Condensed Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 325,756	$ 1,425,815
Joint interest and other receivables	71,687	61,592
Prepaid expenses and other current assets	30,141	23,941
Inventory	62,768	65,286
Short-term restricted funds	90,449	90,440
Short-term investments	1,287,298	789,668
Total current assets	1,868,099	2,456,742
Property, plant, and equipment:
Oil and gas properties, successful efforts method of accounting, net of accumulated depletion of $-0-	1,124,770	1,094,464
Other property and equipment, net of accumulated depreciation and amortization of $2,992 and $2,533, as of March 31, 2013 and December 31, 2012, respectively	4,944	5,292
Total property, plant, and equipment, net	1,129,714	1,099,756
Long-term restricted funds	305,208	395,652
Long-term investments	512,754	36,267
Other assets	25,538	23,042
Total assets	3,841,313	4,011,459
Current liabilities:
Trade and other accounts payable	6,625	67,876
Accrued liabilities	88,881	44,061
Short-term contractual obligations	49,019	49,019
Total current liabilities	144,525	160,956
Long-term debt	1,002,055	991,191
Long-term contractual obligations	125,383	168,238
Other long-term liabilities	1,862	1,856
Total long-term liabilities	1,129,300	1,161,285
Stockholders' Equity:
Common stock, $0.01 par value per share; 2,000,000,000 shares authorized, 406,707,716 and 406,596,884 issued and outstanding as of March 31, 2013 and December 31, 2012, respectively	4,067	4,066
Additional paid-in capital	3,619,343	3,612,987
Accumulated deficit during the development stage	(1,055,922)	(927,835)
Total stockholders' equity	2,567,488	2,689,218
Total liabilities and stockholders' equity	$ 3,841,313	$ 4,011,459