Basis of Presentation and Significant Accounting Policies (Policies)	9 Months Ended
Sep. 30, 2018
Accounting Policies [Abstract]
Basis of Presentation	The accompanying unaudited consolidated financial statements and corresponding footnotes have been prepared by Northrim BanCorp, Inc. (the “Company”) in accordance with accounting principles generally accepted in the United States of America (“GAAP”) and with instructions to Form 10-Q under the Securities Exchange Act of 1934, as amended. The year-end Consolidated Balance Sheet data was derived from the Company's audited financial statements. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. The Company owns a 100% interest in Residential Mortgage Holding Company, LLC, the parent company of Residential Mortgage, LLC (collectively "RML") and consolidates their balance sheets and income statement into its financial statements. The Company owned a 50.1% interest in Northrim Benefits Group, LLC ("NBG") through August 14, 2017, and consolidated NBG's balance sheets and income statements into its financial statements through the date of the sale on August 14, 2017. In the opinion of management, all adjustments (consisting of normal recurring accruals) considered necessary for a fair presentation have been included. Certain immaterial reclassifications have been made to prior year amounts to maintain consistency with the current year with no impact on net income or total shareholders’ equity. The Company determined that it operates in two primary operating segments: Community Banking and Home Mortgage Lending. The Company has evaluated subsequent events and transactions for potential recognition or disclosure. Operating results for the interim period ended September 30, 2018, are not necessarily indicative of the results anticipated for the year ending December 31, 2018. These consolidated financial statements should be read in conjunction with the Company’s Annual Report on Form 10-K for the year ended December 31, 2017. The Company’s significant accounting policies are discussed in Note 1 to the audited consolidated financial statements included in the Company's Annual Report on Form 10-K for the year ended December 31, 2017.
Recent Accounting Pronouncements	Recent Accounting Pronouncements Accounting pronouncements implemented in 2018 In May 2014, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") 2014-09, Revenue from Contracts with Customers (“ASU 2014-09”). The core principle of the guidance is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. In general, this new guidance requires companies to use more judgment and make more estimates than under current guidance, including identifying performance obligations in the contract, estimating the amount of variable consideration to include in the transaction price and allocating the transaction price to each separate performance obligation. For financial reporting purposes, the standard allows for either full retrospective adoption, meaning the standard is applied to all of the periods presented, or modified retrospective adoption, meaning the standard is applied only to the most current period presented in the financial statements with the cumulative effect of initially applying the standard recognized at the date of initial application. The Company has reviewed all revenue sources to determine the sources that are in scope for this guidance. As a bank, key revenue sources, including interest income and mortgage banking income have been identified as out of scope of this new guidance. The Company's overall assessment of material in-scope revenue sources include service charges on deposits, bankcard fees, and other miscellaneous revenue sources. The Company adopted the guidance on January 1, 2018, utilizing the modified retrospective approach, which did not have a material impact on how the Company recognizes revenue or on our consolidated financial statements and disclosures. See Note 2 of the Notes to Consolidated Financial Statements included in Item 1 of this report for disclosures related to revenue generated from contracts with customers. In January 2016, the FASB issued ASU 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities (“ASU 2016-01”). The new guidance is intended to improve the recognition and measurement of financial instruments. ASU 2016-01 requires that equity investments (except those accounted for under the equity method of accounting or those that result in consolidation of the investee) be measured at fair value with changes in fair value recognized in net income. In addition, the amendment requires public business entities to use the exit price notion when measuring the fair value of financial instruments for disclosure purposes and requires separate presentation of financial assets and financial liabilities by measurement category and form of financial asset (i.e., securities or loans and receivables) on the balance sheet or the accompanying notes to the financial statements. ASU 2016-01 also eliminates the requirement for public business entities to disclose the method(s) and significant assumptions used to estimate the fair value that is required to be disclosed for financial instruments measured at amortized cost on the balance sheet. The amendment also requires a reporting organization to present separately in other comprehensive income the portion of the total change in the fair value of a liability resulting from a change in the instrument specific credit risk (also referred to as "own credit") when the organization has elected to measure the liability at fair value in accordance with the fair