Note 7 - Investment and Equity Securities (Details Textual) - USD ($)		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Equity Securities, FV-NI, Unrealized Gain (Loss), Total	[1]	$ (160,000)	$ 58,000
Equity Securities, FV-NI, Realized Gain (Loss), Total		0	0
Proceeds from Sale of Debt Securities, Available-for-sale		0	0
Security Owned and Pledged as Collateral, Fair Value, Total		$ 53,100,000		$ 55,600,000
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions, Total		86
Available-for-sale Securities, Percentage of Portfolio		96.00%
Other than Temporary Impairment, Credit Losses Recognized in Earnings, Credit Losses on Debt Securities Held, Ending Balance		$ 0	$ 0

[1] Not within scope of ASC 606