Cash Flow Information (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Cash flows from operating activities:
Net loss		$ (3,892)	$ (10,659)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization		952	1,548
Accretion of asset retirement obligation		196	193
Write off of loss contingency, net			(212)
Asset write off			24
Gain on reduction of asset retirement obligation		(56)
Gain on sale of assets		(608)	(1,791)
Amortization of deferred loan costs			57
Warrant liability fair market adjustment	$ (400)		1,688
Derivative liability fair market adjustment			778
Accretion of loan discount			372
Loss on debt extinguishment			1,653
Stock compensation		296	593
Changes in operating assets and liabilities:
Decrease in trade accounts receivable		683	166
Increase in prepaid expenses and other assets		(142)	(152)
Decrease in inventories		3	85
(Increase) decrease in value added tax recoverable, net		(149)	346
Increase in accrued interest payable net of amounts capitalized			85
Increase (decrease) in deferred revenue		892	(500)
Decrease in reclamation liability		(8)	(11)
Increase (decrease) in accounts payable and accrued liabilities		226	(450)
Decrease in deferred leasehold payments		(23)	(18)
Net cash used in operating activities		$ (1,630)	$ (6,205)