Note 10 - Income Tax (Details Textual) - USD ($)	1 Months Ended	12 Months Ended
	Feb. 28, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Deferred Tax Assets, Gross, Total		$ 2,917,000	$ 2,881,000
Deferred Tax Assets, Valuation Allowance, Total		$ 64,000	$ 136,000
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent		21.00%	21.00%	21.00%
Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities	$ 156,000
Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member]
Open Tax Year		2016 2017 2018 2019
State and Local Jurisdiction [Member]
Open Tax Year		2016 2017 2018 2019
One State Jurisdiction [Member]
Tax Credit Carryforward, Amount		$ 156,000