Note 1 - Organization and Summary of Significant Accounting Policies (Details Textual) - USD ($)	12 Months Ended	216 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2020
Cost Method Investments	$ 1,921,000	$ 3,081,000	$ 1,921,000
Share-based Payment Arrangement, Expense	$ 386,000	$ 191,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross (in shares)		42,000	1,356,500
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share)		$ 16.15
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total	$ 235,000		$ 235,000
The 2020 Non-employee Director Stock Option Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period (in shares)	4,380
The 2011 Non-employee Director Stock Option Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross (in shares)	0	12,000
General and Administrative Expense [Member]
Depreciation, Total	$ 2,138,000	$ 1,012,000

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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