Note 13 - Commitments and Contingent Liabilities (Details Textual) $ in Thousands	Jun. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)
Number of Mines Sold	5
Guarantees, Maximum Exposure	$ 18,000	$ 20,000
Guarantees, Fair Value Disclosure	378	$ 482
Minimum [Member]
Servicing Liability, Estimated Annual Costs	10,000
Maximum [Member]
Servicing Liability, Estimated Annual Costs	$ 20,000

Fair value portion of guarantee, including, but not limited to, financial standby letter of credit, fair value guarantee, guarantee of collection of scheduled contractual cash flows from financial assets, and contracts that contingently require the guarantor to make payments or perform services.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121555522&loc=d3e12201-110248

Name:	us-gaap_GuaranteesFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant