Note 5 - Premises and Equipment - Components of Premises and Equipment (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Building [Member] | Minimum
Useful lives (Year)	15 years	15 years
Building [Member] | Maximum
Useful lives (Year)	50 years	50 years
Furniture and Fixtures [Member] | Minimum
Useful lives (Year)	3 years	3 years
Furniture and Fixtures [Member] | Maximum
Useful lives (Year)	10 years	10 years