Note 8 - Fair Value of Financial Instruments - Assets Measured on a Nonrecurring Basis (Details) - Fair Value, Measurements, Nonrecurring [Member] - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Assets measured on a nonrecurring basis	$ 22,732	$ 13,803
Fair Value, Inputs, Level 1 [Member]
Assets measured on a nonrecurring basis
Fair Value, Inputs, Level 2 [Member]
Assets measured on a nonrecurring basis	22,732	13,803
Fair Value, Inputs, Level 3 [Member]
Assets measured on a nonrecurring basis
Impaired Loans [Member]
Assets measured on a nonrecurring basis	21,437	13,576
Impaired Loans [Member] | Fair Value, Inputs, Level 1 [Member]
Assets measured on a nonrecurring basis
Impaired Loans [Member] | Fair Value, Inputs, Level 2 [Member]
Assets measured on a nonrecurring basis	21,437	13,576
Impaired Loans [Member] | Fair Value, Inputs, Level 3 [Member]
Assets measured on a nonrecurring basis
Repossessed Assets [Member]
Assets measured on a nonrecurring basis	1,295	227
Repossessed Assets [Member] | Fair Value, Inputs, Level 1 [Member]
Assets measured on a nonrecurring basis
Repossessed Assets [Member] | Fair Value, Inputs, Level 2 [Member]
Assets measured on a nonrecurring basis	1,295	227
Repossessed Assets [Member] | Fair Value, Inputs, Level 3 [Member]
Assets measured on a nonrecurring basis