Condensed Consolidated Statements of Operations and Comprehensive Income (Unaudited) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Sales of products	$ 76,450	$ 91,153
Cost of sales and other direct production costs	36,825	33,290
Depreciation, depletion and amortization	14,007	9,661
	50,832	42,951
Gross profit	25,618	48,202
Other operating expenses:
General and administrative	6,939	4,501
Exploration	6,493	5,611
Pre-development	4,791	3,366
Other operating expense	1,024	944
Provision for closed operations and environmental matters	1,794	2,178
Lucky Friday suspension-related costs	1,498	6,166
Aurizon acquisition costs	5,292
	27,831	22,766
Income (loss) from operations	(2,213)	25,436
Other income (expense):
Gain (loss) on derivative contracts	21,539	(5,231)
Interest and other income (expense)	(113)	149
Interest expense	(704)	(467)
	20,722	(5,549)
Income before income taxes	18,509	19,887
Income tax provision	(7,415)	(7,315)
Net income	11,094	12,572
Preferred stock dividends	(138)	(138)
Income applicable to common shareholders	10,956	12,434
Net income	11,094	12,572
Unrealized holding gains (losses) on investments	(2,831)	(219)
Comprehensive income	$ 8,263	$ 12,353
Basic income per common share after preferred dividends (in Dollars per share)	$ 0.04	$ 0.04
Diluted income per common share after preferred dividends (in Dollars per share)	$ 0.04	$ 0.04
Weighted average number of common shares outstanding - basic (in Shares)	285,171	285,292
Weighted average number of common shares outstanding - diluted (in Shares)	297,164	296,928