Significant Accounting Policies (Policies)	6 Months Ended
Jun. 30, 2022
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, 2021. 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 six months ended June 30, 2022, 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 loan losses ("ALLL"), fair value of financial instruments, and deferred tax assets and liabilities.
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 controlling interest in Quin Ventures, Inc. All material intercompany accounts and transactions have been eliminated in consolidation. While First Northwest and POM share equal ownership in Quin Ventures, it has been determined that First Northwest has a controlling interest for financial reporting purposes under Accounting Standards Codification 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 and has included additional information where appropriate.
New Accounting Pronouncements, Policy [Policy Text Block]	Recently adopted accounting pronouncements In November 2019, the FASB issued Accounting Standards Update ("ASU") 2019- 10, which defers the effective date of the current expected credit loss model (CECL) guidance issued in ASUs 2016- 13, 2019- 04, and 2019- 05. The effective date for smaller reporting companies was changed from the interim and annual periods beginning after December 15, 2020 to the interim and annual periods beginning after December 15, 2022. Early adoption is permitted for interim and annual periods beginning after December 15, 2018. The Company adopted this ASU and anticipates implementing CECL effective January 1, 2023. In January 2021, the FASB issued ASU No. 2021- 01, Reference Rate Reform (Topic 848): Scope. ASU No. 2021- 01 clarifies that certain optional expedients and exceptions in ASC 848 for contract modifications and hedge accounting apply to derivatives that are affected by the discounting transition. ASU No. 2021- 01 also amends the expedients and exceptions in ASC 848 to capture the incremental consequences of the scope clarification and to tailor the existing guidance to derivative instruments affected by the discounting transition. This ASU was effective upon issuance and generally can be applied through December 31, 2022. The adoption of ASU 2021- 01 did not have a material impact on the Company’s financial statements. *Recently issued accounting pronouncements not* yet adopted** Credit Losses In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments - Credit Loss, which updates the guidance on recognition and measurement of credit losses for financial assets. The new requirements, known as the current expected credit loss model (CECL) will require entities to adopt an impairment model based on expected losses rather than incurred losses. ASU No. 2016-13 is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Upon adoption, the Company will change processes and procedures to calculate the allowance for credit losses, including changes in assumptions and estimates to consider expected credit losses over the life of the loan versus the current accounting practice that utilizes the incurred loss model. In addition, the current accounting policy and procedures for other-than-temporary impairment on investment securities available for sale will be replaced with an allowance approach. Additional updates were issued in ASU No. 2019-04, Codification Improvements to Topic 326,* Financial Instruments - Credit Losses, Topic 815, Derivatives and Hedging (Topic 825), Financial Instruments. This ASU clarifies and improves guidance related to the previously issued standards on credit losses, hedging and recognition and measurement of financial instruments. The amendments provide entities with various measurement alternatives and policy elections related to accounting for credit losses and accrued interest receivable balances. Entities are also able to elect a practical expedient to separately disclose the total amount of accrued interest included in the amortized cost basis as a single balance to meet certain disclosure requirements. The amendments clarify that the estimated allowance for credit losses should include all expected recoveries of financial assets and trade receivables that were previously written off and expected to be written off. The amendments also allow entities to use projections of future interest rate environments when using a discounted cash flow method to measure expected credit losses on variable-rate financial instruments. In addition, new updates were issued through ASU No.* 2019-05, Financial Instruments - Credit Losses (Topic 326): Targeted Transition Relief. This amendment allows entities to elect the fair value option on certain financial instruments. On adoption, an entity is allowed to irrevocably elect the fair value option on an instrument-by-instrument basis. This alternative is available for all instruments in the scope of Subtopic 326-20 except for existing held-to-maturity debt securities. If an entity elects the fair value option, the difference between the instrument’s fair value and carrying amount is recognized as a cumulative-effect adjustment. The Company is evaluating the provisions of ASU No. 2016-13, ASU No. 2019-04 and ASU No. 2019-05, and will closely monitor developments and additional guidance to determine the potential impact on the Company’s consolidated financial statements. At this time, we cannot reasonably estimate the impact the implementation of these ASUs will have on the Company's consolidated financial statements. The Company's internal project management team continues to review models, work with our third-party vendor, and discuss changes to processes and procedures to ensure the Company is fully compliant with the amendments at the adoption date, which is anticipated to be January 1, 2023. As of June 30, 2022, the Bank has been running a parallel analysis comparing actual ALLL results to potential CECL results. Initial results indicate a modest increase to the reserve; however, the modeling effort is ongoing with final decisions regarding valuation criteria for each segment yet to be made. Other Pronouncements In March 2020, the FASB issued ASU No. 2020-04 Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting. ASU 2020-04 provides temporary optional guidance to ease the potential burden in accounting for reference rate reform. The ASU provides optional expedients and exceptions for applying generally accepted accounting principles to contract modifications and hedging relationships, subject to meeting certain criteria, that reference the London Inter-Bank Offered Rate (“LIBOR”) or another reference rate expected to be discontinued. It is intended to help stakeholders during the global market-wide reference rate transition period. This ASU is effective for all entities as of March 12, 2020 through December 31, 2022. The Company is implementing a transition plan to identify and modify its loans and other financial instruments that are either directly or indirectly influenced by LIBOR. The Company is in the process of evaluating ASU No. 2020-04 and its impact on the Company’s transition away from LIBOR for its loan and other financial instruments, with no material expected impact on the Company's financial statements. In March 2022, the FASB issued ASU No. 2022-01, Derivatives and Hedging (Topic 815): Fair Value Hedging—Portfolio Layer Method. ASU 2022-01 expands the portfolio layer method of hedge accounting prescribed in ASU No. 2017-12 to allow multiple hedged layers of a single closed portfolio and to include portfolios of both prepayable and non-prepayable financial assets. This scope expansion is consistent with the FASB’s efforts to simplify hedge accounting and allows entities to apply the same accounting method to similar hedging strategies. The ASU also specifies eligible hedging instruments in a single-layer hedge, provides additional guidance on accounting and disclosure of hedge basis adjustments and specifies how hedge basis adjustments should be considered in determining credit losses for assets in the designated closed portfolio. This ASU is effective for public business entities for interim and annual periods in fiscal years beginning after December 15, 2022. The Company is evaluating the effect that ASU 2022-01 will have on its consolidated financial statements. In March 2022, the FASB issued ASU No. 2022-02, Financial Instruments—Credit Losses (Topic 326): Troubled Debt Restructurings and Vintage Disclosures. ASU 2022-02 eliminates the accounting guidance for troubled debt restructurings ("TDRs") in ASC 310-40, "Receivables - Troubled Debt Restructurings by Creditors" for entities that have adopted the current expected credit loss model introduced by ASU 2016-13, “Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments”. ASU 2022-02 also requires that public business entities disclose current-period gross charge-offs by year of origination for financing receivables and net investments in leases within the scope of Subtopic 326-20, "Financial Instruments—Credit Losses—Measured at Amortized Cost". ASU 2022-02 is effective for the Company for fiscal years beginning after December 15, 2022, including interim periods within those fiscal years, with early adoption permitted. The Company is evaluating the effect that ASU 2022-02 will have on its consolidated financial statements and related disclosures. 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 Company is evaluating the effect that ASU 2022-03 will have on its consolidated financial statements and related disclosures.
Reclassification, Comparability Adjustment [Policy Text Block]	Reclassifications - Certain amounts in the unaudited interim consolidated financial statements for prior periods have been reclassified to conform to the current unaudited financial statement presentation with no effect on net income or shareholders' equity.

