Note 5 - Securities - Securities Held-to-maturity (Details) - USD ($)	Jun. 30, 2016	Dec. 31, 2015
US Government Agencies Debt Securities [Member]
Securities held-to-maturity, AmortizedCosts	$ 3,934,000	$ 13,909,000
Securities held-to-maturity, Gross Unrealized Gains	379,000	288,000
Securities held-to-maturity, Gross Unrealized Losses	0	177,000
Fair value, Total securities held to maturity	4,313,000	14,020,000
US States and Political Subdivisions Debt Securities [Member]
Securities held-to-maturity, AmortizedCosts	132,773,000	136,373,000
Securities held-to-maturity, Gross Unrealized Gains	7,407,000	6,179,000
Securities held-to-maturity, Gross Unrealized Losses	36,000	330,000
Fair value, Total securities held to maturity	140,144,000	142,222,000
Collateralized Mortgage Backed Securities [Member]
Securities held-to-maturity, AmortizedCosts	295,000	327,000
Securities held-to-maturity, Gross Unrealized Gains	36,000	36,000
Securities held-to-maturity, Gross Unrealized Losses	0	0
Fair value, Total securities held to maturity	331,000	363,000
Corporate Debt Securities [Member]
Securities held-to-maturity, AmortizedCosts	1,422,000	1,419,000
Securities held-to-maturity, Gross Unrealized Gains	31,000	10,000
Securities held-to-maturity, Gross Unrealized Losses	0	2,000
Fair value, Total securities held to maturity	1,453,000	1,427,000
Securities held-to-maturity, AmortizedCosts	138,424,000	152,028,000
Securities held-to-maturity, Gross Unrealized Gains	7,853,000	6,513,000
Securities held-to-maturity, Gross Unrealized Losses	36,000	509,000
Fair value, Total securities held to maturity	$ 146,241,000	$ 158,032,000