Note 12 - Fair Value Measurement (Tables)

3 Months Ended

Mar. 31, 2016

Notes Tables

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

Description	Balance at March 31, 2016		Balance at December 31, 2015		Input Hierarchy Level
Assets:
Cash and cash equivalents:
Money market funds and other bank deposits	$	134,018	$	155,209	Level 1
Available for sale securities:
Equity securities – mining industry		2,086		1,515	Level 1
Trade accounts receivable:
Receivables from provisional concentrate sales		30,127		13,490	Level 2
Restricted cash balances:
Certificates of deposit and other bank deposits		4,899		999	Level 1
Total assets	$	171,130	$	171,213
Liabilities:
Derivative contracts:
Metal forward contracts	$	453	$	283	Level 2
Total Liabilities	$	453	$	283