Note 16 - Acquisitions (Details Textual) $ / shares in Units, $ / shares in Units, $ in Thousands, $ in Millions					1 Months Ended		12 Months Ended			34 Months Ended
	Jul. 20, 2018 USD ($) $ / shares shares	Jul. 19, 2018 shares	Sep. 13, 2016 USD ($) $ / shares shares	Jun. 27, 2016 CAD ($) $ / shares shares	Sep. 30, 2016 USD ($) shares	Jun. 30, 2015 USD ($) $ / shares shares	Dec. 31, 2018 USD ($) shares	Dec. 31, 2017 USD ($) shares	Dec. 31, 2016 USD ($) shares	Dec. 31, 2018 USD ($) shares
Common Stock, Shares, Issued, Total | shares							482,603,937	399,176,425		482,603,937
Stock Issued During Period, Shares, New Issues | shares							2,564,767			7,173,614
Class of Warrant or Right, Outstanding | shares							0	0	0	0
Business Combination, Acquisition Related Costs							$ 10,045	$ 25	$ 2,695
Common Stock, Shares, Outstanding, Ending Balance | shares							482,603,937	399,176,425		482,603,937
Warrants in Connection with Klondex Mines Acquisition [Member]
Class of Warrant or Right, Issued During Period | shares	4,136,000
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right | shares	1
Warrants in Connection with Klondex Mines Acquisition Expiring April 2032 [Member]
Class of Warrant or Right, Outstanding | shares	2,068,000
Warrants in Connection with Klondex Mines Acquisition Expiring February 2029 [Member]
Class of Warrant or Right, Outstanding | shares	2,068,000
Class of Warrant or Right, Exercise Price of Warrants or Rights | $ / shares	$ 1.57
Klondex Mines Ltd [Member]
Common Stock, Shares, Issued, Total | shares	182,048,945	180,499,319
Stock Issued During Period, Shares, New Issues | shares		1,549,626
Common Stock, Shares, Outstanding, Ending Balance | shares	182,048,945	180,499,319
Klondex Mines Ltd [Member]
Business Acquisition, Share Price | $ / shares	$ 2.24
Business Acquisition, Percentage of Voting Interests Acquired	100.00%
Business Combination, Consideration, Cash Alternative, Price Per Share | $ / shares	$ 2.47
Business Combination, Consideration, Share Alternative, Share Exchange Rate	0.6272
Business Combination Consideration, Combined Alternative, Price Per Share | $ / shares	$ 0.8411
Business Combination Consideration, Combined Alternative, Share Exchange Rate	0.4136
Payments to Acquire Businesses, Gross	$ 161,704
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares | shares	75,276,176
Stock Issued During Period, Shares, New Issues | shares	75,276,176
Class of Warrant or Right, Exercise Price of Warrants or Rights | $ / shares	$ 8.02
Employee Service Share-based Compensation, Cash Flow Effect, Cash Used to Settle Awards	$ 2,000
Business Combination, Consideration Transferred, Equity Interests Issued and Issuable	242,389
Business Combination, Consideration Transferred, Total	414,248
Business Combination, Subscrition of New Formed Company, Value	7,000
Business Combination, Settlement of Certain Equity Compensation Value	1,500
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment, Total	521,495						$ 19,200			$ 19,200
Business Combination, Pro Forma Information, Revenue of Acquiree since Acquisition Date, Actual							31,200
Business Combination, Pro Forma Information, Earnings or Loss of Acquiree since Acquisition Date, Actual							$ 26,700
Klondex Mines Ltd [Member] | Hecla Warrants [Member]
Class of Warrant or Right, Issued During Period, Value	10,200
Klondex Mines Ltd [Member] | Maximum [Member]
Payments to Acquire Businesses, Gross	$ 153,200
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares | shares	75,276,176
Revett Mining Company, Inc. [Member]
Business Acquisition, Share Price | $ / shares			$ 5.79
Payments to Acquire Businesses, Gross			$ 4,025			$ 4,000
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares | shares			8,309,006			8,309,006
Business Combination, Consideration Transferred, Equity Interests Issued and Issuable			$ 48,109			$ 48,100
Business Combination, Consideration Transferred, Total			52,134
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment, Total			$ 74,320			$ 74,300
Ownership Percentage			100.00%
Business Acquistion, Number of Common Stock Shares Exchanged for Each Share of Acquiree Common Stock | shares						0.2218
Business Acquisition, Common Shares Outstanding of Acquiree | shares						36,498,625
Business Acquisition, Shares Owned by Subsidary, Number of Shares Cancelled | shares						963,079
Business Acquisition Per Share Consideration | $ / shares						$ 5.79
Revett Mining Company, Inc. [Member] | Plant and Equipment [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment, Total						$ 800
Revett Mining Company, Inc. [Member] | Land [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment, Total						100
Revett Mining Company, Inc. [Member] | Mineral Interests [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment, Total						$ 73,400
Mines Management [Member]
Business Combination, Pro Forma Information, Earnings or Loss of Acquiree since Acquisition Date, Actual									32
Business Combination, Acquisition Related Costs, Shares Issued | shares					181,048
Business Combination, Acquisition Related Costs									$ 4,700
Mines Management [Member] | Acquisition Costs [Member]
Business Combination, Acquisition Related Costs					$ 1,000
Dolly Varden [Member]
Business Acquisition, Share Price | $ / shares				$ 0.69
Business Combination, Consideration Transferred, Total				$ 13.6
Ownership Percentage				100.00%
Business Combination, Step Acquisition, Equity Interest in Acquiree, Shares | shares				4,478,087
Business Combination, Step Acquisition, Equity Interest in Acquiree, Warrants | shares				1,351,762
Business Combination, Step Acquisition, Equity Interest in Acquiree, Percentage				18.50%