Note 14 - Employee Retirement Benefit Plans (Details Textual) - USD ($)		1 Months Ended	12 Months Ended
	Oct. 11, 2016	Oct. 31, 2016	Dec. 31, 2019	Dec. 31, 2018	Jan. 31, 2020	Jul. 01, 2019	Dec. 31, 2016	Dec. 31, 2014
Loan Receivable, ESOP		$ 1,500,000					$ 1,800,000	$ 266,000
Stock Issued During Period, Shares, Employee Stock Purchase Plans	150,358	150,358
Shares Issued, Price Per Share	$ 10	$ 10
Loan Receivable, ESOP, Repayment Term		30 years
Senior Officers and Directors [Member]
Deferred Compensation Arrangement with Individual, Maximum Contractual Term			10 years
Deferred Compensation Arrangement, Stated Interest Rate			5.00%
Deferred Compensation Arrangement, Effective Interest Rate			5.50%	5.00%
Deferred Compensation Arrangement, Interest Expense			$ 77,000	$ 57,000
Deferred Compensation Liability, Current, Total			1,500,000	1,300,000
Multiemployer Plans, Pension [Member] | Pentegra Defined Benefit Plan [Member]
Multiemploye Plan, Contributions by Employer			$ 225,000	82,000
Multiemployer Plan, Contributions by Employer, Percentage			5.00%
Multiemployer Plan, Unfunded Pension Liability						$ 572,000
Multiemployer Plan, Funded Percentage						87.00%
Pension Cost (Reversal of Cost)			$ 158,000	44,000
Multiemployer Plans, Pension [Member] | Pentegra Defined Benefit Plan [Member] | Subsequent Event [Member]
Multiemployer Plans, Expected Future Employer Contributions, Next Fiscal Year					$ 1,500,000
Treasury Stock [Member]
Employee Stock Ownership Plan (ESOP), Compensation Expense			99,000	90,000
Deferred Profit Sharing [Member]
Deferred Compensation Arrangement with Individual, Compensation Expense			$ 336,000	$ 375,000
Profit Sharing Plan [Member]
Defined Contribution Plan, Vesting Period			6 years
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay			4.00%
Profit Sharing Plan, First 3% of Employee Contribution [Member]
Defined Contribution Plan, Employer Matching Contribution, Percent of Match			100.00%
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay			3.00%
Profit Sharing Plan, Next 2% of Employee Contribution [Member]
Defined Contribution Plan, Employer Matching Contribution, Percent of Match			50.00%
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay			2.00%