Note 6 - Business Segments (Details Textual) $ in Thousands	3 Months Ended
Mar. 31, 2017 USD ($)	Mar. 31, 2016 USD ($)
Number of Reportable Segments	4
Employee Labor Strike Related Costs	$ 1,581
Lucky Friday [Member]
Employee Labor Strike Related Costs	$ 1,600

Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

No definition available.

Name:	us-gaap_NumberOfReportableSegments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration