Note 12 - Fair Value Measurement (Tables)

9 Months Ended

Sep. 30, 2017

Notes Tables

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

Description	Balance at September 30, 2017		Balance at December 31, 2016		Input Hierarchy Level
Assets:
Cash and cash equivalents:
Money market funds and other bank deposits	$	172,923	$	169,777	Level 1
Available for sale securities:
Debt securities - municipal and corporate bonds		32,973		29,117	Level 2
Equity securities – mining industry		7,098		5,002	Level 1
Trade accounts receivable:
Receivables from provisional concentrate sales		6,982		20,082	Level 2
Restricted cash balances:
Certificates of deposit and other bank deposits		1,076		2,200	Level 1
Derivative contracts:
Foreign exchange contracts		6,533		27	Level 2
Metal forward contracts		394		5,403	Level 2
Total assets	$	227,979	$	231,608
Liabilities:
Derivative contracts:
Foreign exchange contracts	$	—	$	5,288	Level 2
Metal forward contracts		11,902		192	Level 2
Total liabilities	$	11,902	$	5,480