value option for financial instruments. The Company adopted the guidance on January 1, 2018 and reclassified $191,000 in unrealized gains on its investments in preferred stock from other comprehensive income to retained earnings. Adoption of the guidance does not have a material or significant impact on the Company's consolidated financial statements. As of January 1, 2018, unrealized gains and losses on marketable equity securities are included in other operating income in the Consolidated Statement of Income. In August 2016, the FASB issued ASU 2016-15, Classification of Certain Cash Receipts and Cash Payments (“ASU 2016-15”). ASU 2016-15 provides guidance on eight specific cash flow issues: debt prepayment or debt extinguishment costs; settlement of zero-coupon debt instruments or other debt instruments with coupon interest rates that are insignificant in relation to the effective interest rate of the borrowing; contingent consideration payments made after a business combination; proceeds from the settlement of insurance claims; proceeds from the settlement of corporate-owned life insurance policies, including bank-owned life insurance policies; distributions received from equity method investees; beneficial interests in securitization transactions; and separately identifiable cash flows and application of the predominance principle. The Company adopted the guidance on January 1, 2018 and made an accounting policy election to classify distributions from equity method investees using the cumulative earnings approach. Accordingly, these distributions are recorded as cash inflows in the operating activity section of the Statement of Cash Flows. Adoption of the guidance does not have a material or significant impact on the Company's consolidated financial statements. In May 2017, the FASB issued ASU 2017-09, Compensation-Stock Compensation (“ASU 2017-09”). ASU 2017-09 provides guidance about which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting in Topic 718. The Company adopted the guidance on January 1, 2018 and it did not have a material impact on the Company’s consolidated financial position or results of operations. In March 2017, the FASB issued ASU 2017-08, Receivables-Nonrefundable Fees and Other Costs (“ASU 2017-08”). ASU 2017-08 amends the amortization period for certain purchased callable debt securities held at a premium by shortening the amortization period for the premium to the earliest call date. Under the current guidance, entities generally amortize the premium as an adjustment of yield over the contractual life of the instrument. ASU 2017-08 is effective for the Company’s financial statements for annual and interim periods beginning on or after December 15, 2018, and should be applied on a modified retrospective basis through a cumulative-effect adjustment directly to retained earnings. The Company early adopted this standard in the first quarter of 2018, which resulted in a $62,000 decrease in beginning retained earnings through a cumulative-effect adjustment. In August 2017, the FASB issued ASU 2017-12, Derivatives and Hedging (“ASU 2017-12”). ASU 2017-12 improves the financial reporting of hedging relationships to better portray the economic results of an entity’s risk management activities in its financial statements. In addition to that main objective, the amendments in this ASU make certain targeted improvements to simplify the application of the hedge accounting guidance in current GAAP based on the feedback received from preparers, auditors, users, and other stakeholders. ASU 2017-12 is effective for the Company’s financial statements for annual and interim periods beginning on or after December 15, 2018, and all transition requirements and elections must be applied to hedging relationships existing (that is, hedging relationships in which the hedging instrument has not expired, been sold, terminated, or exercised or the entity has not removed the designation of the hedging relationship) on the date of adoption. The Company early adopted this standard in the first quarter of 2018, and it did not have a significant impact on the Company’s consolidated financial position or results of operations. Accounting pronouncements to be implemented in future periods In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) (“ASU 2016-02”). ASU 2016-02 requires lessees, among other things, to recognize lease assets and lease liabilities on the balance sheet for those leases classified as operating leases under previous authoritative guidance. This update also introduces new disclosure requirements for leasing arrangements. ASU 2016-02 is effective for the Company’s financial statements for annual and interim periods beginning on or after December 15, 2018. All entities are required to use a modified retrospective approach for leases that exist or are entered into after the beginning of the earliest comparative period in the financial statements. As the Company expects to elect the transition option provided in ASU No. 2018-11 (see below), the modified retrospective approach will be applied on January 1, 2019 (as opposed to January 1, 2017). The Company also expects to elect certain relief options offered in ASU 2016-02 including the package of practical expedients, the option not to separate lease and non-lease components and instead to account for them as a single lease component, and the option not to recognize right-of-use assets and lease liabilities that arise from short-term leases (i.e., leases with terms of twelve months or less). The Company will likely not elect the hindsight practical expedient, which