Note 6 - Investment Securities - Amortized Costs and Estimated Fair Value of the Securities Portfolio (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Available for Sale Securities - Amortized Cost	$ 448,995	$ 486,038
Available for Sale Securities - Gross Unrealized Gains	2,630	2,518
Available for Sale Securities - Gross Unrealized Losses	4,110	7,692
Available for Sale Securities - Estimated Fair Value	447,515	480,864
Held to Maturity Securities - Amortized Cost	3,448	3,488
Held to Maturity Securities - Estimated Fair Value	3,597	3,597
US Government-sponsored Enterprises Debt Securities [Member]
Available for Sale Securities - Amortized Cost	72,945	71,941
Available for Sale Securities - Gross Unrealized Gains	132	213
Available for Sale Securities - Gross Unrealized Losses	337	460
Available for Sale Securities - Estimated Fair Value	72,740	71,694
US States and Political Subdivisions Debt Securities [Member]
Available for Sale Securities - Amortized Cost	121,403	134,055
Available for Sale Securities - Gross Unrealized Gains	1,021	773
Available for Sale Securities - Gross Unrealized Losses	837	2,536
Available for Sale Securities - Estimated Fair Value	121,587	132,292
Held to Maturity Securities - Amortized Cost	3,448	3,488
Held to Maturity Securities - Gross Unrealized Gains	149	109
Held to Maturity Securities - Gross Unrealized Losses	0	0
Held to Maturity Securities - Estimated Fair Value	3,597	3,597
Residential Mortgage Backed Securities [Member]
Available for Sale Securities - Amortized Cost	200,058	225,489
Available for Sale Securities - Gross Unrealized Gains	1,360	1,505
Available for Sale Securities - Gross Unrealized Losses	1,819	2,687
Available for Sale Securities - Estimated Fair Value	199,599	224,307
Commercial Mortgage Backed Securities [Member]
Available for Sale Securities - Amortized Cost	46,173	47,164
Available for Sale Securities - Gross Unrealized Gains	1	6
Available for Sale Securities - Gross Unrealized Losses	1,114	1,557
Available for Sale Securities - Estimated Fair Value	45,060	45,613
Corporate Debt Securities [Member]
Available for Sale Securities - Amortized Cost	7,576	6,565
Available for Sale Securities - Gross Unrealized Gains	51	1
Available for Sale Securities - Gross Unrealized Losses	3	441
Available for Sale Securities - Estimated Fair Value	7,624	6,125
Mutual Funds and Equity Securities [Member]
Available for Sale Securities - Amortized Cost	840	824
Available for Sale Securities - Gross Unrealized Gains	65	20
Available for Sale Securities - Gross Unrealized Losses	0	11
Available for Sale Securities - Estimated Fair Value	$ 905	$ 833

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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-Name Accounting Standards Codification
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