Note 1 - Basis of Preparation of Financial Statements (Details Textual) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2021 USD ($)	Dec. 31, 2020 USD ($) oz	Jan. 01, 2021 USD ($)
Retained Earnings (Accumulated Deficit), Ending Balance	$ (377,229)	$ (391,374)	$ 365,200
Recognition of Previously Omitted Deferred Income Taxes on Certain State Mining Income Taxes [Member]
Retained Earnings (Accumulated Deficit), Ending Balance			$ (11,900)
Casa Berardi [Member]
Decrease in Expected Gold Production Due to Suspension (Ounce) | oz		11,700
Suspension Costs		$ 1,600
San Sebastian [Member]
Suspension Costs		1,800
Greens Creek [Member]
Suspension Costs from Quarantining Employee Per Week	$ 600	$ 2,300