Note 4 - Investment Securities - Amortized Cost and Fair Value of Debt Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Securities available for sale, amortized cost, due in one year or less	$ 3,047
Securities available for sale, fair value, due in one year or less	3,049
Securities held to maturity, amortized cost, due in one year or less	0
Securities held to maturity, fair value, due in one year or less	0
Securities available for sale, amortized cost, due after one year through five years	76,481
Securities available for sale, fair value, due after one year through five years	75,767
Securities held to maturity, amortized cost, due after one year through five years	0
Securities held to maturity, fair value, due after one year through five years	0
Securities available for sale, amortized cost, due after five years through ten years	18,692
Securities available for sale, fair value, due after five years through ten years	18,479
Securities held to maturity, amortized cost, due after five years through ten years	0
Securities held to maturity, fair value, due after five years through ten years	0
Securities available for sale, amortized cost, due after ten years	34,376
Securities available for sale, fair value, due after ten years	34,210
Securities held to maturity, amortized cost, due after ten years	0
Securities held to maturity, fair value, due after ten years	0
Securities available for sale, amortized cost, singal maturity	132,596
Securities available for sale, fair value, singal maturity	131,505
Securities held to maturity, amortized cost, singal maturity	0
Securities held to maturity, fair value, singal maturity	0
Securities available for sale, amortized cost, mortgage-backed securities and CMO	126,786
Securities available for sale, fair value, mortgage-backed securities and CMO	124,265
Securities held to maturity, amortized cost, mortgage-backed securities and CMO	2
Securities held to maturity, fair value, mortgage-backed securities and CMO	2
Securities held to maturity, amortized cost	2	$ 4
Securities held to maturity, fair value	2	$ 4
Debt Securities [Member]
Securities available for sale, amortized cost	259,382
Securities available for sale, fair value	255,770
Securities held to maturity, amortized cost	2
Securities held to maturity, fair value	$ 2