Note 5 - Securities - Securities Available-for-sale (Details) - USD ($)	Sep. 30, 2016	Dec. 31, 2015
US Government Agencies Debt Securities [Member]
Securities available-for-sale, Amortized Costs	$ 268,925,000	$ 216,897,000
Securities available-for-sale, Gross Unrealized Gains	2,038,000	519,000
Securities available-for-sale, Gross Unrealized Losses	253,000	4,952,000
Securities available-for-sale, Fair Values	270,710,000	212,464,000
US States and Political Subdivisions Debt Securities [Member]
Securities available-for-sale, Amortized Costs	12,572,000	15,934,000
Securities available-for-sale, Gross Unrealized Gains	352,000	541,000
Securities available-for-sale, Gross Unrealized Losses	0	0
Securities available-for-sale, Fair Values	12,924,000	16,475,000
Collateralized Mortgage Backed Securities [Member]
Securities available-for-sale, Amortized Costs	932,000	1,199,000
Securities available-for-sale, Gross Unrealized Gains	103,000	120,000
Securities available-for-sale, Gross Unrealized Losses	0	0
Securities available-for-sale, Fair Values	1,035,000	1,319,000
Corporate Debt Securities [Member]
Securities available-for-sale, Amortized Costs	6,016,000	6,015,000
Securities available-for-sale, Gross Unrealized Gains	440,000	22,000
Securities available-for-sale, Gross Unrealized Losses		291,000
Securities available-for-sale, Fair Values	6,456,000	5,746,000
Other Securities [Member]
Securities available-for-sale, Amortized Costs	189,000	189,000
Securities available-for-sale, Gross Unrealized Gains	0	0
Securities available-for-sale, Gross Unrealized Losses	37,000	62,000
Securities available-for-sale, Fair Values	152,000	127,000
Securities available-for-sale, Amortized Costs	288,634,000	240,234,000
Securities available-for-sale, Gross Unrealized Gains	2,933,000	1,202,000
Securities available-for-sale, Gross Unrealized Losses	290,000	5,305,000
Securities available-for-sale, Fair Values	$ 291,277,000	$ 236,131,000