Consolidated Statements of Operations and Comprehensive Income (Loss) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Sales of products	$ 382,589	$ 321,143	$ 477,634
Cost of sales and other direct production costs	235,316	134,105	165,573
Depreciation, depletion and amortization	81,127	43,522	47,066
Total cost of sales	316,443	177,627	212,639
Gross profit	66,146	143,516	264,995
Other operating expenses:
General and administrative	28,925	21,253	18,540
Exploration	23,502	31,822	26,959
Pre-development	14,148	17,916	4,446
Other operating expense	1,641	4,423	7,658
(Gain) loss on disposition of property, plants, equipment and mineral interests	(75)	275
Lucky Friday suspension-related (income) costs	(1,401)	25,309
Aurizon acquisition costs	26,397
Provision for closed operations and environmental matters	5,403	4,652	9,747
Total other operating expense	98,540	105,650	67,350
Income (loss) from operations	(32,394)	37,866	197,645
Other income (expense):
Gain (loss) on derivative contracts	17,979	(10,457)	37,988
Net gain on sale of investments	197		611
Unrealized loss on investments	(2,639)	(1,171)	(140)
Net foreign exchange gain (loss)	2,959	(63)	(216)
Interest and other income	662	85	129
Interest expense	(21,689)	(2,427)	(2,875)
Total other income (expense):	(2,531)	(14,033)	35,497
Income (loss) before income taxes	(34,925)	23,833	233,142
Income tax benefit (provision)	9,795	(8,879)	(81,978)
Net income (loss)	(25,130)	14,954	151,164
Unrealized gain (loss) and amortization of prior service on pension plans	2,230	(1,644)	(7,754)
Unrealized holding gains (losses) on investments	(7,249)	53	(767)
Reclassification of impairment of investments included in net income (loss)	2,638	1,171	140
Total change in accumulated other comprehensive income (loss), net	(2,381)	(420)	(8,381)
Preferred stock dividends	(552)	(552)	(552)
Income (loss) applicable to common stockholders	(25,682)	14,402	150,612
Net income (loss)	(25,130)	14,954	151,164
Unrealized gain (loss) and amortization of prior service on pension plans	2,230	(1,644)	(7,754)
Unrealized holding gains (losses) on investments	(7,249)	53	(767)
Reclassification of impairment of investments included in net income (loss)	2,638	1,171	140
Total change in accumulated other comprehensive income (loss), net	(2,381)	(420)	(8,381)
Comprehensive income (loss)	$ (27,511)	$ 14,534	$ 142,783
Basic income (loss) per common share after preferred dividends (in Dollars per share)	$ (0.08)	$ 0.05	$ 0.54
Diluted income (loss) per common share after preferred dividends (in Dollars per share)	$ (0.08)	$ 0.05	$ 0.51
Weighted average number of common shares outstanding – basic (in Shares)	318,679	285,375	280,956
Weighted average number of common shares outstanding – diluted (in Shares)	318,679	297,566	297,033