Note 7 - Loans and the Allowance for Loan Losses - Past Due Loans Receivable (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Past due	$ 14,835,000	$ 11,242,000
Current	1,513,634,000	964,042,000
Loans	1,528,469,000	975,284,000
Recorded investment over 90 days past due and still accruing	1,876,000	132,000
Financing Receivables, 30 to 59 Days Past Due [Member]
Past due	4,959,000	2,820,000
Financing Receivables, 60 to 89 Days Past Due [Member]
Past due	1,073,000	422,000
Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due	8,803,000	8,000,000
Commercial Real Estate Portfolio Segment [Member] | Construction and Land [Member]
Past due	427,000	91,000
Current	210,627,000	143,444,000
Loans	211,054,000	143,535,000
Recorded investment over 90 days past due and still accruing	60,000	0
Commercial Real Estate Portfolio Segment [Member] | Construction and Land [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due	325,000
Commercial Real Estate Portfolio Segment [Member] | Construction and Land [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due	13,000	0
Commercial Real Estate Portfolio Segment [Member] | Construction and Land [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due	89,000	91,000
Commercial Real Estate Portfolio Segment [Member] | Farmland [Member]
Past due	96,000	0
Current	45,893,000	10,480,000
Loans	45,989,000	10,480,000
Recorded investment over 90 days past due and still accruing	0	0
Commercial Real Estate Portfolio Segment [Member] | Farmland [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due	0	0
Commercial Real Estate Portfolio Segment [Member] | Farmland [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due	96,000	0
Commercial Real Estate Portfolio Segment [Member] | Farmland [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due	0	0
Commercial Real Estate Portfolio Segment [Member] | Nonfarm Nonresidential [Member]
Past due	6,404,000	5,776,000
Current	512,256,000	331,923,000
Loans	518,660,000	337,699,000
Recorded investment over 90 days past due and still accruing	450,000	0
Commercial Real Estate Portfolio Segment [Member] | Nonfarm Nonresidential [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due	2,437,000	2,344,000
Commercial Real Estate Portfolio Segment [Member] | Nonfarm Nonresidential [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due		103,000
Commercial Real Estate Portfolio Segment [Member] | Nonfarm Nonresidential [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due	3,967,000	3,329,000
Residential Portfolio Segment [Member] | Real Estate Residential One- to Four-Family [Member]
Past due	3,584,000	1,728,000
Current	266,999,000	155,777,000
Loans	270,583,000	157,505,000
Recorded investment over 90 days past due and still accruing	270,000	73,000
Residential Portfolio Segment [Member] | Real Estate Residential One- to Four-Family [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due	1,596,000	470,000
Residential Portfolio Segment [Member] | Real Estate Residential One- to Four-Family [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due	588,000	319,000
Residential Portfolio Segment [Member] | Real Estate Residential One- to Four-Family [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due	1,400,000	939,000
Residential Portfolio Segment [Member] | Multi-family Residential [Member]
Past due	36,000	0
Current	39,237,000	20,717,000
Loans	39,273,000	20,717,000
Recorded investment over 90 days past due and still accruing	0	0
Residential Portfolio Segment [Member] | Multi-family Residential [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due	36,000	0
Residential Portfolio Segment [Member] | Multi-family Residential [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due	0	0
Residential Portfolio Segment [Member] | Multi-family Residential [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due	0	0
Commercial Portfolio Segment [Member]
Past due	3,856,000	3,274,000
Current	359,784,000	251,153,000
Loans	363,640,000	254,427,000
Recorded investment over 90 days past due and still accruing	1,038,000	59,000
Commercial Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due	328,000
Commercial Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due	287,000
Commercial Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due	3,241,000	3,274,000
Consumer Portfolio Segment [Member]
Past due	432,000	373,000
Current	78,838,000	50,548,000
Loans	79,270,000	50,921,000
Recorded investment over 90 days past due and still accruing	58,000	0
Consumer Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past due	237,000	6,000
Consumer Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past due	89,000	0
Consumer Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past due	$ 106,000	$ 367,000