allows entities to use hindsight when determining lease term and impairment of right-of-use assets. The Company has several lease agreements, such as branch locations, which are currently considered operating leases, and therefore, not recognized on the Company’s consolidated statements of condition. The Company expects the new accounting standard will require these lease agreements to be recognized on the consolidated statements of condition as a right-of-use asset and a corresponding lease liability. Therefore, the Company’s preliminary evaluation indicates the provisions of ASU 2016-02 are expected to impact the Company’s consolidated statements of condition, along with the Company’s regulatory capital ratios. However, the Company does not expect the new guidance to have a material impact on the Company’s consolidated statements of income. The Company has an implementation team working through the provisions of ASU 2016-02 and ASU 2018-11 to assess the impact on its accounting, disclosures, processes, internal control over financial reporting, regulatory capital, and risk-weighted assets. The Company is substantially complete with the evaluation of its lease population. It is expected that the Company will recognize right-of-use assets and lease liabilities (estimated between $15 and $25 million) upon adoption on January 1, 2019. The estimates will change due to changes in the lease portfolio prior to the adoption date. In July 2018, the FASB issued ASU 2018-11, Leases - Targeted Improvements ("ASU 2018-11") to provide entities with relief from the costs of implementing certain aspects of the new leasing standard, ASU 2016-02. Specifically, under the amendments in ASU 2018-11: (1) entities may elect not to recast the comparative periods presented when transitioning to the new leasing standard, and (2) lessors may elect not to separate lease and non-lease components when certain conditions are met. The amendments have the same effective date as ASU 2016-02 (January 1, 2019 for the Company). The Company expects to elect both transition options. ASU 2018-11 is not expected to have a material impact on the Company’s Consolidated Financial Statements. In June 2016, the FASB issued ASU 2016-13, Financial Instruments - Credit Losses (“ASU 2016-13”). ASU 2016-13 is intended to improve financial reporting by requiring timelier recording of credit losses on loans and other financial instruments held by financial institutions and other organizations. The standard requires the measurement of all expected credit losses for certain financial assets held at the reporting date based on historical experience, current conditions, and reasonable and supportable forecasts. Financial institutions and other organizations will now use forward-looking information to better inform their credit loss estimates, but will continue to use judgment to determine which loss estimation method is appropriate for their circumstances. ASU 2016-13 requires enhanced disclosures to help investors and other financial statement users better understand significant estimates and judgments used in estimating credit losses, as well as the credit quality and underwriting standards of an organization's portfolio. These disclosures include qualitative and quantitative requirements that provide additional information about the amounts recorded in the financial statements. In addition, the ASU amends the accounting for credit losses on available-for-sale debt securities and purchased financial assets with credit deterioration. The ASU is effective for fiscal years, and interim periods within those fiscal years, beginning on or after December 15, 2019. Early application will be permitted for specified periods. ASU 2016-13 is effective for the Company’s financial statements for annual and interim periods beginning on or after December 15, 2019, and must be applied prospectively. The Company has formed a cross-functional team to begin implementation efforts of this new guidance. The team is evaluating the data elements and modeling options that are expected to be critical to the new process and has engaged external consulting services related to this effort. An estimate of the impact of this standard on the Company's consolidated financial position and results of operations has not yet been determined; however, the impact on the Company's process for calculating the allowance for loan losses ("Allowance") is expected to be significant. In January 2017, the FASB issued ASU 2017-04, Intangibles-Goodwill and Other (“ASU 2017-04”). ASU 2017-04 simplifies how an entity is required to test goodwill for impairment by eliminating Step 2 from the goodwill impairment test. ASU 2017-04 is effective for the Company’s financial statements for annual and interim periods beginning on or after December 15, 2019, and must be applied on a prospective basis. The Company does not believe that the adoption of this standard will have a material impact on the Company’s consolidated financial position or results of operations. In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820) (“ASU 2018-13”). ASU 2018-13 modifies the disclosure requirements on fair value measurements in Topic 820, Fair Value Measurement, based on the concepts in the Concepts Statement, including the consideration of costs and benefits. ASU 2018-13 is effective for the Company’s financial statements for annual and interim periods beginning on or after December 15, 2019. The Company does not believe that the adoption of this standard will have a material impact on the Company’s consolidated financial position or results of operations.

