NORTHWEST NATURAL GAS CO, 10-Q filed on 5/6/2026
Quarterly Report
v3.26.1
Cover Page - shares
 3 Months Ended
Mar. 31, 2026
Apr. 28, 2026
Document Information [Line Items]    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Mar. 31, 2026  
Document Transition Report false  
Entity Registrant Name NORTHWEST NATURAL HOLDING COMPANY  
Entity File Number 1-38681  
Entity Incorporation, State or Country Code OR  
Entity Tax Identification Number 82-4710680  
Entity Address, Address Line One 250 SW Taylor Street  
Entity Address, City or Town Portland  
Entity Address, State or Province OR  
Entity Address, Postal Zip Code 97204  
City Area Code (503)  
Local Phone Number 226-4211  
Title of 12(b) Security Common Stock  
Trading Symbol NWN  
Security Exchange Name NYSE  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Large Accelerated Filer  
Entity Small Business false  
Entity Emerging Growth Company false  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding   42,080,352
Current Fiscal Year End Date --12-31  
Document Fiscal Year Focus 2026  
Document Fiscal Period Focus Q1  
Amendment Flag false  
Entity Central Index Key 0001733998  
NW Natural    
Document Information [Line Items]    
Document Type 10-Q  
Document Period End Date Mar. 31, 2026  
Entity Registrant Name NORTHWEST NATURAL GAS COMPANY  
Entity File Number 1-15973  
Entity Incorporation, State or Country Code OR  
Entity Tax Identification Number 93-0256722  
Entity Address, Address Line One 250 SW Taylor Street  
Entity Address, City or Town Portland  
Entity Address, State or Province OR  
Entity Address, Postal Zip Code 97204  
City Area Code (503)  
Local Phone Number 226-4211  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Non-accelerated Filer  
Entity Small Business false  
Entity Emerging Growth Company false  
Entity Shell Company false  
Current Fiscal Year End Date --12-31  
Document Fiscal Year Focus 2026  
Document Fiscal Period Focus Q1  
Amendment Flag false  
Entity Central Index Key 0000073020  
v3.26.1
Consolidated Statements of Comprehensive Income (Unaudited) - USD ($)
shares in Thousands, $ in Thousands
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Operating revenues [Abstract]    
Operating revenues $ 490,403 $ 494,284
Operating expenses:    
Cost of gas 158,149 172,991
Operations and maintenance 83,109 83,683
Environmental remediation 6,325 6,253
General taxes 16,343 15,771
Revenue taxes 18,100 19,405
Depreciation 44,134 40,500
Other operating expenses 1,375 1,327
Total operating expenses 327,535 339,930
Income from operations 162,868 154,354
Other income (expense), net 512 (2,516)
Interest expense, net 33,352 29,395
Income before income taxes 130,028 122,443
Income tax expense 32,539 34,527
Net income 97,489 87,916
Other comprehensive income (loss):    
Amortization of non-qualified employee benefit plan liability, net of taxes $33 and $25 for the three months ended March 31, 2026 and 2025, respectively 91 175
Unrealized gain (loss) on interest rate swaps, net of taxes $(6) and $47 for the three months ended March 31, 2026 and 2025, respectively 30 (130)
Comprehensive income $ 97,610 $ 87,961
Average common shares outstanding:    
Basic (in shares) 41,708 40,244
Diluted (in shares) 41,816 40,304
Earnings per share of common stock:    
Basic (in dollars per share) $ 2.34 $ 2.18
Diluted (in dollars per share) $ 2.33 $ 2.18
NW Natural    
Operating revenues [Abstract]    
Operating revenues $ 433,896 $ 448,813
Operating expenses:    
Cost of gas 140,144 159,436
Operations and maintenance 70,530 67,766
Environmental remediation 6,325 6,253
General taxes 16,037 14,979
Revenue taxes 17,037 18,565
Depreciation 39,444 36,036
Other operating expenses 693 746
Total operating expenses 290,210 303,781
Income from operations 143,686 145,032
Other income (expense), net (104) (2,749)
Interest expense, net 17,678 15,580
Income before income taxes 125,904 126,703
Income tax expense 32,155 35,664
Net income 93,749 91,039
Other comprehensive income (loss):    
Amortization of non-qualified employee benefit plan liability, net of taxes $33 and $25 for the three months ended March 31, 2026 and 2025, respectively 91 175
Comprehensive income $ 93,840 $ 91,214
v3.26.1
Consolidated Balance Sheets (Unaudited) - USD ($)
$ in Thousands
Mar. 31, 2026
Dec. 31, 2025
Mar. 31, 2025
Current assets:      
Cash and cash equivalents $ 34,945 $ 36,673 $ 100,050
Accounts receivable 150,545 121,875 154,746
Accrued unbilled revenue 61,236 97,238 59,936
Allowance for uncollectible accounts (4,510) (4,068) (4,427)
Regulatory assets 146,545 143,745 88,623
Derivative instruments 2,719 3,922 4,363
Inventories 134,745 127,697 90,334
Other current assets 57,895 75,850 46,275
Total current assets 584,120 602,932 539,900
Non-current assets:      
Property, plant, and equipment 5,722,356 5,640,435 5,268,063
Less: Accumulated depreciation 1,300,897 1,288,422 1,266,222
Total property, plant, and equipment, net 4,421,459 4,352,013 4,001,841
Regulatory assets 637,563 424,194 371,258
Derivative instruments 459 366 864
Total other investments 69,441 80,676 82,663
Operating lease right of use asset, net 68,113 68,224 70,455
Assets under sales-type leases 120,450 121,470 124,623
Goodwill 371,257 370,815 354,534
Other non-current assets 146,105 146,351 160,754
Total non-current assets 5,834,847 5,564,109 5,166,992
Total assets 6,418,967 6,167,041 5,706,892
Current liabilities:      
Short-term debt 171,276 171,989 81,100
Current maturities of long-term debt 160,669 160,627 36,838
Accounts payable 124,844 175,566 132,814
Taxes accrued 17,197 18,123 24,115
Interest accrued 22,036 26,121 16,297
Regulatory liabilities 113,914 137,974 111,050
Derivative instruments 42,097 63,631 26,122
Operating lease liabilities 3,270 3,228 2,662
Other current liabilities 75,225 79,186 82,958
Total current liabilities 730,528 836,445 513,956
Long-term debt 2,272,444 2,272,202 2,193,071
Deferred credits and other non-current liabilities:      
Deferred tax liabilities 467,134 437,467 424,338
Regulatory liabilities 762,429 758,407 730,084
Pension and other postretirement benefit liabilities 108,929 112,139 127,853
Derivative instruments 17,318 14,039 8,224
Operating lease liabilities 74,918 74,986 77,226
Other non-current liabilities 408,366 186,280 175,922
Total deferred credits and other non-current liabilities 1,839,094 1,583,318 1,543,647
Commitments and contingencies (Note 16)
Equity:      
Common stock - no par value; authorized 100,000,000 shares; issued and outstanding 42,080,010, 40,308,777, and 41,563,577 at March 31, 2026 and 2025, and December 31, 2025, respectively 1,069,314 1,044,000 992,278
Retained earnings 512,213 435,823 470,795
Accumulated other comprehensive loss (4,626) (4,747) (6,855)
Total equity 1,576,901 1,475,076 1,456,218
Total liabilities and equity 6,418,967 6,167,041 5,706,892
NW Natural      
Current assets:      
Cash and cash equivalents 24,274 29,347 81,767
Accounts receivable 128,410 102,165 135,432
Accrued unbilled revenue 55,023 86,600 55,961
Receivables from affiliates 4,350 997 2,789
Allowance for uncollectible accounts (3,285) (3,048) (3,533)
Regulatory assets 145,946 143,135 88,598
Derivative instruments 2,719 3,922 4,339
Inventories 126,669 119,319 85,641
Other current assets 50,078 61,024 40,698
Total current assets 534,184 543,461 491,692
Non-current assets:      
Property, plant, and equipment 5,046,862 5,000,329 4,780,480
Less: Accumulated depreciation 1,257,950 1,256,289 1,237,907
Total property, plant, and equipment, net 3,788,912 3,744,040 3,542,573
Regulatory assets 632,054 419,847 369,628
Derivative instruments 459 366 858
Total other investments 48,821 61,049 63,436
Operating lease right of use asset, net 65,005 65,650 67,717
Assets under sales-type leases 120,450 121,470 124,623
Other non-current assets 93,425 93,235 107,141
Total non-current assets 4,749,126 4,505,657 4,275,976
Total assets 5,283,310 5,049,118 4,767,668
Current liabilities:      
Short-term debt 0 9,990 0
Current maturities of long-term debt 54,962 54,948 29,995
Accounts payable 96,129 138,931 112,502
Payables to affiliates 17,732 2,354 15,706
Taxes accrued 15,099 15,682 15,416
Interest accrued 14,690 15,399 12,050
Regulatory liabilities 113,728 137,908 110,856
Derivative instruments 42,081 63,578 26,122
Operating lease liabilities 2,457 2,515 1,895
Other current liabilities 71,401 75,667 78,936
Total current liabilities 428,279 516,972 403,478
Long-term debt 1,480,109 1,479,942 1,335,572
Deferred credits and other non-current liabilities:      
Deferred tax liabilities 449,691 426,093 408,249
Regulatory liabilities 752,402 748,846 729,139
Pension and other postretirement benefit liabilities 108,929 112,139 127,853
Derivative instruments 17,318 14,039 8,224
Operating lease liabilities 72,580 73,097 75,230
Other non-current liabilities 391,798 169,746 163,718
Total deferred credits and other non-current liabilities 1,792,718 1,543,960 1,512,413
Commitments and contingencies (Note 16)
Equity:      
Common stock - no par value; authorized 100,000,000 shares; issued and outstanding 42,080,010, 40,308,777, and 41,563,577 at March 31, 2026 and 2025, and December 31, 2025, respectively 854,903 854,903 839,903
Retained earnings 731,915 658,046 683,179
Accumulated other comprehensive loss (4,614) (4,705) (6,877)
Total equity 1,582,204 1,508,244 1,516,205
Total liabilities and equity $ 5,283,310 $ 5,049,118 $ 4,767,668
v3.26.1
Consolidated Statement of Shareholders' Equity (Unaudited) - USD ($)
$ in Thousands
Total
NW Natural
Common Stock
Common Stock
NW Natural
Retained Earnings
Retained Earnings
NW Natural
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss)
NW Natural
Beginning balance at Dec. 31, 2024 $ 1,385,371 $ 1,324,050 $ 989,346 $ 719,903 $ 402,925 $ 611,199 $ (6,900) $ (7,052)
Increase (Decrease) in Stockholders' Equity [Roll Forward]                
Capital contributions from parent   (120,000)   120,000        
Net income 87,916 91,039     87,916 91,039    
Dividends on common stock         (20,046) (19,059)    
Other comprehensive income 87,961 91,214         45 175
Stock-based compensation     1,931          
Shares issued pursuant to equity based plans, net of shares withheld for taxes     (16)          
Issuance of common stock, net of issuance costs     1,017          
Ending balance at Mar. 31, 2025 $ 1,456,218 1,516,205 992,278 839,903 470,795 683,179 (6,855) (6,877)
Increase (Decrease) in Stockholders' Equity [Roll Forward]                
Dividends per share of common stock (in dollars per share) $ 0.4900              
Beginning balance at Dec. 31, 2025 $ 1,475,076 1,508,244 1,044,000 854,903 435,823 658,046 (4,747) (4,705)
Increase (Decrease) in Stockholders' Equity [Roll Forward]                
Capital contributions from parent   0   0        
Net income 97,489 93,749     97,489 93,749    
Dividends on common stock         (21,099) (19,880)    
Other comprehensive income 97,610 93,840         121 91
Stock-based compensation     3,907          
Shares issued pursuant to equity based plans, net of shares withheld for taxes     (760)          
Issuance of common stock, net of issuance costs     22,167          
Ending balance at Mar. 31, 2026 $ 1,576,901 $ 1,582,204 $ 1,069,314 $ 854,903 $ 512,213 $ 731,915 $ (4,626) $ (4,614)
Increase (Decrease) in Stockholders' Equity [Roll Forward]                
Dividends per share of common stock (in dollars per share) $ 0.4925              
v3.26.1
Consolidated Statement of Cash Flows (Unaudited) - USD ($)
$ in Thousands
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Operating activities:    
Net income $ 97,489 $ 87,916
Adjustments to reconcile net income to cash provided by operations:    
Depreciation 44,134 40,500
Amortization 6,131 5,583
Deferred income taxes 24,998 23,997
Qualified defined benefit pension plan expense 2,307 2,719
Contributions to qualified defined benefit pension plans (2,900) (2,610)
Deferred environmental expenditures, net (6,079) (6,991)
Environmental remediation expense 6,325 6,253
Asset optimization revenue sharing bill credits (23,156) (15,549)
Other 4,207 3,016
Changes in assets and liabilities:    
Receivables, net 21,656 15,509
Inventories (7,598) 18,279
Income and other taxes 13,408 18,084
Accounts payable (31,219) 4,187
Deferred gas costs (29,651) (16,959)
Asset optimization revenue sharing 4,297 4,357
Decoupling mechanism (15,803) (1,422)
Cloud-based software (2,490) (2,195)
Regulatory accounts 13,208 2,155
Other, net (3,137) (7,219)
Cash provided by operating activities 116,127 179,610
Investing activities:    
Capital expenditures (113,656) (102,184)
Acquisitions, net of cash acquired 0 (270,492)
Purchase of equity method investment (1,000) (1,000)
Other (1,397) (1,299)
Cash used by investing activities (116,053) (374,975)
Financing activities:    
Proceeds from common stock issued, net 22,264 961
Long-term debt issued 0 375,000
Long-term debt retired (121) (1,511)
Changes in other short-term debt, net (713) (94,010)
Cash dividend payments on common stock (19,775) (19,104)
Payment of financing fees (54) (4,307)
Shares withheld for tax purposes (1,988) (1,536)
Other (392) (1,125)
Cash (used in) provided by financing activities (779) 254,368
(Decrease) increase in cash, cash equivalents and restricted cash (705) 59,003
Cash, cash equivalents and restricted cash, beginning of period 41,077 47,982
Cash, cash equivalents and restricted cash, end of period 40,372 106,985
Supplemental disclosure of cash flow information:    
Interest paid, net of capitalization 36,443 30,109
Income taxes paid, net of refunds 1,400 750
NW Natural    
Operating activities:    
Net income 93,749 91,039
Adjustments to reconcile net income to cash provided by operations:    
Depreciation 39,444 36,036
Amortization 5,453 5,375
Deferred income taxes 19,022 22,321
Qualified defined benefit pension plan expense 2,307 2,719
Contributions to qualified defined benefit pension plans (2,900) (2,610)
Deferred environmental expenditures, net (6,079) (6,991)
Environmental remediation expense 6,325 6,253
Asset optimization revenue sharing bill credits (23,156) (15,549)
Other 4,398 3,843
Changes in assets and liabilities:    
Receivables, net 15,160 17,855
Inventories (7,900) 19,390
Income and other taxes 19,345 17,516
Accounts payable (27,708) (2,484)
Deferred gas costs (29,651) (16,959)
Asset optimization revenue sharing 4,297 4,357
Decoupling mechanism (15,803) (1,422)
Cloud-based software (2,760) (2,194)
Regulatory accounts 13,197 1,878
Other, net 1,594 857
Cash provided by operating activities 108,334 181,230
Investing activities:    
Capital expenditures (79,615) (83,608)
Other (909) (1,145)
Cash used by investing activities (80,524) (84,753)
Financing activities:    
Cash contributions received from parent 0 120,000
Changes in other short-term debt, net (9,990) (136,510)
Cash dividend payments on common stock (19,880) (19,059)
Shares withheld for tax purposes (1,988) (1,536)
Other (2) (123)
Cash (used in) provided by financing activities (31,860) (37,228)
(Decrease) increase in cash, cash equivalents and restricted cash (4,050) 59,249
Cash, cash equivalents and restricted cash, beginning of period 33,726 29,428
Cash, cash equivalents and restricted cash, end of period 29,676 88,677
Supplemental disclosure of cash flow information:    
Interest paid, net of capitalization 17,479 17,386
Income taxes paid, net of refunds $ 1,400 $ 3,000
v3.26.1
Consolidated Statements of Comprehensive Income (Parenthetical) (Unaudited) - USD ($)
$ in Thousands
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Amortization of non-qualified employee benefit plan liability, tax $ 33 $ 25
Unrealized loss on derivative, tax (6) 47
NW Natural    
Amortization of non-qualified employee benefit plan liability, tax $ 33 $ 25
v3.26.1
Consolidated Balance Sheets (Parenthetical) (Unaudited) - $ / shares
Mar. 31, 2026
Dec. 31, 2025
Mar. 31, 2025
Par value (in dollars per share) $ 0 $ 0 $ 0
Shares authorized (in shares) 100,000,000 100,000,000 100,000,000
Shares issued (in shares) 42,080,010 41,563,577 40,308,777
Shares outstanding (in shares) 42,080,010 41,563,577 40,308,777
NW Natural      
Other receivable, after allowance for credit loss, related party [Extensible Enumeration] Affiliated Entity [Member] Affiliated Entity [Member] Affiliated Entity [Member]
Accounts payable, related party [Extensible Enumeration] Affiliated Entity [Member] Affiliated Entity [Member] Affiliated Entity [Member]
v3.26.1
Organization and Principles of Consolidation
 3 Months Ended
Mar. 31, 2026
Organization, Consolidation and Presentation of Financial Statements [Abstract]  
Organization and Principles of Consolidation ORGANIZATION AND PRINCIPLES OF CONSOLIDATION
The accompanying consolidated financial statements represent the respective, consolidated financial results of Northwest Natural Holding Company (NW Holdings) and Northwest Natural Gas Company (NW Natural) and all respective companies that each registrant directly or indirectly controls, either through majority ownership or otherwise. This is a combined report of NW Holdings and NW Natural, which includes separate consolidated financial statements for each registrant.