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 controlling interest in Quin Ventures, Inc. All material intercompany accounts and transactions have been eliminated in consolidation. While First Northwest and POM share equal ownership in Quin Ventures, it has been determined that First Northwest has a controlling interest for financial reporting purposes under Accounting Standards Codification 810. The Quin Ventures net loss allocable to POM is shown on the financial statements where applicable through a noncontrolling interest adjustment.

New Accounting Pronouncements, Policy [Policy Text Block]

Recently adopted accounting pronouncements

In November 2019, the FASB issued Accounting Standards Update ("ASU") 2019- 10, which defers the effective date of the current expected credit loss model (CECL) guidance issued in ASUs 2016- 13, 2019- 04, and 2019- 05. The effective date for smaller reporting companies was changed from the interim and annual periods beginning after December 15, 2020 to the interim and annual periods beginning after December 15, 2022. Early adoption is permitted for interim and annual periods beginning after December 15, 2018. The Company adopted this ASU and anticipates implementing CECL effective January 1, 2023.

In January 2021, the FASB issued ASU No. 2021- 01, Reference Rate Reform (Topic 848): Scope. ASU No. 2021- 01 clarifies that certain optional expedients and exceptions in ASC 848 for contract modifications and hedge accounting apply to derivatives that are affected by the discounting transition. ASU No. 2021- 01 also amends the expedients and exceptions in ASC 848 to capture the incremental consequences of the scope clarification and to tailor the existing guidance to derivative instruments affected by the discounting transition. This ASU was effective upon issuance and generally can be applied through December 31, 2022. The adoption of ASU 2021- 01 did not have a material impact on the Company’s financial statements.

Recently issued accounting pronouncements not yet adopted

Credit Losses

In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments - Credit Loss, which updates the guidance on recognition and measurement of credit losses for financial assets. The new requirements, known as the current expected credit loss model (CECL) will require entities to adopt an impairment model based on expected losses rather than incurred losses. ASU No. 2016-13 is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Upon adoption, the Company will change processes and procedures to calculate the allowance for credit losses, including changes in assumptions and estimates to consider expected credit losses over the life of the loan versus the current accounting practice that utilizes the incurred loss model. In addition, the current accounting policy and procedures for other-than-temporary impairment on investment securities available for sale will be replaced with an allowance approach.

