CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY - USD ($) $ in Thousands	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive income (loss)	Total
Balance at Dec. 31, 2015	$ 534	$ 484,742	$ (477,378)	$ (127)	$ 7,771
Balance (in shares) at Dec. 31, 2015	53,335,333
Increase (Decrease) in Stockholders' Equity
Stock compensation accrued and shares issued for vested stock awards	$ 2	250			252
Stock compensation accrued and shares issued for vested stock awards (in shares)	317,968
Shares issued on conversion of Sentient Note	$ 273	6,944			7,217
Shares issued on conversion of Sentient Note (in shares)	27,366,740
Registered offering common stock, net and warrants	$ 80	3,519			3,599
Registered offering common stock, net and warrants (in shares)	8,000,000
Unrealized gain on marketable equity securities, net of tax				182	182
Net loss			(10,659)		(10,659)
Balance (ASU 2017-11 Earnings Per Share) at Dec. 31, 2016	$ 889	514,501	(505,185)	55	10,260
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
Cumulative adjustment related to change in accounting principle | Cumulative Effect Adjustment | ASU 2017-11 Earnings Per Share		19,046	(17,148)		1,898
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
Unrealized gain on marketable equity securities, net of tax				(95)	(95)
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)
Deemed dividend on warrants		5	(5)
Net loss			(3,892)		(3,892)
Balance at Dec. 31, 2017	$ 919	$ 516,284	$ (509,082)	$ (40)	$ 8,081
Balance (in shares) at Dec. 31, 2017	91,929,709