Fair Value Measurement (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net allowance for doubtful accounts	$ 1,400
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash bank deposits	18,366	$ 11,076
Gold and silver rounds/bullion	4,111	4,265
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Receivables from provisional concentrate sales	4,043	8,362
Loans Payable	$ 1,444	$ 1,661