NW Natural operates as one reportable business segment on a consolidated basis. Prior to the first quarter of 2026, the reportable business segment NW Natural was represented as NWN Gas Utility and excluded certain gas storage and other business activities that were included in Other. Consistent with the method in which the Chief Operating Decision Maker (CODM) reviews each business, these activities were consolidated into NWN Gas Utility and presented as the reportable business segment NW Natural beginning in the first quarter of 2026. The NW Natural segment serves residential, commercial, and industrial customers in Oregon and southwest Washington and includes interstate storage services, third-party asset management services, and appliance center retail operations. NW Holdings and NW Natural historical segment reporting has been recast to reflect their current organizational structure. The recasting did not have a material effect on the consolidated financial statements of NW Holdings or NW Natural.


SiEnergy Operating, LLC (SiEnergy), which was acquired January 7, 2025, owns SiEnergy Gas, LLC, which is a regulated natural gas distribution utility, and serves residential and commercial customers in the greater metropolitan areas of Houston, Dallas, and Austin, Texas. SiEnergy also serves several transmission customers in Dallas and Austin, Texas. SiEnergy activities are reported in the SiEnergy reportable segment.

NW Natural Water Company, LLC (NW Natural Water or NWN Water) activities are reported in the NWN Water reportable segment, which provides water distribution and wastewater services to communities throughout the Pacific Northwest, Texas, Arizona, and California. NW Holdings also has investments and business activities not specifically related to the NW Natural, SiEnergy and NWN Water segments, which are aggregated and reported as Other.

NW Holdings and NW Natural consolidate all entities in which they have a controlling financial interest. Investments in corporate joint ventures and partnerships that NW Holdings does not directly or indirectly control, and for which it is not the primary beneficiary, include NNG Financial's investment in Kelso-Beaver Pipeline and NWN Water's investment in Avion Water Company, Inc., which are accounted for under the equity method. See Note 13 for activity related to equity method investments. NW Holdings and its direct and indirect subsidiaries are collectively referred to herein as NW Holdings, and NW Natural and its direct and indirect subsidiaries are collectively referred to herein as NW Natural. The consolidated financial statements of NW Holdings and NW Natural are presented after elimination of all intercompany balances and transactions.

Information presented in these interim consolidated financial statements is unaudited but includes all material adjustments management considers necessary for a fair statement of the results for each period reported including normal recurring accruals. These consolidated financial statements should be read in conjunction with the audited consolidated financial statements and related notes included in NW Holdings' and NW Natural's combined Annual Report on Form 10-K for the year ended December 31, 2025 (2025 Form 10-K). A significant part of NW Holdings' and NW Natural's business is of a seasonal nature; therefore, NW Holdings and NW Natural results of operations for interim periods are not necessarily indicative of full year results. Seasonality affects the comparability of the results of other operations across quarters but not across years.

Notes to the consolidated financial statements reflect the activity for both NW Holdings and NW Natural for all periods presented, unless otherwise noted. NW Holdings and NW Natural historical segment reporting has been recast to reflect their current organizational structure. The recasting did not have a material effect on the consolidated financial statements of NW Holdings or NW Natural.
v3.26.1
Significant Accounting Policies
 3 Months Ended
Mar. 31, 2026
Accounting Policies [Abstract]  
Significant Accounting Policies SIGNIFICANT ACCOUNTING POLICIES
Significant accounting policies are described in Note 2 of the 2025 Form 10-K. There were no material changes to those accounting policies during the three months ended March 31, 2026 other than those set forth in this Note 2. The following are updates to certain critical accounting policy estimates and new accounting standards.
  
Industry Regulation  
NW Holdings' principal business is to operate as a holding company for NW Natural, SiEnergy, NWN Water and its other subsidiaries. NW Natural's principal business is the distribution of natural gas, which is regulated by the Oregon Public Utility Commission (OPUC) and Washington Utilities and Transportation Commission (WUTC). NW Natural also has natural gas storage services, which are regulated by the Federal Energy Regulatory Commission (FERC), and to a certain extent by the OPUC and WUTC. SiEnergy's principal business is the distribution of natural gas in Texas; primarily in the Houston, Dallas and Austin metropolitan areas. SiEnergy also includes a natural gas transmission utility serving customers in the greater metropolitan areas of Dallas and Austin, Texas. SiEnergy's natural gas utilities are subject to regulation by the Railroad Commission of Texas and the cities in which it provides services. NWN Water's principal business is water and wastewater utility services. NWN Water's 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. Accounting records and practices of the regulated businesses conform to the requirements and uniform system of accounts prescribed by these regulatory authorities in accordance with U.S. GAAP. The businesses in which customer rates are regulated have approved cost-based rates which are intended to allow such businesses to earn a reasonable return on invested capital.

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.
Amounts deferred as regulatory assets and liabilities for NW Holdings and NW Natural were as follows:
Regulatory Assets
March 31,December 31,
In thousands202620252025
Current:
NW Natural:
Unrealized loss on derivatives(1)
$42,081 $26,122 $63,578 
Gas costs15,523 5,085 6,284 
Environmental costs(2)
12,271 10,819 12,148 
Decoupling(3)
22,136 351 11,631 
Pension balancing(4)
7,131 7,131 7,131 
Income taxes2,208 2,208 2,208 
Washington Climate Commitment Act compliance7,754 8,219 7,482 
Security and systems improvements1,391 2,182 1,771 
Industrial demand side management(5)
12,149 12,530 10,539 
Other(6)
23,302 13,951 20,363 
Total current - NW Natural145,946 88,598 143,135 
SiEnergy275 — 410 
NWN Water324 25 200 
Total current - NW Holdings$146,545 $88,623 $143,745 
Non-current:
NW Natural:
Unrealized loss on derivatives(1)
$17,318 $8,224 $14,039 
Pension balancing(4)
13,076 19,174 15,647 
Income taxes9,289 8,993 9,148 
Pension and other postretirement benefit liabilities93,773 108,970 96,008 
Environmental costs(2)
386,358 159,744 180,063 
Gas costs9,343 1,804 9,434 
Decoupling(3)
11,746 188 8,891 
Washington Climate Commitment Act compliance44,082 28,292 33,085 
Security and systems improvements8,158 8,452 8,234 
Industrial demand side management(5)
4,787 4,682 9,334 
Other(6)
34,124 21,105 35,964 
Total non-current - NW Natural632,054 369,628 419,847 
SiEnergy HB 4384 depreciation deferral3,288 — 2,095 
SiEnergy other1,427 876 1,412 
NWN Water794 754 840 
Total non-current - NW Holdings$637,563 $371,258 $424,194 
(1)Unrealized gains or losses on derivatives are non-cash items and therefore do not earn a rate of return or a carrying charge. These amounts are recoverable through NW Natural rates as part of the annual Purchased Gas Adjustment (PGA) mechanism when realized at settlement.
(2)Refer to the Environmental Cost Deferral and Recovery table in Note 17 for a description of environmental costs.
(3)This deferral represents the margin adjustment resulting from differences between actual and expected volumes. 
(4)Balance represents deferred net periodic benefit costs as approved by the OPUC.
(5)Energy efficiency program for industrial sales customers in Oregon to provide assistance with reducing their gas usage.
(6)Balances consist of deferrals and amortizations under approved regulatory mechanisms and typically earn a rate of return or carrying charge.
Regulatory Liabilities
March 31,December 31,
In thousands202620252025
Current:
NW Natural:
Gas costs$21,838 $33,864 $34,172 
Unrealized gain on derivatives(1)
2,719 4,339 3,922 
Decoupling(2)
2,738 8,177 5,181 
Income taxes5,406 4,726 5,406 
Asset optimization revenue sharing9,508 8,381 25,981 
Washington Climate Commitment Act compliance65,523 46,241 57,441 
Other(3)
5,996 5,128 5,805 
Total current - NW Natural113,728 110,856 137,908 
SiEnergy90 61 66 
NWN Water96 133 — 
Total current - NW Holdings$113,914 $111,050 $137,974 
Non-current:
NW Natural:
Gas costs$903 $9,168 $687 
Unrealized gain on derivatives(1)
459 858 366 
Decoupling(2)
— 2,538 — 
Income taxes(4)
154,830 160,975 159,176 
Accrued asset removal costs(5)
571,035 535,075 561,594 
Asset optimization revenue sharing— — 2,386 
Other(3)
25,175 20,525 24,637 
Total non-current - NW Natural752,402 729,139 748,846 
SiEnergy asset removal costs8,621 — 8,155 
NWN Water1,406 945 1,406 
Total non-current - NW Holdings$762,429 $730,084 $758,407 
(1)Unrealized gains or losses on derivatives are non-cash items and therefore do not earn a rate of return or a carrying charge. These amounts are recoverable through NW Natural rates as part of the annual Purchased Gas Adjustment (PGA) mechanism when realized at settlement.
(2)This deferral represents the margin adjustment resulting from differences between actual and expected volumes. 
(3)Balances consist of deferrals and amortizations under approved regulatory mechanisms and typically earn a rate of return or carrying charge.
(4)Balance represents excess deferred income tax benefits subject to regulatory flow-through. See Note 11.
(5)Estimated costs of removal on certain regulated properties are collected through rates.

We believe all costs incurred and deferred at March 31, 2026 are prudent. All regulatory assets are reviewed annually for recoverability, or more often if circumstances warrant. If we should determine that all or a portion of these regulatory assets no longer meet the criteria for continued application of regulatory accounting, then NW Holdings and NW Natural would be required to write-off the net unrecoverable balances in the period such determination is made.

Supplemental Cash Flow Information
Cash and Cash Equivalents
Cash and cash equivalents include cash on hand plus highly liquid investment accounts with original maturity dates of three months or less. These investments are readily convertible to cash with fair value approximating cost. As of March 31, 2026, the amount invested in money market funds was $2.5 million at NW Holdings and NW Natural. As of March 31, 2025, the amount invested in money market funds was $68.1 million at NW Holdings and NW Natural. These investments are measured using net asset value per share.

Restricted Cash
Restricted cash is primarily comprised of funds from public purpose charges for programs that assist low-income customers with bill payments or energy efficiency. These balances are included in other current assets in the NW Holdings and NW Natural balance sheets.
The following table provides a reconciliation of the cash, cash equivalents and restricted cash balances at NW Holdings as of March 31, 2026 and 2025 and December 31, 2025:
March 31,December 31,
In thousands202620252025
Cash and cash equivalents$34,945 $100,050 $36,673 
Restricted cash included in other current assets5,427 6,935 4,404 
Cash, cash equivalents and restricted cash$40,372 $106,985 $41,077 

The following table provides a reconciliation of the cash, cash equivalents and restricted cash balances at NW Natural as of March 31, 2026 and 2025 and December 31, 2025:
March 31,December 31,
In thousands202620252025
Cash and cash equivalents$24,274 $81,767 $29,347 
Restricted cash included in other current assets5,402 6,910 4,379 
Cash, cash equivalents and restricted cash$29,676 $88,677 $33,726 

Accounts Receivable and Allowance for Uncollectible Accounts
NW Holdings receivable balances primarily consist of trade receivables for the sale of natural gas and natural gas transportation services from NW Natural and SiEnergy and water sales and wastewater services from NWN Water. These businesses establish an allowance for uncollectible accounts for trade receivables (allowance), including accrued unbilled revenue, based on the age of receivable balances, collection experience of past due balances and payment plans, and historical trends of write-offs. Differences between the estimated allowance and actual write-offs will occur based on a number of factors, including changes in economic conditions, customer creditworthiness, and natural gas and water prices. The allowance is adjusted quarterly, as necessary, based on information currently available.

The following table presents the activity related to the NW Holdings provision for uncollectible accounts by pool:

As ofAs of
December 31, 2025Three Months Ended March 31, 2026March 31, 2026
In thousandsBeginning BalanceProvision recorded, net of adjustmentsWrite-offs recognized, net of recoveriesEnding Balance
Allowance for uncollectible accounts:
Residential$2,280 $402 $(54)$2,628 
Commercial374 (27)(48)299 
Industrial46 10 — 56 
Accrued unbilled and other348 (49)3 302 
Total NW Natural3,048 336 (99)3,285 
Other - NW Holdings1,020 312 (107)1,225 
Total NW Holdings$4,068 $648 $(206)$4,510 

Allowance for Net Investments in Sales-Type Leases
NW Natural currently holds two net investments in sales-type leases, with substantially all of the net investment balance related to the North Mist natural gas storage agreement with Portland General Electric (PGE) which is billed under an OPUC-approved rate schedule. See Note 7 for more information on the North Mist lease. There is no allowance for uncollectible accounts recorded for sales-type lease receivables. NW Natural will continue monitoring the credit health of the lessees and the overall economic environment, including the economic factors closely tied to the financial health of our current and future lessees.

