Note 4 - Investments (Details Textual)	3 Months Ended		9 Months Ended
	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)
Equity Securities, FV-NI	$ 348,000		$ 348,000		$ 258,000
Number of Equity Securities Sold	0	20,000
Equity Securities, FV-NI, Gain (Loss), Total	$ (387,000)	$ 25,000	223,000	$ (40,000)
Equity Securities, FV-NI, Unrealized Gain (Loss), Total	$ (387,000)		168,000	(43,000)
Equity Securities, FV-NI, Realized Gain (Loss), Total			$ 55,000	$ 3,000