Note 12 - Fair Value Measurement (Tables)

6 Months Ended

Jun. 30, 2019

Notes Tables

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]

Description	Balance at June 30, 2019		Balance at December 31, 2018		Input Hierarchy Level
Assets:
Cash and cash equivalents:
Money market funds and other bank deposits	$	9,434	$	27,389	Level 1
Available for sale securities:
Equity securities – mining industry		5,815		6,583	Level 1
Trade accounts receivable:
Receivables from provisional concentrate sales		6,877		4,184	Level 2
Restricted cash balances:
Certificates of deposit and other deposits		1,025		1,025	Level 1
Derivative contracts:
Foreign exchange contracts		1,014		209	Level 2
Metal forward and put option contracts		5,936		23	Level 2
Total assets	$	30,101	$	39,413
Liabilities:
Derivative contracts:
Foreign exchange contracts	$	1,702	$	373	Level 2
Metal forward and put option contracts		—		8,595	Level 2
Total Liabilities	$	1,702	$	8,968