Additional updates were issued in ASU No. 2019-04, Codification Improvements to Topic 326, Financial Instruments - Credit Losses, Topic 815, Derivatives and Hedging (Topic 825), Financial Instruments. This ASU clarifies and improves guidance related to the previously issued standards on credit losses, hedging and recognition and measurement of financial instruments. The amendments provide entities with various measurement alternatives and policy elections related to accounting for credit losses and accrued interest receivable balances. Entities are also able to elect a practical expedient to separately disclose the total amount of accrued interest included in the amortized cost basis as a single balance to meet certain disclosure requirements. The amendments clarify that the estimated allowance for credit losses should include all expected recoveries of financial assets and trade receivables that were previously written off and expected to be written off. The amendments also allow entities to use projections of future interest rate environments when using a discounted cash flow method to measure expected credit losses on variable-rate financial instruments.

In addition, new updates were issued through ASU No. 2019-05, Financial Instruments - Credit Losses (Topic 326): Targeted Transition Relief. This amendment allows entities to elect the fair value option on certain financial instruments. On adoption, an entity is allowed to irrevocably elect the fair value option on an instrument-by-instrument basis. This alternative is available for all instruments in the scope of Subtopic 326-20 except for existing held-to-maturity debt securities. If an entity elects the fair value option, the difference between the instrument’s fair value and carrying amount is recognized as a cumulative-effect adjustment.

The Company is evaluating the provisions of ASU No. 2016-13, ASU No. 2019-04 and ASU No. 2019-05, and will closely monitor developments and additional guidance to determine the potential impact on the Company’s consolidated financial statements. At this time, we cannot reasonably estimate the impact the implementation of these ASUs will have on the Company's consolidated financial statements. The Company's internal project management team continues to review models, work with our third-party vendor, and discuss changes to processes and procedures to ensure the Company is fully compliant with the amendments at the adoption date, which is anticipated to be January 1, 2023. As of June 30, 2022, the Bank has been running a parallel analysis comparing actual ALLL results to potential CECL results. Initial results indicate a modest increase to the reserve; however, the modeling effort is ongoing with final decisions regarding valuation criteria for each segment yet to be made.

Other Pronouncements

In March 2020, the FASB issued ASU No. 2020-04 Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting. ASU 2020-04 provides temporary optional guidance to ease the potential burden in accounting for reference rate reform. The ASU provides optional expedients and exceptions for applying generally accepted accounting principles to contract modifications and hedging relationships, subject to meeting certain criteria, that reference the London Inter-Bank Offered Rate (“LIBOR”) or another reference rate expected to be discontinued. It is intended to help stakeholders during the global market-wide reference rate transition period. This ASU is effective for all entities as of March 12, 2020 through December 31, 2022. The Company is implementing a transition plan to identify and modify its loans and other financial instruments that are either directly or indirectly influenced by LIBOR. The Company is in the process of evaluating ASU No. 2020-04 and its impact on the Company’s transition away from LIBOR for its loan and other financial instruments, with no material expected impact on the Company's financial statements.

In March 2022, the FASB issued ASU No. 2022-01, Derivatives and Hedging (Topic 815): Fair Value Hedging—Portfolio Layer Method. ASU 2022-01 expands the portfolio layer method of hedge accounting prescribed in ASU No. 2017-12 to allow multiple hedged layers of a single closed portfolio and to include portfolios of both prepayable and non-prepayable financial assets. This scope expansion is consistent with the FASB’s efforts to simplify hedge accounting and allows entities to apply the same accounting method to similar hedging strategies. The ASU also specifies eligible hedging instruments in a single-layer hedge, provides additional guidance on accounting and disclosure of hedge basis adjustments and specifies how hedge basis adjustments should be considered in determining credit losses for assets in the designated closed portfolio. This ASU is effective for public business entities for interim and annual periods in fiscal years beginning after December 15, 2022. The Company is evaluating the effect that ASU 2022-01 will have on its consolidated financial statements.

In March 2022, the FASB issued ASU No. 2022-02, Financial Instruments—Credit Losses (Topic 326): Troubled Debt Restructurings and Vintage Disclosures. ASU 2022-02 eliminates the accounting guidance for troubled debt restructurings ("TDRs") in ASC 310-40, "Receivables - Troubled Debt Restructurings by Creditors" for entities that have adopted the current expected credit loss model introduced by ASU 2016-13, “Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments”. ASU 2022-02 also requires that public business entities disclose current-period gross charge-offs by year of origination for financing receivables and net investments in leases within the scope of Subtopic 326-20, "Financial Instruments—Credit Losses—Measured at Amortized Cost". ASU 2022-02 is effective for the Company for fiscal years beginning after December 15, 2022, including interim periods within those fiscal years, with early adoption permitted. The Company is evaluating the effect that ASU 2022-02 will have on its consolidated financial statements and related disclosures.

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 Company is evaluating the effect that ASU 2022-03 will have on its consolidated financial statements and related disclosures.