Note 7 - Income and Mining Taxes (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Deferred Tax Liabilities, Net, Total	$ 104,144	$ 153,179
Deferred Tax Assets, Valuation Allowance, Total	$ 39,152	77,210	$ 86,634	$ 94,981
Operating Loss Carryforwards Expiration Period (Year)	20 years
Unrecognized Tax Benefits, Ending Balance	$ 0	0
Nevada Operations [Member]
Deferred Tax Assets, Valuation Allowance, Total	19,400
Foreign Tax Authority [Member]
Tax Credit Carryforward, Valuation Allowance	8,900
Operating Loss Carryforwards, Total	69,700
Foreign Tax Authority [Member] | Mexican Tax Authority [Member]
Deferred Tax Assets, Valuation Allowance, Total	7,700
Foreign Tax Authority [Member] | Canada Revenue Agency [Member]
Deferred Tax Assets, Valuation Allowance, Total	3,200
Domestic Tax Authority [Member]
Operating Loss Carryforwards, Total	869,200
Operating Loss Carryforwards, Indefinite Carryforward Period	381,200
State and Local Jurisdiction [Member]
Operating Loss Carryforwards, Total	470,600
Decrease Related to Release of Valuation Allowance [Member]
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	$ (58,400)
Klondex Mines Ltd [Member]
Deferred Tax Liabilities, Net, Total		$ 55,200