Recent Accounting Pronouncements

Accounting pronouncements implemented in 2018

In May 2014, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") 2014-09, Revenue from Contracts with Customers (“ASU 2014-09”). The core principle of the guidance is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. In general, this new guidance requires companies to use more judgment and make more estimates than under current guidance, including identifying performance obligations in the contract, estimating the amount of variable consideration to include in the transaction price and allocating the transaction price to each separate performance obligation. For financial reporting purposes, the standard allows for either full retrospective adoption, meaning the standard is applied to all of the periods presented, or modified retrospective adoption, meaning the standard is applied only to the most current period presented in the financial statements with the cumulative effect of initially applying the standard recognized at the date of initial application. The Company has reviewed all revenue sources to determine the sources that are in scope for this guidance. As a bank, key revenue sources, including interest income and mortgage banking income have been identified as out of scope of this new guidance. The Company's overall assessment of material in-scope revenue sources include service charges on deposits, bankcard fees, and other miscellaneous revenue sources. The Company adopted the guidance on January 1, 2018, utilizing the modified retrospective approach, which did not have a material impact on how the Company recognizes revenue or on our consolidated financial statements and disclosures. See Note 2 of the Notes to Consolidated Financial Statements included in Item 1 of this report for disclosures related to revenue generated from contracts with customers.

In January 2016, the FASB issued ASU 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities (“ASU 2016-01”). The new guidance is intended to improve the recognition and measurement of financial instruments. ASU 2016-01 requires that equity investments (except those accounted for under the equity method of accounting or those that result in consolidation of the investee) be measured at fair value with changes in fair value recognized in net income. In addition, the amendment requires public business entities to use the exit price notion when measuring the fair value of financial instruments for disclosure purposes and requires separate presentation of financial assets and financial liabilities by measurement category and form of financial asset (i.e., securities or loans and receivables) on the balance sheet or the accompanying notes to the financial statements. ASU 2016-01 also eliminates the requirement for public business entities to disclose the method(s) and significant assumptions used to estimate the fair value that is required to be disclosed for financial instruments measured at amortized cost on the balance sheet. The amendment also requires a reporting organization to present separately in other comprehensive income the portion of the total change in the fair value of a liability resulting from a change in the instrument specific credit risk (also referred to as "own credit") when the organization has elected to measure the liability at fair value in accordance with the fair value option for financial instruments. The Company adopted the guidance on January 1, 2018 and reclassified $191,000 in unrealized gains on its investments in preferred stock from other comprehensive income to retained earnings. Adoption of the guidance does not have a material or significant impact on the Company's consolidated financial statements. As of January 1, 2018, unrealized gains and losses on marketable equity securities are included in other operating income in the Consolidated Statement of Income.

