Note 12 - Fair Value Measurement - Assets and Liabilities Accounted for at Fair Value (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Other, net	$ 6,642	$ 6,421
Fair Value, Recurring [Member]
Other, net	28,464	11,952
Certificates of deposit and other deposits	1,053	1,025
Total assets	146,557	82,820
Total liabilities	14,391	7,214
Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member]
Money market funds and other bank deposits	98,669	62,452
Equity securities – mining industry	17,362	6,207
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Recurring [Member]
Foreign exchange contracts	1,009	1,184
Metal forward and put option contracts	0	0
Foreign exchange contracts	4,130	1,437
Metal forward and put option contracts	$ 10,261	$ 5,777

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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Amount of equity securities categorized neither as held-to-maturity nor as trading.

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Amount of deposits in accounts that offer many of the same services as checking accounts although transactions may be somewhat more limited, share some of the characteristics of a money market fund and are insured by the Federal government, also known as money market accounts.

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Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

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Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

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Fair value portion of asset contracts related to the exchange of different currencies, including, but not limited to, foreign currency options, forward contracts, and swaps.

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Fair value portion of liability contracts related to the exchange of different currencies, including, but not limited to, foreign currency options, forward (delivery or nondelivery) contracts, and swaps entered into.

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Fair value of financial and nonfinancial obligations.

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Amount due from parties in nontrade transactions, classified as other.

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