Note 15 - Acquisitions (Details Textual) CAD / shares in Units, $ / shares in Units, CAD in Millions				1 Months Ended	3 Months Ended	12 Months Ended
	Sep. 13, 2016 USD ($) $ / shares shares	Jun. 27, 2016 CAD CAD / shares shares	Jun. 15, 2015 USD ($) $ / shares shares	Sep. 30, 2016 USD ($) shares	Sep. 30, 2016 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Jun. 30, 2015 USD ($)
Business Combination, Acquisition Related Costs						$ 25,000	$ 2,695,000	$ 2,162,000
Proceeds from Insurance Settlement, Investing Activities						$ 7,745,000
Dolly Varden Historic Silver Property [Member] | Dolly Varden [Member]
Ownership Percentage		100.00%
Mines Management [Member]
Business Combination, Consideration Transferred	$ 52,134,000
Payments to Acquire Businesses, Gross	4,025,000
Business Combination, Consideration Transferred, Equity Interests Issued and Issuable	$ 48,109,000
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, Outstanding Options to Purchase Common Shares of Acquiree | shares	963,079
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares | shares	8,309,006
Business Acquisition, Share Price | $ / shares	$ 5.79
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment	$ 74,320,000
Business Combination, Acquisition Related Costs, Shares Issued | shares				181,048
Business Combination, Acquisition Related Costs							4,700,000
Business Combination, Pro Forma Information, Earnings or Loss of Acquiree since Acquisition Date, Actual							$ 32,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Reclamation Liability	1,124,000
Mines Management [Member] | Acquisition Costs [Member]
Business Combination, Acquisition Related Costs				$ 1,000,000
Mines Management [Member] | Plant and Equipment [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment	800,000
Mines Management [Member] | Land [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment	100,000
Mines Management [Member] | Mineral Interests [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment	$ 73.40
Mines Management [Member] | Montanore Project [Member]
Ownership Percentage				100.00%	100.00%
Dolly Varden [Member]
Business Combination, Consideration Transferred | CAD		CAD 13.6
Business Acquisition, Share Price | CAD / shares		CAD 0.69
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%
Revett Mining Company, Inc. [Member]
Business Combination, Consideration Transferred			$ 20,082,000
Ownership Percentage			100.00%
Payments to Acquire Businesses, Gross			$ 949,000
Business Combination, Consideration Transferred, Equity Interests Issued and Issuable			$ 19,133,000
Business Acquistion, Number of Common Stock Shares Exchanged for Each Share of Acquiree Common Stock | shares			0.1622
Business Acquisition, Common Shares Outstanding of Acquiree | shares			38,548,989
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares | shares			6,252,646
Business Acquisition, Share Price | $ / shares			$ 3.06
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment			$ 17,609,000
Business Combination, Acquisition Related Costs								2,400,000
Business Combination, Pro Forma Information, Earnings or Loss of Acquiree since Acquisition Date, Actual								$ 1,700,000
Number of Properties			2
Business Acquisition, Equity Interest Issued or Issuable, Value Assigned			$ 19,100,000
Business Acquisition, Shares Owned by Subsidary, Number of Shares Cancelled | shares			725,000
Business Acquisition Per Share Consideration | $ / shares			$ 3.06
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Reclamation Liability			$ 17,513,000						$ 17,500,000
Insurance Policy			16,800,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Reclamation Insurance Asset			16,800,000						$ 16,800,000
Proceeds from Insurance Settlement, Investing Activities					$ 16,000,000
Insured Event, Gain (Loss)					$ (700,000)
Revett Mining Company, Inc. [Member] | Plant and Equipment [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment			4,100,000
Revett Mining Company, Inc. [Member] | Land [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment			4,600,000
Revett Mining Company, Inc. [Member] | Mineral Interests [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment			$ 8,900,000