Note 19 - Fair Value Measurements - Available for Sale Investment Securities Measured At Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Available for Sale Securities - Estimated Fair Value	$ 424,253	$ 480,864
Fair Value, Inputs, Level 1 [Member]
Available for Sale Securities - Estimated Fair Value	935	833
Fair Value, Inputs, Level 2 [Member]
Available for Sale Securities - Estimated Fair Value	423,318	480,031
Fair Value, Inputs, Level 3 [Member]
Available for Sale Securities - Estimated Fair Value	0	0
US Government-sponsored Enterprises Debt Securities [Member]
Available for Sale Securities - Estimated Fair Value	43,208	71,694
US Government-sponsored Enterprises Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Available for Sale Securities - Estimated Fair Value	0	0
US Government-sponsored Enterprises Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Available for Sale Securities - Estimated Fair Value	43,208	71,694
US Government-sponsored Enterprises Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Available for Sale Securities - Estimated Fair Value	0	0
US States and Political Subdivisions Debt Securities [Member]
Available for Sale Securities - Estimated Fair Value	114,249	132,292
US States and Political Subdivisions Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Available for Sale Securities - Estimated Fair Value	0	0
US States and Political Subdivisions Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Available for Sale Securities - Estimated Fair Value	114,249	132,292
US States and Political Subdivisions Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Available for Sale Securities - Estimated Fair Value	0	0
Residential Mortgage Backed Securities [Member]
Available for Sale Securities - Estimated Fair Value	193,393	224,307
Residential Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Available for Sale Securities - Estimated Fair Value	0	0
Residential Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Available for Sale Securities - Estimated Fair Value	193,393	224,307
Residential Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Available for Sale Securities - Estimated Fair Value	0	0
Commercial Mortgage Backed Securities [Member]
Available for Sale Securities - Estimated Fair Value	49,352	45,613
Commercial Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Available for Sale Securities - Estimated Fair Value	0	0
Commercial Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Available for Sale Securities - Estimated Fair Value	49,352	45,613
Commercial Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Available for Sale Securities - Estimated Fair Value	0	0
Asset-backed Securities [Member]
Available for Sale Securities - Estimated Fair Value	15,574
Asset-backed Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Available for Sale Securities - Estimated Fair Value	0
Asset-backed Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Available for Sale Securities - Estimated Fair Value	15,574
Asset-backed Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Available for Sale Securities - Estimated Fair Value	0
Corporate Debt Securities [Member]
Available for Sale Securities - Estimated Fair Value	7,542	6,125
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Available for Sale Securities - Estimated Fair Value	0	0
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Available for Sale Securities - Estimated Fair Value	7,542	6,125
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Available for Sale Securities - Estimated Fair Value	0	0
Mutual Funds and Equity Securities [Member]
Available for Sale Securities - Estimated Fair Value	935	833
Mutual Funds and Equity Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Available for Sale Securities - Estimated Fair Value	935	833
Mutual Funds and Equity Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Available for Sale Securities - Estimated Fair Value	0	0
Mutual Funds and Equity Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Available for Sale Securities - Estimated Fair Value	$ 0	$ 0