Note 15 - Assets and Liabilities Measured and Reported at Fair Value (Details) - Assets Measured at Fair Value On a Recurring Basis - USD ($)	Sep. 30, 2015	Dec. 31, 2014
Investment securities available for sale
Investment securities available for sale	$ 504,366,000	$ 513,056,000
Fair Value, Measurements, Recurring [Member]
Investment securities available for sale
Investment securities available for sale	504,366,000	513,056,000
Interest rate swaps	487,000	425,000
Total assets	504,853,000	513,481,000
Liabilities
Interest rate swaps	848,000	401,000
US Treasury and Government [Member] | Fair Value, Measurements, Recurring [Member]
Investment securities available for sale
Investment securities available for sale	100,000,000	70,000,000
US Government-sponsored Enterprises Debt Securities [Member]
Investment securities available for sale
Investment securities available for sale	186,810,000	204,986,000
US Government-sponsored Enterprises Debt Securities [Member] | Fair Value, Measurements, Recurring [Member]
Investment securities available for sale
Investment securities available for sale	186,810,000	204,986,000
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Investment securities available for sale
Investment securities available for sale	154,347,000	174,270,000
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] | Fair Value, Measurements, Recurring [Member]
Investment securities available for sale
Investment securities available for sale	154,347,000	174,270,000
US States and Political Subdivisions Debt Securities [Member]
Investment securities available for sale
Investment securities available for sale	62,508,000	62,834,000
US States and Political Subdivisions Debt Securities [Member] | Fair Value, Measurements, Recurring [Member]
Investment securities available for sale
Investment securities available for sale	62,508,000	62,834,000
Common Stock [Member]
Investment securities available for sale
Investment securities available for sale	701,000	966,000
Common Stock [Member] | Fair Value, Measurements, Recurring [Member]
Investment securities available for sale
Investment securities available for sale	701,000	966,000
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Investment securities available for sale
Investment securities available for sale	100,701,000	70,966,000
Total assets	100,701,000	70,966,000
Fair Value, Inputs, Level 1 [Member] | US Treasury and Government [Member] | Fair Value, Measurements, Recurring [Member]
Investment securities available for sale
Investment securities available for sale	100,000,000	70,000,000
Fair Value, Inputs, Level 1 [Member] | Common Stock [Member] | Fair Value, Measurements, Recurring [Member]
Investment securities available for sale
Investment securities available for sale	701,000	966,000
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Investment securities available for sale
Investment securities available for sale	403,665,000	442,090,000
Interest rate swaps	487,000	425,000
Total assets	404,152,000	442,515,000
Liabilities
Interest rate swaps	848,000	401,000
Fair Value, Inputs, Level 2 [Member] | US Government-sponsored Enterprises Debt Securities [Member] | Fair Value, Measurements, Recurring [Member]
Investment securities available for sale
Investment securities available for sale	186,810,000	204,986,000
Fair Value, Inputs, Level 2 [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] | Fair Value, Measurements, Recurring [Member]
Investment securities available for sale
Investment securities available for sale	154,347,000	174,270,000
Fair Value, Inputs, Level 2 [Member] | US States and Political Subdivisions Debt Securities [Member] | Fair Value, Measurements, Recurring [Member]
Investment securities available for sale
Investment securities available for sale	62,508,000	62,834,000
Fair Value, Inputs, Level 3 [Member]
Investment securities available for sale
Total assets	$ 0	$ 0