Condensed Consolidated Statements of Operations and Comprehensive Income (Loss) (Unaudited) (USD $) In Thousands, except Per Share data	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Condensed Consolidated Statements of Operations and Comprehensive Income (Loss) [Abstract]
Sales of metal	$ 343,575	$ 118,564	$ 774,289	$ 307,871
Production costs applicable to sales	(141,253)	(60,402)	(310,829)	(170,795)
Depreciation, depletion and amortization	(58,652)	(37,801)	(166,334)	(95,503)
Gross profit	143,670	20,361	297,126	41,573
COSTS AND EXPENSES
Administrative and general	8,236	5,963	22,294	19,758
Exploration	4,772	3,840	11,611	9,521
Pre-development, care, maintenance and other	3,271	82	17,949	814
Total cost and expenses	16,279	9,885	51,854	30,093
OPERATING INCOME	127,391	10,476	245,272	11,480
OTHER INCOME AND EXPENSE
Loss on debt extinguishments	(784)	(806)	(1,640)	(12,714)
Fair value adjustments, net	(53,351)	(19,107)	(71,051)	(65,881)
Interest income and other	(6,610)	(638)	(1,946)	(2,725)
Interest expense, net of capitalized interest	(7,980)	(9,951)	(26,553)	(21,402)
Total other income and expense	(68,725)	(30,502)	(101,190)	(102,722)
Income (loss) from continuing operations before income taxes	58,666	(20,026)	144,082	(91,242)
Income tax benefit (provision)	(27,606)	(3,233)	(61,947)	13,137
Income (loss) from continuing operations	31,060	(23,259)	82,135	(78,105)
Loss from discontinued operations, net of income taxes		(251)		(6,029)
Gain (loss) on sale of net assets of discontinued operations, net of income taxes		882		(2,095)
NET INCOME (LOSS)	31,060	(22,628)	82,135	(86,229)
Other comprehensive income (loss), net of income taxes	(2,789)	164	(4,176)	159
COMPREHENSIVE INCOME (LOSS)	$ 28,271	$ (22,464)	$ 77,959	$ (86,070)
Basic income (loss) per share:
Income (loss) from continuing operations	$ 0.35	$ (0.26)	$ 0.92	$ (0.90)
Income (loss) from discontinued operations		$ 0.01		$ (0.10)
Net income (loss)	$ 0.35	$ (0.25)	$ 0.92	$ (1.00)
Diluted income (loss) per share:
Income (loss) from continuing operations	$ 0.35	$ (0.26)	$ 0.92	$ (0.90)
Income (loss) from discontinued operations		$ 0.01		$ (0.10)
Net income (loss)	$ 0.35	$ (0.25)	$ 0.92	$ (1.00)
Weighted average number of shares of common stock
Basic	89,449	89,236	89,350	86,489
Diluted	89,739	89,236	89,702	86,489