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Note 4 - Loans Receivable and Allowance for Credit Losses on Loans (Details Textual) | 12 Months Ended
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Dec. 31, 2023 USD ($) | Dec. 31, 2022 USD ($) | Dec. 31, 2021 USD ($)
Financing Receivable, Unamortized Loan Cost (Fee) | $ (8,400,000) | $ (7,800,000) |
Financing Receivable, Unamortized Purchase Premium (Discount) | 2,600,000 | (437,000) |
Financing Receivable, before Allowance for Credit Loss | 2,433,015,000 | 2,218,852,000 | $ 1,754,175,000
Financing Receivable, Modified, Commitment to Lend |  | 0 |
Financing Receivable, Modified, Subsequent Default |  | 0 |
Financing Receivable, 90 Days or More Past Due, Still Accruing | 0 | 0 |
Financing Receivable, Nonaccrual, Interest Income | 579,000 | 506,000 | 351,000
Loans and Leases Receivable, Commitment to Lend, Related Party | 3,700,000 | 3,400,000 |
Commercial Business Portfolio Segment [Member] |  |  |
Financing Receivable, before Allowance for Credit Loss | 255,881,000 | 228,020,000 | $ 241,829,000
Commercial Business Portfolio Segment [Member] | Commercial And Industrial [Member] |  |  |
Financing Receivable, before Allowance for Credit Loss | 238,301,000 | $ 196,791,000 |
Financing Receivable, Modified, Number of Contracts |  | 2 |
Financing Receivable, Modified in Period, Amount |  | $ 3,700,000 |
Asset Pledged as Collateral [Member] | Federal Home Loan Bank Advances [Member] |  |  |
Financing Receivable, before Allowance for Credit Loss | 1,070,000,000.00 | 840,200,000 |
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 | 631,100,000 | 579,800,000 |
Accrued Interest Receivable [Member] |  |  |
Financing Receivable, Accrued Interest, after Allowance for Credit Loss | $ 11,500,000 | $ 9,600,000 |

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- Definition Amount, after allowance for credit loss, of accrued interest on financing receivable. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 45 -Paragraph 5 -Publisher FASB -URI https://asc.fasb.org//1943274/2147479344/326-20-45-5 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 3A -Publisher FASB -URI https://asc.fasb.org//1943274/2147479319/326-20-50-3A + Details
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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. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 310 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 12A -Publisher FASB -URI https://asc.fasb.org//1943274/2147481933/310-10-55-12A Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 310 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 44 -Subparagraph (a)(2) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481962/310-10-50-44 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 310 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 34 -Subparagraph (a)(2) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481962/310-10-50-34 + Details
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- Definition 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. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 310 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481962/310-10-50-4 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 310 -SubTopic 20 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481598/310-20-45-1 Reference 3: http://www.xbrl.org/2003/role/recommendedDisclosureRef -Name Accounting Standards Codification -Section 50 -Paragraph 3 -SubTopic 20 -Topic 310 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481569/310-20-50-3 + Details
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