Note 2 - Summary of Significant Accounting Policies (Details Textual) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($) oz	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Jan. 01, 2019 USD ($)
Restricted Cash and Cash Equivalents, Noncurrent, Total	$ 1,053	$ 1,025
Capitalized Drilling Costs	4,400	14,400	$ 11,600
Operating Lease, Liability, Total	10,642
Foreign Currency Transaction Gain (Loss), Realized	(4,605)	(8,236)	$ 10,310
Operating Lease, Right-of-Use Asset	$ 10,628	$ 16,381
Accounting Standards Update 2016-02 [Member]
Operating Lease, Liability, Total				$ 22,400
Minimum [Member]
Property, Plant and Equipment, Useful Life (Year)	3 years
Maximum [Member]
Property, Plant and Equipment, Useful Life (Year)	17 years
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	$ 2,300