Note 12 - Fair Value Measurement (Tables)

6 Months Ended

Jun. 30, 2016

Notes Tables

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

Description	Balance at June 30, 2016		Balance at December 31, 2015		Input Hierarchy Level
Assets:
Cash and cash equivalents:
Money market funds and other bank deposits	$	143,613	$	155,209	Level 1
Available for sale securities:
Debt securities - municipal and corporate bonds		15,070		—	Level 2
Equity securities – mining industry		4,453		1,515	Level 1
Trade accounts receivable:
Receivables from provisional concentrate sales		25,667		13,490	Level 2
Restricted cash balances:
Certificates of deposit and other deposits		4,899		999	Level 1
Derivative contracts:
Foreign exchange contracts		537		—	Level 2
Total assets	$	194,239	$	171,213
Liabilities:
Derivative contracts:
Foreign exchange contracts	$	497	$	—	Level 2
Metal forward contracts		3,401		283	Level 2
Total Liabilities	$	3,898	$	283