Note 12 - Fair Value Measurement (Tables)

6 Months Ended

Jun. 30, 2020

Notes Tables

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

Description	Balance at June 30, 2020		Balance at December 31, 2019		Input Hierarchy Level
Assets:
Cash and cash equivalents:
Money market funds and other bank deposits	$	75,923	$	62,452	Level 1
Available for sale securities:
Equity securities – mining industry		12,162		6,207	Level 1
Trade accounts receivable:
Receivables from provisional concentrate sales		26,003		11,952	Level 2
Restricted cash balances:
Certificates of deposit and other deposits		1,053		1,025	Level 1
Derivative contracts:
Foreign exchange contracts		295		1,184	Level 2
Metal forward and put option contracts		221		—	Level 2
Total assets	$	115,657	$	82,820
Liabilities:
Derivative contracts:
Foreign exchange contracts	$	9,174	$	1,437	Level 2
Metal forward and put option contracts		9,887		5,777	Level 2
Total Liabilities	$	19,061	$	7,214