Significant Accounting Policies (Policies)	9 Months Ended
Sep. 30, 2024
Accounting Policies [Abstract]
Basis of Accounting, Policy [Policy Text Block]	Basis of presentation - The accompanying unaudited interim consolidated financial statements have been prepared pursuant to the rules and regulations of the U.S. Securities and Exchange Commission ("SEC"). Accordingly, they do not include all the information and footnotes required by U.S. Generally Accepted Accounting Principles ("GAAP") for complete financial statements. These unaudited interim consolidated financial statements should be read in conjunction with our audited consolidated financial statements and accompanying notes included in the Company's Annual Report on Form 10-K for the year ended December 31, 2023. In our opinion, all adjustments (consisting only of normal recurring adjustments) considered necessary for a fair presentation of the consolidated financial statements in accordance with GAAP have been included. Operating results for the three and nine months ended September 30, 2024, are not necessarily indicative of the results that may be expected for future periods. In preparing the unaudited interim consolidated financial statements, we are required to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues, and expenses. Actual results could differ from those estimates. Material estimates that are particularly susceptible to significant change in the near term relate to a determination of the allowance for credit losses ("ACL"), fair value of financial instruments and derivatives, and deferred tax assets and liabilities.
Reclassification, Comparability Adjustment [Policy Text Block]	Restatement - On October 21, 2024, the Audit Committee of the Board of Directors (the "Audit Committee") of the Company, based on the recommendation of, and after consultation with, the Company’s management and independent registered public accounting firm, concluded that certain charge-offs of commercial construction loans, commercial business loans and the Splash unsecured consumer loan program as well as increased provision on Splash consumer loans should have been reported in the interim period ending June 30, 2024. On October 25, 2024, the Company filed amendments to its quarterly report for the period ended June 30, 2024 to restate the consolidated financial statements included therein. The consolidated financial statements as of and for the nine months ended September 30, 2024, reflect the effects of the restatement as of and for the period ended June 30, 2024.
Consolidation, Policy [Policy Text Block]	Principles of consolidation - The accompanying consolidated financial statements include the accounts of First Northwest; its wholly owned subsidiary, First Fed, and its former controlling interest in Quin Ventures. All material intercompany accounts and transactions have been eliminated in consolidation. Through June 2023, First Northwest and POM shared equal ownership in Quin Ventures; however, it was previously determined that First Northwest had a controlling interest for financial reporting purposes under Accounting Standards Codification Topic 810. The Quin Ventures net loss allocable to POM is shown on the financial statements where applicable through a noncontrolling interest adjustment.
Subsequent Events, Policy [Policy Text Block]	Subsequent events - The Company has evaluated subsequent events for potential recognition and disclosure.
New Accounting Pronouncements, Policy [Policy Text Block]	Recently adopted accounting pronouncements In June 2022, the FASB issued ASU No. 2022- 03, Fair Value Measurement (Topic 820): Fair Value Measurement of Equity Securities Subject to Contractual Sale Restrictions. ASU 2022- 03 clarifies that a contractual restriction on the sale of an equity security should not be considered in measuring fair value, nor should the contractual restriction be recognized and measured separately. Further, this ASU requires disclosure of the fair value of equity securities subject to contractual sale restrictions reflected in the balance sheet, the nature and remaining duration of the restriction(s), and the circumstances that could cause a lapse in the restriction(s). ASU 2022- 03 is effective for the Company for fiscal years beginning after December 15, 2023, including interim periods within those fiscal years, with early adoption permitted. The adoption of this ASU did not have a material impact on the consolidated financial statements and related disclosures. In March 2023, the FASB issued ASU 2023-02, Investments - Equity Method and Joint Ventures (Topic 323): Accounting for Investments in Tax Credit Structures Using the Proportional Amortization Method, a consensus of the Emerging Issues Task Force. ASU 2023-02 allows an entity the option to apply the proportional amortization method of accounting to other equity investments that are made for the primary purpose of receiving tax credits or other income tax benefits if certain conditions are met. Prior to this ASU, the application of the proportional amortization method of accounting was limited to investments in low-income housing tax credit structures. The proportional amortization method of accounting results in the amortization of applicable investments, as well as the related income tax credits or other income tax benefits received, being presented on a single line in the statements of income, income tax expense. Under this ASU, an entity has the option to apply the proportional amortization method of accounting to applicable investments on a tax-credit-program-by-tax-credit-program basis. In addition, the amendments in this ASU require that all tax equity investments accounted for using the proportional amortization method use the delayed equity contribution guidance in paragraph 323-740-25-3, requiring a liability to be recognized for delayed equity contributions that are unconditional and legally binding or for equity contributions that are contingent upon a future event when that contingent event becomes probable. Under this ASU, low-income housing tax credit investments for which the proportional amortization method is not applied can no longer be accounted for using the delayed equity contribution guidance. Further, this ASU specifies that impairment of low-income housing tax credit investments not accounted for using the equity method must apply the impairment guidance in Subtopic 323-10: Investments - Equity Method and Joint Ventures - Overall. This ASU also clarifies that for low-income housing tax credit investments not accounted for under the proportional amortization method or the equity method, an entity shall account for them under Topic 321: Investments - Equity Securities. The amendments in this ASU also require additional disclosures in interim and annual periods concerning investments for which the proportional amortization method is applied, including (i) the nature of tax equity investments, and (ii) the effect of tax equity investments and related income tax credits and other income tax benefits on the financial position and results of operations. ASU 2023-02 is effective for the Company for fiscal years beginning after December 15, 2023, including interim periods within those fiscal years, with early adoption permitted. The adoption of this ASU did not have a material impact on the consolidated financial statements and related disclosures. In November 2023, the FASB issued ASU 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures. ASU 2023-07 requires public companies to provide more transparency in both quarterly and annual reports about the expenses they incur from revenue generating business units to better understand the Company's overall performance and potential future cash flows. The Company has identified one reporting segment. ASU 2023-07 is effective for the Company for fiscal years beginning after December 15, 2023, including interim periods within those fiscal years, with early adoption permitted. The adoption of this ASU did not have a material impact on the consolidated financial statements and related disclosures. *Recently issued accounting pronouncements not* yet adopted** In March 2024, the FASB issued ASU 2024-01, Compensation—Stock Compensation (Topic 718): Scope Application of Profits Interest and Similar Awards. ASU 2024-01 added an illustrative example to demonstrate how an entity should apply the scope guidance in paragraph 718-10-15-3 to determine whether a profits interest award should be accounted for in accordance with Topic 718. Awards not meeting the criteria should be accounted for in accordance with Topic 710. The illustrative example provides four fact patterns which are intended to reduce complexity in determining whether a profits interest award is subject to the guidance in Topic 718 and reduce existing diversity in practice. ASU 2024-01 is effective for the Company for fiscal years beginning after December 15, 2024, including interim periods within those fiscal years, with early adoption permitted. The adoption of this ASU is not expected to have a material impact on the consolidated financial statements and related disclosures. In November 2024, the FASB issued ASU 2024-03, Income Statement—Reporting Comprehensive Income—Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses. ASU 2024-03 requires additional disclosure of the nature of expenses included in the income statement in response to requests from investors for more information to better understand an entity's performance and potential future cash flows. The new standard requires disclosures about specific types of expenses included in the expense captions presented on the face of the income statement as well as disclosures about selling expenses. ASU 2024-03 is effective for the Company for fiscal years beginning after December 15, 2026, including interim periods within those fiscal years, with early adoption permitted. The adoption of this ASU is not expected to have a material impact on the consolidated financial statements and related disclosures.

