Note 2 - Fair Value Measurements - Investments Measured at Fair Value Using Significant Unobservable Inputs (Details) - USD ($)	Sep. 30, 2021	Dec. 31, 2020
Private Company Common Stock [Member] \| Valuation, Cost Approach [Member] \| Purchase Price [Member]
Investments, fair value	$ 178,824
Private Company Preferred Stock [Member] \| Valuation, Market Approach [Member] \| Measurement Input, Quoted Price [Member]
Investments, fair value	$ 4,781,521	$ 2,574,665

Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123874694&loc=d3e19207-110258

Name:	us-gaap_InvestmentsFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant