Note 3 - Securities - Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Amortized cost, Due in one year or less, available for sale securities	$ 3,414
Fair value, Due in one year or less, available for sale securities	3,423
Amortized cost, Due after one year through five years, available for sale securities	199,430
Fair value, Due after one year through five years, available for sale securities	196,433
Amortized cost, Due after five years through ten years, available for sale securities	80,548
Fair value, Due after five years through ten years, available for sale securities	78,001
Amortized cost, Due after ten years, available for sale securities	26,221
Fair value, Due after ten years, available for sale securities	26,262
Amortized cost, No maturity, available for sale securities	189
Fair value, No maturity, available for sale securities	163
Amortized cost, Total securities available for sale	309,802
Fair value, Total securities available for sale	304,282	$ 236,131
Amortized cost, Due in one year or less, held to maturity securities	3,902
Fair value, Due in one year or less, held to maturity securities	3,988
Amortized cost, Due after one year through five years, held to maturity securities	28,249
Fair value, Due after one year through five years, held to maturity securities	29,761
Amortized cost, Due after five years through ten years, held to maturity securities	16,615
Fair value, Due after give years through ten years, held to maturity securities	17,155
Amortized cost, Due after ten years, held to maturity securities	86,191
Fair value, Due after ten years, held to maturity securities	86,788
Amortized cost, Total securities held to maturity	134,957	152,028
Fair value, Total securities held to maturity	$ 137,692	$ 158,032