Note 12. Fair Value Measurement (Tables)

9 Months Ended

Sep. 30, 2011

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis, Valuation Techniques [Table Text Block]

Description	Balance at September 30, 2011		Balance at December 31, 2010		Input Hierarchy Level
Assets:
Cash and cash equivalents:
Money market funds and other bank deposits	$	413,743	$	283,606	Level 1
Available for sale securities:
Equity securities – mining industry		3,305		2,668	Level 1
Trade accounts receivable:
Receivables from provisional concentrate sales		24,466		36,295	Level 2
Restricted cash balances:
Certificates of deposit and other bank deposits		926		10,314	Level 1
Derivative contracts:
Base metal forward contracts		35,717		—	Level 2
Total assets	$	478,157	$	332,883
Liabilities:
Derivative contracts:
Base metal forward contracts	$	—	$	20,795	Level 2