Note 13 - Employee Benefit Plans (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Requisite Service Period	3 years
Defined Benefit Plan, Accumulated Benefit Obligation	$ 12,300,000	$ 10,600,000
Defined Benefit Plan, Expected Amortization of Prior Service Cost (Credit), Next Fiscal Year	$ 269,000
Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent	20.00%
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay	4.00%
Defined Contribution Plan, Employer Discretionary Contribution Amount	$ 266,000	235,000
Liability, Defined Benefit Plan, Total	1,900,000	1,800,000
Pension and Other Postretirement Benefits Cost (Reversal of Cost), Total	224,000	156,000
Board of Directors [Member]
Defined Contribution Plan, Employer Discretionary Contribution Amount	$ 140,000	$ 124,000