Note 13 - Acquisition of Klondex (Details Textual)			3 Months Ended	6 Months Ended	40 Months Ended
	Jul. 20, 2018 USD ($) $ / shares shares	Jul. 19, 2018 shares	Jun. 30, 2019 USD ($) shares	Jun. 30, 2019 USD ($) shares	Jun. 30, 2019 USD ($) shares	Dec. 31, 2018 shares	Jul. 24, 2018 USD ($)	Jun. 30, 2018 shares
Common Stock, Shares, Issued, Total | shares			488,870,345	488,870,345	488,870,345	482,603,937
Stock Issued During Period, Shares, New Issues | shares				0	7,173,614
Class of Warrant or Right, Outstanding | shares								0
Common Stock, Shares, Outstanding, Ending Balance | shares			488,870,345	488,870,345	488,870,345	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
Klondex Mines Ltd [Member]
Business Acquisition, Share Price | $ / shares	$ 2.27
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	$ 161,704,000
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
Share-based Payment Arrangement, Cash Used to Settle Award	$ 2,000,000.0
Business Combination, Consideration Transferred, Equity Interests Issued and Issuable	242,389,000
Business Combination, Consideration Transferred, Total	413,923,000
Business Combination, Subscrition of New Formed Company, Value	7,000,000.0
Business Combination, Settlement of Certain Equity Compensation Value	1,500,000
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Property, Plant, and Equipment			$ 2,800,000
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Accounts Payable and Accrued Liabilities			2,100,000
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Noncurrent Deferred Tax Liability			700,000
Weighted Average Gold Price Per Ounce			1,280	$ 1,280	$ 1,280		$ 1,345
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment, Total	510,015,000		545,400,000	545,400,000	545,400,000
Klondex Mines Ltd [Member] | Beyond Proven and Probable Reserves [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment, Total			$ 382,200,000	$ 382,200,000	$ 382,200,000
Klondex Mines Ltd [Member] | Hecla Warrants [Member]
Class of Warrant or Right, Issued During Period, Value	9,800,000
Klondex Mines Ltd [Member] | Maximum [Member]
Payments to Acquire Businesses, Gross	$ 153,200,000
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares | shares	75,276,176