Note 12 - Fair Value Measurement (Tables)

6 Months Ended

Jun. 30, 2014

Fair Value Disclosures [Abstract]

Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Table Text Block]

Description	Balance at June 30, 2014		Balance at December 31, 2013		Input Hierarchy Level
Assets:
Cash and cash equivalents:
Money market funds and other bank deposits	$	222,083	$	212,175	Level 1
Available for sale securities:
Equity securities – mining industry		7,466		7,019	Level 1
Trade accounts receivable:
Receivables from provisional concentrate sales		21,033		17,672	Level 2
Restricted cash balances:
Certificates of deposit and other bank deposits		883		5,217	Level 1
Derivative contracts:
Metal forward contracts		995		4,461	Level 2
Total assets	$	252,460	$	246,544
Liabilities:
Derivative contracts:
Metal forward contracts		2,764		—	Level 2