Note 6 - Loans and the Allowance for Loan Losses - Summary of Aged Analysis of Past Due Loans Receivable (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Credit quality indicators	$ 874,506	$ 810,951
Recorded Investment Over 90 Days Past Due and Still Accruing	55	168
Past Due	12,574	6,071
Current	861,932	804,880
Financing Receivables, 30 to 59 Days Past Due [Member]
Past Due	3,755	2,935
Financing Receivables, 60 to 89 Days Past Due [Member]
Past Due	3,415	1,124
Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past Due	5,404	2,012
Commercial Real Estate Portfolio Segment [Member] | Construction and Land [Member]
Credit quality indicators	112,199	94,426
Recorded Investment Over 90 Days Past Due and Still Accruing	0	0
Past Due	178	571
Current	112,021	93,855
Commercial Real Estate Portfolio Segment [Member] | Construction and Land [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past Due	37	465
Commercial Real Estate Portfolio Segment [Member] | Construction and Land [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past Due	4	0
Commercial Real Estate Portfolio Segment [Member] | Construction and Land [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past Due	137	106
Commercial Real Estate Portfolio Segment [Member] | Farmland [Member]
Credit quality indicators	10,524	9,217
Recorded Investment Over 90 Days Past Due and Still Accruing	0	0
Past Due	0	0
Current	10,524	9,217
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	0	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]
Credit quality indicators	304,278	298,057
Recorded Investment Over 90 Days Past Due and Still Accruing	0	0
Past Due	3,831	2,075
Current	300,447	295,982
Commercial Real Estate Portfolio Segment [Member] | Nonfarm Nonresidential [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past Due	241	1,370
Commercial Real Estate Portfolio Segment [Member] | Nonfarm Nonresidential [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past Due	3,260	173
Commercial Real Estate Portfolio Segment [Member] | Nonfarm Nonresidential [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past Due	330	532
Residential Portfolio Segment [Member] | Real Estate Residential One- to Four-Family [Member]
Credit quality indicators	139,398	129,052
Recorded Investment Over 90 Days Past Due and Still Accruing	0	117
Past Due	1,963	2,531
Current	137,435	126,521
Residential Portfolio Segment [Member] | Real Estate Residential One- to Four-Family [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past Due	781	989
Residential Portfolio Segment [Member] | Real Estate Residential One- to Four-Family [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past Due	151	579
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	1,031	963
Residential Portfolio Segment [Member] | Multi-family Residential [Member]
Credit quality indicators	23,039	22,737
Recorded Investment Over 90 Days Past Due and Still Accruing	0	0
Past Due	0	0
Current	23,039	22,737
Residential Portfolio Segment [Member] | Multi-family Residential [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past Due	0	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]
Credit quality indicators	238,924	213,120
Recorded Investment Over 90 Days Past Due and Still Accruing	55	51
Past Due	6,372	679
Current	232,552	212,441
Commercial Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past Due	2,690	45
Commercial Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past Due	0	372
Commercial Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past Due	3,682	262
Consumer Portfolio Segment [Member]
Credit quality indicators	46,144	44,342
Recorded Investment Over 90 Days Past Due and Still Accruing	0	0
Past Due	230	215
Current	45,914	44,127
Consumer Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Past Due	6	66
Consumer Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Past Due	0	0
Consumer Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Past Due	$ 224	$ 149