Note 6 - Income Taxes (Details Textual) - USD ($) $ in Thousands	11 Months Ended	12 Months Ended
	Dec. 13, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Deferred Tax Liabilities, Net, Total		$ 171,550	$ 122,843
Liability Related to Withholding Taxes on Foreign Earnings Repatriated			300
Foreign Earnings Repatriated				$ 0
Income Tax Expense (Benefit), Total		(6,701)	20,963	28,090
Net Income (Loss) Attributable to Parent, Total		(26,563)	(28,520)	61,569
Deferred Tax Assets, Valuation Allowance, Total		$ 94,981	78,684	$ 99,602	$ 115,806
Operating Loss Carryforwards Expiration Period		20 years
Deferred Tax Assets, Net Operating Loss		$ 5,000
Unrecognized Tax Benefits, Ending Balance		0
Income Tax Expense (Benefit), Continuing Operations, Adjustment of Deferred Tax (Asset) Liability			30,000
Domestic Tax Authority [Member]
Deferred Tax Assets, Valuation Allowance, Total		92,000
Operating Loss Carryforwards, Total		605,900
Foreign Tax Authority [Member]
Operating Loss Carryforwards, Total		50,000
Foreign Tax Authority [Member] | Hecla Canada Limited [Member] | Canada Revenue Agency [Member]
Deferred Tax Assets, Valuation Allowance, Total		1,300
Foreign Tax Authority [Member] | Minera Hecla S.A. [Member] | Mexican Tax Authority [Member]
Deferred Tax Assets, Valuation Allowance, Total		1,700
Foreign Tax Authority [Member] | Hecla Quebec. Inc [Member] | Canada Revenue Agency [Member]
Deferred Tax Assets, Valuation Allowance, Total		0
State and Local Jurisdiction [Member]
Operating Loss Carryforwards, Total		383,300
Klondex Mines Ltd [Member]
Deferred Tax Liabilities, Net, Total		69,400
Income Tax Expense (Benefit), Total	$ 6,300
Net Income (Loss) Attributable to Parent, Total		$ (30,000)
Reclassification From Current Deferred Tax Assets to Non-Current Deferred Tax Assets [Member] | As of December 31, 2016 [Member]
Prior Period Reclassification Adjustment			12,300
Reclassification From Current Deferred Tax Liabilities to Non-Current Deferred Tax Liabilities [Member] | As of December 31, 2016 [Member]
Prior Period Reclassification Adjustment			$ 1,300