Note 7 - Loans and the Allowance for Loan Losses - Past Due Loans Receivable (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Past due	$ 8,789,000	$ 14,835,000
Current	1,701,476,000	1,513,634,000
Loans	1,710,265,000	1,528,469,000
Recorded investment over 90 days past due and still accruing	72,000	1,876,000
Financial Asset, 30 to 59 Days Past Due [Member]
Past due	2,228,000	4,959,000
Financial Asset, 60 to 89 Days Past Due [Member]
Past due	1,794,000	1,073,000
Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Past due	4,767,000	8,803,000
Commercial Real Estate Portfolio Segment [Member] | Construction and Land [Member]
Past due	879,000	427,000
Current	243,302,000	210,627,000
Loans	244,181,000	211,054,000
Recorded investment over 90 days past due and still accruing		60,000
Commercial Real Estate Portfolio Segment [Member] | Construction and Land [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Past due	483,000	325,000
Commercial Real Estate Portfolio Segment [Member] | Construction and Land [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Past due	17,000	13,000
Commercial Real Estate Portfolio Segment [Member] | Construction and Land [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Past due	379,000	89,000
Commercial Real Estate Portfolio Segment [Member] | Farmland [Member]
Past due	177,000	96,000
Current	48,504,000	45,893,000
Loans	48,681,000	45,989,000
Recorded investment over 90 days past due and still accruing		0
Commercial Real Estate Portfolio Segment [Member] | Farmland [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Past due	18,000	0
Commercial Real Estate Portfolio Segment [Member] | Farmland [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Past due	16,000	96,000
Commercial Real Estate Portfolio Segment [Member] | Farmland [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Past due	143,000	0
Commercial Real Estate Portfolio Segment [Member] | Nonfarm Nonresidential [Member]
Past due	2,320,000	6,404,000
Current	610,288,000	512,256,000
Loans	612,608,000	518,660,000
Recorded investment over 90 days past due and still accruing		450,000
Commercial Real Estate Portfolio Segment [Member] | Nonfarm Nonresidential [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Past due	181,000	2,437,000
Commercial Real Estate Portfolio Segment [Member] | Nonfarm Nonresidential [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Past due	610,000
Commercial Real Estate Portfolio Segment [Member] | Nonfarm Nonresidential [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Past due	1,529,000	3,967,000
Residential Portfolio Segment [Member] | Real Estate Residential One- to Four-Family [Member]
Past due	3,220,000	3,584,000
Current	289,922,000	266,999,000
Loans	293,142,000	270,583,000
Recorded investment over 90 days past due and still accruing	29,000	270,000
Residential Portfolio Segment [Member] | Real Estate Residential One- to Four-Family [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Past due	1,245,000	1,596,000
Residential Portfolio Segment [Member] | Real Estate Residential One- to Four-Family [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Past due	975,000	588,000
Residential Portfolio Segment [Member] | Real Estate Residential One- to Four-Family [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Past due	1,000,000	1,400,000
Residential Portfolio Segment [Member] | Multi-family Residential [Member]
Past due	32,000	36,000
Current	36,422,000	39,237,000
Loans	36,454,000	39,273,000
Recorded investment over 90 days past due and still accruing	0	0
Residential Portfolio Segment [Member] | Multi-family Residential [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Past due	32,000	36,000
Residential Portfolio Segment [Member] | Multi-family Residential [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Past due	0	0
Residential Portfolio Segment [Member] | Multi-family Residential [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Past due	0	0
Commercial Portfolio Segment [Member]
Past due	1,579,000	3,856,000
Current	388,819,000	359,784,000
Loans	390,398,000	363,640,000
Recorded investment over 90 days past due and still accruing		1,038,000
Commercial Portfolio Segment [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Past due	126,000	328,000
Commercial Portfolio Segment [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Past due	142,000	287,000
Commercial Portfolio Segment [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Past due	1,311,000	3,241,000
Consumer Portfolio Segment [Member]
Past due	582,000	432,000
Current	84,219,000	78,838,000
Loans	84,801,000	79,270,000
Recorded investment over 90 days past due and still accruing	43,000	58,000
Consumer Portfolio Segment [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Past due	143,000	237,000
Consumer Portfolio Segment [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Past due	34,000	89,000
Consumer Portfolio Segment [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Past due	$ 405,000	$ 106,000