In August 2016, the FASB issued ASU 2016-15, Classification of Certain Cash Receipts and Cash Payments (“ASU 2016-15”). ASU 2016-15 provides guidance on eight specific cash flow issues: debt prepayment or debt extinguishment costs; settlement of zero-coupon debt instruments or other debt instruments with coupon interest rates that are insignificant in relation to the effective interest rate of the borrowing; contingent consideration payments made after a business combination; proceeds from the settlement of insurance claims; proceeds from the settlement of corporate-owned life insurance policies, including bank-owned life insurance policies; distributions received from equity method investees; beneficial interests in securitization transactions; and separately identifiable cash flows and application of the predominance principle. The Company adopted the guidance on January 1, 2018 and made an accounting policy election to classify distributions from equity method investees using the cumulative earnings approach. Accordingly, these distributions are recorded as cash inflows in the operating activity section of the Statement of Cash Flows. Adoption of the guidance does not have a material or significant impact on the Company's consolidated financial statements.

In May 2017, the FASB issued ASU 2017-09, Compensation-Stock Compensation (“ASU 2017-09”). ASU 2017-09 provides guidance about which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting in Topic 718. The Company adopted the guidance on January 1, 2018 and it did not have a material impact on the Company’s consolidated financial position or results of operations.

In March 2017, the FASB issued ASU 2017-08, Receivables-Nonrefundable Fees and Other Costs (“ASU 2017-08”). ASU 2017-08 amends the amortization period for certain purchased callable debt securities held at a premium by shortening the amortization period for the premium to the earliest call date. Under the current guidance, entities generally amortize the premium as an adjustment of yield over the contractual life of the instrument. ASU 2017-08 is effective for the Company’s financial statements for annual and interim periods beginning on or after December 15, 2018, and should be applied on a modified retrospective basis through a cumulative-effect adjustment directly to retained earnings. The Company early adopted this standard in the first quarter of 2018, which resulted in a $62,000 decrease in beginning retained earnings through a cumulative-effect adjustment.

In August 2017, the FASB issued ASU 2017-12, Derivatives and Hedging (“ASU 2017-12”). ASU 2017-12 improves the financial reporting of hedging relationships to better portray the economic results of an entity’s risk management activities in its financial statements. In addition to that main objective, the amendments in this ASU make certain targeted improvements to simplify the application of the hedge accounting guidance in current GAAP based on the feedback received from preparers, auditors, users, and other stakeholders. ASU 2017-12 is effective for the Company’s financial statements for annual and interim periods beginning on or after December 15, 2018, and all transition requirements and elections must be applied to hedging relationships existing (that is, hedging relationships in which the hedging instrument has not expired, been sold, terminated, or exercised or the entity has not removed the designation of the hedging relationship) on the date of adoption. The Company early adopted this standard in the first quarter of 2018, and it did not have a significant impact on the Company’s consolidated financial position or results of operations.

Accounting pronouncements to be implemented in future periods

In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) (“ASU 2016-02”). ASU 2016-02 requires lessees, among other things, to recognize lease assets and lease liabilities on the balance sheet for those leases classified as operating leases under previous authoritative guidance. This update also introduces new disclosure requirements for leasing arrangements. ASU 2016-02 is effective for the Company’s financial statements for annual and interim periods beginning on or after December 15, 2018. All entities are required to use a modified retrospective approach for leases that exist or are entered into after the beginning of the earliest comparative period in the financial statements. As the Company expects to elect the transition option provided in ASU No. 2018-11 (see below), the modified retrospective approach will be applied on January 1, 2019 (as opposed to January 1, 2017). The Company also expects to elect certain relief options offered in ASU 2016-02 including the package of practical expedients, the option not to separate lease and non-lease components and instead to account for them as a single lease component, and the option not to recognize right-of-use assets and lease liabilities that arise from short-term leases (i.e., leases with terms of twelve months or less). The Company will likely not elect the hindsight practical expedient, which allows entities to use hindsight when determining lease term and impairment of right-of-use assets. The Company has several lease agreements, such as branch locations, which are currently considered operating leases, and therefore, not recognized on the Company’s consolidated statements of condition. The Company expects the new accounting standard will require these lease agreements to be recognized on the consolidated statements of condition as a right-of-use asset and a corresponding lease liability. Therefore, the Company’s preliminary evaluation indicates the provisions of ASU 2016-02 are expected to impact the Company’s consolidated statements of condition, along with the Company’s regulatory capital ratios. However, the Company does not expect the new guidance to have a material impact on the Company’s consolidated statements of income. The Company has an implementation team working through the provisions of ASU 2016-02 and ASU 2018-11 to assess the impact on its accounting, disclosures, processes, internal control over financial reporting, regulatory capital, and risk-weighted assets. The Company is substantially complete with the evaluation of its lease population. It is expected that the Company will recognize right-of-use assets and lease liabilities (estimated between $15 and $25 million) upon adoption on January 1, 2019. The estimates will change due to changes in the lease portfolio prior to the adoption date.

