Note 15 - Acquisitions - Preliminary Purchase Price Allocation (Details) (Parentheticals) - $ / shares	Sep. 13, 2016	Jun. 15, 2015
Mines Management [Member]
Stock Issued, shares (in shares)	8,309,006
Stock Issued, per share (in dollars per share)	$ 5.79
Revett Mining Company, Inc. [Member]
Stock Issued, shares (in shares)		6,252,646
Stock Issued, per share (in dollars per share)		$ 3.06

Number of shares of equity interests issued or issuable to acquire entity.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (b)(4)
-URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479

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