Condensed Consolidated Statements of Operations and Comprehensive Income (Unaudited) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Sales of products	$ 81,871	$ 120,543	$ 240,043	$ 374,767
Cost of sales and other direct production costs	32,961	41,639	99,423	125,033
Depreciation, depletion and amortization	11,601	11,099	31,141	34,565
	44,562	52,738	130,564	159,598
Gross profit	37,309	67,805	109,479	215,169
Other operating expenses:
General and administrative	5,695	5,559	15,723	14,808
Exploration	11,722	9,872	24,479	19,012
Pre-development	5,409	1,752	12,246	1,752
Other operating expense	736	1,612	3,285	5,699
Provision (credit) for closed operations and environmental matters	(1,093)	5,521	3,320	7,883
Lucky Friday suspension-related costs	6,114		18,745
	28,583	24,316	77,798	49,154
Income from operations	8,726	43,489	31,681	166,015
Other income (expense):
Gain (loss) on derivative contracts	(9,053)	40,382	(8,113)	38,907
Interest and other income (loss)	47	(214)	228	520
Interest expense	(591)	(411)	(1,563)	(2,384)
	(9,597)	39,757	(9,448)	37,043
Income (loss) before income taxes	(871)	83,246	22,233	203,058
Income tax provision	(14)	(27,325)	(8,022)	(70,463)
Net income	(885)	55,921	14,211	132,595
Reclassification of net gain on sale of marketable securities included in net income				(611)
Unrealized holding gains (losses) on investments	3,085	(798)	2,280	(913)
Comprehensive income	2,200	55,123	16,491	131,071
Basic income (loss) per common share after preferred dividends (in Dollars per share)	$ 0.00	$ 0.20	$ 0.05	$ 0.47
Diluted income (loss) per common share after preferred dividends (in Dollars per share)	$ 0.00	$ 0.19	$ 0.05	$ 0.45
Weighted average number of common shares outstanding - basic (in Shares)	285,492	279,541	285,400	279,067
Weighted average number of common shares outstanding - diluted (in Shares)	285,492	295,000	296,739	295,739
Cash dividends declared per common share (in Dollars per share)	$ 0.0025	$ 0.0000	$ 0.0375	$ 0.0000
Preferred stock dividends	(138)	(138)	(414)	(414)
Income (loss) applicable to common shareholders	$ (1,023)	$ 55,783	$ 13,797	$ 132,181