Note 3 - Loans and Allowance for Loan Losses - Loans Modified As Troubled Debt Restructurings Within the Previous Twelve Months That Became Over 30 Days Past Due (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)
Number of Contracts	0	0	1	1
Recorded Principal Balance	$ 0	$ 0	$ 31,000	$ 6,000
Commercial Portfolio Segment [Member]
Number of Contracts	0	0	0	0
Recorded Principal Balance	$ 0	$ 0	$ 0	$ 0
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Number of Contracts	0	0	0	0
Recorded Principal Balance	$ 0	$ 0	$ 0	$ 0
Commercial Portfolio Segment [Member] | Vacant Land and Land Development and Residential Construction Loan [Member]
Number of Contracts	0	0	0	0
Recorded Principal Balance	$ 0	$ 0	$ 0	$ 0
Commercial Portfolio Segment [Member] | Real Estate Owner Occupied Loan [Member]
Number of Contracts	0	0	0	0
Recorded Principal Balance	$ 0	$ 0	$ 0	$ 0
Commercial Portfolio Segment [Member] | Real Estate Non Owner Occupied Loan [Member]
Number of Contracts	0	0	0	0
Recorded Principal Balance	$ 0	$ 0	$ 0	$ 0
Commercial Portfolio Segment [Member] | Real Estate Multi Family and Residential Rental Loan [Member]
Number of Contracts	0	0	0	0
Recorded Principal Balance	$ 0	$ 0	$ 0	$ 0
Retail Portfolio Segment [Member]
Number of Contracts	0	0	1	1
Recorded Principal Balance	$ 0	$ 0	$ 31,000	$ 6,000
Retail Portfolio Segment [Member] | Home Equity and Other [Member]
Number of Contracts	0	0	0	0
Recorded Principal Balance	$ 0	$ 0	$ 0	$ 0
Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
Number of Contracts	0	0	1	1
Recorded Principal Balance	$ 0	$ 0	$ 31,000	$ 6,000