Note 16 - Acquisitions - Preliminary Purchase Price Allocation (Details) - USD ($) $ in Thousands			1 Months Ended
	Jul. 20, 2018	Sep. 13, 2016	Jun. 30, 2015	Dec. 31, 2018
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	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	521,495			$ 19,200
Non-current investments	1,596
Non-current restricted cash and investments	9,504
Total assets	568,371
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	69,343
Total liabilities	154,123
Net assets	414,248
Hecla stock issued (8,309,006 shares at $5.79 per share)	242,389
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment, Total	$ 521,495			$ 19,200
Revett Mining Company, Inc. [Member]
Payments to Acquire Businesses, Gross		$ 4,025	$ 4,000
Business Combination, Consideration Transferred, Equity Interests Issued and Issuable		48,109	48,100
Total consideration		52,134
Cash		94
Properties, plants, equipment and mineral interests		74,320	74,300
Total assets		75,928
Accounts payable and accrued liabilities		2,357
Total liabilities		23,794
Net assets		52,134
Hecla stock issued (8,309,006 shares at $5.79 per share)		48,109	48,100
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment, Total		74,320	$ 74,300
Restricted cash		1,185
Other assets		329
Deferred tax liability		20,313
Non-current reclamation liability		$ 1,124