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Note 3 - Loans Receivable and Allowance for Credit Losses - Loans (Details Textual) - USD ($)	3 Months Ended		6 Months Ended		15 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Dec. 31, 2024
Financing Receivable, Unamortized Loan Cost (Fee)	$ 8,700,000		$ 8,700,000		$ 8,700,000	$ 8,000,000
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	2,614,461,000		2,614,461,000		2,614,461,000	2,533,821,000
Financing Receivable, Modified, Commitment to Lend	1,200,000		1,200,000		1,200,000
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	140,000	$ 92,000	245,000	$ 203,000
Real Estate Owned (OREO) [Member]
Mortgage Loans in Process of Foreclosure, Amount	1,500,000		1,500,000		1,500,000	84,000
Commercial Business Portfolio Segment [Member]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	312,515,000		312,515,000		312,515,000	299,932,000
Commercial Business Portfolio Segment [Member] | Commercial And Industrial [Member]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	294,563,000		294,563,000		294,563,000	287,014,000
Commercial Business Portfolio Segment [Member] | Commercial And Industrial [Member] | SBA USDA Guaranteed Certificates [Member]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	48,800,000		48,800,000		48,800,000	52,600,000
Asset Pledged as Collateral [Member] | Federal Home Loan Bank Advances [Member]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	1,090,000,000.00		1,090,000,000.00		1,090,000,000.00	1,110,000,000
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	$ 591,000,000		$ 591,000,000		$ 591,000,000	$ 606,500,000

X

- Definition

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

+ References

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- Definition

Amortized cost of financing receivable with payment default in current period and modified within previous 12 months preceding payment default for debtor experiencing financial difficulty.

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Amount of interest income on financing receivable on nonaccrual status.

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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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Amount of commitment to lend additional funds to debtor experiencing financial difficulty for which creditor has modified terms of financing receivable.

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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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