INVESTMENT IN MINERA SANTA CRUZ S.A. ("MSC") - SAN JOSE MINE - Summary of Operating Results from MSC (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
INVESTMENT IN MINERA SANTA CRUZ S.A. ("MSC") - SAN JOSE MINE
Revenue from gold and silver sales	$ 31,400	$ 15,583
Production costs applicable to sales	(28,387)	(11,148)
Depreciation and depletion	(6,698)	(3,006)
Gross Profit	(3,685)	1,429
Net income (loss) before tax	(100,285)	(10,018)
Net loss	(99,191)	(10,136)
Income and mining tax recovery (note 19)	(1,094)	118
(Loss) from investment in MSC, net of amortization	$ (2,676)	(2,310)
Subsidiary (as a percent)	100.00%
Ownership interest (as a percent)	49.00%
MSC
INVESTMENT IN MINERA SANTA CRUZ S.A. ("MSC") - SAN JOSE MINE
Revenue from gold and silver sales	$ 37,390	47,885
Production costs applicable to sales	(28,316)	(29,533)
Depreciation and depletion	(7,327)	(15,380)
Gross Profit	1,747	2,972
Exploration	(2,866)	(3,338)
Other expenses	(2,217)	(1,617)
Net income (loss) before tax	(3,336)	(1,983)
Current and deferred tax expense	49	(789)
Net loss	(3,287)	(2,772)
Net income (loss)	(1,611)	(1,358)	$ (2,097)
Amortization of fair value increments	(1,385)	(1,913)	(9,448)
Income and mining tax recovery (note 19)	320	961	$ 2,791
(Loss) from investment in MSC, net of amortization	$ (2,676)	$ (2,310)
Ownership interest (as a percent)	49.00%