Greenhouse Gas Allowances
Washington
NW Natural is subject to greenhouse gas (GHG) emission reduction requirements under the Washington Climate Commitment Act (CCA) regulations. Under Washington's CCA, emission reduction compliance mechanisms include: 1) allowances distributed at no cost by the state, 2) purchasing allowances at state-run auctions or secondary markets, 3) purchasing carbon offsets, and 4) supplying alternative gaseous fuels, such as renewable natural gas and hydrogen.

NW Natural accounts for all purchased Washington allowances as inventory at the lower of cost or net realizable value. Any compliance instruments or allowances that are acquired through government allocations at no cost will be accounted for as inventory at no cost. As of March 31, 2026 and 2025, NW Natural had $80.4 million and $49.0 million of emissions allowances for compliance in Washington recorded as inventory.
The CCA allows for the sale of compliance instruments or allowances, and as a result, should NW Natural sell these it will recognize revenue when title to the instrument or allowance is transferred to a counterparty, and NW Natural will recognize expense at the time of recognition of the related sale. As of March 31, 2026, NW Natural consigned no-cost allowances to Washington auctions and has received a total of $47.1 million in cash, which proceeds were recorded as a regulatory liability for the benefit of customers.

We measure the compliance obligation, which is based on emissions, at the carrying value of inventory held plus the fair value of any additional emission allowances NW Natural would need to purchase to satisfy the obligations. Under the Washington program, NW Natural has recognized a $51.8 million and $36.0 million liability as of March 31, 2026 and 2025. A portion of the costs to comply with the Washington program are currently being recovered from utility customers through rates. NW Natural recognized $51.8 million and $36.0 million of deferred costs as of March 31, 2026 and 2025.

Oregon
NW Natural is subject to GHG emission reduction requirements under the Oregon Climate Protection Program (CPP). Under Oregon’s CPP, emission reduction compliance mechanisms include: 1) compliance instruments distributed at no cost by the Oregon Department of Environmental Quality (ODEQ), 2) purchasing credits through funding Community Climate Investments (CCIs), and 3) supplying alternative gaseous fuels, such as renewable natural gas and hydrogen.

NW Natural accounts for purchased Oregon instruments or credits as inventory at the lower of cost or net realizable value. Any compliance instruments that are acquired through government allocations at no cost will be accounted for as inventory at no cost.

We measure the compliance obligation, which is based on emissions, at the carrying value of inventory held plus the fair value of any additional emission allowances NW Natural would need to purchase to satisfy the obligations. NW Natural is currently recovering in Oregon rates costs associated with RNG, as well as costs related to NW Natural’s transportation energy efficiency program, all of which reduce NW Natural’s compliance obligation under the CPP. Under the Oregon program, NW Natural has not recorded a liability as of March 31, 2026 and 2025.

The CPP allows for the sale of compliance instruments, and as a result, should NW Natural sell these, it will recognize revenue when title to the instrument is transferred to a counterparty, and NW Natural will recognize expense at the time of recognition of the related sale. As of March 31, 2026, NW Natural has not sold compliance instruments on the market.

Cloud Computing Arrangements
For GAAP accounting purposes, implementation costs associated with cloud computing arrangements are capitalized consistent with costs capitalized for internal-use software. Capitalized implementation costs are included in other assets in the consolidated balance sheets. The implementation costs are amortized over the term of the related hosting agreement, including renewal periods that are reasonably certain to be exercised. Amortization expense of implementation costs are recorded as operations and maintenance expenses in the consolidated statements of comprehensive income. The implementation costs are included within operating activities in the consolidated statements of cash flows.

For regulatory accounting purposes, cloud-based software is reflected in rate base as property, plant and equipment and amortized over the expected useful life through depreciation expense. NW Natural is allowed recovery of and a return on cloud computing arrangements like other property, plant and equipment in rate base. The amount of cloud-based software capital expenditures for the first three months of 2026 and 2025 was $2.2 million and $2.1 million, respectively. The amount of cloud computing amortization for the first three months of 2026 and 2025 was $3.1 million and $3.1 million, respectively.

Other Current Assets
Other current assets consist of various items that are expected to be realized within the next twelve months and are not classified elsewhere on the balance sheet. Other current assets are comprised primarily of prepaid assets, restricted cash and gas reserves. As of March 31, 2026, NW Holdings and NW Natural had $36.0 million and $28.2 million of prepaid assets, respectively, and $2.6 million of gas reserves. As of March 31, 2025. NW Holdings and NW Natural had $31.9 million and $26.4 million of prepaid assets, respectively, and $2.7 million of gas reserves. See the Restricted Cash section above for restricted cash balances.

New Accounting Standards
NW Holdings and NW Natural 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
DISAGGREGATION OF EXPENSE DISCLOSURES. In November 2024, the FASB issued ASU 2024-03, which requires additional disclosures of disaggregated income statement expenses. The disclosures are required beginning with our annual report for the year ending December 31, 2027. The FASB issued ASU 2025-01 on January 6, 2025, to amend the effective date language of ASU 2024-03 clarifying that all public business entities are required to adopt the guidance in annual reporting periods beginning after December 15, 2026, and interim periods within annual reporting periods beginning after December 15, 2027. ASU 2025-01 did not impact the effective date of ASU 2024-03 for NW Holdings and NW Natural. The adoption of this standard is not anticipated to have an impact on our results of operations, liquidity, or capital resources.

FINANCIAL INSTRUMENTS-CREDIT LOSSES. In July 2025, the FASB issued ASU 2025-05, which simplifies how entities estimate credit losses on current accounts receivable and current contract assets arising from revenue transactions under ASC 606. It introduced a practical expedient that allows all entities to assume that economic conditions at the balance sheet date remain unchanged for the life of the asset, eliminating the need for forward-looking forecasts. The Company elected the practical expedient and adopted this ASU effective January 1, 2026. The adoption of this standard did not have a material impact
on our results of operations, liquidity or capital resources.

IMPROVEMENTS TO INTANGIBLE ASSET ACCOUNTING AND DISCLOSURES. In September 2025, the FASB issued ASU 2025-06, Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Targeted Improvements to the Accounting for Internal-Use Software (“ASU 2025-06”). This ASU modernizes the accounting for software costs to adapt to an incremental and iterative software development method. ASU 2025-06 is effective for annual periods beginning after December 15, 2027, and may be applied using a prospective, modified prospective or retrospective transition approach. The adoption of this standard is not anticipated to have a material impact on our results of operations, liquidity or capital resources.

INTERIM REPORTING. In December 2025, the FASB issued ASU 2025-11, which improves the guidance in Topic 270, Interim Reporting, by clarifying the current disclosure requirements for interim periods. The ASU adds to Topic 270 a principle that requires entities to disclose events since the end of the last annual reporting period that have a material impact on the entity. ASU 2025-11 is effective for interim reporting periods within annual reporting periods beginning after December 15, 2027. The adoption of this standard is not anticipated to have an impact on our results of operations, liquidity, or capital resources.

CODIFICATION IMPROVEMENTS. In December 2025, the FASB issued ASU 2025-12, which makes changes to the Codification that clarify, correct errors, or make minor improvements. The amendments make the Codification easier to understand and apply. The amendments in this ASU are varied in nature and may affect the application of guidance in cases in which the original guidance may have been unclear. ASU 2025-12 is effective for annual reporting periods beginning after December 15, 2026, and interim reporting periods within those annual reporting periods. The adoption of this standard is not anticipated to have an impact on our results of operations, liquidity, or capital resources.
v3.26.1
Earnings Per Share
 3 Months Ended
Mar. 31, 2026
Earnings Per Share [Abstract]  
Earnings Per Share EARNINGS PER SHARE
Basic earnings or loss per share are computed using NW Holdings' net income or loss and the weighted average number of common shares outstanding for each period presented. Diluted earnings per share are computed in the same manner, except using the weighted average number of common shares outstanding plus the effects of the assumed exercise of stock options and the payment of estimated stock awards from other stock-based compensation plans that are outstanding at the end of each period presented. Anti-dilutive stock awards are excluded from the calculation of diluted earnings or loss per common share.

NW Holdings' diluted earnings or loss per share are calculated as follows:
Three Months Ended March 31,
In thousands, except per share data20262025
Net income$97,489 $87,916 
Average common shares outstanding - basic41,708 40,244 
Additional shares for stock-based compensation plans (See Note 8)
108 60 
Average common shares outstanding - diluted41,816 40,304 
Earnings per share of common stock:
Basic$2.34 $2.18 
Diluted2.33 2.18 
Additional information:
Anti-dilutive shares 13 10 
v3.26.1
Segment Information
 3 Months Ended
Mar. 31, 2026
Segment Reporting [Abstract]  
Segment Information SEGMENT INFORMATION
NW Holdings operates three reportable business segments, which are NW Natural, SiEnergy and NWN Water. NW Holdings also has investments and business activities not specifically related to its reportable business segments, which are aggregated and reported as Other. NW Natural operates as one reportable business segment on a consolidated basis. Prior to the first quarter of 2026, the reportable business segment NW Natural was represented as NWN Gas Utility and excluded certain gas storage and other business activities that were included in Other. Consistent with the method in which the Chief Operating Decision Maker (CODM) reviews each business, these activities were consolidated into NWN Gas Utility and presented as the reportable business segment NW Natural beginning in the first quarter of 2026. NW Holdings and NW Natural historical segment reporting has been recast to reflect their current organizational structure. The recasting did not have a material effect on the consolidated financial statements of NW Holdings or NW Natural.

NW Natural
NW Natural is primarily a regulated local gas distribution company serving customers in Oregon and southwest Washington. NW Natural also provides regulated storage services at its Mist underground storage facility. The Mist underground storage facility serves distribution and interstate storage customers, and owns the North Mist gas storage facility, which serves a local electric company. NW Natural also owns NWN Gas Reserves and NW Natural RNG Holding Company, LLC, which procures regulated renewable natural gas for distribution customers. Additionally, NW Natural encompasses interstate storage services, third-party asset management services, and appliance center retail operations.

SiEnergy
SiEnergy Operating, LLC (SiEnergy), which was acquired January 7, 2025, owns SiEnergy Gas, LLC, which is a regulated natural gas distribution utility, and serves residential and commercial customers in the greater metropolitan areas of Houston, Dallas, and Austin, Texas. SiEnergy also serves several transmission customers in Dallas and Austin, Texas.

NWN Water
NWN Water is a regulated water and wastewater utility serving residential and commercial customers in Oregon, Washington, Idaho, Texas, and Arizona. NWN Water also includes non-regulated wastewater utilities and water services businesses in Oregon, Washington and Idaho, and an equity method investment in Avion Water Company, Inc. (a regulated entity). In addition, NWN Water provides water services to communities throughout the Pacific Northwest and California.

Other
NW Holdings' activities in Other includes activities of NW Natural Renewables Holdings, LLC (NWN Renewables), which is engaged in non-regulated renewable natural gas activities; NNG Financial and its pipeline assets; and NWN Energy including its wholly owned subsidiary NW Natural Gas Storage, LLC (NWN Gas Storage), which was formerly involved in a gas storage business. Other also includes corporate revenues and expenses that cannot be allocated to other operations, including certain business development activities.

Segment Information Summary
Inter-segment transactions were immaterial for the periods presented. Total assets by segment is not regularly provided to the CODM and is therefore omitted. The following table presents summary financial information concerning the reportable segments and other:
Three Months Ended March 31,
In thousandsNW Natural
SiEnergy(2)
NWN WaterOtherNW Holdings
2026
Operating revenues$433,896 $31,695 $14,969 $9,843 $490,403 
Depreciation39,444 1,797 2,893 — 44,134 
Income from operations(1)
143,686 13,834 2,399 2,949 162,868 
Interest expense, net17,678 2,543 688 12,443 33,352 
Income tax expense (benefit)32,155 2,537 554 (2,707)32,539 
Capital expenditures79,615 24,944 9,097 — 113,656 
2025
Operating revenues$448,813 $22,666 $13,909 $8,896 $494,284 
Depreciation36,036 2,070 2,394 — 40,500 
Income from operations(1)
145,032 9,613 3,043 (3,334)154,354 
Interest expense, net15,580 2,257 792 10,766 29,395 
Income tax expense (benefit)35,664 1,944 631 (3,712)34,527 
Capital expenditures83,608 10,525 8,051 — 102,184 
(1)     Income from operations is not a financial measure used by the CODM for NW Natural or SiEnergy, but is included in the table above to enable the reconciliation of NW Natural and SiEnergy margin to consolidated income before taxes in accordance with ASU 2023-07.
(2)    SiEnergy was acquired by NW Holdings on January 7, 2025. Results for the period from January 7, 2025 to March 31, 2025 are presented in the table above. Prior to January 7, 2025, NW Holdings did not operate any assets that fall within its SiEnergy segment.
NW Holdings and NW Natural's CODM is the chief executive officer. The CODM uses NW Natural margin, SiEnergy margin and NWN Water income from operations to allocate resources, predominantly in the annual budget and forecasting process. The CODM considers budget-to-actual variances on a monthly basis when making decisions about allocating capital and personnel. The CODM also uses NW Natural margin, SiEnergy margin and NWN Water income from operations to assess the performance of NW Natural, SiEnergy and NWN Water, respectively.
NW Natural Margin
NW Natural margin is the primary financial measure used by the CODM, consisting of NW Natural operating revenues, reduced by the associated cost of gas, environmental remediation expense, and revenue taxes. The cost of gas purchased for customers is generally a pass-through cost in the amount of revenues billed. Environmental remediation expense represents collections received from customers through environmental recovery mechanisms in Oregon and Washington as well as adjustments for the Oregon environmental earnings test when applicable. This is offset by environmental remediation expense presented in operating expenses. Revenue taxes are collected from customers and remitted to taxing authorities. The collections from customers are offset by the expense recognition of the obligation to the taxing authority. Regulated gas storage margin is equivalent to operating revenues. By subtracting cost of gas, environmental remediation expense, and revenue taxes from NW Natural operating revenues, NW Natural margin provides a key metric used by the CODM in assessing the performance of the NW Natural segment.
The following table presents additional segment information concerning NW Natural margin:
Three Months Ended March 31,
In thousands20262025
NW Natural margin calculation:
Distribution revenues$421,234 $435,908 
Regulated gas storage9,606 9,784 
Other revenue3,056 3,121 
Total operating revenues433,896 448,813 
Less: Cost of gas140,144 159,436 
          Environmental remediation6,325 6,253 
 Revenue taxes17,037 18,565 
NW Natural margin270,390 264,559 
Operations and maintenance70,530 67,766 
General taxes16,037 14,979 
Depreciation39,444 36,036 
Other Operating Expenses693 746 
NW Natural income from operations$143,686 $145,032 

SiEnergy Margin
SiEnergy margin is the primary financial measure used by the CODM, consisting of SiEnergy operating revenues, reduced by the associated cost of gas and revenue taxes. The cost of gas purchased for SiEnergy customers is generally a pass-through cost in the amount of revenues billed to regulated SiEnergy customers. Revenue taxes are collected from customers and remitted to taxing authorities. The collections from customers are offset by the expense recognition of the obligation to the taxing authority. By subtracting cost of gas and revenue taxes from SiEnergy operating revenues, SiEnergy margin provides a key metric used by the CODM in assessing the performance of the segment.

