Condensed Consolidated Statements of Operations and Comprehensive Income (Loss) (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Sales of products	$ 104,197	$ 117,502	$ 223,289	$ 243,289
Cost of sales and other direct production costs	67,567	71,039	141,532	148,780
Depreciation, depletion and amortization	27,166	27,735	52,420	53,538
	94,733	98,774	193,952	202,318
Gross profit	9,464	18,728	29,337	40,971
Other operating expenses:
General and administrative	8,296	8,159	17,016	16,100
Exploration	4,592	3,140	9,208	7,290
Pre-development	1,618	437	2,138	856
Other operating expense	766	693	1,394	1,411
Provision for closed operations and environmental matters	9,335	1,267	9,802	2,371
Acquisition costs	2,147		2,147
	26,754	13,696	41,705	28,028
Income (loss) from operations	(17,290)	5,032	(12,368)	12,943
Other income (expense):
Loss on disposition of investments	(166)		(166)
Unrealized gain (loss) on investments	(117)	(608)	(2,960)	80
Gain (loss) on derivative contracts	(887)	(11,601)	4,905	(2,149)
Net foreign exchange gain (loss)	(1,833)	(5,382)	10,441	(1,248)
Interest and other income	35	97	73	176
Interest expense, net of amount capitalized	(6,541)	(6,962)	(12,733)	(13,802)
	(9,509)	(24,456)	(440)	(16,943)
Loss before income taxes	(26,799)	(19,424)	(12,808)	(4,000)
Income tax benefit (provision)	132	5,025	(1,307)	1,242
Net loss	(26,667)	(14,399)	(14,115)	(2,758)
Unrealized loss and amortization of prior service on pension plans		(1,192)		(1,192)
Reclassification of loss on disposition or impairment of marketable securities included in net loss	166		2,993
Unrealized holding (losses) gains on investments	(1,321)	(996)	(2,212)	354
Preferred stock dividends	(138)	(138)	(276)	(276)
Loss applicable to common shareholders	(26,805)	(14,537)	(14,391)	(3,034)
Comprehensive loss:
Net loss	(26,667)	(14,399)	(14,115)	(2,758)
Comprehensive income (loss)	$ (27,822)	$ (16,587)	$ (13,334)	$ (3,596)
Basic loss per common share after preferred dividends (in Dollars per share)	$ (0.07)	$ (0.04)	$ (0.04)	$ (0.01)
Diluted loss per common share after preferred dividends (in Dollars per share)	$ (0.07)	$ (0.04)	$ (0.04)	$ (0.01)
Weighted average number of common shares outstanding - basic (in Shares)	371,295	344,216	370,042	343,437
Weighted average number of common shares outstanding - diluted (in Shares)	371,295	344,216	370,042	343,437
Cash dividends declared per common share (in Dollars per share)	$ 0.0025	$ 0.0025	$ 0.0050	$ 0.0050