Note 4 - Premises and Equipment, Net - Summary of Premises and Equipment (Details) - USD ($)	Sep. 30, 2017	Dec. 31, 2016
Property, plant and equipment, gross	$ 75,989,000	$ 74,171,000
Less: accumulated depreciation	30,383,000	28,715,000
Premises and equipment, net	45,606,000	45,456,000
Land and Land Improvements [Member]
Property, plant and equipment, gross	17,970,000	16,649,000
Building [Member]
Property, plant and equipment, gross	40,245,000	40,327,000
Furniture and Fixtures [Member]
Property, plant and equipment, gross	$ 17,774,000	$ 17,195,000