Note 4 - Investment Securities (Details Textual)	12 Months Ended
	Dec. 31, 2019
Maturity Period of Mutual Funds	1 year
Term of Mutual Fund	180 days
Percentage of Holdings Non-investment Grade Rated	0.00%
Mutual Fund [Member] | Fitch, AAA Rating [Member]
Percentage of Investment Holdings Grade Rated	24.00%