Note 1 - Significant Accounting Policies - Noninterest Income (Details) - USD ($)	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Service Charges on Deposit and Sweep Accounts [Member]
Noninterest revenue	$ 976,000	$ 1,416,000
Credit and Debit Card [Member]
Noninterest revenue	2,060,000	1,881,000
Payroll Processing [Member]
Noninterest revenue	746,000	638,000
Customer Service [Member]
Noninterest revenue	$ 220,000	$ 242,000