Note 3 - Loans Receivable and Allowance for Credit Losses - Loans (Details Textual) - USD ($)	3 Months Ended	6 Months Ended	12 Months Ended
Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025	Dec. 31, 2025
Financing Receivable, Unamortized Loan Cost (Fee)	$ 7,000,000		$ 7,000,000		$ 8,600,000
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	2,660,157,000		2,660,157,000		2,655,109,000
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff	4,439,000	$ 1,641,000	7,289,000	$ 3,710,000	10,464,000
Financing Receivable, Modified, Commitment to Lend	0		0		0
Financing Receivable, Excluding Accrued Interest, Modified in Period, Amount			0
Financing Receivable, Modified, Subsequent Default	0	0	0	0
Financing Receivable, 90 Days or More Past Due, Still Accruing	0		0		0
Financing Receivable, Nonaccrual, Interest Income	142,000	140,000	274,000	245,000
Real Estate Owned (OREO) [Member]
Mortgage Loans in Process of Foreclosure, Amount	776,000		776,000		156,000
Commercial Business Portfolio Segment [Member]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	288,467,000		288,467,000		329,291,000
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff	39,000	(0)	269,000	433,000	433,000
Commercial Business Portfolio Segment [Member] \| Commercial And Industrial [Member]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	281,181,000		281,181,000		301,111,000
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff			269,000		433,000
Commercial Business Portfolio Segment [Member] \| Commercial And Industrial [Member] \| SBA USDA Guaranteed Certificates [Member]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	38,300,000		38,300,000		44,800,000
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	1,004,990,000		1,004,990,000		969,471,000
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff	2,277,000	$ (0)	2,277,000	$ (0)	2,300,000
Asset Pledged as Collateral [Member] \| Federal Home Loan Bank Advances [Member]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss	1,100,000,000		1,100,000,000		1,080,000,000.00
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	$ 559,000,000		$ 559,000,000		$ 580,900,000

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

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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 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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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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