Condensed Consolidated Statements of Operations and Comprehensive Income (Unaudited) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Sales of products	$ 85,330	$ 67,019	$ 161,780	$ 158,172
Cost of sales and other direct production costs	60,008	33,172	96,833	66,462
Depreciation, depletion and amortization	20,211	9,879	34,218	19,540
	80,219	43,051	131,051	86,002
Gross profit	5,111	23,968	30,729	72,170
Other operating expenses:
General and administrative	7,482	5,527	14,421	10,028
Exploration	6,221	7,146	12,714	12,757
Pre-development	4,512	3,471	9,303	6,837
Other operating expense	205	1,605	1,229	2,549
Provision for closed operations and environmental matters	1,845	2,235	3,639	4,413
Lucky Friday suspension-related (income) expense	(2,840)	6,465	(1,342)	12,631
Aurizon acquisition costs	20,308		25,600
	37,733	26,449	65,564	49,215
Income (loss) from operations	(32,622)	(2,481)	(34,835)	22,955
Other income (expense):
Gain on sale of investments	197		197
Gain on derivative contracts	6,541	6,171	28,080	940
Interest and other income	685	32	572	181
Interest expense, net of amount capitalized	(6,454)	(505)	(7,158)	(972)
	969	5,698	21,691	149
Income (loss) before income taxes	(31,653)	3,217	(13,144)	23,104
Income tax benefit (provision)	6,795	(693)	(620)	(8,008)
Net income (loss)	(24,858)	2,524	(13,764)	15,096
Preferred stock dividends	(138)	(138)	(276)	(276)
Income (loss) applicable to common shareholders	(24,996)	2,386	(14,040)	14,820
Net income (loss)	(24,858)	2,524	(13,764)	15,096
Reclassification of net gain on sale of marketable securities included in net income	(197)		(197)
Unrealized holding losses on investments	(1,747)	(586)	(4,578)	(805)
Comprehensive income (loss)	$ (26,802)	$ 1,938	$ (18,539)	$ 14,291
Basic income (loss) per common share after preferred dividends (in Dollars per share)	$ (0.08)	$ 0.01	$ (0.05)	$ 0.05
Diluted income (loss) per common share after preferred dividends (in Dollars per share)	$ (0.08)	$ 0.01	$ (0.05)	$ 0.05
Weighted average number of common shares outstanding - basic (in Shares)	303,566	285,312	294,317	285,303
Weighted average number of common shares outstanding - diluted (in Shares)	303,566	295,160	294,317	296,100
Cash dividends declared per common share (in Dollars per share)	$ 0.0025	$ 0.0225	$ 0.0050	$ 0.0350