CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenues and other income:
Oil and gas revenue	$ 310,377	$ 446,696	$ 855,877
Gain on sale of assets		24,651	23,769
Other income	74,978	209	3,092
Total revenues and other income	385,355	471,556	882,738
Costs and expenses:
Oil and gas production	119,367	105,336	100,122
Facilities insurance modifications	14,961
Exploration expenses	202,280	156,203	93,519
General and administrative	87,623	136,809	135,231
Depletion and depreciation	140,404	155,966	198,080
Interest and other financing costs, net	44,147	37,209	45,548
Derivatives, net	48,021	(210,649)	(281,853)
Restructuring charges			11,742
Other expenses, net	23,116	5,246	2,081
Total costs and expenses	679,919	386,120	304,470
Income (Loss) before taxes	(294,564)	85,436	578,268
Income tax expense (benefit)	(10,784)	155,272	298,898
Net income (loss)	$ (283,780)	$ (69,836)	$ 279,370
Net income (loss) per share:
Basic (in dollars per share)	$ (0.74)	$ (0.18)	$ 0.73
Diluted (in dollars per share)	$ (0.74)	$ (0.18)	$ 0.72
Weighted average number of shares used to compute net income (loss) per share:
Basic (in shares)	385,402	382,610	379,195
Diluted (in shares)	385,402	382,610	386,119