Basis of Presentation and Significant Accounting Policies (Policies)	9 Months Ended
Sep. 30, 2017
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 Generally Accepted Accounting Principles ("GAAP") for complete financial statements. The Company owns a 100% interest in Residential Mortgage Holding Company, LLC ("RML"), the parent company of Residential Mortgage, LLC ("Residential Mortgage") 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 consolidates 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, 2017, are not necessarily indicative of the results anticipated for the year ending December 31, 2017. 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, 2016. 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, 2016.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In May 2014, the FASB issued 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. To achieve that core principle, an entity should apply the following steps: identify the contract(s) with a customer, identify the performance obligations in the contract, determine the transaction price, allocate the transaction price to the performance obligations in the contract, and recognize revenue when (or as) the entity satisfies a performance obligation. ASU 2014-09 is effective for the Company’s financial statements for annual and interim periods beginning on or after December 15, 2017, and the Company should apply the amendments retrospectively. The Company has determined that interest income is out of the scope of this new guidance, but is reviewing its other revenue sources for impact from this new guidance. While the assessment is not complete, 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 February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) (“ASU 2016-02”). ASU 2016-02 increases transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet and disclosing key information about lease arrangements. ASU 2016-02 is effective for the Company’s financial statements for annual and interim periods beginning on or after December 15, 2018, and must be applied prospectively. The Company is currently evaluating how the adoption of this standard will impact the Company’s consolidated financial position and results of operations. The Company is reviewing its existing lease portfolio to determine the impact of the new accounting guidance on the financial statements, as well as the impact to regulatory capital and risk-weighted assets. The Company does not expect the new accounting guidance to have a material impact on its consolidated results of operations. In June 2016, the FASB issued ASU 2016-13, Financial Instruments - Credit Losses (“ASU 2016-13”). ASU 2016-13 requires a financial asset (or a group of financial assets) that is measured at amortized cost basis to be presented at the net amount expected to be collected. The allowance for credit losses is a valuation account that is deducted from the amortized cost basis of the financial asset or assets to present the net carrying value at the amount expected to be collected on the financial asset. The income statement reflects the measurement of credit losses for newly recognized financial assets, as well as the expected increases or decreases of expected credit losses that have taken place during the period. The measurement of expected credit losses is based on relevant information about past events, including historical experience, current conditions, and reasonable and supportable forecasts that affect the collectability of the reported amount. An entity must use judgment in determining the relevant information and estimation methods that are appropriate in its circumstances. The allowance for credit losses for purchased financial assets with a more-than insignificant amount of credit deterioration since origination ("PCD assets") that are measured at amortized cost basis is determined in a similar manner to other financial assets measured at amortized cost basis; however, the initial allowance for credit losses is added to the purchase price rather than being reported as a credit loss expense. Only subsequent changes in the allowance for credit losses are recorded as a credit loss expense for these assets. Interest income for PCD assets should be recognized based on the effective interest rate, excluding the discount embedded in the purchase price that is attributable to the acquirer’s assessment of credit losses at acquisition. ASU 2016-13 requires credit losses relating to available-for-sale debt securities to be recorded through an allowance for credit losses. Available-for-sale accounting recognizes that value may be realized either through collection of contractual cash flows or through sale of the security. Therefore, the amendments limit the amount of the allowance for credit losses to the amount by which fair value is below amortized cost because the classification as available for sale is premised on an investment strategy that recognizes that the investment could be sold at fair value, if cash collection would result in the realization of an amount less than fair value. The allowance for credit losses for purchased available-for-sale securities with a more-than-insignificant amount of credit deterioration since origination is determined in a similar manner to other available-for-sale debt securities; however, the initial allowance for credit losses is added to the purchase price rather than reported as a credit loss expense. Only subsequent changes in the allowance for credit losses are recorded in credit loss expense. Interest income should be recognized based on the effective interest rate, excluding the discount embedded in the purchase price. 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 is currently evaluating the impact that the adoption of this standard will have on the Company’s consolidated financial position and results of operations. The Company has formed an implementation team and is in the process of reviewing different software systems which will assist the Company with the various calculations, modeling, and other changes anticipated in order to comply with the standard. 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 management of our processes for determining and disclosing estimated credit losses 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 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 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 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. ASU 2017-09 is effective for the Company’s financial statements for annual and interim periods beginning on or after December 15, 2017, and will be applied prospectively to an award modified on or after the adoption date. 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 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. Early adoption is permitted in any interim period after issuance of the ASU. 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

