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Note 3 - Loans Receivable and Allowance for Credit Losses - Loans (Details Textual) Pure in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024 USD ($)	Jun. 30, 2023 USD ($)	Jun. 30, 2024 USD ($)	Jun. 30, 2023 USD ($)	Dec. 31, 2023 USD ($)
Assets [Abstract]
Interest Receivable	$ 13,792,000		$ 13,792,000		$ 14,005,000
Financing Receivable, Unamortized Loan Cost (Fee)	(7,200,000)		(7,200,000)		(8,400,000)
Financing Receivable, Unamortized Purchase Premium (Discount)	2,200,000		2,200,000		2,600,000
Financing Receivable, Accrued Interest, after Allowance for Credit Loss	11,800,000		11,800,000		11,500,000
Financing Receivable, before Allowance for Credit Loss	$ 2,488,422,000		$ 2,488,422,000		2,433,015,000
Financing Receivable, Modified, Subsequent Default, Number of Contracts	0	0	0	0
Financing Receivable, Modified, Commitment to Lend	$ 0		$ 0
Financing Receivable, 90 Days or More Past Due, Still Accruing	0		0		$ 0
Financing Receivable, Nonaccrual, Interest Income	$ 92,000	$ 106,000	$ 203,000	$ 168,000
Financing Receivable, Accrued Interest, after Allowance for Credit Loss, Statement of Financial Position [Extensible Enumeration]	Interest Receivable		Interest Receivable		Interest Receivable
Commercial Business Portfolio Segment [Member]
Financing Receivable, before Allowance for Credit Loss	$ 310,731,000		$ 310,731,000		$ 255,881,000
Commercial Business Portfolio Segment [Member] | Commercial And Industrial [Member]
Financing Receivable, before Allowance for Credit Loss	285,183,000		285,183,000		238,301,000
Commercial Business Portfolio Segment [Member] | Commercial And Industrial [Member] | SBA USDA Guaranteed Certificates [Member]
Financing Receivable, before Allowance for Credit Loss	35,200,000		35,200,000		10,600,000
Asset Pledged as Collateral [Member] | Federal Home Loan Bank Advances [Member]
Financing Receivable, before Allowance for Credit Loss	1,110,000,000		1,110,000,000		1,070,000,000.00
Asset Pledged as Collateral [Member] | Federal Home Loan Bank Advances [Member] | Federal Home Loan Bank of San Francisco [Member]
Financing Receivable, before Allowance for Credit Loss	$ 627,100,000		$ 627,100,000		$ 631,100,000

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