Note 3 - Investment Securities Available for Sale - Investment Securities With Unrealized Losses (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Less than 12 months fair value	$ 7,217	$ 13,284
Less than 12 months unrealized losses	60	60
12 months or more fair value	0	19,733
12 months or more unrealized losses	0	155
Total fair value	7,217	33,017
Total unrealized losses	60	215
Residential Mortgage Backed Securities Issued by US Government Sponsored Enterprises [Member]
Less than 12 months fair value	3,849	10,319
Less than 12 months unrealized losses	2	31
12 months or more fair value	0	19,733
12 months or more unrealized losses	0	155
Total fair value	3,849	30,052
Total unrealized losses	2	186
Commercial Mortgage Backed Securities Issued by US Government Agencies [Member]
Less than 12 months fair value	0
Less than 12 months unrealized losses	0
12 months or more fair value	0
12 months or more unrealized losses	0
Total fair value	0
Total unrealized losses	0
US States and Political Subdivisions Debt Securities [Member]
Less than 12 months fair value	3,368	2,965
Less than 12 months unrealized losses	58	29
12 months or more fair value	0	0
12 months or more unrealized losses	0	0
Total fair value	3,368	2,965
Total unrealized losses	$ 58	$ 29