Note 14 - Acquisition of Klondex Mines Ltd. - Preliminary Purchase Price Allocation (Details) - Klondex Mines Ltd [Member] $ in Thousands	Jul. 20, 2018 USD ($)
Payments to Acquire Businesses, Gross	$ 161,704
Business Combination, Consideration Transferred, Equity Interests Issued and Issuable	242,389
Hecla warrants issued	10,155
Total consideration	414,248
Cash	12,874
Accounts receivable	3,453
Inventory - supplies	6,564
Inventory - finished goods, in-process material and stockpiled ore	10,302
Other current assets	2,583
Properties, plants, equipment and mineral interests	502,285
Non-current investments	1,596
Non-current restricted cash and investments	9,504
Total assets	549,161
Accounts payable and accrued liabilities	17,270
Accrued payroll and related benefits	10,352
Accrued taxes	421
Lease liability	2,080
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Long-term Debt	35,086
Asset retirement obligation	19,571
Deferred tax liability	50,133
Total liabilities	134,913
Net assets	$ 414,248