Note 12. Fair Value Measurement (Tables)

3 Months Ended

Mar. 31, 2012

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

Description	Balance at  March 31, 2012		Balance at December 31, 2011		Input Hierarchy Level
Assets:
Cash and cash equivalents:
Money market funds and other bank deposits	$	278,504	$	266,463	Level 1
Available for sale securities:
Equity securities – mining industry		3,584		3,923	Level 1
Trade accounts receivable:
Receivables from provisional concentrate sales		5,849		10,996	Level 2
Restricted cash balances:
Certificates of deposit and other bank deposits		866		866	Level 1
Derivative contracts:
Base metal forward contracts		20,610		32,750	Level 2
Total assets	$	309,413	$	314,998