Condensed Consolidated Statements of Operations and Comprehensive Income (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Sales of products	$ 140,839	$ 179,393	$ 417,662	$ 481,712
Cost of sales and other direct production costs	68,358	90,529	224,537	249,162
Depreciation, depletion and amortization	28,844	30,179	83,365	84,592
Total cost of sales	97,202	120,708	307,902	333,754
Gross profit	43,637	58,685	109,760	147,958
Other operating expenses:
General and administrative	9,529	11,155	29,044	31,728
Exploration	7,255	3,859	17,622	10,171
Pre-development	1,757	550	4,061	1,475
Research and development	1,130		2,125
Other operating expense	134	962	1,615	2,535
Gain on disposition of properties, plants, equipment and mineral interests	(4,830)	(8)	(4,924)	(319)
Provision for closed operations and reclamation	2,940	2,162	5,044	4,779
Lucky Friday suspension-related costs	4,780		14,385
Acquisition costs		1,765		2,167
Total other operating expense	22,695	20,445	68,972	52,536
Income from operations	20,942	38,240	40,788	95,422
Other income (expense):
(Loss) gain on derivative contracts	(11,226)	7	(16,548)
Loss on disposition of investments			(167)
Unrealized (loss) gain on investments	(124)	49	(73)	488
Foreign exchange (loss) gain	(4,764)	2,375	(10,909)	(7,713)
Interest and other income	541	145	1,185	346
Interest expense, net of amount capitalized	(9,358)	(5,574)	(28,423)	(16,655)
Total other expense	(24,931)	(2,998)	(54,935)	(23,534)
(Loss) income before income taxes	(3,989)	35,242	(14,147)	71,888
Income tax benefit (provision)	5,401	(9,453)	18,377	(22,603)
Net income (loss)	1,412	25,789	4,230	49,285
Preferred stock dividends	(138)	(138)	(414)	(414)
Income applicable to common shareholders	1,274	25,651	3,816	48,871
Comprehensive income:
Net income	1,412	25,789	4,230	49,285
Reclassification of loss on disposition or impairment of marketable securities included in net income			167	1,000
Unrealized loss and amortization of prior service on pension plans	(16)
Change in fair value of derivative contracts designated as hedge transactions	6,760	(1,602)	12,068	(1,556)
Unrealized holding gains on investments	892	987	1,483	2,245
Comprehensive income	$ 9,048	$ 25,174	$ 17,948	$ 50,974
Basic income per common share after preferred dividends (in dollars per share)	$ 0	$ 0.07	$ 0.01	$ 0.13
Diluted income per common share after preferred dividends (in dollars per share)	$ 0	$ 0.07	$ 0.01	$ 0.13
Weighted average number of common shares outstanding - basic (in shares)	398,848	387,578	396,809	383,458
Weighted average number of common shares outstanding - diluted (in shares)	401,258	389,918	400,176	386,318
Cash dividends declared per common share (in dollars per share)	$ 0.0025	$ 0.0025	$ 0.0075	$ 0.0075