Note 9 - Fair Value Measurement (Tables)

6 Months Ended

Jun. 30, 2022

Notes Tables

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

	Three Months Ended June 30,						Six Months Ended June 30,
	2022			2021			2022			2021
(Loss) gain on derivative contracts	$	(689	)	$	(17,313	)	$	(893	)	$	(16,840	)
Unrealized gain (loss) on investments in equity securities		(15,739	)		(750	)		(9,639	)		(4,256	)
Gain on disposition or exchange of investments		—			—			69			1,158
Total fair value adjustments, net	$	(16,428	)	$	(18,063	)	$	(10,463	)	$	(19,938	)

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

Description	Balance at June 30, 2022		Balance at December 31, 2021		Input Hierarchy Level
Assets:
Cash and cash equivalents:
Money market funds and other bank deposits	$	198,193	$	210,010	Level 1
Current and non-current investments
Equity securities		23,931		14,470	Level 1
Trade accounts receivable:
Receivables from provisional concentrate sales		17,828		36,437	Level 2
Restricted cash balances:
Certificates of deposit and other deposits		1,041		1,053	Level 1
Derivative contracts - current and non-current derivatives assets:
Foreign exchange contracts		2,414		5,207	Level 2
Metal forward and put option contracts		20,406		—	Level 2
Total assets	$	263,813	$	267,177
Liabilities:
Derivative contracts - current derivatives liabilities and other non-current liabilities:
Foreign exchange contracts	$	529	$	8	Level 2
Metal forward and put option contracts		4,221		37,873	Level 2
Total liabilities	$	4,750	$	37,881