Note 4 - Properties, Plants, Equipment and Mineral Interests, and Lease Commitments (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Payments to Acquire Property, Plant, and Equipment, Total	$ 91,016	$ 121,421	$ 136,933
Suspension Related Costs	13,500
Assets on Care and Maintenance, Depreciation Expense	5,600
Costs for Mining Material	7,700
Costs Related to Mining Non-refractory Ore	11,500
Property, Plant and Equipment, Net, Ending Balance	2,345,219	2,423,698
Capital Leased Assets, Gross, Total	74,000	64,900
Capital Leases, Lessee Balance Sheet, Assets by Major Class, Accumulated Depreciation	51,700	$ 44,300
Mineral Interests [Member] | NEVADA
Property, Plant and Equipment, Net, Ending Balance	474,300
Lucky Friday [Member]
Payments to Acquire Property, Plant, and Equipment, Total	25,700
Greens Creek [Member]
Payments to Acquire Property, Plant, and Equipment, Total	19,700
Mining Assets, Value Beyond Proven and Probable Reserves (VBPP)	132,600
Casa Berardi [Member]
Payments to Acquire Property, Plant, and Equipment, Total	40,900
Mining Assets, Value Beyond Proven and Probable Reserves (VBPP)	321,100
San Sebastian [Member]
Payments to Acquire Property, Plant, and Equipment, Total	500
Nevada Operations [Member]
Payments to Acquire Property, Plant, and Equipment, Total	4,000
Mining Assets, Value Beyond Proven and Probable Reserves (VBPP)	$ 382,200