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, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Sales of products	$ 106,629	$ 81,871	$ 268,409	$ 240,043
Cost of sales and other direct production costs	66,937	32,961	163,770	99,423
Depreciation, depletion and amortization	19,006	11,601	53,224	31,141
	85,943	44,562	216,994	130,564
Gross profit	20,686	37,309	51,415	109,479
Other operating expenses:
General and administrative	7,720	5,695	22,141	15,723
Exploration	5,797	11,722	18,511	24,479
Pre-development	3,444	5,409	12,747	12,246
Other operating expense	342	736	1,571	3,285
Provision (credit) for closed operations and reclamation	933	(1,093)	4,572	3,320
Lucky Friday suspension-related (income) expense	(59)	6,114	(1,401)	18,745
Aurizon acquisition costs	768		26,368
	18,945	28,583	84,509	77,798
Income (loss) from operations	1,741	8,726	(33,094)	31,681
Other income (expense):
Gain (loss) on derivative contracts	(4,564)	(9,053)	23,516	(8,113)
Gains on sale of investments			197
Interest and other income (loss)	(829)	47	(257)	228
Interest expense, net of amount capitalized	(7,348)	(591)	(14,506)	(1,563)
	(12,741)	(9,597)	8,950	(9,448)
Income (loss) before income taxes	(11,000)	(871)	(24,144)	22,233
Income tax benefit (provision)	2,542	(14)	1,922	(8,022)
Net income (loss)	(8,458)	(885)	(22,222)	14,211
Preferred stock dividends	(138)	(138)	(414)	(414)
Income (loss) applicable to common shareholders	(8,596)	(1,023)	(22,636)	13,797
Net income (loss)	(8,458)	(885)	(22,222)	14,211
Reclassification of net gain on sale of marketable securities included in net income			(197)
Defined benefit pension plan costs	3,366		3,366
Unrealized holding gains (losses) on investments	(877)	3,085	(5,455)	2,280
Comprehensive income (loss)	$ (5,969)	$ 2,200	$ (24,508)	$ 16,491
Basic income (loss) per common share after preferred dividends (in Dollars per share)	$ (0.03)		$ (0.07)	$ 0.05
Diluted income (loss) per common share after preferred dividends (in Dollars per share)	$ (0.03)		$ (0.07)	$ 0.05
Weighted average number of common shares outstanding - basic (in Shares)	342,638	285,492	310,601	285,400
Weighted average number of common shares outstanding - diluted (in Shares)	342,638	285,492	310,601	296,739
Cash dividends declared per common share (in Dollars per share)	$ 0.0025	$ 0.0025	$ 0.0075	$ 0.0375