$ 2,787,116,000	$ 5,288,933,000	$ 5,312,686,000
Gain (loss) on sale of assets	154,155,000	138,903,000	(87,000)
Interest and other income	91,809,000	48,248,000	77,490,000
Total revenues	3,033,080,000	5,476,084,000	5,390,089,000
Costs and Expenses
Lease operating expenses	832,306,000	1,089,888,000	1,252,812,000
Severance and ad valorem taxes	65,794,000	107,215,000	87,331,000
Exploration expenses, including undeveloped lease amortization	470,924,000	513,600,000	502,215,000
Selling and general expenses	306,663,000	364,004,000	379,167,000
Depreciation, depletion and amortization	1,619,824,000	1,906,247,000	1,553,394,000
Impairment of assets	2,493,156,000	51,314,000	21,587,000
Accretion of asset retirement obligations	48,665,000	50,778,000	48,996,000
Deepwater rig contract exit costs	282,001,000
Interest expense	124,665,000	136,424,000	124,423,000
Interest capitalized	(7,290,000)	(20,605,000)	(52,523,000)
Other expense	78,634,000	24,949,000
Total costs and expenses	6,315,342,000	4,223,814,000	3,917,402,000
Income (loss) from continuing operations before income taxes	(3,282,262,000)	1,252,270,000	1,472,687,000
Income tax expense (benefit)	(1,026,490,000)	227,297,000	584,550,000
Income (loss) from continuing operations	(2,255,772,000)	1,024,973,000	888,137,000
Income (loss) from discontinued operations, net of income taxes	(15,061,000)	(119,362,000)	235,336,000
Net Income (Loss)	$ (2,270,833,000)	$ 905,611,000	$ 1,123,473,000
Per Common Share - Basic
Income (loss) from continuing operations	$ (12.94)	$ 5.73	$ 4.73
Inocme (loss) from discontinued operations	(0.09)	(0.67)	1.25
Net income (loss)	(13.03)	5.06	5.98
Per Common Share - Diluted
Income (loss) from continuing operations	(12.94)	5.69	4.69
Income (loss) from discontinued operations	(0.09)	(0.66)	1.25
Net income (loss)	$ (13.03)	$ 5.03	$ 5.94
Average Common shares outstanding - basic	174,351,227	178,852,942	187,921,062
Average Common shares outstanding - diluted	174,351,227	180,070,984	189,271,398