Note 5 - Securities - Securities by Contractual Maturity (Details) - USD ($)	Sep. 30, 2016	Dec. 31, 2015
Amortized cost, Due in one year or less, available for sale securities	$ 1,980,000
Fair value, Due in one year or less, available for sale securities	2,009,000
Amortized cost, Due after one year through five years, available for sale securities	192,986,000
Fair value, Due after one year through five years, available for sale securities	193,116,000
Amortized cost, Due after give years through ten years, available for sale securities	67,113,000
Fair value, Due after give years through ten years, available for sale securities	67,335,000
Amortized cost, Due after ten years, available for sale securities	26,366,000
Fair value, Due after ten years, available for sale securities	28,665,000
Amortized cost, No maturity, available for sale securities	189,000
Fair value, No maturity, available for sale securities	152,000
Amortized cost, Total securities available for sale	288,634,000
Fair value, Total securities available for sale	291,277,000	$ 236,131,000
Amortized cost, Due in one year or less, held to maturity securities	2,813,000
Fair value, Due in one year or less, held to maturity securities	2,871,000
Amortized cost, Due after one year through five years, held to maturity securities	24,020,000
Fair value, Due after one year through five years, held to maturity securities	25,525,000
Amortized cost, Due after give years through ten years, held to maturity securities	16,370,000
Fair value, Due after give years through ten years, held to maturity securities	17,264,000
Amortized cost, Due after ten years, held to maturity securities	94,844,000
Fair value, Due after ten years, held to maturity securities	99,618,000
Amortized cost, Total securities held to maturity	138,047,000	152,028,000
Fair value, Total securities held to maturity	$ 145,278,000	$ 158,032,000