In July 2018, the FASB issued ASU 2018-11, Leases - Targeted Improvements ("ASU 2018-11") to provide entities with relief from the costs of implementing certain aspects of the new leasing standard, ASU 2016-02. Specifically, under the amendments in ASU 2018-11: (1) entities may elect not to recast the comparative periods presented when transitioning to the new leasing standard, and (2) lessors may elect not to separate lease and non-lease components when certain conditions are met. The amendments have the same effective date as ASU 2016-02 (January 1, 2019 for the Company). The Company expects to elect both transition options. ASU 2018-11 is not expected to have a material impact on the Company’s Consolidated Financial Statements.

In June 2016, the FASB issued ASU 2016-13, Financial Instruments - Credit Losses (“ASU 2016-13”). ASU 2016-13 is intended to improve financial reporting by requiring timelier recording of credit losses on loans and other financial instruments held by financial institutions and other organizations. The standard requires the measurement of all expected credit losses for certain financial assets held at the reporting date based on historical experience, current conditions, and reasonable and supportable forecasts. Financial institutions and other organizations will now use forward-looking information to better inform their credit loss estimates, but will continue to use judgment to determine which loss estimation method is appropriate for their circumstances. ASU 2016-13 requires enhanced disclosures to help investors and other financial statement users better understand significant estimates and judgments used in estimating credit losses, as well as the credit quality and underwriting standards of an organization's portfolio. These disclosures include qualitative and quantitative requirements that provide additional information about the amounts recorded in the financial statements. In addition, the ASU amends the accounting for credit losses on available-for-sale debt securities and purchased financial assets with credit deterioration. The ASU is effective for fiscal years, and interim periods within those fiscal years, beginning on or after December 15, 2019. Early application will be permitted for specified periods. ASU 2016-13 is effective for the Company’s financial statements for annual and interim periods beginning on or after December 15, 2019, and must be applied prospectively. The Company has formed a cross-functional team to begin implementation efforts of this new guidance. The team is evaluating the data elements and modeling options that are expected to be critical to the new process and has engaged external consulting services related to this effort. An estimate of the impact of this standard on the Company's consolidated financial position and results of operations has not yet been determined; however, the impact on the Company's process for calculating the allowance for loan losses ("Allowance") is expected to be significant.

In January 2017, the FASB issued ASU 2017-04, Intangibles-Goodwill and Other (“ASU 2017-04”). ASU 2017-04 simplifies how an entity is required to test goodwill for impairment by eliminating Step 2 from the goodwill impairment test. ASU 2017-04 is effective for the Company’s financial statements for annual and interim periods beginning on or after December 15, 2019, and must be applied on a prospective basis. The Company does not believe that the adoption of this standard will have a material impact on the Company’s consolidated financial position or results of operations.

In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820) (“ASU 2018-13”). ASU 2018-13 modifies the disclosure requirements on fair value measurements in Topic 820, Fair Value Measurement, based on the concepts in the Concepts Statement, including the consideration of costs and benefits. ASU 2018-13 is effective for the Company’s financial statements for annual and interim periods beginning on or after December 15, 2019. The Company does not believe that the adoption of this standard will have a material impact on the Company’s consolidated financial position or results of operations.