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Note 3 - Loans Receivable and Allowance for Credit Losses - Loans (Details Textual) Pure in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2024 USD ($)	Sep. 30, 2023 USD ($)	Dec. 31, 2023 USD ($)
Assets [Abstract]
Interest Receivable	$ 14,014,000		$ 14,014,000		$ 14,005,000
Financing Receivable, Unamortized Loan Cost (Fee)	(5,900,000)		(5,900,000)		(8,400,000)
Financing Receivable, Unamortized Purchase Premium (Discount)	2,100,000		2,100,000		2,600,000
Financing Receivable, Accrued Interest, after Allowance for Credit Loss	11,800,000		11,800,000		11,500,000
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	$ 2,494,929,000		$ 2,494,929,000		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	$ 41,000	$ 55,000	$ 244,000	$ 164,000
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, Excluding Accrued Interest, before Allowance for Credit Loss	$ 312,022,000		$ 312,022,000		$ 255,881,000
Commercial Business Portfolio Segment [Member] | Commercial And Industrial [Member]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	296,773,000		296,773,000		238,301,000
Commercial Business Portfolio Segment [Member] | Commercial And Industrial [Member] | SBA USDA Guaranteed Certificates [Member]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	54,800,000		54,800,000		10,600,000
Asset Pledged as Collateral [Member] | Federal Home Loan Bank Advances [Member]
Financing Receivable, Excluding Accrued Interest, 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, Excluding Accrued Interest, before Allowance for Credit Loss	$ 617,900,000		$ 617,900,000		$ 631,100,000

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Amount, after allowance for credit loss, of accrued interest on financing receivable.

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Amortized cost excluding accrued interest, before allowance for credit loss, of financing receivable. Excludes net investment in lease.

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Amount of unamortized loan commitment, origination, and other costs (fees) on financing receivable recognized as adjustment to yield. Excludes financing receivable covered under loss sharing agreement.

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