Note 8 - Fair Value Measurements - Estimated Fair Values and Related Carrying Amounts of Financial Instruments (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015	Dec. 31, 2014
Fair Value, Inputs, Level 1 [Member]
Cash and due from banks	$ 14,320	$ 12,152
Interest-bearing deposits	75,892	130,811
Fair Value, Inputs, Level 2 [Member]
Securities	449,483	394,163
Restricted securities	1,170	1,129
Loans held for sale	663	634
Accrued interest receivable	5,259	5,769
Bank-owned life insurance	22,699	22,401
Deposits	842,198	826,476
Accrued interest payable	56	56
Fair Value, Inputs, Level 3 [Member]
Loans, net	638,760	621,590
Deposits	178,399	193,912
Cash and due from banks	14,320	12,152	$ 11,353	$ 12,894
Interest-bearing deposits	75,892	130,811
Securities	441,666	388,159
Restricted securities	1,170	1,129
Loans held for sale	663	634
Loans, net	622,721	610,711
Accrued interest receivable	5,259	5,769
Bank-owned life insurance	22,699	22,401
Deposits	1,021,738	1,018,859
Accrued interest payable	$ 56	$ 56