Note 2 - Investment Securities - Available-for-sale Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
One year or less, available-for-sale-securities, amortized cost	$ 246
One year or less, available-for-sale-securities, fair value	247
Over one through five years, available-for-sale securities, amortized cost	3,153
Over one through five years, available-for-sale securities, fair value	3,147
Over five through ten years, available-for-sale securities, amortized cost	14,651
Over five through ten years, available-for-sale securities, fair value	14,807
Greater than 10 years, available-for-sale securities, amortized cost	35,382
Greater than 10 years, available-for-sale securities, fair value	35,393
Available-for-sale securities, amortized cost	53,432	$ 53,060
Available-for-sale securities, fair value	$ 53,594	$ 52,975	[1]

[1] Derived from consolidated audited financial statements.