In May 2014, the FASB issued 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. To achieve that core principle, an entity should apply the following steps: identify the contract(s) with a customer, identify the performance obligations in the contract, determine the transaction price, allocate the transaction price to the performance obligations in the contract, and recognize revenue when (or as) the entity satisfies a performance obligation. ASU 2014-09 is effective for the Company’s financial statements for annual and interim periods beginning on or after December 15, 2017, and the Company should apply the amendments retrospectively. The Company has determined that interest income is out of the scope of this new guidance, but is reviewing its other revenue sources for impact from this new guidance. While the assessment is not complete, 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 February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) (“ASU 2016-02”). ASU 2016-02 increases transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet and disclosing key information about lease arrangements. ASU 2016-02 is effective for the Company’s financial statements for annual and interim periods beginning on or after December 15, 2018, and must be applied prospectively. The Company is currently evaluating how the adoption of this standard will impact the Company’s consolidated financial position and results of operations. The Company is reviewing its existing lease portfolio to determine the impact of the new accounting guidance on the financial statements, as well as the impact to regulatory capital and risk-weighted assets. The Company does not expect the new accounting guidance to have a material impact on its consolidated results of operations.

In June 2016, the FASB issued ASU 2016-13, Financial Instruments - Credit Losses (“ASU 2016-13”). ASU 2016-13 requires a financial asset (or a group of financial assets) that is measured at amortized cost basis to be presented at the net amount expected to be collected. The allowance for credit losses is a valuation account that is deducted from the amortized cost basis of the financial asset or assets to present the net carrying value at the amount expected to be collected on the financial asset. The income statement reflects the measurement of credit losses for newly recognized financial assets, as well as the expected increases or decreases of expected credit losses that have taken place during the period. The measurement of expected credit losses is based on relevant information about past events, including historical experience, current conditions, and reasonable and supportable forecasts that affect the collectability of the reported amount. An entity must use judgment in determining the relevant information and estimation methods that are appropriate in its circumstances. The allowance for credit losses for purchased financial assets with a more-than insignificant amount of credit deterioration since origination ("PCD assets") that are measured at amortized cost basis is determined in a similar manner to other financial assets measured at amortized cost basis; however, the initial allowance for credit losses is added to the purchase price rather than being reported as a credit loss expense. Only subsequent changes in the allowance for credit losses are recorded as a credit loss expense for these assets. Interest income for PCD assets should be recognized based on the effective interest rate, excluding the discount embedded in the purchase price that is attributable to the acquirer’s assessment of credit losses at acquisition. ASU 2016-13 requires credit losses relating to available-for-sale debt securities to be recorded through an allowance for credit losses. Available-for-sale accounting recognizes that value may be realized either through collection of contractual cash flows or through sale of the security. Therefore, the amendments limit the amount of the allowance for credit losses to the amount by which fair value is below amortized cost because the classification as available for sale is premised on an investment strategy that recognizes that the investment could be sold at fair value, if cash collection would result in the realization of an amount less than fair value. The allowance for credit losses for purchased available-for-sale securities with a more-than-insignificant amount of credit deterioration since origination is determined in a similar manner to other available-for-sale debt securities; however, the initial allowance for credit losses is added to the purchase price rather than reported as a credit loss expense. Only subsequent changes in the allowance for credit losses are recorded in credit loss expense. Interest income should be recognized based on the effective interest rate, excluding the discount embedded in the purchase price. 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 is currently evaluating the impact that the adoption of this standard will have on the Company’s consolidated financial position and results of operations. The Company has formed an implementation team and is in the process of reviewing different software systems which will assist the Company with the various calculations, modeling, and other changes anticipated in order to comply with the standard. 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 management of our processes for determining and disclosing estimated credit losses 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 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 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 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. ASU 2017-09 is effective for the Company’s financial statements for annual and interim periods beginning on or after December 15, 2017, and will be applied prospectively to an award modified on or after the adoption date. 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 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. Early adoption is permitted in any interim period after issuance of the ASU. 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.