Note 6 - Loans Receivable and Allowance for Loan Losses - Past Due Loans (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Loans receivable, total past due	$ 15,209	$ 15,958
Loans receivable, current	1,363,554	1,146,091
Loans receivable	1,378,763	1,162,049
Loans receivable greater than 90 days and accruing
Financing Receivables, 30 to 59 Days Past Due [Member]
Loans receivable, total past due	1,494	1,113
Financing Receivables, 60 to 89 Days Past Due [Member]
Loans receivable, total past due	236
Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans receivable, total past due	13,479	14,845
Commercial Real Estate Portfolio Segment [Member]
Loans receivable, total past due	8,435	8,963
Loans receivable, current	487,094	424,341
Loans receivable	495,529	433,304
Loans receivable greater than 90 days and accruing
Commercial Real Estate Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Loans receivable, total past due	1,148
Commercial Real Estate Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Loans receivable, total past due	128
Commercial Real Estate Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans receivable, total past due	7,159	8,963
Construction and Land Development Portfolio Segment [Member]
Loans receivable, total past due
Loans receivable, current	125,512	104,617
Loans receivable	125,512	104,617
Loans receivable greater than 90 days and accruing
Construction and Land Development Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Loans receivable, total past due
Construction and Land Development Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Loans receivable, total past due
Construction and Land Development Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans receivable, total past due
Commercial Portfolio Segment [Member]
Loans receivable, total past due	3,976	3,864
Loans receivable, current	191,517	169,479
Loans receivable	195,493	173,343
Loans receivable greater than 90 days and accruing
Commercial Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Loans receivable, total past due		969
Commercial Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Loans receivable, total past due	108
Commercial Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans receivable, total past due	3,868	2,895
Owner Occupied Real Estate [Member]
Loans receivable, total past due	1,651	2,136
Loans receivable, current	357,305	307,702
Loans receivable	358,956	309,838
Loans receivable greater than 90 days and accruing
Owner Occupied Real Estate [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Loans receivable, total past due
Owner Occupied Real Estate [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Loans receivable, total past due
Owner Occupied Real Estate [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans receivable, total past due	1,651	2,136
Consumer Portfolio Segment [Member]
Loans receivable, total past due	1,022	995
Loans receivable, current	85,875	75,188
Loans receivable	86,897	76,183
Loans receivable greater than 90 days and accruing
Consumer Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Loans receivable, total past due	221	144
Consumer Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Loans receivable, total past due
Consumer Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans receivable, total past due	801	851
Residential Portfolio Segment [Member]
Loans receivable, total past due	125
Loans receivable, current	116,251	64,764
Loans receivable	116,376	64,764
Loans receivable greater than 90 days and accruing
Residential Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Loans receivable, total past due	125
Residential Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Loans receivable, total past due
Residential Portfolio Segment [Member] | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Loans receivable, total past due