Note 12 - Fair Value Measurement (Tables)

3 Months Ended

Mar. 31, 2017

Notes Tables

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

Description	Balance at March 31, 2017		Balance at December 31, 2016		Input Hierarchy Level
Assets:
Cash and cash equivalents:
Money market funds and other bank deposits	$	176,786	$	169,777	Level 1
Available for sale securities:
Debt securities – municipal and corporate bonds		36,505		29,117	Level 2
Equity securities – mining industry		5,104		5,002	Level 1
Trade accounts receivable:
Receivables from provisional concentrate sales		17,210		20,082	Level 2
Restricted cash balances:
Certificates of deposit and other bank deposits		2,200		2,200	Level 1
Derivative contracts:
Metal forward contracts		254		5,403	Level 2
Foreign exchange contracts		364		27	Level 2
Total assets	$	238,423	$	231,608
Liabilities:
Derivative contracts:
Metal forward contracts	$	2,386	$	192	Level 2
Foreign exchange contracts		2,723		5,288	Level 2
Total Liabilities	$	5,109	$	5,480