Note 11 - Marketable Securities - Marketable Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Estimated Fair Value - Equity securities	$ 9,045	$ 11,936
Estimated Fair Value - Debt securities	1,257	1,329
Estimated Fair Value - Total marketable securities	$ 10,302	$ 13,265

Fair value of investment in debt security measured at amortized cost (held-to-maturity).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (aa)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27232-111563

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant