Fair Value Measurement (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net allowance for doubtful accounts	$ 1,400
Realized/unrealized derivative gain (loss), net	(100)	$ 200
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash bank deposits	13,328	11,076
Gold and silver rounds/bullion	4,717	4,265
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Receivables from provisional concentrate sales	3,363	8,362
Loans Payable	$ 1,226	$ 1,661