Note 6 - Investments - Gross Realized Gains and Losses on Available-for-sale Investments, Limited Liability Investment (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020
Gross realized gains	$ 1,917	$ 806
Gross realized losses	(108)	(226)
Net realized gains	$ 1,809	$ 580

Amount of realized gain (loss) on investment.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04.3(a))
-URI http://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263

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