Note 21 - Disclosure of Financial Instruments Not Reported at Fair Value - Financial Assets and Financial Liabilities That Are Not Measured and Reported at Fair Value (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Financial assets
Cash and short-term investments	$ 139,248	$ 47,973
Accrued interest receivable	8,369	6,878
Financial liabilities
Accrued interest payable	232	144
Reported Value Measurement [Member]
Financial assets
Cash and short-term investments	139,248	47,973
Mortgage loans held for sale	2,964	3,213
Federal Home Loan Bank stock and other securities	7,646	6,347
Loans, net	2,384,685	2,281,368
Accrued interest receivable	8,369	6,878
Financial liabilities
Deposits	2,578,295	2,520,548
Securities sold under agreement to repurchase	70,473	67,595
Federal funds purchased	161,352	47,374
FHLB Advances	49,458	51,075
Accrued interest payable	232	144
Estimate of Fair Value Measurement [Member]
Financial assets
Cash and short-term investments	139,248	47,973
Mortgage loans held for sale	2,964	3,481
Federal Home Loan Bank stock and other securities	7,646	6,347
Loans, net	2,338,464	2,284,569
Accrued interest receivable	8,369	6,878
Financial liabilities
Deposits	2,576,385	2,519,725
Securities sold under agreement to repurchase	70,473	67,595
Federal funds purchased	161,352	47,374
FHLB Advances	48,642	50,806
Accrued interest payable	232	144
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member]
Financial assets
Cash and short-term investments	139,248	47,973
Mortgage loans held for sale
Federal Home Loan Bank stock and other securities
Loans, net
Accrued interest receivable	8,369	6,878
Financial liabilities
Deposits
Securities sold under agreement to repurchase
Federal funds purchased
FHLB Advances
Accrued interest payable	232	144
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Financial assets
Cash and short-term investments
Mortgage loans held for sale	2,964	3,481
Federal Home Loan Bank stock and other securities	7,646	6,347
Loans, net
Accrued interest receivable
Financial liabilities
Deposits
Securities sold under agreement to repurchase	70,473	67,595
Federal funds purchased	161,352	47,374
FHLB Advances	48,642	50,806
Accrued interest payable
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Financial assets
Cash and short-term investments
Mortgage loans held for sale
Federal Home Loan Bank stock and other securities
Loans, net	2,338,464	2,284,569
Accrued interest receivable
Financial liabilities
Deposits	2,576,385	2,519,725
Securities sold under agreement to repurchase
Federal funds purchased
FHLB Advances
Accrued interest payable