Note 19 - Fair Value Measurements - Assets Measured At Fair Value On a Nonrecurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Impaired Loans [Member]
Assets fair value, nonrecurring	$ 8,885	$ 6,397
Impaired Loans [Member] | Fair Value, Inputs, Level 1 [Member]
Assets fair value, nonrecurring	0	0
Impaired Loans [Member] | Fair Value, Inputs, Level 2 [Member]
Assets fair value, nonrecurring	0	0
Impaired Loans [Member] | Fair Value, Inputs, Level 3 [Member]
Assets fair value, nonrecurring	8,885	6,397
Impaired Loans [Member] | Real Estate Portfolio Segment [Member] | Real Estate Construction and Land Development [Member]
Assets fair value, nonrecurring	1,553	2,909
Impaired Loans [Member] | Real Estate Portfolio Segment [Member] | Real Estate Construction and Land Development [Member] | Fair Value, Inputs, Level 1 [Member]
Assets fair value, nonrecurring	0	0
Impaired Loans [Member] | Real Estate Portfolio Segment [Member] | Real Estate Construction and Land Development [Member] | Fair Value, Inputs, Level 2 [Member]
Assets fair value, nonrecurring	0	0
Impaired Loans [Member] | Real Estate Portfolio Segment [Member] | Real Estate Construction and Land Development [Member] | Fair Value, Inputs, Level 3 [Member]
Assets fair value, nonrecurring	1,553	2,909
Impaired Loans [Member] | Real Estate Portfolio Segment [Member] | Real Estate Mortgage Residential [Member]
Assets fair value, nonrecurring	4,687	3,137
Impaired Loans [Member] | Real Estate Portfolio Segment [Member] | Real Estate Mortgage Residential [Member] | Fair Value, Inputs, Level 1 [Member]
Assets fair value, nonrecurring	0	0
Impaired Loans [Member] | Real Estate Portfolio Segment [Member] | Real Estate Mortgage Residential [Member] | Fair Value, Inputs, Level 2 [Member]
Assets fair value, nonrecurring	0	0
Impaired Loans [Member] | Real Estate Portfolio Segment [Member] | Real Estate Mortgage Residential [Member] | Fair Value, Inputs, Level 3 [Member]
Assets fair value, nonrecurring	4,687	3,137
Impaired Loans [Member] | Real Estate Portfolio Segment [Member] | Real Estate Mortgage Farmland and Other Commercial Enterprises [Member]
Assets fair value, nonrecurring	2,645	351
Impaired Loans [Member] | Real Estate Portfolio Segment [Member] | Real Estate Mortgage Farmland and Other Commercial Enterprises [Member] | Fair Value, Inputs, Level 1 [Member]
Assets fair value, nonrecurring	0	0
Impaired Loans [Member] | Real Estate Portfolio Segment [Member] | Real Estate Mortgage Farmland and Other Commercial Enterprises [Member] | Fair Value, Inputs, Level 2 [Member]
Assets fair value, nonrecurring	0	0
Impaired Loans [Member] | Real Estate Portfolio Segment [Member] | Real Estate Mortgage Farmland and Other Commercial Enterprises [Member] | Fair Value, Inputs, Level 3 [Member]
Assets fair value, nonrecurring	2,645	351
OREO [Member]
Assets fair value, nonrecurring	4,446	6,187
OREO [Member] | Fair Value, Inputs, Level 1 [Member]
Assets fair value, nonrecurring	0	0
OREO [Member] | Fair Value, Inputs, Level 2 [Member]
Assets fair value, nonrecurring	0	0
OREO [Member] | Fair Value, Inputs, Level 3 [Member]
Assets fair value, nonrecurring	4,446	6,187
OREO [Member] | Real Estate Portfolio Segment [Member] | Real Estate Construction and Land Development [Member]
Assets fair value, nonrecurring	3,468	4,883
OREO [Member] | Real Estate Portfolio Segment [Member] | Real Estate Construction and Land Development [Member] | Fair Value, Inputs, Level 1 [Member]
Assets fair value, nonrecurring	0	0
OREO [Member] | Real Estate Portfolio Segment [Member] | Real Estate Construction and Land Development [Member] | Fair Value, Inputs, Level 2 [Member]
Assets fair value, nonrecurring	0	0
OREO [Member] | Real Estate Portfolio Segment [Member] | Real Estate Construction and Land Development [Member] | Fair Value, Inputs, Level 3 [Member]
Assets fair value, nonrecurring	3,468	4,883
OREO [Member] | Real Estate Portfolio Segment [Member] | Real Estate Mortgage Residential [Member]
Assets fair value, nonrecurring	157	234
OREO [Member] | Real Estate Portfolio Segment [Member] | Real Estate Mortgage Residential [Member] | Fair Value, Inputs, Level 1 [Member]
Assets fair value, nonrecurring	0	0
OREO [Member] | Real Estate Portfolio Segment [Member] | Real Estate Mortgage Residential [Member] | Fair Value, Inputs, Level 2 [Member]
Assets fair value, nonrecurring	0	0
OREO [Member] | Real Estate Portfolio Segment [Member] | Real Estate Mortgage Residential [Member] | Fair Value, Inputs, Level 3 [Member]
Assets fair value, nonrecurring	157	234
OREO [Member] | Real Estate Portfolio Segment [Member] | Real Estate Mortgage Farmland and Other Commercial Enterprises [Member]
Assets fair value, nonrecurring	821	1,070
OREO [Member] | Real Estate Portfolio Segment [Member] | Real Estate Mortgage Farmland and Other Commercial Enterprises [Member] | Fair Value, Inputs, Level 1 [Member]
Assets fair value, nonrecurring	0	0
OREO [Member] | Real Estate Portfolio Segment [Member] | Real Estate Mortgage Farmland and Other Commercial Enterprises [Member] | Fair Value, Inputs, Level 2 [Member]
Assets fair value, nonrecurring	0	0
OREO [Member] | Real Estate Portfolio Segment [Member] | Real Estate Mortgage Farmland and Other Commercial Enterprises [Member] | Fair Value, Inputs, Level 3 [Member]
Assets fair value, nonrecurring	$ 821	$ 1,070