Condensed Consolidated Statements of Operations and Comprehensive Income (Loss) (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Sales of products	$ 104,941	$ 135,507	$ 328,230	$ 378,796
Cost of sales and other direct production costs	79,273	86,680	220,805	235,460
Depreciation, depletion and amortization	28,229	26,804	80,649	80,342
	107,502	113,484	301,454	315,802
Gross profit (loss)	(2,561)	22,023	26,776	62,994
Other operating expenses:
General and administrative	9,461	7,884	26,477	23,984
Exploration	5,540	5,797	14,748	13,086
Pre-development	1,696	391	3,834	1,247
Other operating expense	743	442	2,137	1,853
Provision for closed operations and reclamation	1,181	1,238	10,983	3,609
Acquisition costs	15		2,162
	18,636	15,752	60,341	43,779
Income (loss) from operations	(21,197)	6,271	(33,565)	19,215
Other income (expense):
Gain (loss) on derivative contracts	3,347	(411)	8,252	(2,560)
Unrealized loss on investments	(100)	(2,830)	(3,226)	(2,750)
Foreign exchange gain	9,077	7,299	19,518	6,051
Interest and other income	100	32	173	208
Interest expense, net of amount capitalized	(6,617)	(6,505)	(19,350)	(20,307)
	5,807	(2,415)	5,367	(19,358)
Income (loss) before income taxes	(15,390)	3,856	(28,198)	(143)
Income tax benefit (provision)	5,500	(180)	4,193	1,062
Net income (loss)	(9,890)	3,676	(24,005)	919
Reclassification of loss on disposition or impairment of marketable securities included in net income (loss)		2,425	2,993	2,425
Defined benefit pension plan costs				(1,192)
Unrealized holding gains (losses) on investments	(391)	(149)	(2,603)	205
Preferred stock dividends	(138)	(138)	(414)	(414)
Income (loss) applicable to common shareholders	(10,028)	3,538	(24,419)	505
Comprehensive income (loss):
Net income (loss)	(9,890)	3,676	(24,005)	919
Comprehensive income (loss)	$ (10,281)	$ 5,952	$ (23,615)	$ 2,357
Basic income (loss) per common share after preferred dividends (in Dollars per share)	$ (0.03)	$ 0.01	$ (0.07)
Diluted income (loss) per common share after preferred dividends (in Dollars per share)	$ (0.03)	$ 0.01	$ (0.07)
Weighted average number of common shares outstanding - basic (in Shares)	377,508	359,472	372,555	348,801
Weighted average number of common shares outstanding - diluted (in Shares)	377,508	362,262	372,555	354,673
Cash dividends declared per common share (in Dollars per share)	$ 0.0025	$ 0.0025	$ 0.0075	$ 0.0075