Note 17 - Employee Benefit Plans (Details Textual) - USD ($) $ in Thousands	12 Months Ended			31 Months Ended	255 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2020	May 31, 2018
Minimum Number of Years Allowed to Participate in Employee Stock Ownership Plan (Year)	2 years
Stock Issued During Period, Shares, Employee Stock Ownership Plan (in shares)	32,128	22,933	17,559
Stock Issued During Period, Value, Employee Stock Ownership Plan	$ 818	$ 827	$ 706
Employee Stock Ownership Plan (ESOP), Number of Allocated Shares (in shares)	33,629	22,309	58,988	33,629
Employee Stock Ownership Plan (ESOP), Shares in ESOP, Total (in shares)	777,128			777,128
Percentage of Outstanding Common Stock under Employee Stock Ownership Plan	1.00%			1.00%
Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent					75.00%
Defined Contribution Plan, Employers Matching Contribution, Vesting Percentage, Less Than Two Years of Service					0.00%
Defined Contribution Plan, Employers Matching Contribution, Vesting Percentage, After Two Years of Service					25.00%
Defined Contribution Plan, Employers Matching Contribution, Vesting Percentage, After Two Years of Service, Increment					25.00%
Defined Contribution Plan, Employers Matching Contribution, Vesting Percentage, After Five Years of Service					100.00%
Defined Contribution Plan, Employer Matching Contribution, Percent of Match				100.00%
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay				5.00%
Defined Contribution Plan, Employer Discretionary Contribution Amount	$ 3,700	$ 3,500	$ 3,100
Percentage of Participant Borrowing Capacity of Vested Amount	50.00%
Cash Surrender Value of Life Insurance	$ 52,200			$ 52,200
Maximum [Member]
Employee Stock Ownership Plan (ESOP), Debt Structure, Direct Loan, Employer Cash Payments Used for Debt Service	50
Minimum [Member]
Employee Stock Ownership Plan (ESOP), Debt Structure, Direct Loan, Employer Cash Payments Used for Debt Service	$ 1