Note 9 - Fair Value Measurements - Assets Measured at Fair Value on a Nonrecurring Basis (Details) - Fair Value, Nonrecurring [Member] - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
Jun. 30, 2019	Dec. 31, 2018
Fair Value	$ 10,441	$ 10,657
Total Losses	0	(240)
Fair Value, Inputs, Level 1 [Member]
Fair Value	0	0
Fair Value, Inputs, Level 2 [Member]
Fair Value	0	0
Fair Value, Inputs, Level 3 [Member]
Fair Value	10,441	10,657
Other Real Estate Owned [Member]
Fair Value	43	350
Total Losses	0	0
Other Real Estate Owned [Member] \| Fair Value, Inputs, Level 1 [Member]
Fair Value	0	0
Other Real Estate Owned [Member] \| Fair Value, Inputs, Level 2 [Member]
Fair Value	0	0
Other Real Estate Owned [Member] \| Fair Value, Inputs, Level 3 [Member]
Fair Value	43	350
Impaired Loans [Member] \| Commercial Portfolio Segment [Member]
Fair Value	6,026	6,437
Total Losses	0	0
Impaired Loans [Member] \| Commercial Real Estate Portfolio Segment [Member]
Fair Value	4,100	3,870
Total Losses	0	(240)
Impaired Loans [Member] \| Residential Portfolio Segment [Member]
Fair Value	195
Total Losses	0
Impaired Loans [Member] \| Consumer Portfolio Segment [Member]
Fair Value	77
Total Losses	0
Impaired Loans [Member] \| Fair Value, Inputs, Level 1 [Member] \| Commercial Portfolio Segment [Member]
Fair Value	0	0
Impaired Loans [Member] \| Fair Value, Inputs, Level 1 [Member] \| Commercial Real Estate Portfolio Segment [Member]
Fair Value	0	0
Impaired Loans [Member] \| Fair Value, Inputs, Level 1 [Member] \| Residential Portfolio Segment [Member]
Fair Value	0
Impaired Loans [Member] \| Fair Value, Inputs, Level 1 [Member] \| Consumer Portfolio Segment [Member]
Fair Value	0
Impaired Loans [Member] \| Fair Value, Inputs, Level 2 [Member] \| Commercial Portfolio Segment [Member]
Fair Value	0	0
Impaired Loans [Member] \| Fair Value, Inputs, Level 2 [Member] \| Commercial Real Estate Portfolio Segment [Member]
Fair Value	0	0
Impaired Loans [Member] \| Fair Value, Inputs, Level 2 [Member] \| Residential Portfolio Segment [Member]
Fair Value	0
Impaired Loans [Member] \| Fair Value, Inputs, Level 2 [Member] \| Consumer Portfolio Segment [Member]
Fair Value	0
Impaired Loans [Member] \| Fair Value, Inputs, Level 3 [Member] \| Commercial Portfolio Segment [Member]
Fair Value	6,026	6,437
Impaired Loans [Member] \| Fair Value, Inputs, Level 3 [Member] \| Commercial Real Estate Portfolio Segment [Member]
Fair Value	4,100	$ 3,870
Impaired Loans [Member] \| Fair Value, Inputs, Level 3 [Member] \| Residential Portfolio Segment [Member]
Fair Value	195
Impaired Loans [Member] \| Fair Value, Inputs, Level 3 [Member] \| Consumer Portfolio Segment [Member]
Fair Value	$ 77