Note 11 - Fair Value of Financial Instruments and Fair Value Measurements - Assets and Liabilities Measured at Fair Value on a Recurring and Nonrecurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Recurring Securities Available for Sale	$ 368,869	$ 353,066
Fair Value, Inputs, Level 1 [Member]
Recurring Securities Available for Sale
Fair Value, Inputs, Level 2 [Member]
Recurring Securities Available for Sale		348,789
Fair Value, Inputs, Level 3 [Member]
Recurring Securities Available for Sale		4,277
US Government Agencies Debt Securities [Member]
Recurring Securities Available for Sale	362,311	346,205
US Treasury Securities [Member]
Recurring Securities Available for Sale	149
US States and Political Subdivisions Debt Securities [Member]
Recurring Securities Available for Sale	3,579	3,989
Corporate Debt Securities [Member]
Recurring Securities Available for Sale	2,830	2,872
Fair Value, Recurring [Member]
Recurring Securities Available for Sale	368,869
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Recurring Securities Available for Sale
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Recurring Securities Available for Sale	368,654
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Recurring Securities Available for Sale	215
Fair Value, Recurring [Member] | US Government Agencies Debt Securities [Member]
Recurring Securities Available for Sale	362,311	346,205
Fair Value, Recurring [Member] | US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Recurring Securities Available for Sale
Fair Value, Recurring [Member] | US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Recurring Securities Available for Sale	362,311	342,142
Fair Value, Recurring [Member] | US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Recurring Securities Available for Sale		4,063
Fair Value, Recurring [Member] | US Treasury Securities [Member]
Recurring Securities Available for Sale	149
Fair Value, Recurring [Member] | US Treasury Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Recurring Securities Available for Sale
Fair Value, Recurring [Member] | US Treasury Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Recurring Securities Available for Sale	149
Fair Value, Recurring [Member] | US Treasury Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Recurring Securities Available for Sale
Fair Value, Recurring [Member] | US States and Political Subdivisions Debt Securities [Member]
Recurring Securities Available for Sale	3,579	3,989
Fair Value, Recurring [Member] | US States and Political Subdivisions Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Recurring Securities Available for Sale
Fair Value, Recurring [Member] | US States and Political Subdivisions Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Recurring Securities Available for Sale	3,364	3,775
Fair Value, Recurring [Member] | US States and Political Subdivisions Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Recurring Securities Available for Sale	215	214
Fair Value, Recurring [Member] | Corporate Debt Securities [Member]
Recurring Securities Available for Sale	2,830	2,872
Fair Value, Recurring [Member] | Corporate Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Recurring Securities Available for Sale
Fair Value, Recurring [Member] | Corporate Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Recurring Securities Available for Sale	2,830	2,872
Fair Value, Recurring [Member] | Corporate Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Recurring Securities Available for Sale
Fair Value, Nonrecurring [Member]
Impaired Loans	2,930	3,352
Other Real Estate	421	1,183
Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 1 [Member]
Impaired Loans
Other Real Estate
Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 2 [Member]
Impaired Loans
Other Real Estate
Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member]
Impaired Loans	2,930	3,352
Other Real Estate	$ 421	$ 1,183