Note 2 - Loans and Allowance for Loan Losses - Loan Portfolio by Risk Rating (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019
Loans, gross	$ 2,169,687	$ 2,093,042	$ 2,058,001
Real Estate Portfolio Segment [Member]
Loans, gross	2,006,766	1,929,325
Real Estate Portfolio Segment [Member] | Residential 1 to 4 Family [Member]
Loans, gross	519,775	511,250	458,304
Real Estate Portfolio Segment [Member] | Multifamily Real Estate [Member]
Loans, gross	151,929	97,104	136,385
Real Estate Portfolio Segment [Member] | Commercial Real Estate [Member]
Loans, gross	841,521	793,379	727,394
Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Loans, gross	388,769	425,185	495,061
Real Estate Portfolio Segment [Member] | Farmland [Member]
Loans, gross	18,610	19,268	23,438
Real Estate Portfolio Segment [Member] | Second Mortgages [Member]
Loans, gross	11,254	10,760	11,465
Real Estate Portfolio Segment [Member] | Home Equity Line of Credit [Member]
Loans, gross	74,908	72,379	61,656
Commercial Portfolio Segment [Member]
Loans, gross	95,547	98,265	77,921
Agricultural Installment and Other Portfolio Segment [Member]
Loans, gross	67,374	65,452	$ 66,377
Pass [Member]
Loans, gross	2,160,063	2,082,391
Pass [Member] | Real Estate Portfolio Segment [Member] | Residential 1 to 4 Family [Member]
Loans, gross	511,772	503,861
Pass [Member] | Real Estate Portfolio Segment [Member] | Multifamily Real Estate [Member]
Loans, gross	151,929	97,104
Pass [Member] | Real Estate Portfolio Segment [Member] | Commercial Real Estate [Member]
Loans, gross	840,914	791,610
Pass [Member] | Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Loans, gross	388,674	424,517
Pass [Member] | Real Estate Portfolio Segment [Member] | Farmland [Member]
Loans, gross	18,453	19,106
Pass [Member] | Real Estate Portfolio Segment [Member] | Second Mortgages [Member]
Loans, gross	10,857	10,458
Pass [Member] | Real Estate Portfolio Segment [Member] | Home Equity Line of Credit [Member]
Loans, gross	74,754	72,237
Pass [Member] | Commercial Portfolio Segment [Member]
Loans, gross	95,525	98,243
Pass [Member] | Agricultural Installment and Other Portfolio Segment [Member]
Loans, gross	67,185	65,255
Special Mention [Member]
Loans, gross	5,622	3,936
Special Mention [Member] | Real Estate Portfolio Segment [Member] | Residential 1 to 4 Family [Member]
Loans, gross	5,096	2,923
Special Mention [Member] | Real Estate Portfolio Segment [Member] | Multifamily Real Estate [Member]
Loans, gross	0	0
Special Mention [Member] | Real Estate Portfolio Segment [Member] | Commercial Real Estate [Member]
Loans, gross	0	0
Special Mention [Member] | Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Loans, gross	63	635
Special Mention [Member] | Real Estate Portfolio Segment [Member] | Farmland [Member]
Loans, gross	102	103
Special Mention [Member] | Real Estate Portfolio Segment [Member] | Second Mortgages [Member]
Loans, gross	273	174
Special Mention [Member] | Real Estate Portfolio Segment [Member] | Home Equity Line of Credit [Member]
Loans, gross	10	0
Special Mention [Member] | Commercial Portfolio Segment [Member]
Loans, gross	0	0
Special Mention [Member] | Agricultural Installment and Other Portfolio Segment [Member]
Loans, gross	78	101
Substandard [Member]
Loans, gross	4,002	6,715
Substandard [Member] | Real Estate Portfolio Segment [Member] | Residential 1 to 4 Family [Member]
Loans, gross	2,907	4,466
Substandard [Member] | Real Estate Portfolio Segment [Member] | Multifamily Real Estate [Member]
Loans, gross	0	0
Substandard [Member] | Real Estate Portfolio Segment [Member] | Commercial Real Estate [Member]
Loans, gross	607	1,769
Substandard [Member] | Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Loans, gross	32	33
Substandard [Member] | Real Estate Portfolio Segment [Member] | Farmland [Member]
Loans, gross	55	59
Substandard [Member] | Real Estate Portfolio Segment [Member] | Second Mortgages [Member]
Loans, gross	124	128
Substandard [Member] | Real Estate Portfolio Segment [Member] | Home Equity Line of Credit [Member]
Loans, gross	144	142
Substandard [Member] | Commercial Portfolio Segment [Member]
Loans, gross	22	22
Substandard [Member] | Agricultural Installment and Other Portfolio Segment [Member]
Loans, gross	111	96
Doubtful [Member]
Loans, gross	0	0
Doubtful [Member] | Real Estate Portfolio Segment [Member] | Residential 1 to 4 Family [Member]
Loans, gross	0	0
Doubtful [Member] | Real Estate Portfolio Segment [Member] | Multifamily Real Estate [Member]
Loans, gross	0	0
Doubtful [Member] | Real Estate Portfolio Segment [Member] | Commercial Real Estate [Member]
Loans, gross	0	0
Doubtful [Member] | Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Loans, gross	0	0
Doubtful [Member] | Real Estate Portfolio Segment [Member] | Farmland [Member]
Loans, gross	0	0
Doubtful [Member] | Real Estate Portfolio Segment [Member] | Second Mortgages [Member]
Loans, gross	0	0
Doubtful [Member] | Real Estate Portfolio Segment [Member] | Home Equity Line of Credit [Member]
Loans, gross	0	0
Doubtful [Member] | Commercial Portfolio Segment [Member]
Loans, gross	0	0
Doubtful [Member] | Agricultural Installment and Other Portfolio Segment [Member]
Loans, gross	$ 0	$ 0