CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY - USD ($) $ in Thousands	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive income (loss)	Registered direct purchase agreement	Total
Increase (Decrease) in Stockholders' Equity
Cumulative adjustment related to change in accounting principle | Cumulative Effect Adjustment | ASU 2017-11 Earnings Per Share		$ 19,046	$ (17,148)			$ 1,898
Adjusted balance at beginning of period | ASU 2017-11 Earnings Per Share		514,501	(505,185)	$ 55		10,260
Balance (ASU 2017-11 Earnings Per Share) at Dec. 31, 2016	$ 889
Balance at Dec. 31, 2016	$ 889	495,455	(488,037)	55		8,362
Balance (in shares) (ASU 2017-11 Earnings Per Share) at Dec. 31, 2016	89,020,041
Balance (in shares) at Dec. 31, 2016	89,020,041
Increase (Decrease) in Stockholders' Equity
Stock compensation accrued and shares issued for vested stock awards	$ 1	196				197
Stock compensation accrued and shares issued for vested stock awards (in shares)	200,000
Shares issued under the at-the-market offering agreement, net	$ 10	671				681
Shares issued under the at-the-market offering agreement, net (in shares)	1,024,392
Consideration shares sold to Hecla, net	$ 18	912				$ 930
Consideration shares sold to Hecla, net (in shares)	1,811,015
Cancellation of treasury shares	$ 1	(1)
Cancellation of treasury shares (in shares)	(125,739)					(125,739)
Deemed dividend on warrants		5	(5)
Unrealized loss on marketable equity securities, net of tax				(95)		$ (95)
Net loss			(3,892)			(3,892)
Balance (ASU 2017-11 Earnings Per Share) at Dec. 31, 2017	$ 919
Balance at Dec. 31, 2017	$ 919	516,284	(509,082)	(40)		8,081
Balance (in shares) (ASU 2017-11 Earnings Per Share) at Dec. 31, 2017	91,929,709
Balance (in shares) at Dec. 31, 2017	91,929,709
Increase (Decrease) in Stockholders' Equity
Cumulative adjustment related to change in accounting principle | Cumulative Effect Adjustment | ASU 2017-11 Earnings Per Share			(89)	$ 40		(49)
Adjusted balance at beginning of period | ASU 2017-11 Earnings Per Share		516,284	(509,171)			8,032
Stock compensation accrued and shares issued for vested stock awards	$ 4	312				316
Stock compensation accrued and shares issued for vested stock awards (in shares)	537,279
Registered direct purchase agreement, net	$ 32	1,202				1,234
Registered direct purchase agreement, net (in shares)	3,153,808				0
Deemed dividend on warrants		8	(8)
Net loss			(1,945)			(1,945)
Balance at Dec. 31, 2018	$ 955	$ 517,806	$ (511,124)			$ 7,637
Balance (in shares) at Dec. 31, 2018	95,620,796