CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($)		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenues
Sales and other operating revenues		$ 1,809,575,000	$ 2,787,116,000	$ 5,288,933,000
Gain on sale of assets		1,663,000	154,155,000	138,903,000
Interest and other income		62,891,000	91,809,000	48,248,000
Total revenues		1,874,129,000	3,033,080,000	5,476,084,000
Costs and Expenses
Lease operating expenses		559,360,000	832,306,000	1,089,888,000
Severance and ad valorem taxes		43,826,000	65,794,000	107,215,000
Exploration expenses, including undeveloped lease amortization		101,861,000	470,924,000	513,600,000
Selling and general expenses		265,210,000	306,663,000	364,004,000
Depreciation, depletion and amortization		1,054,081,000	1,619,824,000	1,906,247,000
Impairment of assets		95,088,000	2,493,156,000	51,314,000
Redetermination expense	[1]	39,100,000
Accretion of asset retirement obligations		46,742,000	48,665,000	50,778,000
Deepwater rig contract exit costs		(4,344,000)	282,001,000
Interest expense		152,492,000	124,665,000	136,424,000
Interest capitalized		(4,322,000)	(7,290,000)	(20,605,000)
Other expense		18,150,000	78,634,000	24,949,000
Total costs and expenses		2,367,244,000	6,315,342,000	4,223,814,000
Income (loss) from continuing operations before income taxes		(493,115,000)	(3,282,262,000)	1,252,270,000
Income tax expense (benefit)		(219,172,000)	(1,026,490,000)	227,297,000
Income (loss) from continuing operations		(273,943,000)	(2,255,772,000)	1,024,973,000
Loss from discontinued operations, net of income taxes		(2,027,000)	(15,061,000)	(119,362,000)
Net Income (Loss)		$ (275,970,000)	$ (2,270,833,000)	$ 905,611,000
Per Common Share - Basic
Income (loss) from continuing operations		$ (1.59)	$ (12.94)	$ 5.73
Loss from discontinued operations		(0.01)	(0.09)	(0.67)
Net income (loss)		(1.60)	(13.03)	5.06
Per Common Share - Diluted
Income (loss) from continuing operations		(1.59)	(12.94)	5.69
Loss from discontinued operations		(0.01)	(0.09)	(0.66)
Net income (loss)		$ (1.60)	$ (13.03)	$ 5.03
Average Common shares outstanding - basic		172,173,012	174,351,227	178,852,942
Average Common shares outstanding - diluted		172,173,012	174,351,227	180,070,984

[1] Results exclude corporate overhead, interest and discontinued operations.