Significant Accounting Policies	9 Months Ended
Significant Accounting Policies	Sep. 30, 2023
Accounting Policies [Abstract]
Industry Regulation	Industry Regulation NW Holdings' principal business is to operate as a holding company for NW Natural and its other subsidiaries. NW Natural's principal business is the distribution of natural gas, which is regulated by the OPUC and WUTC. NW Natural also has natural gas storage services, which are regulated by the FERC, and to a certain extent by the OPUC and WUTC. Additionally, certain of NW Holdings' subsidiaries own water businesses, which are regulated by the public utility commission in the state in which the water utility is located, which is currently Oregon, Washington, Idaho, Texas and Arizona. Wastewater businesses, to the extent they are regulated, are generally regulated by the public utility commissions in the state in which the wastewater utility is located, which is currently Texas and Arizona. In applying regulatory accounting principles, NW Holdings and NW Natural capitalize or defer certain costs and revenues as regulatory assets and liabilities pursuant to orders of the applicable state public utility commission, which provide for the recovery of revenues or expenses from, or refunds to, utility customers in future periods, including a return or a carrying charge in certain cases.
New Accounting Standards	New Accounting Standards NW Natural and NW Holdings consider the applicability and impact of all accounting standards updates (ASUs) issued by the Financial Accounting Standards Board (FASB). ASUs not listed below were assessed and determined to be either not applicable or are expected to have minimal impact on consolidated financial position or results of operations. Recently Issued Accounting Pronouncements JOINT VENTURE FORMATIONS. In August 2023, the FASB issued ASU 2023-05, which requires a joint venture to initially measure all contributions received upon its formation at fair value. The standard is effective for all joint venture entities with a formation date on or after January 1, 2025, with early adoption permitted. The adoption of this standard is not anticipated to have a material impact on our results of operations, liquidity or capital resources. Recent Securities and Exchange Commission (SEC) Final Rules INSIDER TRADING ARRANGEMENTS. In December 2022, the SEC adopted the final rule under SEC Release No. 33-11138, Insider Trading Arrangements and Related Disclosures, which requires new disclosures regarding insider trading policies and procedures, the use of certain insider trading plans and director and executive compensation regarding equity compensation awards made close in time to disclosure of material nonpublic information. The adoption of this final rule is not anticipated to have a material impact on our results of operations, liquidity or capital resources. SHARE REPURCHASES. In May 2023, the SEC adopted the final rule under SEC Release No. 34-97424, Share Repurchase Disclosure Modernization, requiring disclosures related to issuers’ share repurchases that will provide investors with enhanced information to assess the purposes and effects of the repurchases. The adoption of this final rule is not anticipated to have a material impact on our results of operations, liquidity or capital resources. CYBERSECURITY DISCLOSURES. In July 2023, the SEC issued a final rule that requires new disclosures regarding cybersecurity risk management, strategy, governance, and incidents. The disclosures are required beginning with our annual report for the year ending December 31, 2023. The adoption of this final rule is not anticipated to have a material impact on our results of operations, liquidity or capital resources.