Note 4 - Investment Securities - Maturities of Debt Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Available for sale, amortized cost, within one year	$ 6,944
Available for sale, fair value, within one year	$ 6,950
Available for sale, weighted average rate, within one year	1.35%
Held to maturity, amortized cost, within one year	$ 0
Held to maturity, fair value, within one year	$ 0
Held to maturity, weighted average rate, within one year	0.00%
Available for sale, amortized cost, due from one year to five years	$ 19,686
Available for sale, fair value, due from one year to five years	$ 19,736
Available for sale, weighted average rate, due from one year to five years	2.25%
Held to maturity, amortized cost, due from one year to five years	$ 0
Held to maturity, fair value, due from one year to five years	$ 0
Held to maturity, weighted average rate, due from one year to five years	0.00%
Available for sale, amortized cost, due from five years to ten years	$ 14,463
Available for sale, fair value, due from five years to ten years	$ 14,585
Available for sale, weighted average rate, due from five years to ten years	2.86%
Held to maturity, amortized cost, due from five years to ten years	$ 0
Held to maturity, fair value, due from five years to ten years	$ 0
Held to maturity, weighted average rate, due from five years to ten years	0.00%
Available for sale, amortized cost, due after ten years	$ 52,840
Available for sale, fair value, due after ten years	$ 51,410
Available for sale, weighted average rate, due after ten years	3.07%
Held to maturity, amortized cost, due after ten years	$ 26,977
Held to maturity, fair value, due after ten years	$ 25,090
Held to maturity, weighted average rate, due after ten years	2.92%
Available for sale, amortized cost, with maturity dates	$ 93,933
Available for sale, fair value, with maturity dates	$ 92,681
Available for sale, weighted average rate, with maturity dates	2.74%
Held to maturity, amortized cost, with maturity dates	$ 26,977
Held to maturity, fair value, with maturity dates	$ 25,090
Held to maturity, weighted average rate, with maturity dates	2.92%
Available for sale, amortized cost	$ 190,803
Available for sale, fair value	$ 188,476	$ 198,585
Available for sale, weighted average rate	2.52%
Held to maturity, amortized cost	$ 26,977	0
Held to maturity, fair value	$ 25,090	0
Held to maturity, weighted average rate	2.92%
Collateralized Mortgage Backed Securities [Member]
Available for sale, amortized cost, without maturity dates	$ 96,870
Available for sale, fair value, without maturity dates	$ 95,795
Available for sale, weighted average rate, without maturity dates	2.31%
Held to maturity, amortized cost, without maturity dates	$ 0
Held to maturity, fair value, without maturity dates	$ 0
Held to maturity, weighted average rate, without maturity dates	0.00%
Available for sale, fair value	$ 95,795	$ 85,152