Note 13 - Employee Benefit Plans (Details Textual) - USD ($)		12 Months Ended
	Dec. 31, 1998	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Contribution Plan, Employer Discretionary Contribution Amount		$ 520,000	$ 478,000	$ 472,000
Stock Purchased by Employee Stock Ownership Plan, Shares	61,501
Employee Stock Ownership Plan (ESOP) Loan Payments From ESOP Loan Term	10 years
Employee Stock Ownership Plan (ESOP), Compensation Expense		$ 0	$ 0	$ 0
Employee Stock Ownership Plan (ESOP), Number of Allocated Shares		52,455	53,181