Note 8 - Commitments and Off-balance Sheet Risk (Details Textual) - USD ($)	Sep. 30, 2023	Jun. 30, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Dec. 31, 2021
Financing Receivable, Allowance for Credit Loss	$ 48,008,000	$ 44,721,000	$ 42,246,000	$ 39,120,000	$ 35,974,000	$ 35,363,000
Retail and Commercial Lines of Credit and Credit Card Receivables Reserve on Commitments [Member] \| Maximum [Member]
Financing Receivable, Allowance for Credit Loss	$ 700,000		$ 100,000

Amount of allowance for credit loss on financing receivable. Excludes allowance for financing receivable covered under loss sharing agreement.

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Name:	us-gaap_FinancingReceivableAllowanceForCreditLosses
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant