Note 1 - Nature of Operations and Summary of Significant Accounting Policies - Estimated Useful Lives of Property, Plant and Equipment (Details)	12 Months Ended
	Dec. 31, 2020
Building and Building Improvements [Member] | Minimum [Member]
Premises and equipment, useful life (Year)	35 years
Building and Building Improvements [Member] | Maximum [Member]
Premises and equipment, useful life (Year)	40 years
Furniture and Fixtures and Vehicles [Member] | Minimum [Member]
Premises and equipment, useful life (Year)	3 years
Furniture and Fixtures and Vehicles [Member] | Maximum [Member]
Premises and equipment, useful life (Year)	10 years