Note 9 - Fair Value Measurement (Tables)

3 Months Ended

Mar. 31, 2022

Notes Tables

Fair Value, Measured on Recurring Basis, Gain (Loss) Included in Earnings [Table Text Block]

	Three Months Ended March 31,
	2022			2021
(Loss) gain on derivative contracts	$	(201	)	$	473
Unrealized gain (loss) on investments in equity securities		6,100			(3,506	)
Gain on disposition or exchange of investments		66			1,158
Total fair value adjustments, net	$	5,965		$	(1,875	)

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

Description	Balance at March 31, 2022		Balance at December 31, 2021		Input Hierarchy Level
Assets:
Cash and cash equivalents:
Money market funds and other bank deposits	$	212,029	$	210,010	Level 1
Current and non-current investments:
Equity securities – mining industry		29,204		14,470	Level 1
Trade accounts receivable:
Receivables from provisional concentrate sales		33,324		36,437	Level 2
Restricted cash balances:
Certificates of deposit and other bank deposits		1,041		1,053	Level 1
Derivative contracts - other current assets and other non-current assets:
Metal forward contracts		74		—	Level 2
Foreign exchange contracts		7,829		5,207	Level 2
Total assets	$	283,501	$	267,177
Liabilities:
Derivative contracts - current and non-current derivatives liabilities:
Metal forward contracts	$	82,394	$	37,873	Level 2
Foreign exchange contracts		—		8	Level 2
Total Liabilities	$	82,394	$	37,881