Note 1 - Significant Accounting Policies - Noninterest Income (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Service Charges on Deposit and Sweep Accounts [Member]
Noninterest revenue	$ 1,064,000	$ 1,495,000	$ 2,041,000	$ 2,910,000
Credit and Debit Card [Member]
Noninterest revenue	2,426,000	2,134,000	4,485,000	4,015,000
Payroll Processing [Member]
Noninterest revenue	572,000	464,000	1,317,000	1,102,000
Customer Service [Member]
Noninterest revenue	$ 187,000	$ 202,000	$ 407,000	$ 444,000