The following table presents additional segment information concerning SiEnergy margin:
Three Months Ended March 31,Three Months Ended March 31,
In thousands2026
2025(1)
SiEnergy margin calculation:
Distribution revenues$31,695 $22,666 
Total operating revenues31,695 22,666 
Less: Cost of gas12,279 8,303 
 Revenue taxes961 779 
SiEnergy margin18,455 13,584 
Operations and maintenance2,814 1,682 
General taxes10 219 
Depreciation1,797 2,070 
SiEnergy income from operations$13,834 $9,613 
(1)    SiEnergy was acquired by NW Holdings on January 7, 2025. Results for the period from January 7, 2025 to March 31, 2025 are presented in the table above. Prior to January 7, 2025, NW Holdings did not operate any assets that fall within its SiEnergy segment.
Significant Segment Expenses
Public entities are required to disclose significant segment expenses for each reportable segment if they are regularly provided to the CODM and included in the reported measure of segment profit/loss. This requirement does not necessitate additional disclosure for the NW Natural and SiEnergy segments, as all expense categories are presented above in the NW Natural margin table and SiEnergy margin table, respectively. Significant segment expenses for NWN Water are presented below.
Three Months Ended March 31,
In thousands20262025
Operating revenues$14,969 $13,909 
Operating expenses:
Operations and maintenance8,607 7,265 
Depreciation2,893 2,394 
Other operating expenses(1)
1,070 1,207 
Income from operations$2,399 $3,043 
(1) Other operating expenses include general and revenue taxes and other expenses.
v3.26.1
Common Stock
 3 Months Ended
Mar. 31, 2026
Equity [Abstract]  
Common Stock COMMON STOCK
In August 2024, the Finance Committee of the NW Holdings' Board of Directors authorized NW Holdings' sale of $200 million in the aggregate gross sales price under the at-the-market (ATM) equity program first initiated in August 2021. NW Holdings is under no obligation to offer and sell common stock under the ATM equity program. Any shares of common stock offered under the ATM equity program are registered on NW Holdings’ universal shelf registration statement filed with the SEC, which expires in August 2027, or will be registered on a subsequent registration statement to be filed by NW Holdings.
During the three months ended March 31, 2026, NW Holdings issued and sold 441,034 shares of common stock pursuant to the ATM equity program resulting in cash proceeds of $22.2 million, net of fees and commissions paid to agents of $0.3 million. As of March 31, 2026, $75.2 million of equity remained available for issuance under the ATM equity program.
v3.26.1
Revenue
 3 Months Ended
Mar. 31, 2026
Revenue from Contract with Customer [Abstract]  
Revenue REVENUE
The following tables present disaggregated revenue of NW Holdings:
Three Months Ended March 31,
In thousandsNW Natural
SiEnergy(1)
NWN WaterOtherNW Holdings
2026
Natural gas sales$399,119 $28,376 $— $1,378 $428,873 
Gas storage revenue, net4,365 — — — 4,365 
Asset management revenue, net1,747 — — — 1,747 
Water and wastewater revenue— — 14,969 — 14,969 
Gas appliance retail revenue1,309 — — — 1,309 
Renewable natural gas sales— — — 8,465 8,465 
Other revenue876 — — — 876 
    Revenue from contracts with customers407,416 28,376 14,969 9,843 460,604 
Alternative revenue22,027 3,319 — — 25,346 
Leasing revenue4,453 — — — 4,453 
    Total operating revenues$433,896 $31,695 $14,969 $9,843 $490,403 
2025
Natural gas sales$430,249 $22,327 $— $1,170 $453,746 
Gas storage revenue, net4,616 — — — 4,616 
Asset management revenue, net1,749 — — — 1,749 
Water and wastewater revenue— — 13,909 — 13,909 
Gas appliance retail revenue1,372 — — — 1,372 
Renewable natural gas sales— — — 7,726 7,726 
Other revenue952 — — — 952 
    Revenue from contracts with customers438,938 22,327 13,909 8,896 484,070 
Alternative revenue5,569 339 — — 5,908 
Leasing revenue4,306 — — — 4,306 
    Total operating revenues$448,813 $22,666 $13,909 $8,896 $494,284 
(1)    SiEnergy was acquired by NW Holdings on January 7, 2025. Results for the period from January 7, 2025 to March 31, 2025 are presented in the table above. Prior to January 7, 2025, NW Holdings did not operate any assets that fall within its SiEnergy segment.
Natural gas sales represent the majority of NW Holdings' revenue and is recognized when the obligation to customers is satisfied and in the amount expected to be received in exchange for transferring goods or providing services. Revenue from contracts with customers contains one performance obligation that is generally satisfied over time as the customer receives the natural gas. The transaction price is determined by a set price agreed upon in the contract or dependent on regulatory tariffs. Customer accounts are settled on a monthly basis or paid at time of sale. Based on historical experience, it is probable that we will collect substantially all of the consideration to which we are entitled. We evaluated the probability of collection in accordance with the current expected credit losses standard.

NW Holdings and NW Natural do not have any material contract assets, as net accounts receivable and accrued unbilled revenue balances are unconditional and only involve the passage of time until such balances are billed and collected. NW Holdings and NW Natural do not have any material contract liabilities.

Revenue taxes are included in operating revenues with an equal and offsetting expense recognized in operating expenses in the consolidated statements of comprehensive income. Revenue-based taxes are primarily franchise taxes, which are collected from utility customers and remitted to taxing authorities.

Components of Revenue
The components of NW Holdings' revenue, by reportable business segment, are explained below.

NW Natural
Natural Gas Sales
NW Natural's primary source of revenue is providing natural gas to customers in the NW Natural service territory, which includes residential, commercial, industrial and transportation customers. NW Natural revenue is generally recognized over time upon
delivery of the gas commodity or service to the customer, and the amount of consideration received and recognized as revenue is dependent on the Oregon and Washington tariffs. There is no right of return or warranty for services provided. Revenues include firm and interruptible sales and transportation services, franchise taxes recovered from the customer, late payment fees, service fees, and accruals for gas delivered but not yet billed (accrued unbilled revenue). The accrued unbilled revenue balance is based on estimates of deliveries during the period from the last meter reading and management judgment is required for a number of factors used in this calculation, including customer use and weather factors.

Customer accounts are to be paid in full each month and there is no significant financing component for this source of revenue. Due to the election of the right to invoice practical expedient, we do not disclose the value of unsatisfied performance obligations.

Gas Storage Revenue
NW Natural's gas storage revenue includes gas storage activity, which includes Interstate Storage Services used to store natural gas for customers. Gas storage revenue is generally recognized over time as the gas storage service is provided to the customer and the amount of consideration received and recognized as revenue is dependent on set rates defined per the storage agreements. Noncash consideration in the form of dekatherms of natural gas is received as consideration for providing gas injection services to gas storage customers. This noncash consideration is measured at fair value using the average spot rate. Customer accounts are generally paid in full each month, and there is no right of return or warranty for services provided. Revenues include firm and interruptible storage services, net of the profit sharing amount refunded to NW Natural customers.

Asset Management Revenue
Revenues include the optimization of storage assets and pipeline capacity by a third-party and are provided net of the profit sharing amount refunded to NW Natural customers. Certain asset management revenues received are recognized over time using a straight-line approach over the term of each contract, and the amount of consideration received and recognized as revenue is dependent on a variable pricing model. Variable revenues earned above guaranteed amounts are estimated and recognized at the end of each period using the most likely amount approach. Additionally, other asset management revenues may be based on a fixed rate. Generally, asset management accounts are settled on a monthly basis.

As of March 31, 2026, unrecognized revenue for the fixed component of the transaction price related to gas storage and asset management revenue was approximately $112.3 million. Of this amount, approximately $23.0 million will be recognized during the remainder of 2026, $21.8 million in 2027, $16.8 million in 2028, $16.8 million in 2029, $16.3 million in 2030 and $17.6 million thereafter. The amounts presented here are calculated using current contracted rates.

Gas Appliance Retail Revenue
NW Natural owns and operates an appliance store that is open to the public, where customers can purchase natural gas home appliances. Revenue from the sale of appliances is recognized at the point in time in which the appliance is transferred to the third party responsible for delivery and installation services and when the customer has legal title to the appliance. It is required that the sale be paid for in full prior to transfer of legal title. The amount of consideration received and recognized as revenue varies with changes in marketing incentives and discounts offered to customers.

Alternative Revenue
Weather normalization (WARM) and decoupling mechanisms are considered to be alternative revenue programs. Alternative revenue programs are considered to be contracts between NW Natural and its regulator and are excluded from revenue from contracts with customers.

Leasing Revenue
Leasing revenue primarily consists of revenues from NW Natural's North Mist Storage contract with PGE (Portland General Electric) in support of PGE's gas-fired electric power generation facilities under an initial 30-year contract with options to extend, totaling up to an additional 50 years upon mutual agreement of the parties. The facility is accounted for as a sales-type lease and qualifies for regulatory accounting deferral treatment. The investment is included in rate base under an established cost-of-service tariff schedule, with revenues recognized according to the tariff schedule and profit upon commencement was deferred and will be amortized over the lease term.

Billing rates under the cost-of-service tariff will be updated annually to reflect current information including depreciable asset levels, forecasted operating expenses, and the results of regulatory proceedings, as applicable, and revenue received under this agreement is recognized as operating revenue on the consolidated statements of comprehensive income. There are no variable payments or residual value guarantees. The lease does not contain an option to purchase the underlying assets. NW Natural also maintains other immaterial sales type leases that are subject to an OPUC approved rate schedule. None of these other leases have variable payments or residual value guarantees and no significant selling profit upon lease commencement.

NW Natural also maintains a sales-type lease for specialized compressor facilities to provide high pressure compressed natural gas (CNG) services. Lease payments are outlined in an OPUC-approved rate schedule over a 10-year term. There are no variable payments or residual value guarantees. The selling profit computed upon lease commencement was not significant.
Leasing revenue also contains rental revenue from small leases of property owned by NW Natural to third parties. The majority of these transactions are accounted for as operating leases and the revenue is recognized over the term of the lease agreement. Lease revenue is excluded from revenue from contracts with customers.

The components of lease revenue at NW Holdings and NW Natural were as follows:

In thousandsThree Months Ended March 31,
20262025
NW Natural:
Lease revenue
Operating leases$19 $21 
Sales-type leases4,434 4,285 
Total lease revenue$4,453 $4,306 

SiEnergy
SiEnergy's primary source of revenue is providing natural gas to customers in the SiEnergy service territory, which includes residential and commercial customers. SiEnergy revenue is generally recognized over time upon delivery of the gas commodity or service to the customer, and the amount of consideration received and recognized as revenue is dependent on the Texas tariff. There is no right of return or warranty for services provided. The accrued unbilled revenue balance is based on estimates of deliveries during the period from the last meter reading and management judgment is required for a number of factors used in this calculation, including customer use and weather factors.

Customer accounts are to be paid in full each month and there is no significant financing component for this source of revenue. Due to the election of the right to invoice practical expedient, we do not disclose the value of unsatisfied performance obligations.

Alternative Revenue
Weather normalization (WNA) is considered to be an alternative revenue program. An alternative revenue program is considered to be a contract between SiEnergy and its regulators and is excluded from revenue from contracts with customers.

NWN Water
NWN Water provides water and wastewater services to customers. Water and wastewater service revenue is generally recognized over time upon delivery of the water commodity or service to the customer, and the amount of consideration received and recognized as revenue is dependent on the tariffs established in the states we operate. There is no right of return or warranty for services provided.

Customer accounts are to be paid in full each month, bi-monthly, or quarterly and as such, there is no significant financing component for this source of revenue. Due to the election of the right to invoice practical expedient, we do not disclose the value of unsatisfied performance obligations.

Other
Renewable Natural Gas Sales
NWN Renewables is an unregulated subsidiary of NW Holdings established to pursue investments in renewable natural gas (RNG) activities. NWN Renewables' primary source of revenue is from the sale of RNG under long-term contracts. RNG revenue is generally recognized over time upon delivery of the gas commodity to the customer at the designated delivery point and the amount of consideration received and recognized as revenue is dependent on a variable pricing model defined per the contract. Customer accounts are to be paid in full each month and as such, there is no significant financing component for this source of revenue. Due to the election of the right to invoice practical expedient, we do not disclose the value of unsatisfied performance obligations.
v3.26.1
Leases
 3 Months Ended
Mar. 31, 2026
Leases [Abstract]  
Leases LEASES
Lease Expense
Operating Leases
We have operating leases for land, buildings and equipment. Our primary lease is for NW Natural's headquarters and operations center. Our leases have remaining lease terms of 2 months to 14 years. Many of our lease agreements include options to extend the lease, which we do not include in our minimum lease terms unless they are reasonably certain to be exercised. Short-term leases with a term of 12 months or less are not recorded on the balance sheet. As most of our leases do not provide an implicit rate and are entered into by NW Natural, we use an estimated discount rate representing the rate we would have incurred to finance the funds necessary to purchase the leased asset and is based on information available at the lease commencement date in determining the present value of lease payments.
The components of lease expense, a portion of which is capitalized, were as follows:
In thousandsThree Months Ended March 31,
20262025
NW Holdings:
Operating lease expense$2,252 $2,111 
Short-term lease expense 218 189 
NW Natural:
Operating lease expense$1,954 $1,867 
Short-term lease expense 120 189 

The Company’s lease arrangements are described in Note 7 to the consolidated financial statements included in the Company’s Annual Report on Form 10‑K, which should be read in conjunction with this Form 10‑Q. There have been no material changes to the Company’s lease portfolio during the current quarter.

The weighted-average remaining lease terms and weighted-average discount rates for the operating leases were as follows:
In thousandsMarch 31,December 31,
202620252025
NW Natural:
Weighted-average remaining lease term (years)14.015.014.3
Weighted-average discount rate7.3 %7.3 %7.3 %

Supplemental Cash Flow
Supplemental cash flow information related to leases was as follows:
In thousandsThree Months Ended March 31,
20262025
NW Holdings:
Cash paid for amounts included in the measurement of lease liabilities
Operating cash flows from operating leases$2,107 $1,918 
Right of use assets obtained in exchange for lease obligations
Operating leases$978 $2,647 
NW Natural:
Cash paid for amounts included in the measurement of lease liabilities
Operating cash flows from operating leases$1,931 $1,861 
Right of use assets obtained in exchange for lease obligations
Operating leases$250 $346 
Lessor, Operating Leases LEASES
Lease Expense
Operating Leases
We have operating leases for land, buildings and equipment. Our primary lease is for NW Natural's headquarters and operations center. Our leases have remaining lease terms of 2 months to 14 years. Many of our lease agreements include options to extend the lease, which we do not include in our minimum lease terms unless they are reasonably certain to be exercised. Short-term leases with a term of 12 months or less are not recorded on the balance sheet. As most of our leases do not provide an implicit rate and are entered into by NW Natural, we use an estimated discount rate representing the rate we would have incurred to finance the funds necessary to purchase the leased asset and is based on information available at the lease commencement date in determining the present value of lease payments.
The components of lease expense, a portion of which is capitalized, were as follows:
In thousandsThree Months Ended March 31,
20262025
NW Holdings:
Operating lease expense$2,252 $2,111 
Short-term lease expense 218 189 
NW Natural:
Operating lease expense$1,954 $1,867 
Short-term lease expense 120 189 

The Company’s lease arrangements are described in Note 7 to the consolidated financial statements included in the Company’s Annual Report on Form 10‑K, which should be read in conjunction with this Form 10‑Q. There have been no material changes to the Company’s lease portfolio during the current quarter.

