Note 2 - Summary of Significant Accounting Policies - Fair Value of Financial Assets (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Assets:
Investment	$ 343,000	$ 607,000
Marketable Securities [Member]
Assets:
Investment	343,000	607,000
Marketable Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Assets:
Investment	343,000	607,000
Marketable Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Assets:
Investment
Marketable Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Assets:
Investment