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Note 1 - Summary of Significant Accounting Policies (Details Textual) $ / shares in Units, $ in Thousands		12 Months Ended		48 Months Ended
	Mar. 06, 2019 $ / shares shares	Dec. 31, 2020 USD ($) a	Dec. 31, 2019 USD ($)	Mar. 09, 2014
Asset Impairment Charges, Total		$ 196	$ 3,643
Impairment of Deferred Development Costs		$ 0	$ 0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period (in shares) \| shares	25,000
Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price (in dollars per share) \| $ / shares	$ 5.20
Vested Annually [Member] \| Share-based Payment Arrangement, Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage				20.00%
Minimum [Member]
Property, Plant and Equipment, Useful Life (Year)		3 years
Maximum [Member]
Property, Plant and Equipment, Useful Life (Year)		40 years
HAWAII
Area of Land (Acre) \| a		23,000