Note 17 - Commitments and Credit Risk (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Letters of Credit Outstanding, Amount	$ 12,733,000	$ 11,596,000
Commercial Loans [Member] | Unused lines of Credit [Member]
Other Commitment	117,068,000	89,103,000
Open End Consumer Lines [Member] | Unused lines of Credit [Member]
Other Commitment	15,929,000	15,960,000
Confirming Letters of Credit From FHLB [Member]
Letters of Credit Outstanding, Amount	$ 39,422,000	19,725,000
Standby Letters of Credit [Member] | Minimum [Member]
Debt Instrument, Term	1 year
Standby Letters of Credit [Member] | Maximum [Member]
Debt Instrument, Term	2 years
Commitments to Originate Fixed Rate Mortgages [Member]
Other Commitment	$ 7,692,000	$ 6,152,000
Commitment, Mortgage Loan Origination, Disbursed Period	30 days