Condensed Consolidated Statements of Operations and Comprehensive Income (Unaudited) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Sales of products	$ 91,153	$ 136,364
Cost of sales and other direct production costs	33,290	44,529
Depreciation, depletion and amortization	9,661	12,262
	42,951	56,791
Gross profit	48,202	79,573
Other operating expenses:
General and administrative	4,501	4,699
Exploration	5,611	3,301
Pre-development	3,366
Other operating expense	944	1,817
Provision for closed operations and environmental matters	2,178	1,021
Lucky Friday suspension-related costs	6,166
	22,766	10,838
Income from operations	25,436	68,735
Other income (expense):
Gain on sale of investments		611
Loss on derivative contracts	(5,231)	(2,034)
Interest and other income	149	18
Interest expense	(467)	(477)
	(5,549)	(1,882)
Income before income taxes	19,887	66,853
Income tax provision	(7,315)	(23,496)
Net income	12,572	43,357
Preferred stock dividends	(138)	(138)
Income applicable to common shareholders	12,434	43,219
Comprehensive income:
Reclassification of net gain on sale of marketable securities included in net income		(611)
Unrealized holding gains (losses) on investments	(219)	967
Comprehensive income	$ 12,353	$ 43,713
Basic income per common share after preferred dividends (in Dollars per share)	$ 0.04	$ 0.16
Diluted income per common share after preferred dividends (in Dollars per share)	$ 0.04	$ 0.15
Weighted average number of common shares outstanding - basic (in Shares)	285,292	278,448
Weighted average number of common shares outstanding - diluted (in Shares)	296,928	296,244