Note 4 - Securities - Expected Maturities of Investment Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Available-for-sale securities, amortized cost, one year or less	$ 2,062
Available-for-sale securities, fair value, one year or less	2,067
Held-to-maturity securities, amortized cost, one year or less
Held-to-maturity securities, fair value, one year or less
Available-for-sale securities, amortized cost, after one year through five years	78,246
Available-for-sale securities, fair value, after one year through five years	77,523
Held-to-maturity securities, amortized cost, after one year through five years	6,327
Held-to-maturity securities, fair value, after one year through five years	6,547
Available-for-sale securities, amortized cost, after five years through ten years	48,087
Available-for-sale securities, fair value, after five years through ten years	48,105
Held-to-maturity securities, amortized cost, after five years through ten years	11,808
Held-to-maturity securities, fair value, after five years through ten years	12,016
Available-for-sale securities, amortized cost, after ten years	54,030
Available-for-sale securities, fair value, after ten years	53,839
Held-to-maturity securities, amortized cost, after ten years	13,122
Held-to-maturity securities, fair value, after ten years	13,232
Available-for-sale securities, amortized cost, total	182,425
Available-for-sale securities, fair value, total	181,534	$ 175,174
Held-to-maturity securities, amortized cost, total	31,257	$ 31,187
Held-to-maturity securities, fair value, total	$ 31,795