Note 7 - Income and Mining Taxes - Components of the Net Deferred Tax Asset (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accrued reclamation costs	$ 31,558	$ 32,938
Deferred exploration	17,959	11,623
Foreign net operating losses	18,152	13,303
Domestic net operating losses	213,637	198,438
Pension and benefit obligation	1,824	12,341
Foreign exchange loss	19,542	19,808
Foreign tax credit carryforward	2,493	3,358
Miscellaneous	29,505	18,385
Total deferred tax assets	334,670	310,194
Valuation allowance	(39,152)	(77,210)	$ (86,634)	$ (94,981)
Total deferred tax assets	295,518	232,984
Miscellaneous	(2,751)	(2,551)
Properties, plants and equipment	(396,911)	(383,612)
Total deferred tax liabilities	(399,662)	(386,163)
Net deferred tax liability	$ (104,144)	$ (153,179)