Note 6 - Loans and the Allowance for Loan Losses - Past Due Loans Receivable (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Past due	$ 14,033	$ 14,835
Current	1,572,149	1,513,634
Loans	1,586,182	1,528,469
Recorded investment over 90 days past due and still accruing	77	1,876
Financial Asset, 30 to 59 Days Past Due [Member]
Past due	2,818	4,959
Financial Asset, 60 to 89 Days Past Due [Member]
Past due	1,176	1,073
Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Past due	10,039	8,803
Commercial Real Estate Portfolio Segment [Member] | Construction and Land [Member]
Past due	510	427
Current	211,378	210,627
Loans	211,888	211,054
Recorded investment over 90 days past due and still accruing		60
Commercial Real Estate Portfolio Segment [Member] | Construction and Land [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Past due	480	325
Commercial Real Estate Portfolio Segment [Member] | Construction and Land [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Past due		13
Commercial Real Estate Portfolio Segment [Member] | Construction and Land [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Past due	30	89
Commercial Real Estate Portfolio Segment [Member] | Farmland [Member]
Past due	24	96
Current	44,042	45,893
Loans	44,066	45,989
Recorded investment over 90 days past due and still accruing	0	0
Commercial Real Estate Portfolio Segment [Member] | Farmland [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Past due	24	0
Commercial Real Estate Portfolio Segment [Member] | Farmland [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Past due		96
Commercial Real Estate Portfolio Segment [Member] | Farmland [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Past due	0	0
Commercial Real Estate Portfolio Segment [Member] | Nonfarm Nonresidential [Member]
Past due	6,360	6,404
Current	543,743	512,256
Loans	550,103	518,660
Recorded investment over 90 days past due and still accruing		450
Commercial Real Estate Portfolio Segment [Member] | Nonfarm Nonresidential [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Past due	191	2,437
Commercial Real Estate Portfolio Segment [Member] | Nonfarm Nonresidential [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Past due	730
Commercial Real Estate Portfolio Segment [Member] | Nonfarm Nonresidential [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Past due	5,439	3,967
Residential Portfolio Segment [Member] | Real Estate Residential One- to Four-Family [Member]
Past due	3,360	3,584
Current	272,250	266,999
Loans	275,610	270,583
Recorded investment over 90 days past due and still accruing		270
Residential Portfolio Segment [Member] | Real Estate Residential One- to Four-Family [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Past due	1,646	1,596
Residential Portfolio Segment [Member] | Real Estate Residential One- to Four-Family [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Past due	318	588
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	1,396	1,400
Residential Portfolio Segment [Member] | Multi-family Residential [Member]
Past due	35	36
Current	39,513	39,237
Loans	39,548	39,273
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	35	36
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	3,322	3,856
Current	386,533	359,784
Loans	389,855	363,640
Recorded investment over 90 days past due and still accruing	72	1,038
Commercial Portfolio Segment [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Past due	218	328
Commercial Portfolio Segment [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Past due	96	287
Commercial Portfolio Segment [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Past due	3,008	3,241
Consumer Portfolio Segment [Member]
Past due	422	432
Current	74,690	78,838
Loans	75,112	79,270
Recorded investment over 90 days past due and still accruing	5	58
Consumer Portfolio Segment [Member] | Financial Asset, 30 to 59 Days Past Due [Member]
Past due	224	237
Consumer Portfolio Segment [Member] | Financial Asset, 60 to 89 Days Past Due [Member]
Past due	32	89
Consumer Portfolio Segment [Member] | Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Past due	$ 166	$ 106