The weighted-average remaining lease terms and weighted-average discount rates for the operating leases were as follows:
In thousandsMarch 31,December 31,
202620252025
NW Natural:
Weighted-average remaining lease term (years)14.015.014.3
Weighted-average discount rate7.3 %7.3 %7.3 %

Supplemental Cash Flow
Supplemental cash flow information related to leases was as follows:
In thousandsThree Months Ended March 31,
20262025
NW Holdings:
Cash paid for amounts included in the measurement of lease liabilities
Operating cash flows from operating leases$2,107 $1,918 
Right of use assets obtained in exchange for lease obligations
Operating leases$978 $2,647 
NW Natural:
Cash paid for amounts included in the measurement of lease liabilities
Operating cash flows from operating leases$1,931 $1,861 
Right of use assets obtained in exchange for lease obligations
Operating leases$250 $346 
v3.26.1
Stock-Based Compensation
 3 Months Ended
Mar. 31, 2026
Share-Based Payment Arrangement [Abstract]  
Stock-Based Compensation STOCK-BASED COMPENSATION
Stock-based compensation plans are designed to promote stock ownership in NW Holdings by employees, including officers. These compensation plans include a Long Term Incentive Plan (LTIP) and an Employee Stock Purchase Plan (ESPP). For additional information on stock-based compensation plans, see Note 8 in the 2025 Form 10-K and the updates provided below.

Long Term Incentive Plan
Performance Shares
LTIP performance shares incorporate a combination of market, performance, and service-based factors. During the three months ended March 31, 2026, the final performance factor under the 2024-2026 LTIP was approved and 52,178 performance-based shares were granted under the 2024-2026 LTIP for accounting purposes. As such, NW Natural began recognizing compensation expense.

In February 2025, LTIP shares were awarded to participants; however, the agreement allows for one of the performance factors to remain variable until the first quarter of the third year of the award period. As the performance factor will not be approved until the first quarter of 2027, there is not a mutual understanding of the awards' key terms and conditions between NW Holdings and the participants as of March 31, 2026, and therefore, no expense was recognized for the 2025-2027 award. NW Holdings will
calculate the grant date fair value and the applicable subsidiaries of NW Holdings will recognize expense over the remaining service period for each award once the final performance factor has been approved.

In February 2026, LTIP shares were awarded to certain participants; however, the agreement allows for one of the performance factors to remain variable until the first quarter of the third year of the award period. As the performance factor will not be approved until the first quarter of 2028, there is not a mutual understanding of the awards' key terms and conditions between NW Holdings and the participants as of March 31, 2026, and therefore, no expense was recognized for the 2026-2028 award. NW Holdings will calculate the grant date fair value and the applicable subsidiaries of NW Holdings will recognize expense over the remaining service period for each award once the final performance factor has been approved.

For the 2025-2027 and 2026-2028 LTIP awards, share payouts range from a threshold of 0% to a maximum of 200% based on achievement of pre-established goals. The performance criteria for the 2025-2027 and 2026-2028 performance shares consists of a three-year Return on Invested Capital (ROIC) threshold that must be satisfied and a cumulative EPS factor, which can be modified by a total shareholder return factor (TSR modifier) relative to the performance of peer group companies over the performance period of three years for each respective award. If the targets were achieved for the 2025-2027 and 2026-2028 awards, NW Holdings would grant for accounting purposes 73,640 and 65,240 shares in the first quarters of 2027 and 2028, respectively.

In February 2025 and 2026, 6,135 and 8,675 LTIP shares were awarded to certain participants, respectively. The LTIP awards share payouts range from a threshold of 0% to a maximum of 200% based on achievement of pre-established goals. The performance criteria for the 2025-2027 and 2026-2028 performance shares consist of a three-year ROIC threshold that must be satisfied and a 3-year cumulative EBITDA, which can be modified by a TSR modifier relative to the performance peer group companies over the period group. During the three months ended March 31, 2026, there was mutual understanding of all key terms of the awards. As such, NW Holdings recognized compensation expense.

As of March 31, 2026, there was $1.5 million of unrecognized compensation, which is expected to be recognized through 2028.

Restricted Stock Units
During the three months ended March 31, 2026, 59,349 RSUs were granted under the LTIP with a weighted-average grant date fair value of $49.99 per share. Generally, the RSUs awarded are forfeitable and include a performance-based threshold as well as a vesting period of three years from the grant date. The majority of our RSU grants obligate NW Holdings, upon vesting, to issue the RSU holder one share of common stock. The grant may also include a cash payment equal to the total amount of dividends paid per share between the grant date and vesting date of that portion of the RSU depending on the structure of the award agreement. The fair value of an RSU is equal to the closing market price of NW Holdings' common stock on the grant date.

As of March 31, 2026, there was $5.5 million of unrecognized compensation cost from grants of RSUs, which is expected to be recognized over a period extending through 2029.
v3.26.1
Debt
 3 Months Ended
Mar. 31, 2026
Debt Disclosure [Abstract]  
Debt DEBT
The nature and terms of our debt instruments and credit facilities are described in detail in Note 9 to the consolidated financial statements in our Annual Report on Form 10-K for the fiscal year ended December 31, 2025. Other than as described below, there were no other material changes in the terms of our debt instruments during the three months ended March 31, 2026.

Short-Term Debt
NW Holdings' short-term debt consisted of the following:

March 31, 2026March 31, 2025December 31, 2025
In millionsBalance Outstanding
Weighted Average Interest Rate(1)
Balance Outstanding
Weighted Average Interest Rate(1)
Balance Outstanding
Weighted Average Interest Rate(1)
Commercial Paper Borrowings - NW Holdings(2)
$171.3 4.1 %$— — %$162.0 4.1 %
Commercial Paper Borrowings - NW Natural— — %— — %10.0 4.0 %
NW Holdings Credit Agreement Loans— — %81.1 5.5 %— — %
Total short-term debt$171.3 $81.1 $172.0 
(1) Weighted average interest rate on outstanding short-term debt
(2) NW Holdings initiated a commercial paper program in March 2025.

Long-Term Debt
NW Holdings' long-term debt consisted of the following:

March 31, 2026March 31, 2025December 31, 2025
In millionsBalance Outstanding
Weighted Average Interest Rate(1)
Balance Outstanding
Weighted Average Interest Rate(1)
Balance Outstanding
Weighted Average Interest Rate(2)
NW Natural first mortgage bonds$1,544.7 4.7 %$1,374.7 4.6 %$1,544.7 4.7 %
SiEnergy term loan(3)
— — %149.6 6.1 %— — %
SiEnergy secured senior notes185.0 5.6 %— — %185.0 5.6 %
NWN Water term loan55.0 4.7 %55.0 4.7 %55.0 4.7 %
Other water debt3.9 5.0 4.0 
NW Holdings unsecured senior bonds285.0 5.7 %285.0 5.7 %285.0 5.7 %
NW Holdings term loan50.0 4.7 %50.0 5.3 %50.0 5.2 %
NW Holdings junior subordinated debentures325.0 7.0 %325.0 7.0 %325.0 7.0 %
Long-term debt, gross2,448.6 2,244.3 2,448.7 
Less: unamortized debt issuance costs15.5 14.4 15.9 
Less: current maturities160.7 36.8 160.6 
Total long-term debt$2,272.4 $2,193.1 $2,272.2 

(1)    Weighted average interest rate for the three months ended March 31, 2026 and March 31, 2025
(2)    Weighted average interest rate for the year ended December 31, 2025
(3)    On January 7, 2025, NW Holdings acquired SiEnergy. SiEnergy's subsidiary, Si Investment Co., had this existing term loan outstanding at the date of acquisition. In August 2025, the associated facilities were terminated and are no longer available for financing.

NW Natural's first mortgage bonds (FMBs) have maturity dates ranging from 2026 through 2055 and interest rates ranging from 2.82% to 7.85%. SiEnergy's secured senior notes have maturity dates ranging from 2030 through 2055 and interest rates ranging from 4.86% to 6.04%. NW Holdings' unsecured senior bonds have maturity dates ranging from 2028 through 2034 and interest rates ranging from 5.52% to 5.86%. NW Holdings' Junior Subordinated Debentures has an interest rate of 7.0% and a maturity date of 2055. At March 31, 2026, NW Holdings and NW Natural had long-term debt outstanding of $2,433.1 million and $1,535.1 million, respectively, which included $15.5 million and $9.6 million of unamortized debt issuance costs at NW Holdings and NW Natural, respectively. Debt of $160.7 million is scheduled to mature in the next twelve months, which consists of $55.0 million at NW Natural, $55.7 million at NWN Water, and $50.0 million at NW Holdings.

Summary of Significant Debt Issuances

There were no new debt issuances in in the first quarter of 2026 at either NW Natural or NW Holdings.

Summary of Significant Debt Extinguishments and Repayments

There were no significant debt retirements in the first quarter of 2026 at either NW Natural or NW Holdings.

Fair Value of Long-Term Debt
NW Holdings' and NW Natural's outstanding debt does not trade in active markets. The fair value of debt is estimated using the value of outstanding debt at natural gas distribution companies with similar credit ratings, terms, and remaining maturities to NW Holdings' and NW Natural's debt that actively trade in public markets. These valuations are based on Level 2 inputs as defined in the fair value hierarchy. See Note 2 in the 2025 Form 10-K for a description of the fair value hierarchy.
The following table provides an estimate of the fair value of long-term debt, including current maturities of long-term debt, using market prices in effect on the valuation date:
March 31,December 31,
In millions202620252025
NW Holdings:
Gross long-term debt$2,448.6 $2,244.3 $2,448.7 
Unamortized debt issuance costs(15.5)(14.4)(15.9)
Carrying amount$2,433.1 $2,229.9 $2,432.8 
Estimated fair value(1)
$2,281.4 $2,069.8 $2,317.1 
NW Natural:
Gross long-term debt$1,544.7 $1,374.7 $1,544.7 
Unamortized debt issuance costs(9.6)(9.1)(9.8)
Carrying amount$1,535.1 $1,365.6 $1,534.9 
Estimated fair value(1)
$1,360.8 $1,198.7 $1,383.1 
(1) Estimated fair value does not include unamortized debt issuance costs.
v3.26.1
Pension and Other Postretirement Benefit Costs
 3 Months Ended
Mar. 31, 2026
Pension and Other Postretirement Benefits Cost (Reversal of Cost) [Abstract]  
Pension and Other Postretirement Benefit Costs PENSION AND OTHER POSTRETIREMENT BENEFIT COSTS
NW Natural maintains a qualified non-contributory defined benefit pension plan (Pension Plan), non-qualified supplemental pension plans for eligible executive officers and other key employees, and other postretirement employee benefit plans. NW Natural also has a qualified defined contribution plan (Retirement K Savings Plan) for all eligible employees. The Pension Plan and Retirement K Savings Plan have plan assets, which are held in qualified trusts to fund retirement benefits.

The service cost component of net periodic benefit cost for NW Natural pension and other postretirement benefit plans is recognized in operations and maintenance expense in the consolidated statements of comprehensive income. The other non-service cost components are recognized in other income (expense), net in the consolidated statements of comprehensive income.

The following table provides the components of net periodic benefit cost (credit) for the pension and other postretirement benefit plans:
 Three Months Ended March 31,
Pension BenefitsOther
Postretirement Benefits
In thousands2026202520262025
Service cost$855 $885 $26 $27 
Interest cost5,167 5,410 282 288 
Expected return on plan assets(5,591)(5,433)— — 
Amortization of net actuarial loss2,295 2,444 63 20 
Net periodic benefit cost 2,726 3,306 371 335 
Amount allocated to construction(405)(434)(11)(11)
Net periodic benefit cost charged to expense2,321 2,872 360 324 
Amortization of regulatory balancing account2,801 2,801 — — 
Net amount charged to expense$5,122 $5,673 $360 $324 

Net periodic benefit costs are reduced by amounts capitalized to NW Natural plant. In addition, net periodic benefit costs were recorded to a regulatory balancing account as approved by the OPUC and amortized accordingly.
The following table presents amounts recognized in accumulated other comprehensive loss (AOCL) and the changes in AOCL related to non-qualified employee benefit plans:
Three Months Ended March 31,
In thousands20262025
Beginning balance$(4,705)$(7,052)
Amounts reclassified from AOCL:
Amortization of actuarial losses124 200 
Total reclassifications before tax124 200 
Tax benefit(33)(25)
Total reclassifications for the period91 175 
Ending balance$(4,614)$(6,877)

Employer Contributions to Company-Sponsored Defined Benefit Pension Plans
NW Natural made $2.9 million of cash contributions to its qualified defined benefit pension plans during the three months ended March 31, 2026 and $2.6 million cash contributions during the three months ended March 31, 2025.

Defined Contribution Plan
NW Natural's Retirement K Savings Plan is a qualified defined contribution plan under Internal Revenue Code Sections 401(a) and 401(k). NW Natural contributions totaled $4.3 million and $4.0 million for the three months ended March 31, 2026 and 2025, respectively.

See Note 10 in the 2025 Form 10-K for more information concerning these retirement and other postretirement benefit plans.
v3.26.1
Income Tax
 3 Months Ended
Mar. 31, 2026
Income Tax Disclosure [Abstract]  
Income Tax INCOME TAX
An estimate of annual income tax expense is made each interim period using estimates for annual pre-tax income, regulatory flow-through adjustments, tax credits, and other items. The estimated annual effective tax rate is applied to year-to-date, pre-tax income to determine income tax expense for the interim period consistent with the annual estimate. Discrete events are recorded in the interim period in which they occur or become known.

The effective income tax rate varied from the federal statutory rate due to the following:
Three Months Ended March 31,
NW HoldingsNW Natural
In thousands2026202520262025
Income tax at statutory rate (federal)$27,306 $25,713 $26,440 $26,608 
State income tax8,830 9,980 9,247 10,202 
Increase (decrease): 
Differences required to be flowed-through by regulatory commissions(1,954)(1,668)(1,954)(1,668)
Other, net(1,643)502 (1,578)522 
Total provision for income taxes$32,539 $34,527 $32,155 $35,664 
Effective income tax rate25.0 %28.2 %25.5 %28.1 %

The NW Holdings effective income tax rate for the three months ended March 31, 2026 compared to the same period in 2025, decreased due to lower state income tax rates in the SiEnergy and NW Natural Water segments. In addition, both NW Holdings and NW Natural effective tax rates benefited from lower non-deductible executive compensation expense and higher AFUDC equity income. For further detail on income taxes and effective tax rates, refer to Note 11 in the 2025 Form 10-K.

