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Note 3 - Loans Receivable and Allowance for Credit Losses - Loans (Details Textual) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended	18 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024	Sep. 30, 2025
Financing Receivable, Unamortized Loan Cost (Fee)	$ 8,900,000		$ 8,900,000		$ 8,000,000	$ 8,900,000
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	2,629,657,000		2,629,657,000		2,533,821,000	2,629,657,000
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff	4,344,000	$ 1,964,000	8,054,000	$ 5,606,000	7,135,000
Financing Receivable, Modified, Commitment to Lend	292,000		292,000			292,000
Financing Receivable, Modified, Subsequent Default						0
Financing Receivable, 90 Days or More Past Due, Still Accruing	0		0		0	0
Financing Receivable, Nonaccrual, Interest Income	146,000	41,000	391,000	244,000
Real Estate Owned (OREO) [Member]
Mortgage Loans in Process of Foreclosure, Amount	792,000		792,000		84,000	792,000
Commercial Business Portfolio Segment [Member]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	326,286,000		326,286,000		299,932,000	326,286,000
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff	(0)	(0)	433,000	1,141,000	1,141,000
Commercial Business Portfolio Segment [Member] | Commercial And Industrial [Member]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	311,173,000		311,173,000		287,014,000	311,173,000
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff			433,000		1,141,000
Commercial Business Portfolio Segment [Member] | Commercial And Industrial [Member] | SBA USDA Guaranteed Certificates [Member]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	46,100,000		46,100,000		52,600,000	46,100,000
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	932,689,000		932,689,000		871,337,000	932,689,000
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff	2,300,000	$ (0)	2,300,000	$ (0)
Asset Pledged as Collateral [Member] | Federal Home Loan Bank Advances [Member]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	1,070,000,000.00		1,070,000,000.00		1,110,000,000	1,070,000,000.00
Asset Pledged as Collateral [Member] | Federal Reserve Bank [Member] | Federal Reserve Bank of San Francisco [Member]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	$ 585,200,000		$ 585,200,000		$ 606,500,000	$ 585,200,000

X

- Definition

Amount, excluding accrued interest, of decrease in allowance for credit loss on financing receivable from writeoff. Excludes net investment in lease.

+ References

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-SubTopic 20
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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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Recorded investment of consumer mortgage loan receivables secured by residential real estate properties for which formal foreclosure proceedings are in process.

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