Note 4 - Premises and Equipment, Net - Summary of Premises and Equipment (Details) - USD ($)	Sep. 30, 2019	Dec. 31, 2018
Property, plant and equipment, gross	$ 90,642,000	$ 81,699,000
Less: accumulated depreciation	36,057,000	33,378,000
Premises and equipment, net	54,585,000	48,321,000
Land and Land Improvements [Member]
Property, plant and equipment, gross	18,217,000	18,198,000
Building [Member]
Property, plant and equipment, gross	51,140,000	45,362,000
Furniture and Fixtures [Member]
Property, plant and equipment, gross	$ 21,285,000	$ 18,139,000