OPERATING SEGMENT REPORTING (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Operating Segment Reporting
Revenues	$ 41,285	$ 14,833
Revision of estimates and accretion of reclamation obligations	(294)	(105)
Property holding costs	(1,411)	(1,188)
General and administrative expenses	(5,187)	(4,293)
Income (loss) on investment in Minera Santa Cruz S.A. (net of amortization)	(212)	190
Depreciation	2,327	327
Interest and other expense	(134)	(68)
Reclamation and Remediation	294		$ 635
Revision of estimates and accretion of reclamation obligations	(294)	(105)
Gain on sale of assets		11
Loss on sale of marketable securities	734
Unrealized (loss) gain on derivative instrument	(864)	1,791
(Gain) on disposal of fixed assets		11
Foreign currency gain	927	25
Net loss before income and mining taxes	(6,349)	(5,674)
Long-Lived Assets	508,522		505,265
Investment in MSC	145,001		150,064
Canada
Operating Segment Reporting
Property holding costs	(43)
General and administrative expenses	(88)
Segment income (loss)	(2,325)
Mexico
Operating Segment Reporting
Property holding costs	(1,149)	(982)
General and administrative expenses	(829)	(839)
Segment income (loss)	8,480	4,334
MSC
Operating Segment Reporting
Income (loss) on investment in Minera Santa Cruz S.A. (net of amortization)	(212)	190
Segment income (loss)	(212)	190
Los Azules
Operating Segment Reporting
Property holding costs	(40)	(1)
General and administrative expenses	(278)	(208)
Segment income (loss)	(3,525)	(6,510)
U.S.
Operating Segment Reporting
Property holding costs	(179)	(205)
General and administrative expenses	(863)	(426)
Segment income (loss)	(3,042)	(2,075)
Total Segment
Operating Segment Reporting
Property holding costs	(1,411)	(1,188)
General and administrative expenses	(2,058)	(1,473)
Income (loss) on investment in Minera Santa Cruz S.A. (net of amortization)	(212)	190
Segment income (loss)	(624)	(4,061)
Corporate & Other
Operating Segment Reporting
Revision of estimates and accretion of reclamation obligations	(294)	(105)
Other exploration costs		(120)
General and administrative expenses	(3,129)	(2,820)
Depreciation	(360)	(327)
Interest and other expense	134	(68)
Revision of estimates and accretion of reclamation obligations	(294)	(105)
Gain on sale of assets		11
Loss on sale of marketable securities	(734)
Unrealized fair value loss on marketable equity securities	1,137
Unrealized (loss) gain on derivative instrument	(864)	1,791
Foreign currency gain	927	25
Canada
Operating Segment Reporting
Revenues	15,868
Long-Lived Assets	86,187		85,179
Mexico
Operating Segment Reporting
Revenues	25,417	14,833
Long-Lived Assets	33,377		35,446
United States
Operating Segment Reporting
Long-Lived Assets	52,467		43,086
United States | Gold Bar Complex
Operating Segment Reporting
Construction-in-progress	8,800		14,800
Argentina
Operating Segment Reporting
Long-Lived Assets	336,491		$ 341,554
Gold and silver sales
Operating Segment Reporting
Revenues	41,041	14,833
Gold and silver sales | Canada
Operating Segment Reporting
Revenues	15,624
Gold and silver sales | Mexico
Operating Segment Reporting
Revenues	25,417	14,833
Gold and silver sales | Total Segment
Operating Segment Reporting
Revenues	41,041	14,833
Other revenue
Operating Segment Reporting
Revenues	244
Other revenue | Canada
Operating Segment Reporting
Revenues	244
Other revenue | Total Segment
Operating Segment Reporting
Revenues	244
Production costs applicable to sales
Operating Segment Reporting
Cost of goods and services sold	26,394	6,984
Production costs applicable to sales | Canada
Operating Segment Reporting
Cost of goods and services sold	12,786
Production costs applicable to sales | Mexico
Operating Segment Reporting
Cost of goods and services sold	13,608	6,984
Production costs applicable to sales | Total Segment
Operating Segment Reporting
Cost of goods and services sold	26,394	6,984
Mine development costs
Operating Segment Reporting
Cost of goods and services sold	380	1,115
Mine development costs | Mexico
Operating Segment Reporting
Cost of goods and services sold	380	155
Mine development costs | U.S.
Operating Segment Reporting
Cost of goods and services sold		960
Mine development costs | Total Segment
Operating Segment Reporting
Cost of goods and services sold	380	1,115
Exploration costs
Operating Segment Reporting
Cost of goods and services sold	11,454	8,444
Exploration costs | Canada
Operating Segment Reporting
Cost of goods and services sold	5,276
Exploration costs | Mexico
Operating Segment Reporting
Cost of goods and services sold	971	1,539
Exploration costs | Los Azules
Operating Segment Reporting
Cost of goods and services sold	3,207	6,301
Exploration costs | U.S.
Operating Segment Reporting
Cost of goods and services sold	2,000	484
Exploration costs | Total Segment
Operating Segment Reporting
Cost of goods and services sold	$ 11,454	$ 8,324