Note 5 - Securities - Securities Held-to-maturity (Details) - USD ($)	Mar. 31, 2016	Dec. 31, 2015
US Government Agencies Debt Securities [Member]
Securities held-to-maturity, AmortizedCosts	$ 8,909,000	$ 13,909,000
Securities held-to-maturity, Gross Unrealized Gains	374,000	288,000
Securities held-to-maturity, Gross Unrealized Losses	30,000	177,000
Total securities held to maturity	9,253,000	14,020,000
US States and Political Subdivisions Debt Securities [Member]
Securities held-to-maturity, AmortizedCosts	134,023,000	136,373,000
Securities held-to-maturity, Gross Unrealized Gains	6,390,000	6,179,000
Securities held-to-maturity, Gross Unrealized Losses	212,000	330,000
Total securities held to maturity	140,201,000	142,222,000
Collateralized Mortgage Backed Securities [Member]
Securities held-to-maturity, AmortizedCosts	312,000	327,000
Securities held-to-maturity, Gross Unrealized Gains	37,000	36,000
Securities held-to-maturity, Gross Unrealized Losses	0	0
Total securities held to maturity	349,000	363,000
Corporate Debt Securities [Member]
Securities held-to-maturity, AmortizedCosts	1,420,000	1,419,000
Securities held-to-maturity, Gross Unrealized Gains	31,000	10,000
Securities held-to-maturity, Gross Unrealized Losses	1,000	2,000
Total securities held to maturity	1,450,000	1,427,000
Securities held-to-maturity, AmortizedCosts	144,664,000	152,028,000
Securities held-to-maturity, Gross Unrealized Gains	6,832,000	6,513,000
Securities held-to-maturity, Gross Unrealized Losses	243,000	509,000
Total securities held to maturity	$ 151,253,000	$ 158,032,000