Note 8 - Stockholders' Equity (Details Textual) $ / shares in Units, $ in Thousands			3 Months Ended		37 Months Ended
	May 07, 2019 USD ($) $ / shares	Jul. 20, 2018 $ / shares shares	Mar. 31, 2019 USD ($) $ / shares $ / oz shares	Mar. 31, 2018 USD ($) $ / shares shares	Mar. 31, 2019 USD ($) $ / oz shares	Feb. 23, 2016 USD ($)	May 08, 2012 shares
Share-based Payment Arrangement, Shares Withheld for Tax Withholding Obligation			0	335,349
Payment, Tax Withholding, Share-based Payment Arrangement | $				$ 1,200
Treasury Stock Acquired, Average Cost Per Share | $ / shares				$ 3.65
Dividends, Common Stock, Total | $			$ 1,209	$ 998
Average Realized Silver Price | $ / oz			15.7
Average Realized Silver Price, Minimum Dividend, Threshold | $ / oz			30		30
Stock Issued During Period, Shares, New Issues			0		7,173,614
Stock Issued During Period, Value, New Issues | $					$ 24,500
Payments for Brokerage Fees | $					$ 600
Klondex Mines Ltd [Member]
Stock Issued During Period, Shares, New Issues		75,276,176
Class of Warrant or Right, Exercise Price of Warrants or Rights | $ / shares		$ 8.02
Warrants in Connection with Klondex Mines Acquisition [Member]
Class of Warrant or Right, Issued During Period		4,136,000
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right		1
Warrants in Connection with Klondex Mines Acquisition Expiring April 2032 [Member]
Class of Warrant or Right, Outstanding		2,068,000
Warrants in Connection with Klondex Mines Acquisition Expiring February 2029 [Member]
Class of Warrant or Right, Outstanding		2,068,000
Class of Warrant or Right, Exercise Price of Warrants or Rights | $ / shares		$ 1.57
Common Stock Repurchase Program [Member]
Treasury Stock Acquired, Average Cost Per Share | $ / shares			$ 3.99
Stock Repurchase Program, Number of Shares Authorized to be Repurchased							20,000,000
Cumulative Stock Repurchased			934,100		934,100
Stock Repurchase Program, Remaining Number of Shares Authorized to be Repurchased			19,100,000		19,100,000
Stock Repurchased During Period, Shares			0
Subsequent Event [Member]
Common Stock, Dividends, Per Share, Declared | $ / shares	$ 0.0025
Dividends, Common Stock, Total | $	$ 1,200
Subsequent Event [Member] | Common Stock Repurchase Program [Member]
Share Price | $ / shares	$ 2.10
Minimum [Member]
Common Stock, Dividends, Per Share, Declared | $ / shares			$ 0.01
Maximum [Member]
Common Stock, Aggregate Offering Price | $						$ 75,000
Restricted Stock Units and Performance Shares [Member]
Share-based Payment Arrangement, Expense | $			$ 1,600	$ 1,100