Note 1 - Significant Accounting Policies - Noninterest Income (Details) - USD ($)	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Service Charges on Deposit and Sweep Accounts [Member]
Noninterest revenue	$ 1,416,000	$ 1,155,000
Credit and Debit Card [Member]
Noninterest revenue	1,881,000	1,678,000
Payroll Processing [Member]
Noninterest revenue	638,000	557,000
Customer Service [Member]
Noninterest revenue	$ 242,000	$ 223,000