Note 6 - Loans Receivable and Allowance for Loan Losses - Loans by Internal Risk Rating (Details) - USD ($)	Jun. 30, 2018	Dec. 31, 2017
Loans receivable	$ 1,317,439,000	$ 1,162,049,000
Pass [Member]
Loans receivable	1,296,602,000	1,142,559,000
Special Mention [Member]
Loans receivable	2,438,000	1,226,000
Substandard [Member]
Loans receivable	18,119,000	17,984,000
Doubtful [Member]
Loans receivable	280,000	280,000
Commercial Real Estate Portfolio Segment [Member]
Loans receivable	489,574,000	433,304,000
Commercial Real Estate Portfolio Segment [Member] | Pass [Member]
Loans receivable	481,204	423,382,000
Commercial Real Estate Portfolio Segment [Member] | Special Mention [Member]
Loans receivable	944,000	959,000
Commercial Real Estate Portfolio Segment [Member] | Substandard [Member]
Loans receivable	7,426,000	8,963,000
Commercial Real Estate Portfolio Segment [Member] | Doubtful [Member]
Loans receivable
Construction and Land Development Portfolio Segment [Member]
Loans receivable	120,165,000	104,617,000
Construction and Land Development Portfolio Segment [Member] | Pass [Member]
Loans receivable	120,165,000	104,617,000
Construction and Land Development Portfolio Segment [Member] | Special Mention [Member]
Loans receivable
Construction and Land Development Portfolio Segment [Member] | Substandard [Member]
Loans receivable
Construction and Land Development Portfolio Segment [Member] | Doubtful [Member]
Loans receivable
Commercial Portfolio Segment [Member]
Loans receivable	188,254,000	173,343,000
Commercial Portfolio Segment [Member] | Pass [Member]
Loans receivable	181,452,000	168,702,000
Commercial Portfolio Segment [Member] | Special Mention [Member]
Loans receivable	19,000	140,000
Commercial Portfolio Segment [Member] | Substandard [Member]
Loans receivable	6,503,000	4,221,000
Commercial Portfolio Segment [Member] | Doubtful [Member]
Loans receivable	280,000	280,000
Owner Occupied Real Estate [Member]
Loans receivable	335,871,000	309,838,000
Owner Occupied Real Estate [Member] | Pass [Member]
Loans receivable	331,121,000	306,040,000
Owner Occupied Real Estate [Member] | Special Mention [Member]
Loans receivable	1,350,000
Owner Occupied Real Estate [Member] | Substandard [Member]
Loans receivable	3,400,000	3,798,000
Owner Occupied Real Estate [Member] | Doubtful [Member]
Loans receivable
Consumer Portfolio Segment [Member]
Loans receivable	83,467,000	76,183,000
Consumer Portfolio Segment [Member] | Pass [Member]
Loans receivable	82,677,000	75,181,000
Consumer Portfolio Segment [Member] | Special Mention [Member]
Loans receivable
Consumer Portfolio Segment [Member] | Substandard [Member]
Loans receivable	790,000	1,002,000
Consumer Portfolio Segment [Member] | Doubtful [Member]
Loans receivable
Residential Portfolio Segment [Member]
Loans receivable	100,108,000	64,764,000
Residential Portfolio Segment [Member] | Pass [Member]
Loans receivable	99,983,000	64,637,000
Residential Portfolio Segment [Member] | Special Mention [Member]
Loans receivable	125,000	127,000
Residential Portfolio Segment [Member] | Substandard [Member]
Loans receivable
Residential Portfolio Segment [Member] | Doubtful [Member]
Loans receivable