Significant Accounting Policies (Policies)

9 Months Ended

Sep. 30, 2024

Basis of Accounting, Policy [Policy Text Block]

Basis of presentation - The accompanying unaudited interim consolidated financial statements have been prepared pursuant to the rules and regulations of the U.S. Securities and Exchange Commission ("SEC"). Accordingly, they do not include all the information and footnotes required by U.S. Generally Accepted Accounting Principles ("GAAP") for complete financial statements. These unaudited interim consolidated financial statements should be read in conjunction with our audited consolidated financial statements and accompanying notes included in the Company's Annual Report on Form 10-K for the year ended December 31, 2023. In our opinion, all adjustments (consisting only of normal recurring adjustments) considered necessary for a fair presentation of the consolidated financial statements in accordance with GAAP have been included. Operating results for the three and nine months ended September 30, 2024, are not necessarily indicative of the results that may be expected for future periods.

In preparing the unaudited interim consolidated financial statements, we are required to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues, and expenses. Actual results could differ from those estimates. Material estimates that are particularly susceptible to significant change in the near term relate to a determination of the allowance for credit losses ("ACL"), fair value of financial instruments and derivatives, and deferred tax assets and liabilities.

Reclassification, Comparability Adjustment [Policy Text Block]

Restatement - On October 21, 2024, the Audit Committee of the Board of Directors (the "Audit Committee") of the Company, based on the recommendation of, and after consultation with, the Company’s management and independent registered public accounting firm, concluded that certain charge-offs of commercial construction loans, commercial business loans and the Splash unsecured consumer loan program as well as increased provision on Splash consumer loans should have been reported in the interim period ending June 30, 2024. On October 25, 2024, the Company filed amendments to its quarterly report for the period ended June 30, 2024 to restate the consolidated financial statements included therein. The consolidated financial statements as of and for the nine months ended September 30, 2024, reflect the effects of the restatement as of and for the period ended June 30, 2024.

Consolidation, Policy [Policy Text Block]

Principles of consolidation - The accompanying consolidated financial statements include the accounts of First Northwest; its wholly owned subsidiary, First Fed, and its former controlling interest in Quin Ventures. All material intercompany accounts and transactions have been eliminated in consolidation. Through June 2023, First Northwest and POM shared equal ownership in Quin Ventures; however, it was previously determined that First Northwest had a controlling interest for financial reporting purposes under Accounting Standards Codification Topic 810. The Quin Ventures net loss allocable to POM is shown on the financial statements where applicable through a noncontrolling interest adjustment.

