Condensed Consolidated Statements of Operations and Comprehensive Income (Loss) (Unaudited) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Sales of products	$ 125,787	$ 76,450
Cost of sales and other direct production costs	77,741	36,825
Depreciation, depletion and amortization	25,803	14,007
	103,544	50,832
Gross profit	22,243	25,618
Other operating expenses:
General and administrative	7,941	6,939
Exploration	4,150	6,493
Pre-development	419	4,791
Other operating expense	718	1,024
Provision for closed operations and environmental matters	1,104	1,794
Lucky Friday suspension-related costs		1,498
Aurizon acquisition costs		5,292
	14,332	27,831
Income (loss) from operations	7,911	(2,213)
Other income (expense):
Unrealized gain on investments	688
Gain on derivative contracts	9,452	21,539
Net foreign exchange gain (loss)	4,134	(144)
Interest and other income	79	31
Interest expense, net of amounts capitalized	(6,840)	(704)
	7,513	20,722
Income before income taxes	15,424	18,509
Income tax provision	(3,783)	(7,415)
Net income	11,641	11,094
Preferred stock dividends	(138)	(138)
Income applicable to common stockholders	11,503	10,956
Net income	11,641	11,094
Unrealized holding gains (losses) on investments	1,350	(2,831)
Comprehensive income	$ 12,991	$ 8,263
Basic income per common share after preferred dividends (in Dollars per share)	$ 0.03	$ 0.04
Diluted income per common share after preferred dividends (in Dollars per share)	$ 0.03	$ 0.04
Weighted average number of common shares outstanding - basic (in Shares)	342,666	285,171
Weighted average number of common shares outstanding - diluted (in Shares)	350,018	297,164