Note 5 - Qualified Affordable Housing Partnership Investments (Details Textual) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Qualified Affordable Housing Project Investments Term (Year)	23 years
Proportional Amortization Method Qualified Affordable Housing Project Investments	$ 3,098	$ 2,529
Proportional Amortization Method Qualified Affordable Housing Project Investments Unfunded Liability Obligation	1,325	338
Proportional Amortization Method Qualified Affordable Housing Project Investments Original Amount	8,954	$ 7,954
Boston Capital [Member]
Proportional Amortization Method Qualified Affordable Housing Project Investments	962
Proportional Amortization Method Qualified Affordable Housing Project Investments Unfunded Liability Obligation	987
Proportional Amortization Method Qualified Affordable Housing Project Investments Original Amount	$ 1,000
Minimum [Member]
Qualified Affordable Housing Project Investments Return Rate	2.00%
Maximum [Member]
Qualified Affordable Housing Project Investments Return Rate	6.00%