The IRS Compliance Assurance Process (CAP) examination of the 2024 tax year was ongoing during the first quarter of 2026. The 2025 and 2026 tax years are subject to examination under CAP.
v3.26.1
Property, Plant and Equipment
 3 Months Ended
Mar. 31, 2026
Property, Plant and Equipment [Abstract]  
Property, Plant and Equipment PROPERTY, PLANT, AND EQUIPMENT
The following table sets forth the major classifications of property, plant, and equipment and accumulated depreciation:
March 31,December 31,
In thousands202620252025
NW Holdings:
Plant in service$5,509,029 $5,091,181 $5,468,170 
Construction work in progress213,327 176,882 172,265 
Less: Accumulated depreciation1,300,897 1,266,222 1,288,422 
Total property, plant, and equipment, net$4,421,459 $4,001,841 $4,352,013 
Capital expenditures in accrued liabilities$51,572 $32,042 $57,762 
NW Natural:
Plant in service$4,891,650 $4,634,047 $4,879,816 
Construction work in progress155,212 146,433 120,513 
Less: Accumulated depreciation1,257,950 1,237,907 1,256,289 
Total property, plant, and equipment, net$3,788,912 $3,542,573 $3,744,040 
Capital expenditures in accrued liabilities$34,917 $23,457 $33,582 
v3.26.1
Investments
 3 Months Ended
Mar. 31, 2026
Investments [Abstract]  
Investments INVESTMENTS
Investments include gas reserves, financial investments in life insurance policies, and equity method investments. The following table summarizes other investments:
NW HoldingsNW Natural
March 31,December 31,March 31,December 31,
In thousands202620252025202620252025
Investments in life insurance policies$34,032 $45,936 $45,606 $34,032 $45,936 $45,606 
Investments in gas reserves, non-current14,789 17,500 15,443 14,789 17,500 15,443 
Investment in unconsolidated affiliates20,620 19,227 19,627 — — — 
Total other investments$69,441 $82,663 $80,676 $48,821 $63,436 $61,049 

Investment in Life Insurance Policies
Other investments include financial investments in life insurance policies, which are accounted for at cash surrender value, net of policy loans. See Note 13 in the 2025 Form 10-K.
NW Natural Gas Reserves
NW Natural has invested $188 million through the gas reserves program in the Jonah Field located in Wyoming as of March 31, 2026. Gas reserves are stated at cost, net of regulatory amortization, with the associated deferred tax benefits of $1.5 million, $2.6 million, and $1.8 million, which are recorded as liabilities in the March 31, 2026, March 31, 2025, and December 31, 2025 consolidated balance sheets, respectively. NW Natural's investment is included in NW Holdings' and NW Natural's consolidated balance sheets under other current assets and other investments (non-current portion) with the maximum loss exposure limited to the investment balance. The amount of gas reserves included in other current assets was $2.6 million, $2.7 million, and $2.6 million as of March 31, 2026, March 31, 2025, and December 31, 2025, respectively. See Note 13 in the 2025 Form 10-K.

Investments in Unconsolidated Affiliates
In December 2021, NWN Water purchased a 37.3% ownership stake in Avion Water Company, Inc. (Avion Water), an investor-owned water utility for $14.5 million. NWN Water subsequently increased its ownership stake in Avion Water as follows:
In millionsAmountOwnership %
July 2022$1.0 40.3 %
June 2023$1.0 43.1 %
January 2024$1.0 45.6 %
February 2025$1.0 47.9 %
January 2026$1.0 50.0 %

Avion Water operates in Bend, Oregon and the surrounding communities, serving approximately 17,000 connections and employing 40 people. The carrying value of the equity method investment is $10.1 million higher than the underlying equity in the net assets of the investee at March 31, 2026 due to equity method goodwill. NWN Water's share in the earnings of Avion Water is included in other income (expense), net.
v3.26.1
Business Combinations
 3 Months Ended
Mar. 31, 2026
Business Combination, Asset Acquisition, Transaction between Entities under Common Control, and Joint Venture Formation [Abstract]  
Business Combinations BUSINESS COMBINATIONS
2025 Business Combinations

SiEnergy Acquisition
On January 7, 2025, NW Holdings acquired 100% of the outstanding membership interests of SiEnergy Operating, LLC from SiEnergy Capital Partners, LLC, an affiliate of Ridgewood Infrastructure. Total consideration included $271.1 million in cash and the assumption of $156.1 million of outstanding debt. SiEnergy is a regulated natural gas distribution utility and a transmission utility. Excluding Pines Holdings, which was acquired June 2, 2025 and is described further below, SiEnergy serves approximately 85,000 customers in the greater metropolitan areas of Houston, Dallas, and Austin, Texas.

The SiEnergy acquisition met the criteria of a business combination, and as such an allocation of the consideration to the acquired net assets based on their estimated fair value as of the acquisition date was performed. In accordance with U.S. GAAP, the fair value determination involved management judgment in determining the significant estimates and assumptions used for net assets associated with SiEnergy. This allocation was finalized in the quarter ended March 31, 2026. Acquisition costs totaling $5.3 million in the first quarter of 2025 were expensed as incurred. Acquisition costs related to SiEnergy are included in operations and maintenance expenses in the consolidated statements of comprehensive income. The transaction aligns with NW Holdings' growth strategy and further expands the service territory in Texas.

Goodwill of $171.1 million was recognized from this acquisition. The goodwill recognized is attributable to SiEnergy's natural gas utility service territory, experienced workforce, and the strategic benefits expected from growth in its service territory. No intangible assets aside from goodwill were recognized. The amount of goodwill that is expected to be deductible for income tax purposes is $179.9 million.

The following table summarizes the consideration transferred and the amounts of identified assets acquired and liabilities assumed as the acquisition date:
In thousands
Fair value of consideration transferred:
Cash$271,087 
Recognized amounts of identifiable assets acquired and liabilities assumed:
Current assets$16,770 
Property, plant and equipment262,697 
Non-current assets3,872 
Current liabilities(24,962)
Non-current liabilities(158,397)
Total identifiable net assets$99,980 
Goodwill$171,107 

Hughes Gas Resources, Inc. (Pines Holdings, Inc.) Acquisition
On June 2, 2025, a subsidiary of SiEnergy Operating, LLC (SiEnergy), a wholly owned subsidiary of NW Holdings, acquired 100% of the outstanding equity interests of Hughes Gas Resources, Inc. from EPCOR USA Inc. for total consideration of $60.4 million in cash. Hughes serves approximately 8,000 customers in 12 communities northeast of Houston, Texas. Hughes further expands SiEnergy's regulated gas utility business in the southern United States. Following the closing of the acquisition, Hughes was rebranded as Pines Holdings, Inc. (Pines).

The Pines acquisition met the criteria of a business combination, and as such, a preliminary allocation of the consideration to the acquired net assets based on their estimated fair value as of the acquisition date was performed. In accordance with U.S. GAAP, the fair value determination involves management judgment in determining the significant estimates and assumptions used for net assets associated with Pines. This allocation is considered preliminary as of March 31, 2026, as facts and circumstances that existed as of the acquisition date may be discovered as we continue to integrate Pines. As a result, subsequent adjustments to the preliminary valuation of tangible assets, regulatory assets and liabilities including asset removal costs, contract assets and liabilities, tax positions, and goodwill may be required. Any such adjustments are to be completed within the one-year measurement period.

Preliminary goodwill of $15.1 million was recognized from this acquisition. The goodwill recognized is attributable to Pines' natural gas utility service territory, experienced workforce, and the strategic benefits expected from growth in the service territory. No intangible assets aside from goodwill were recognized. There is no goodwill expected to be deductible for tax purposes.


The following table summarizes the consideration transferred and the amounts of identified assets acquired and liabilities assumed as of the acquisition date:
In thousands
Fair value of consideration transferred:
Cash$60,436 
Recognized amounts of identifiable assets acquired and liabilities assumed:
Current assets$2,032 
Property, plant and equipment43,497 
Non-current assets1,382 
Current liabilities(1,462)
Non-current liabilities(105)
Total identifiable net assets$45,344 
Goodwill$15,092 

The table below presents the unaudited pro forma revenues and earnings of NW Holdings as if the SiEnergy and Pines acquisitions had occurred as of January 1, 2025:
Three Months Ended March 31,Three Months Ended March 31,
In thousands20262025
Operating revenues$490,403 $500,064 
Net income$97,489 $91,671 
The unaudited pro forma results presented above are for informational purposes only and are not necessarily indicative of the results that would have been achieved had the acquisition been completed on January 1, 2025, nor are they indicative of future results of operations of the combined company. Pro forma net income for the three months ended March 31, 2025 were adjusted to reflect the following:

•acquisition costs of $5.3 million incurred by NW Holdings' in the first quarter of 2025 were removed from the three months ended March 31, 2025 pro forma net income;
•the capital structure for NW Holdings was modified to reflect the Junior Subordinated Debentures issued in March 2025 to represent the ongoing capital structure and reflects the issuance to have occurred on January first of 2025;
•the results of SiEnergy and Pines were adjusted to represent results as though they were owned as of January first of 2025; and
•all adjustments were net tax effected using a statutory tax rate of 26.5%

The amount of SiEnergy and Pines revenues included in NW Holdings' consolidated statements of comprehensive income was $31.7 million and $22.7 million for the three months ended March 31, 2026 and 2025, respectively.

The amount of SiEnergy and Pines net income included in NW Holdings' consolidated statements of comprehensive income was $9.1 million and $5.5 million for the three months ended March 31, 2026 and 2025, respectively.

Other 2025 Business Combinations

During the fourth quarter of 2025, NW Water and its subsidiaries acquired the assets of Inline Utilities, LLC ("Inline") located in Texas, qualifying as a business combination. The fair value of the consideration transferred for this acquisition was $7.2 million, most of which was allocated to property, plant and equipment. As of March 31, 2026, preliminary goodwill of $1.0 million was recognized from this acquisition, including adjustments associated with deferred income taxes. The amount of goodwill that is expected to be deductible for income tax purposes is $4.3 million.
During the first quarter of 2025, NWN Water and its subsidiaries acquired the assets of two businesses qualifying as business combinations. The aggregate fair value of the consideration transferred for these acquisitions was $1.6 million, most of which was allocated to property, plant and equipment. These transactions align with NW Holdings' water and wastewater sector strategy as it continues to expand its water and wastewater service territories and included:
•Everett Square, Inc. in Texas
•ES Water Utility Consolidators, Inc. in Texas

Goodwill
NW Holdings allocates goodwill to reporting units based on the expected benefit from the business combination. We perform an annual impairment assessment of goodwill at the reporting unit level, or more frequently if events and circumstances indicate that goodwill might be impaired. An impairment loss is recognized if the carrying value of a reporting unit’s goodwill exceeds its fair value.

As a result of all acquisitions completed, goodwill totaled $371.3 million, $354.5 million, and $370.8 million as of March 31, 2026, March 31, 2025, and December 31, 2025, respectively, and is attributable to gas utility, water and wastewater acquisitions. Goodwill included in the SiEnergy segment category totaled $186.2 million, $171.0 million, and $185.7 million as of March 31, 2026, March 31, 2025, and December 31, 2025, respectively. Goodwill included in the NWN Water segment category totaled $185.1 million, $183.5 million, and $185.1 million as of March 31, 2026, March 31, 2025, and December 31, 2025, respectively. The annual impairment assessment of goodwill occurs in the fourth quarter of each year. There have been no impairments recognized during the three months ended March 31, 2026.
v3.26.1
Derivative Instruments
 3 Months Ended
Mar. 31, 2026
Derivative Instruments and Hedging Activities Disclosure [Abstract]  
Derivative Instruments DERIVATIVE INSTRUMENTS
NW Natural
NW Natural enters into financial derivative contracts primarily to hedge a portion of the NW Natural segment's natural gas sales requirements. These contracts include swaps and forward contracts. These derivative financial instruments are primarily used to manage the price variability of natural gas, interest rates, and foreign currency. A small portion of NW Natural's derivative hedging strategy involves hedging interest rates and foreign currency forward contracts.

NW Natural enters into these financial derivatives, up to prescribed limits, primarily to hedge price variability related to term physical gas supply contracts, and variable rate debt and for pipeline demand charges paid in Canadian dollars.

In the normal course of business, NW Natural also enters into indexed-price physical forward natural gas commodity purchase contracts and options to meet the requirements of NW Natural customers. These contracts qualify for regulatory deferral accounting treatment.
Notional Amounts
The following table presents the absolute notional amounts related to open positions on NW Natural derivative instruments:
March 31,December 31,
In thousands202620252025
Natural gas (in therms):
Financial544,690 611,200 757,895 
Physical487,775 401,750 692,275 
Foreign exchange (in dollars)$5,853 $10,132 $8,596 

Purchased Gas Adjustment (PGA)
Rates and hedging approaches vary between states due to different rate structures and hedging mechanisms. Under the PGA mechanism in Oregon, derivatives entered into by NW Natural for the procurement or hedging of natural gas for future gas years generally receive regulatory deferral accounting treatment. In general, commodity hedging for the current gas year is completed prior to the start of the gas year, and hedge prices are fully recovered and reflected in the weighted-average cost of gas in the PGA filing. Hedge contracts entered into after the start of the PGA period for the current PGA year are subject to the PGA incentive sharing mechanism in Oregon. Under the PGA mechanism in Washington, NW Natural incorporates a risk-responsive hedging strategy, and receives regulatory deferral accounting treatment for Washington gas hedges.

NW Natural entered the 2025-26 gas year with forecasted sales volume hedged at approximately 79% in total, including 64% in financial hedges and 15% in physical gas supplies. The total hedged for Oregon was approximately 84%, including 69% in financial hedges and 15% in physical gas supplies. The total hedged for Washington was approximately 33%, including 20% in financial hedges and 13% in physical gas supplies.

Unrealized and Realized Gain/Loss
The following table reflects the income statement presentation for the unrealized gains and losses from NW Natural's derivative instruments:
Three Months Ended March 31,
20262025
In thousandsNatural gas commodityForeign exchangeNatural gas commodityForeign exchange
Benefit (expense) to cost of gas$(15,029)$(114)$29,697 $(24)
Amounts deferred to regulatory accounts on balance sheet
15,029 114 (29,697)24 
Total gain (loss) in pre-tax earnings$— $— $— $— 

Unrealized Gain/Loss
Outstanding derivative instruments related to regulated NW Natural operations are deferred in accordance with regulatory accounting standards. The cost of foreign currency forward and natural gas derivative contracts are recognized immediately in the cost of gas; however, costs above or below the amount embedded in the current year PGA are subject to a regulatory deferral tariff and therefore, are recorded as a regulatory asset or liability.

Realized Gain/Loss
NW Natural realized net losses of $41.5 million and net losses of $46.2 million for the three months ended March 31, 2026 and 2025, respectively, from the settlement of natural gas financial derivative contracts. Realized gains and losses offset the higher or lower cost of gas purchased, resulting in no incremental amounts to collect or refund to customers.

