Note 5 - Investment Securities - Scheduled Maturities of Investment Securities Available-for-sale and Held-to-maturity (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Available-for-Sale, Maturing within one year, Amortized Cost	$ 2,007
Available-for-Sale, Maturing within one year, Estimated Fair Value	2,016
Held-to-Maturity, Maturing within one year, Amortized Cost
Held-to-Maturity, Maturing within one year, Estimated Fair Value
Available-for-Sale, Maturing after one to five years, Amortized Cost	5,400
Available-for-Sale, Maturing after one to five years, Estimated Fair Value	5,501
Held-to-Maturity, Maturing after one to five years, Amortized Cost	2,064
Held-to-Maturity, Maturing after one to five years, Estimated Fair Value	2,109
Available-for-Sale, Maturing after five to ten years, Amortized Cost	75,845
Available-for-Sale, Maturing after five to ten years, Estimated Fair Value	77,084
Held-to-Maturity, Maturing after five to ten years, Amortized Cost	7,215
Held-to-Maturity, Maturity after five to ten years, Estimated Fair Value	7,247
Available-for-Sale, Maturing after ten years, Amortized Cost	96,018
Available-for-Sale, Maturing after ten years, Estimated Fair Value	96,650
Held-to-Maturity, Maturing after ten years, Amortized Cost	19,036
Held-to-Maturity, Maturing after ten years, Estimated Fair Value	19,127
Available-for-Sale, Amortized Cost	179,270	$ 197,995
Available-for-Sale, Estimated Fair Value	181,251	198,843
Held-to-Maturity, Amortized Cost	28,315	32,359
Held-to-Maturity, Estimated Fair Value	$ 28,483	$ 32,184