Consolidated Statements of Operations and Comprehensive Income (Loss) - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Sales of products	$ 443,567	$ 500,781	$ 382,589
Cost of sales and other direct production costs	293,567	304,446	235,316
Depreciation, depletion and amortization	111,489	111,134	81,127
Total cost of sales	405,056	415,580	316,443
Gross profit	38,511	85,201	66,146
Other operating expenses:
General and administrative	34,201	31,538	28,925
Exploration	17,745	17,698	23,502
Pre-development	4,213	1,969	14,148
Provision for closed operations and environmental matters	12,220	10,098	5,403
Other operating expense	3,177	2,295	1,641
Loss (gain) on disposition of properties, plants, equipment and mineral interests	404	(25)	(75)
Lucky Friday suspension-related income			(1,401)
Acquisition costs	2,162		26,397
Total other operating expense	74,122	63,573	98,540
(Loss) income from operations	(35,611)	21,628	(32,394)
Other income (expense):
Gain on derivative contracts	8,252	9,134	17,979
Net (loss) gain on sale of investments	(44)		197
Unrealized loss on investments	(3,333)	(3,224)	(2,639)
Net foreign exchange gain	24,551	11,535	2,959
Interest and other income	916	286	662
Interest expense, net of amount capitalized	(25,389)	(26,775)	(21,689)
Total other income (expense):	4,953	(9,044)	(2,531)
(Loss) income before income taxes	(30,658)	12,584	(34,925)
Income tax (provision) benefit	(56,310)	5,240	9,795
Net (loss) income	(86,968)	17,824	(25,130)
Unrealized gain (loss) and amortization of prior service on pension plans	(850)	(6,875)	2,230
Unrealized holding (losses) gains on investments	(2,743)	(1,282)	(7,249)
Reclassification of impairment of investments included in net (loss) income	2,993	2,425	2,638
Total change in accumulated other comprehensive (loss) income, net	(600)	(5,732)	(2,381)
Preferred stock dividends	(552)	(552)	(552)
(Loss) income applicable to common stockholders	(87,520)	17,272	(25,682)
Comprehensive (loss) income:
Net (loss) income	(86,968)	17,824	(25,130)
Comprehensive (loss) income	$ (87,568)	$ 12,092	$ (27,511)
Basic (loss) income per common share after preferred dividends (in Dollars per share)	$ (0.23)	$ 0.05	$ (0.08)
Diluted (loss) income per common share after preferred dividends (in Dollars per share)	$ (0.23)	$ 0.05	$ (0.08)
Weighted average number of common shares outstanding – basic (in Shares)	373,954	353,442	318,679
Weighted average number of common shares outstanding – diluted (in Shares)	373,954	357,435	318,679