Credit Risk Management of Financial Derivatives Instruments
No collateral was posted with or by NW Natural counterparties as of March 31, 2026 or 2025. NW Natural attempts to minimize the potential exposure to collateral calls by diversifying counterparties and using credit limits to manage liquidity risk. Counterparties generally allow a certain credit limit threshold based on our credit rating before requiring NW Natural to post collateral against unrealized loss positions. Given NW Natural's credit ratings, counterparty credit limits and portfolio diversification, it was not subject to collateral calls in 2026 or 2025. The collateral call exposure is set forth under credit support agreements, which generally contain credit limits. NW Natural could also be subject to collateral call exposure where it has agreed to provide adequate assurance, which is not specific as to the amount of credit limit allowed but could potentially require additional collateral posting by NW Natural in the event of a material adverse change in NW Natural's ability to perform.

NW Natural's financial derivative instruments are subject to master netting arrangements; however, they are presented on a gross basis in the consolidated balance sheets. NW Natural and its counterparties have the ability to set-off obligations to each other under specified circumstances. Such circumstances may include a defaulting party, a credit change due to a merger affecting either party, or any other termination event.
If netted by its counterparties, NW Natural's physical and financial derivative position would result in an asset of $2.6 million and a liability of $58.8 million as of March 31, 2026, an asset of $2.6 million and a liability of $31.7 million as of March 31, 2025, and an asset of $2.8 million and a liability of $76.1 million as of December 31, 2025.

NW Natural is exposed to derivative credit and liquidity risk primarily through securing fixed-price natural gas commodity swaps and interest rate swaps with financial counterparties. NW Natural utilizes master netting arrangements with International Swaps and Derivatives Association (ISDA) contracts to minimize these risks including ISDA Credit Support Agreements with counterparties based on their credit ratings. Additionally, NW Natural uses counterparty, industry, sector and country diversification to minimize credit risk. In certain cases, NW Natural may require counterparties to post collateral, guarantees, or letters of credit to maintain its minimum credit requirement standards or for liquidity management purposes. See Note 15 in the 2025 Form 10-K for additional information.

Fair Value
In accordance with fair value accounting, NW Natural includes non-performance risk in calculating fair value adjustments. This includes a credit risk adjustment based on the credit spreads of NW Natural counterparties when in an unrealized gain position, or on NW Natural's own credit spread when it is in an unrealized loss position. The inputs in our valuation models include natural gas futures, volatility, credit default swap spreads and interest rates. Additionally, the assessment of non-performance risk is generally derived from the credit default swap market and from bond market credit spreads. The impact of the credit risk adjustment for all financial derivatives outstanding to the fair value calculation was $0.2 million, which decreased the liability at March 31, 2026. The net fair value was a liability of $56.2 million, a liability of $29.1 million, and a liability of $73.3 million as of March 31, 2026 and 2025, and December 31, 2025, respectively. No Level 3 inputs were used in our derivative valuations during the three months ended March 31, 2026, and 2025. See Note 2 in the 2025 Form 10-K.

NWN Water Interest Rate Swap Agreement
In January 2023, NWN Water entered into an interest rate swap agreement with a major financial institution for $55.0 million that effectively converted variable-rate debt to a fixed rate of 3.8%. Interest payments made between the effective date and expiration date are hedged by the swap agreement. The interest rate swap agreement will expire in June 2026, along with the variable-rate debt.

Unrealized gains (losses) related to the interest rate swap agreement are recorded in AOCI on the consolidated balance sheet and were immaterial as of March 31, 2026, March 31, 2025, and December 31, 2025. Realized gains or losses occur as a result of monthly swap settlements. Gains of $0.1 million were reclassified from AOCI to net income during the three months ended March 31, 2025 and were immaterial during the three months ended March 31, 2026. The estimated amount of gains recorded in AOCI as of March 31, 2026 that are expected to be reclassified to net income within the next twelve months is immaterial.
v3.26.1
Commitments and Contingencies
 3 Months Ended
Mar. 31, 2026
Commitments and Contingencies Disclosure [Abstract]  
Commitments and Contingencies COMMITMENTS AND CONTINGENCIES
NWN Renewables is an unregulated subsidiary of NW Holdings established to pursue investments in RNG activities. NWN Renewables, through its subsidiary Ohio Renewables, executed agreements with a subsidiary of EDL, a global producer of sustainable distributed energy, to secure RNG supply from two production facilities that are designed to convert landfill waste gases to RNG. This arrangement consists of a development agreement, an exclusive use agreement, a purchase agreement, and various guarantees.

Under the development agreement, the EDL subsidiary is responsible for the development and construction of the facilities. The first facility was completed and commenced delivery of RNG to Ohio Renewables in September 2024. Upon reaching this milestone, Ohio Renewables paid $26.0 million to the EDL subsidiary. The second facility was completed and commenced delivery of RNG to Ohio Renewables in December 2024 at which point Ohio Renewables made an additional payment of $25.4 million to the EDL subsidiary. The payments were recorded as long-term prepaid assets and will be amortized based on the volumes delivered over the life of the agreement.

NWN Renewables Purchase Agreements
Under the purchase agreement, Ohio Renewables and the subsidiary of EDL executed agreements for Ohio Renewables to purchase up to an annual specified amount of RNG produced by the EDL facilities over a 20-year period at a contractually specified price. In December 2025, Ohio Renewables entered into an agreement to purchase up to an annual specified amount of RNG produced by the EDL facilities from a separate investment-grade counterparty over an 11-year period at a contractually specified price. Purchase volumes are variable based on production, and purchases may not exceed contracted amounts. We currently estimate the amount of RNG purchases from both facilities based on prices and quantities specified in the agreements to be as follows: approximately $31.4 million in 2027, $31.6 million in 2028, $30.8 million in 2029, $31.4 million in 2030 and $599.3 million thereafter. For the three months ended March 31, 2026, purchases totaled $4.1 million, for total expected purchases of $20.9 million in 2026.

NW Holdings entered into a guarantee on behalf of Ohio Renewables with EDL. Per the guarantee, NW Holdings unconditionally and irrevocably guarantees the timely payment and performance when due of all obligations of Ohio Renewables. NW Holdings has not recognized a liability for its obligations under the guarantee in accordance with ASC 460, Guarantees.
NWN Renewables Sale Agreements
2024 - 2026
Ohio Renewables has contracted to sell RNG produced by the EDL facilities up to certain specified volumes beginning in 2024 through 2026 to an investment-grade counterparty. Upon each delivery of RNG, Ohio Renewables will purchase an equal quantity of natural gas without renewable attributes at the same delivery point. Ohio Renewables has separately contracted to sell the natural gas purchased from EDL to another counterparty also at the same delivery point upon receipt. Alongside these agreements, NW Holdings entered into a guarantee on behalf of Ohio Renewables. Per the guarantee, NW Holdings unconditionally and irrevocably guarantees the prompt payment of all present and future obligations of Ohio Renewables. NW Holdings has not recognized a liability for its obligations under the guarantee in accordance with ASC 460, Guarantees.

The guarantee specifies annual cap amounts on the aggregate liability covered by the Guarantee as follows:
In thousands2026
Cap Amount$21,113 

2025 - 2044
Ohio Renewables additionally has contracted to sell a fixed-volume amount of RNG under a long-term agreement with an investment-grade utility beginning in 2025 and extending through 2044. Under the current contract, if less than 75% of the contracted volumes of RNG are not delivered on an annual basis, Ohio Renewables is obligated to pay the per MMbtu price for volumes between the amount delivered and 75% of the contracted volumes on an annual basis. NW Holdings entered into a guarantee on behalf of Ohio Renewables. Per the guarantee, NW Holdings unconditionally and irrevocably guarantees the prompt payment of all present and future obligations of Ohio Renewables. The total liability under this guarantee cannot exceed $2.0 million. NW Holdings has not recognized a liability for its obligations under the guarantee in accordance with ASC 460, Guarantees.
v3.26.1
Environmental Matters
 3 Months Ended
Mar. 31, 2026
Environmental Remediation Obligations [Abstract]  
Environmental Matters ENVIRONMENTAL MATTERS
NW Natural owns, or previously owned, properties that may require environmental remediation or action. The range of loss for environmental liabilities is estimated based on current remediation technology, enacted laws and regulations, industry experience gained at similar sites, and an assessment of the probable level of involvement and financial condition of other potentially responsible parties (PRPs). When amounts are prudently expended related to site remediation of those sites described herein, NW Natural has recovery mechanisms in place to collect 96.7% of remediation costs allocable to Oregon customers and 3.3% of costs allocable to Washington customers.

These sites are subject to the remediation process prescribed by the Environmental Protection Agency (EPA) and the Oregon Department of Environmental Quality (ODEQ). The process begins with a remedial investigation (RI) to determine the nature and extent of contamination and then a risk assessment (RA) to establish whether the contamination at the site poses unacceptable risks to humans and the environment. Next, a feasibility study (FS) or an engineering evaluation/cost analysis (EE/CA) evaluates various remedial alternatives. It is at this point in the process when NW Natural is able to estimate a range of remediation costs and record a reasonable potential remediation liability, or make an adjustment to the existing liability. From this study, the regulatory agency selects a remedy and issues a Record of Decision (ROD). After a ROD is issued, NW Natural would seek to negotiate a consent decree or consent judgment for designing and implementing the remedy. NW Natural would have the ability to further refine estimates of remediation liabilities based upon an approved remedial design.

Remediation may include treatment of contaminated media such as sediment, soil and groundwater, removal and disposal of media, institutional controls such as legal restrictions on future property use, or natural recovery. Following construction of the remedy, the EPA and ODEQ also have requirements for ongoing maintenance, monitoring and other post-remediation care that may continue for many years. Where appropriate and reasonably known, NW Natural will provide for these costs in the remediation liabilities described below.

Due to the numerous uncertainties surrounding the course of environmental remediation and the preliminary nature of several site investigations, in some cases, NW Natural may not be able to reasonably estimate the high end of the range of possible loss. In those cases, the nature of the possible loss has been disclosed, as has the fact that the high end of the range cannot be reasonably estimated where a range of potential loss is available. Unless there is an estimate within the range of possible losses that is more likely than other cost estimates within that range, NW Natural records the liability at the low end of this range. It is likely changes in these estimates and ranges will occur throughout the remediation process for each of these sites due to the continued evaluation and clarification concerning responsibility, the complexity of environmental laws and regulations and the determination by regulators of remediation alternatives. In addition to remediation costs, NW Natural could also be subject to Natural Resource Damages (NRD) claims. NW Natural will assess the likelihood and probability of each claim and recognize a liability if deemed appropriate. Refer to "Other Portland Harbor" below.
Environmental Sites
The following table summarizes information regarding liabilities related to environmental sites, which are recorded in other current liabilities and other noncurrent liabilities in NW Natural's balance sheet:
Current LiabilitiesNon-Current Liabilities
March 31,December 31,March 31,December 31,
In thousands202620252025202620252025
Portland Harbor site:
Gasco Sediments$11,510 $10,816 $13,950 $42,755 $41,565 $43,247 
Other Portland Harbor3,189 3,109 3,669 12,132 11,657 12,770 
Gasco Upland site22,089 20,767 25,643 275,514 63,594 61,782 
Front Street site455 760 486 290 278 292 
Oregon Steel Mills— — — 179 179 179 
Total$37,243 $35,452 $43,748 $330,870 $117,273 $118,270 

Portland Harbor Site
The Portland Harbor is an EPA listed Superfund site that is approximately 10 miles long on the Willamette River and is adjacent to NW Natural's Gasco uplands site. NW Natural is one of over one hundred PRPs, each jointly and severally liable, at the Superfund site. In January 2017, the EPA issued its Record of Decision, which selects the remedy for the clean-up of the Portland Harbor site (Portland Harbor ROD). The Portland Harbor ROD estimates the present value total cost at approximately $1.05 billion with an accuracy between -30% and +50% of actual costs.

NW Natural's potential liability is a portion of the costs of the remedy for the entire Portland Harbor Superfund site. The cost of that remedy is expected to be allocated among more than one hundred PRPs. NW Natural is participating in a non-binding allocation process with other PRPs in an effort to resolve its potential liability. The Portland Harbor ROD does not provide any additional clarification around allocation of costs among PRPs; accordingly, NW Natural has not modified any of the recorded liabilities at this time as a result of the issuance of the Portland Harbor ROD.

NW Natural manages its liability related to the Superfund site as two distinct projects: the Gasco Sediments Site and Other Portland Harbor projects.

GASCO SEDIMENTS. In 2009, NW Natural and Siltronic Corporation entered into a separate Administrative Order on Consent with the EPA to evaluate and design specific remedies for sediments adjacent to the Gasco uplands and Siltronic uplands sites. NW Natural submitted a draft EE/CA to the EPA in May 2012 and the EE/CA estimated the cost of potential remedial alternatives for this site. NW Natural is completing pre-design studies and has submitted a Preliminary Design Report, which the EPA approved in December 2024. These preliminary design steps do not include a cost estimate for cleanup. No remedial design for the Gasco Sediments Site is more likely than the EE/CA alternatives at this time, and NW Natural expects further design discussion and iteration with the EPA.

In March 2020, NW Natural and the EPA amended the Administrative Order on Consent to include additional remedial design activities downstream of the Gasco Sediments Site at the US Moorings and Navigation Channel remedial design project areas. Siltronic Corporation is not a party to the amended order. NW Natural has submitted Basis of Design Reports for the Navigation Channel and US Moorings remedial design project areas to the EPA.

The estimated costs for the various sediment remedy alternatives in the draft EE/CA, for the additional studies and design work needed before the cleanup can occur, and for regulatory oversight throughout the cleanup range from approximately $54 million to $350 million. NW Natural has recorded a liability of $54 million for the Gasco sediment clean-up, which reflects the low end of the range. At this time, we believe sediments at the Gasco sediments site represent the largest portion of NW Natural's liability related to the Portland Harbor site discussed above.

OTHER PORTLAND HARBOR. While we believe liabilities associated with the Gasco sediments site represent NW Natural's largest exposure, there are other potential exposures associated with the Portland Harbor ROD, including NRD costs and harborwide remedial design and cleanup costs (including downstream petroleum contamination), for which allocations among the PRPs have not yet been determined. 

NW Natural and other parties have signed a cooperative agreement with the Portland Harbor Natural Resource Trustee council to participate in a phased NRD assessment to estimate liabilities to support an early restoration-based settlement of NRD claims. One member of this Trustee council, the Yakama Nation, withdrew from the council in 2009, and in 2017, filed suit against NW Natural and 29 other parties seeking remedial costs and NRD assessment costs associated with the Portland Harbor site, set forth in the complaint. The complaint seeks recovery of alleged costs totaling $0.3 million in connection with the selection of a remedial action for the Portland Harbor site as well as declaratory judgment for unspecified future remedial action costs and for costs to assess the injury, loss or destruction of natural resources resulting from the release of hazardous substances at and from the Portland Harbor site. The Yakama Nation has filed two amended complaints addressing certain pleading defects and
dismissing the State of Oregon. On the motion of NW Natural and certain other defendants, the federal court has stayed the case pending the outcome of the non-binding allocation proceeding discussed above. NW Natural has recorded a liability for NRD claims which is at the low end of the range of the potential liability; the high end of the range cannot be reasonably estimated at this time. The NRD liability is not included in the aforementioned range of costs provided in the Portland Harbor ROD.

