Note 15 - Acquisitions - Preliminary Purchase Price Allocation (Details) - USD ($) $ in Thousands	Jul. 20, 2018	Dec. 31, 2019	Dec. 31, 2018
Properties, plants, equipment and mineral interests		$ 2,423,698	$ 2,520,004
Klondex Mines Ltd [Member]
Payments to Acquire Businesses, Gross	$ 161,704
Business Combination, Consideration Transferred, Equity Interests Issued and Issuable	242,389
Hecla warrants issued	9,830
Total consideration	413,923
Cash	12,874
Accounts receivable	3,453
Inventory - supplies	6,565
Inventory - finished goods, in-process material and stockpiled ore	10,075
Other current assets	2,583
Properties, plants, equipment and mineral interests	510,015	511,400
Non-current investments	1,596
Non-current restricted cash and investments	9,504
Total assets	556,665
Accounts payable and accrued liabilities	17,799
Accrued payroll and related benefits	8,245
Accrued taxes	421
Lease liability	2,080
Debt	35,086
Asset retirement obligation	19,571
Deferred tax liability	59,540
Total liabilities	142,742
Net assets	$ 413,923
Nevada Operations [Member]
Properties, plants, equipment and mineral interests		511,400
Beyond Proven and Probable Reserves [Member] | Nevada Operations [Member]
Properties, plants, equipment and mineral interests		382,200
Mills and Tailings Facilities [Member] | Nevada Operations [Member]
Properties, plants, equipment and mineral interests		43,800
Development [Member] | Nevada Operations [Member]
Properties, plants, equipment and mineral interests		32,100
Buildings and Equipment [Member] | Nevada Operations [Member]
Properties, plants, equipment and mineral interests		28,500
Mining Properties and Mineral Rights [Member] | Nevada Operations [Member]
Properties, plants, equipment and mineral interests		18,800
Asset Retirement Obligation [Member] | Nevada Operations [Member]
Properties, plants, equipment and mineral interests		3,100
Land [Member] | Nevada Operations [Member]
Properties, plants, equipment and mineral interests		$ 2,900