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 revenue	$ 228,066	$ 115,771
Interest income	70	746
Other income	254	30
Total revenues and other income	228,390	116,547
Costs and expenses:
Oil and gas production	24,401	7,326
Exploration expenses	23,296	39,644
General and administrative	40,030	39,323
Depletion and depreciation	58,649	31,649
Amortization-deferred financing costs	2,698	2,194
Interest expense	8,991	13,058
Derivatives, net	5,508	3,860
Other expenses, net	632	748
Total costs and expenses	164,205	137,802
Income (loss) before income taxes	64,185	(21,255)
Income tax expense	44,091	16,286
Net income (loss)	$ 20,094	$ (37,541)
Net income (loss) per share:
Basic (in dollars per share)	$ 0.05	$ (0.10)
Diluted (in dollars per share)	$ 0.05	$ (0.10)
Weighted average number of shares used to compute net income (loss) per share:
Basic (in shares)	375,284	369,227
Diluted (in shares)	375,651	369,227