Note 3 - Securities - Securities Held-to-maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Securities held-to-maturity, Amortized Costs	$ 134,957	$ 152,028
Securities held-to-maturity, Gross Unrealized Gains	3,817	6,513
Securities held-to-maturity, Gross Unrealized Losses	1,082	509
Securities held-to-maturity, Fair Values	137,692	158,032
US Government Agencies Debt Securities [Member]
Securities held-to-maturity, Amortized Costs	3,934	13,909
Securities held-to-maturity, Gross Unrealized Gains	201	288
Securities held-to-maturity, Gross Unrealized Losses	0	177
Securities held-to-maturity, Fair Values	4,135	14,020
US States and Political Subdivisions Debt Securities [Member]
Securities held-to-maturity, Amortized Costs	129,783	136,373
Securities held-to-maturity, Gross Unrealized Gains	3,579	6,179
Securities held-to-maturity, Gross Unrealized Losses	1,082	330
Securities held-to-maturity, Fair Values	132,280	142,222
Collateralized Mortgage Backed Securities [Member]
Securities held-to-maturity, Amortized Costs	265	327
Securities held-to-maturity, Gross Unrealized Gains	30	36
Securities held-to-maturity, Gross Unrealized Losses	0	0
Securities held-to-maturity, Fair Values	295	363
Corporate Debt Securities [Member]
Securities held-to-maturity, Amortized Costs	975	1,419
Securities held-to-maturity, Gross Unrealized Gains	7	10
Securities held-to-maturity, Gross Unrealized Losses	0	2
Securities held-to-maturity, Fair Values	$ 982	$ 1,427