Note 2 - Summary of Significant Accounting Policies - Fair Value of Financial Assets (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Assets:
Investment	$ 335,000	$ 258,000	[1]
Marketable Securities [Member]
Assets:
Investment	335,000	258,000
Marketable Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Assets:
Investment	335,000	258,000
Marketable Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Assets:
Investment
Marketable Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Assets:
Investment

[1] The condensed consolidated balance sheet as of December 31, 2018 has been prepared using information from the audited consolidated balance sheet as of that date.