Note 3 - Loans - Types of Troubled Debt Restructuring Loan Modification by Portfolio Segment (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Troubled debt restructuring	$ 475	$ 910
Performing Financial Instruments [Member]
Troubled debt restructuring	475	910
Nonperforming Financial Instruments [Member]
Troubled debt restructuring
Commercial Real Estate Portfolio Segment [Member] | One- to Four-family Residential Properties [Member] | Performing Financial Instruments [Member]
Troubled debt restructuring	400	190
Commercial Real Estate Portfolio Segment [Member] | Nonfarm Nonresidential [Member]
Troubled debt restructuring	400	190
Commercial Real Estate Portfolio Segment [Member] | Nonfarm Nonresidential [Member] | Nonperforming Financial Instruments [Member]
Troubled debt restructuring
Residential Portfolio Segment [Member] | One- to Four-family Residential Properties [Member]
Troubled debt restructuring	75	720
Residential Portfolio Segment [Member] | One- to Four-family Residential Properties [Member] | Performing Financial Instruments [Member]
Troubled debt restructuring	75	720
Residential Portfolio Segment [Member] | One- to Four-family Residential Properties [Member] | Nonperforming Financial Instruments [Member]
Troubled debt restructuring