Subsequent Events, Policy [Policy Text Block]

Subsequent events - The Company has evaluated subsequent events for potential recognition and disclosure.

New Accounting Pronouncements, Policy [Policy Text Block]

Recently adopted accounting pronouncements

In June 2022, the FASB issued ASU No. 2022- 03, Fair Value Measurement (Topic 820): Fair Value Measurement of Equity Securities Subject to Contractual Sale Restrictions. ASU 2022- 03 clarifies that a contractual restriction on the sale of an equity security should not be considered in measuring fair value, nor should the contractual restriction be recognized and measured separately. Further, this ASU requires disclosure of the fair value of equity securities subject to contractual sale restrictions reflected in the balance sheet, the nature and remaining duration of the restriction(s), and the circumstances that could cause a lapse in the restriction(s). ASU 2022- 03 is effective for the Company for fiscal years beginning after December 15, 2023, including interim periods within those fiscal years, with early adoption permitted. The adoption of this ASU did not have a material impact on the consolidated financial statements and related disclosures.

In March 2023, the FASB issued ASU 2023-02, Investments - Equity Method and Joint Ventures (Topic 323): Accounting for Investments in Tax Credit Structures Using the Proportional Amortization Method, a consensus of the Emerging Issues Task Force. ASU 2023-02 allows an entity the option to apply the proportional amortization method of accounting to other equity investments that are made for the primary purpose of receiving tax credits or other income tax benefits if certain conditions are met. Prior to this ASU, the application of the proportional amortization method of accounting was limited to investments in low-income housing tax credit structures. The proportional amortization method of accounting results in the amortization of applicable investments, as well as the related income tax credits or other income tax benefits received, being presented on a single line in the statements of income, income tax expense. Under this ASU, an entity has the option to apply the proportional amortization method of accounting to applicable investments on a tax-credit-program-by-tax-credit-program basis. In addition, the amendments in this ASU require that all tax equity investments accounted for using the proportional amortization method use the delayed equity contribution guidance in paragraph 323-740-25-3, requiring a liability to be recognized for delayed equity contributions that are unconditional and legally binding or for equity contributions that are contingent upon a future event when that contingent event becomes probable. Under this ASU, low-income housing tax credit investments for which the proportional amortization method is not applied can no longer be accounted for using the delayed equity contribution guidance. Further, this ASU specifies that impairment of low-income housing tax credit investments not accounted for using the equity method must apply the impairment guidance in Subtopic 323-10: Investments - Equity Method and Joint Ventures - Overall. This ASU also clarifies that for low-income housing tax credit investments not accounted for under the proportional amortization method or the equity method, an entity shall account for them under Topic 321: Investments - Equity Securities. The amendments in this ASU also require additional disclosures in interim and annual periods concerning investments for which the proportional amortization method is applied, including (i) the nature of tax equity investments, and (ii) the effect of tax equity investments and related income tax credits and other income tax benefits on the financial position and results of operations. ASU 2023-02 is effective for the Company for fiscal years beginning after December 15, 2023, including interim periods within those fiscal years, with early adoption permitted. The adoption of this ASU did not have a material impact on the consolidated financial statements and related disclosures.

In November 2023, the FASB issued ASU 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures. ASU 2023-07 requires public companies to provide more transparency in both quarterly and annual reports about the expenses they incur from revenue generating business units to better understand the Company's overall performance and potential future cash flows. The Company has identified one reporting segment. ASU 2023-07 is effective for the Company for fiscal years beginning after December 15, 2023, including interim periods within those fiscal years, with early adoption permitted. The adoption of this ASU did not have a material impact on the consolidated financial statements and related disclosures.

Recently issued accounting pronouncements not yet adopted

In March 2024, the FASB issued ASU 2024-01, Compensation—Stock Compensation (Topic 718): Scope Application of Profits Interest and Similar Awards. ASU 2024-01 added an illustrative example to demonstrate how an entity should apply the scope guidance in paragraph 718-10-15-3 to determine whether a profits interest award should be accounted for in accordance with Topic 718. Awards not meeting the criteria should be accounted for in accordance with Topic 710. The illustrative example provides four fact patterns which are intended to reduce complexity in determining whether a profits interest award is subject to the guidance in Topic 718 and reduce existing diversity in practice. ASU 2024-01 is effective for the Company for fiscal years beginning after December 15, 2024, including interim periods within those fiscal years, with early adoption permitted. The adoption of this ASU is not expected to have a material impact on the consolidated financial statements and related disclosures.

In November 2024, the FASB issued ASU 2024-03, Income Statement—Reporting Comprehensive Income—Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses. ASU 2024-03 requires additional disclosure of the nature of expenses included in the income statement in response to requests from investors for more information to better understand an entity's performance and potential future cash flows. The new standard requires disclosures about specific types of expenses included in the expense captions presented on the face of the income statement as well as disclosures about selling expenses. ASU 2024-03 is effective for the Company for fiscal years beginning after December 15, 2026, including interim periods within those fiscal years, with early adoption permitted. The adoption of this ASU is not expected to have a material impact on the consolidated financial statements and related disclosures.