Note 7 - Income and Mining Taxes - Reconciliation of Statutory Federal Income Tax Rate to Annual Tax Provision (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Computed “statutory” benefit (provision), Amount	$ (1,161)	$ 264	$ 23,778
Computed “statutory” benefit (provision), Percentage	21.00%	21.00%	21.00%
Percentage depletion, Amount	$ 8,076	$ 5,327	$ 3,030
Percentage depletion, Percentage	(146.00%)	423.00%	3.00%
Change in valuation allowance, Amount	$ 38,058	$ 786	$ 686
Change in valuation allowance, Percentage	(689.00%)	62.00%	0.00%
State taxes, net of federal tax benefit, Amount	$ (5,844)	$ (1,164)	$ 2,648
State taxes, net of federal tax benefit, Percentage	106.00%	(93.00%)	2.00%
Foreign currency remeasurement of monetary assets and liabilities, Amount	$ (3,625)	$ (4,824)	$ (8,629)
Foreign currency remeasurement of monetary assets and liabilities, Percentage	66.00%	(383.00%)	(8.00%)
Rate differential on foreign earnings, Amount	$ 2,445	$ 2,362	$ 3,999
Rate differential on foreign earnings, Percentage	(44.00%)	188.00%	4.00%
Compensation, Amount	$ 1,094	$ (458)	$ (1,056)
Compensation, Percentage	(20.00%)	(36.00%)	(1.00%)
Mining and other taxes, Amount	$ (6,990)	$ (9,245)	$ (4,887)
Mining and other taxes, percentage	126.00%	(735.00%)	(4.00%)
Other, Amount	$ (2,484)	$ (1,247)	$ (1,251)
Other, Percentage	45.00%	(99.00%)	(1.00%)
Total benefit (provision)	$ 29,569	$ (8,199)	$ 18,318
Total benefit (provision)	(535.00%)	(652.00%)	16.00%

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to mining and other taxes.

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The remeasurement of cash balances of assets and liabilities from foreign currencies to USD.

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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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Percentage of difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying domestic federal statutory income tax rate to pretax income (loss) from continuing operation, attributable to nondeductible expense for share-based payment arrangement.

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Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Amount of reported income tax expense (benefit) in excess of (less than) expected income tax expense (benefit) computed by applying domestic federal statutory income tax rate to pretax income (loss) from continuing operation, attributable to nondeductible expense for award under share-based payment arrangement. Includes, but is not limited to, expense determined to be nondeductible upon grant or after for award under share-based payment arrangement.

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