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Note 4 - Loans Receivable and Allowance for Credit Losses - Loans (Details Textual) Pure in Thousands	3 Months Ended
	Mar. 31, 2024 USD ($)	Mar. 31, 2023 USD ($)	Dec. 31, 2023 USD ($)
Assets [Abstract]
Interest Receivable	$ 14,455,000		$ 14,005,000
Financing Receivable, Unamortized Loan Cost (Fee)	(7,500,000)		(8,400,000)
Financing Receivable, Unamortized Purchase Premium (Discount)	2,400,000		2,600,000
Financing Receivable, Accrued Interest, after Allowance for Credit Loss	$ 11,600,000		$ 11,500,000
Financing Receivable, Accrued Interest, after Allowance for Credit Loss, Statement of Financial Position [Extensible Enumeration]	Interest Receivable		Interest Receivable
Financing Receivable, before Allowance for Credit Loss	$ 2,446,858,000		$ 2,433,015,000
Financing Receivable, Modified, Subsequent Default, Number of Contracts	0	0
Financing Receivable, Modified, Commitment to Lend	$ 0
Financing Receivable, 90 Days or More Past Due, Still Accruing	0		0
Financing Receivable, Nonaccrual, Interest Income	111,000	$ 62,000
Asset Pledged as Collateral [Member] | Federal Home Loan Bank Advances [Member]
Financing Receivable, before Allowance for Credit Loss	1,090,000,000.00		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	$ 632,800,000		$ 631,100,000

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

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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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