Note 12 - Fair Value Measurement (Tables)

9 Months Ended

Sep. 30, 2014

Fair Value Disclosures [Abstract]

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

Description	Balance at September 30, 2014		Balance at December 31, 2013		Input Hierarchy Level
Assets:
Cash and cash equivalents:
Money market funds and other bank deposits	$	222,360	$	212,175		Level 1
Available for sale securities:
Equity securities – mining industry		7,022		7,019		Level 1
Trade accounts receivable:
Receivables from provisional concentrate sales		17,433		17,672		Level 2
Restricted cash balances:
Certificates of deposit and other bank deposits		883		5,217		Level 1
Derivative contracts:
Metal forward contracts		163		4,461		Level 2
Total assets	$	247,861	$	246,544
Liabilities:
Derivative contracts:
Metal forward contracts	$	2,160	$	—		Level 2