Gasco Uplands Site
A predecessor of NW Natural, Portland Gas and Coke Company, owned a former gas manufacturing plant that was closed in 1958 (Gasco site) and is adjacent to the Portland Harbor site described above. The Gasco site has been under investigation by NW Natural for environmental contamination under the ODEQ Voluntary Cleanup Program (VCP). It is not included in the range of remedial costs for the Portland Harbor site noted above. The Gasco site is managed in two parts, the uplands portion (including the IRAM) and the groundwater source control action.

NW Natural submitted a revised Remedial Investigation Report for the uplands to ODEQ in May 2007. In March 2015, ODEQ approved the Risk Assessment (RA) for this site, enabling commencement of work on the FS in 2016.

In October 2016, ODEQ and NW Natural agreed to amend their VCP agreement for the Gasco uplands to incorporate a portion of the Siltronic property formerly owned by Portland Gas & Coke between 1939 and 1960 into the Gasco RA and FS. Previously, NW Natural was conducting an investigation of manufactured gas plant constituents on the entire Siltronic uplands for ODEQ. Siltronic will be working with ODEQ directly on environmental impacts to the remainder of its property.

In September 2013, NW Natural completed construction of a groundwater source control system, including a water treatment station, at the Gasco site. NW Natural has estimated the cost associated with the ongoing operation of the system and has recognized a liability which is at the low end of the range of potential cost. NW Natural cannot estimate the high end of the range at this time due to the uncertainty associated with the duration of running the water treatment station, which is highly dependent on the remedy determined for both the upland portion as well as the final remedy for the Gasco sediments site.

In December 2024, NW Natural submitted the Gasco uplands FS to ODEQ. The FS presents a set of remedial action alternatives and provides the basis for range of potential remedial costs for the site. In April 2026, NW Natural submitted a revised FS to ODEQ addressing comments it had received on the original FS submission. The revised FS included changes to the remediation alternatives as well as the addition of the estimated costs to operate and monitor the site for 30 years after remediation. The revised range of alternative remedies excluding the cost of the Interim Remedial Action Measure (IRAM) for the Gasco uplands site is an estimated range from $288 million to $950 million, which includes a range of undiscounted monitoring costs for a 30 year period that range from approximately $230 million to $250 million. NW Natural has recorded a liability of $288 million, which reflects the low end of the range. ODEQ is currently reviewing the revised submission.

Additionally, the EPA's Gasco sediments Administrative Order requires the integration of upland source controls with the sediment remedy. The selected sediment remedy, which is discussed above under "Gasco Sediments," is currently under separate design for the EPA. To comply with the source control integration requirement, some Gasco uplands work must be expedited. An Interim Removal Action Measure (IRAM) for the Gasco uplands is the regulatory mechanism ODEQ has selected to accomplish that goal. As a result, the Gasco uplands FS also includes a separate range of potential remedial costs for the IRAM. The alternative remedies for the IRAM range from $10 million to $78 million. NW Natural has recorded a liability of $10 million, which reflects the low end of the range.

Other Sites
In addition to those sites above, NW Natural has environmental exposures at three other sites: Central Service Center, Front Street and Oregon Steel Mills. NW Natural may have exposure at other sites that have not been identified at this time. Due to the uncertainty of the design of remediation, regulation, timing of the remediation and in the case of the Oregon Steel Mills site, pending litigation, liabilities for each of these sites have been recognized at their respective low end of the range of potential liability; the high end of the range could not be reasonably estimated at this time.

FRONT STREET SITE. The Front Street site was the former location of a gas manufacturing plant NW Natural operated (the former Portland Gas Manufacturing site, or PGM). At ODEQ’s request, NW Natural conducted a sediment and source control investigation and provided findings to ODEQ. In December 2015, an FS on the former Portland Gas Manufacturing site was completed. 

In July 2017, ODEQ issued the PGM ROD. The ROD specifies the selected remedy, which requires a combination of dredging, capping, treatment, and natural recovery. In addition, the selected remedy also requires institutional controls and long-term inspection and maintenance. Construction of the remedy began in July 2020 and was completed in October 2020. The second year of post-construction monitoring was completed in 2022 and demonstrated that the cap was intact and performing as designed. NW Natural has recognized an additional liability of $0.7 million associated with long-term monitoring and post-construction work.

Environmental Cost Deferral and Recovery
NW Natural has authorizations in Oregon and Washington to defer costs related to remediation of properties that are owned or were previously owned by NW Natural. In Oregon, a Site Remediation and Recovery Mechanism (SRRM) is currently in place to recover prudently incurred costs allocable to Oregon customers, subject to an earnings test. On October 21, 2019, the WUTC
authorized an Environmental Cost Recovery Mechanism (ECRM) for recovery of prudently incurred costs allocable to Washington customers beginning November 1, 2019. See Note 17 in the 2025 Form 10-K for a description of SRRM and ECRM collection processes.

The following table presents information regarding the total regulatory asset deferred:
March 31,December 31,
In thousands202620252025
Deferred costs and interest (1)
$72,897 $65,526 $71,954 
Accrued site liabilities (2)
368,090 152,692 161,993 
Insurance proceeds and interest(42,358)(47,655)(41,736)
Total regulatory asset deferral(1)
398,629 170,563 192,211 
Current regulatory assets(3)
12,271 10,819 12,148 
Long-term regulatory assets(3)
386,358 159,744 180,063 
(1)    Includes pre-review and post-review deferred costs, amounts currently in amortization, and interest, net of amounts collected from customers.
(2)    Excludes 3.3% of the Front Street site liability as the OPUC only allows recovery of 96.7% of costs for those sites allocable to Oregon, including those that historically served only Oregon customers. Amounts excluded from regulatory assets were immaterial at March 31, 2026, March 31, 2025, and December 31, 2025.
(3)    Environmental costs relate to specific sites approved for regulatory deferral by the OPUC and WUTC. In Oregon, NW Natural earns a carrying charge on cash amounts paid, whereas amounts accrued but not yet paid do not earn a carrying charge until expended. It also accrues a carrying charge on insurance proceeds for amounts owed to customers. In Washington, neither the cash paid for insurance proceeds received accrue a carrying charge. Current environmental costs represent remediation costs management expects to collect from customers in the next 12 months. Amounts included in this estimate are still subject to a prudence and earnings test review by the OPUC and do not include the $5 million tariff rider. The amounts allocable to Oregon are recoverable through NW Natural rates, subject to an earnings test.

Environmental Earnings Test
To the extent NW Natural earns at or below its authorized Return on Equity (ROE) as defined by the SRRM, remediation expenses and interest in excess of the $5 million tariff rider and $5 million insurance proceeds are recoverable through the SRRM. To the extent NW Natural earns more than its authorized ROE in a year, it is required to cover environmental expenses and interest on expenses greater than the $10 million with those earnings that exceed its authorized ROE.

Legal Proceedings
On October 11, 2024, NW Natural was added as a defendant to an ongoing lawsuit brought by Multnomah County in the Circuit Court for Multnomah County, Oregon (County of Multnomah v. Exxon Mobil Corp., et. al., No.23-cv-25164) against more than a dozen oil and gas producers seeking damages relating to climate change impacts. The County asserts various causes of action, including negligence, fraud, trespass and public nuisance under Oregon law related to the refining, producing and/or marketing of fossil fuels. NW Natural is diligently defending against the claims.

On October 14, 2024, NW Natural and NW Holdings were named as the defendants in a lawsuit filed in the Circuit Court for Multnomah County, Oregon (Blumm et. al. v. Northwest Natural Gas Company, 24-cv-48490), that is seeking class certification on behalf of all Oregon NW Natural Smart Energy-enrolled customers during the past approximately six years. The lawsuit alleges claims under Oregon's Unlawful Trade Practices Act and for breach of contract, with respect to NW Natural's Smart Energy program. The plaintiffs seek injunctive and equitable relief and damages. In October 2025, NW Holdings was dismissed as a party to the proceeding. The plaintiffs subsequently filed a Second Amended Complaint re-alleging claims against NW Holdings. We are diligently defending against the claims.

NW Natural and NW Holdings are subject to claims and litigation arising in the ordinary course of business including the matters discussed above. Although the final outcome of any of these legal proceedings cannot be predicted with certainty, including the matter relating to the Oregon Steel Mills site referenced below, NW Natural and NW Holdings do not expect that the ultimate disposition of any of these matters will have a material effect on their financial condition, results of operations or cash flows. See also Part II, Item 1, “Legal Proceedings".

For additional information regarding other environmental matters, see Note 17 in the 2025 Form 10-K.
v3.26.1
Subsequent Events
 3 Months Ended
Mar. 31, 2026
Subsequent Events [Abstract]  
Subsequent Events SUBSEQUENT EVENTS
On May 1, 2026, NW Natural entered into a Reimbursement Agreement and Continuing Indemnity Relating to Standby Letters of Credit/Letters of Guarantee (LC Reimbursement Agreement), between NW Natural and The Toronto-Dominion Bank, New York Branch (TD Bank), pursuant to which NW Natural agreed to reimburse TD Bank for disbursements in respect of letters of credit issued pursuant to the LC Reimbursement Agreement from time to time. NW Natural expects to use letters of credit issued under the facility created by the LC Reimbursement Agreement (LC Facility) primarily to support its participation in Washington Climate Commitment Act cap-and-invest program auctions.
The 2026 LC Reimbursement Agreement provides that the aggregate undrawn face amount of letters of credit issued thereunder may not exceed $100 million. TD Bank has no commitment to issue letters of credit under the LC Facility and will have the sole discretion to limit and condition the terms for the issuance of letters of credit (including maximum face amounts).

The LC Reimbursement Agreement is cross-defaulted to NW Natural's Amended and Restated Credit Agreement. The occurrence of an Event of Default (as defined in the LC Reimbursement Agreement) would entitle TD Bank to require cash collateral for the Obligations, as defined in the LC Reimbursement Agreement, and to exercise all other rights and remedies available under the LC Reimbursement Agreement and under applicable law.
v3.26.1
Insider Trading Arrangements
 3 Months Ended
Mar. 31, 2026
shares
Trading Arrangements, by Individual  
Non-Rule 10b5-1 Arrangement Adopted false
Rule 10b5-1 Arrangement Terminated false
Non-Rule 10b5-1 Arrangement Terminated false
David H. Anderson [Member]  
Trading Arrangements, by Individual  
Material Terms of Trading Arrangement
On March 27, 2026, David H. Anderson, Director of NW Holdings and NW Natural, adopted a Rule 10b5‑1 trading arrangement for the sale of shares of NW Holdings’ common stock, which is intended to satisfy the affirmative defense conditions of Rule 10b5‑1(c) under the Exchange Act. Mr. Anderson’s Rule 10b5‑1 trading arrangement provides for the potential sale of up to 33,000 shares of NW Holdings’ common stock between June 26, 2026 and June 17, 2027, subject to conditions set forth in the arrangement, and so long as the market price of NW Holdings’ common stock is higher than certain minimum threshold prices specified in Mr. Anderson’s Rule 10b5‑1 trading arrangement.

As previously disclosed, Mr. Anderson retired as CEO of NW Holdings and NW Natural, effective April 1, 2025. Mr. Anderson currently holds over seven times the $450,000 stock ownership requirement for non‑management directors. This trading arrangement allows Mr. Anderson to periodically sell a portion of his NW Holdings common stock to diversify his holdings in connection with his retirement as CEO.
Name David H. Anderson
Title Director
Rule 10b5-1 Arrangement Adopted true
Adoption Date March 27, 2026
Expiration Date June 17, 2027
Arrangement Duration 356 days
Aggregate Available 33,000
v3.26.1
Significant Accounting Policies (Policies)
 3 Months Ended
Mar. 31, 2026
Accounting Policies [Abstract]  
Industry Regulation
Industry Regulation  
NW Holdings' principal business is to operate as a holding company for NW Natural, SiEnergy, NWN Water and its other subsidiaries. NW Natural's principal business is the distribution of natural gas, which is regulated by the Oregon Public Utility Commission (OPUC) and Washington Utilities and Transportation Commission (WUTC). NW Natural also has natural gas storage services, which are regulated by the Federal Energy Regulatory Commission (FERC), and to a certain extent by the OPUC and WUTC. SiEnergy's principal business is the distribution of natural gas in Texas; primarily in the Houston, Dallas and Austin metropolitan areas. SiEnergy also includes a natural gas transmission utility serving customers in the greater metropolitan areas of Dallas and Austin, Texas. SiEnergy's natural gas utilities are subject to regulation by the Railroad Commission of Texas and the cities in which it provides services. NWN Water's principal business is water and wastewater utility services. NWN Water's 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. Accounting records and practices of the regulated businesses conform to the requirements and uniform system of accounts prescribed by these regulatory authorities in accordance with U.S. GAAP. The businesses in which customer rates are regulated have approved cost-based rates which are intended to allow such businesses to earn a reasonable return on invested capital.

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 Holdings and NW Natural 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
DISAGGREGATION OF EXPENSE DISCLOSURES. In November 2024, the FASB issued ASU 2024-03, which requires additional disclosures of disaggregated income statement expenses. The disclosures are required beginning with our annual report for the year ending December 31, 2027. The FASB issued ASU 2025-01 on January 6, 2025, to amend the effective date language of ASU 2024-03 clarifying that all public business entities are required to adopt the guidance in annual reporting periods beginning after December 15, 2026, and interim periods within annual reporting periods beginning after December 15, 2027. ASU 2025-01 did not impact the effective date of ASU 2024-03 for NW Holdings and NW Natural. The adoption of this standard is not anticipated to have an impact on our results of operations, liquidity, or capital resources.

FINANCIAL INSTRUMENTS-CREDIT LOSSES. In July 2025, the FASB issued ASU 2025-05, which simplifies how entities estimate credit losses on current accounts receivable and current contract assets arising from revenue transactions under ASC 606. It introduced a practical expedient that allows all entities to assume that economic conditions at the balance sheet date remain unchanged for the life of the asset, eliminating the need for forward-looking forecasts. The Company elected the practical expedient and adopted this ASU effective January 1, 2026. The adoption of this standard did not have a material impact
on our results of operations, liquidity or capital resources.

IMPROVEMENTS TO INTANGIBLE ASSET ACCOUNTING AND DISCLOSURES. In September 2025, the FASB issued ASU 2025-06, Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Targeted Improvements to the Accounting for Internal-Use Software (“ASU 2025-06”). This ASU modernizes the accounting for software costs to adapt to an incremental and iterative software development method. ASU 2025-06 is effective for annual periods beginning after December 15, 2027, and may be applied using a prospective, modified prospective or retrospective transition approach. The adoption of this standard is not anticipated to have a material impact on our results of operations, liquidity or capital resources.

INTERIM REPORTING. In December 2025, the FASB issued ASU 2025-11, which improves the guidance in Topic 270, Interim Reporting, by clarifying the current disclosure requirements for interim periods. The ASU adds to Topic 270 a principle that requires entities to disclose events since the end of the last annual reporting period that have a material impact on the entity. ASU 2025-11 is effective for interim reporting periods within annual reporting periods beginning after December 15, 2027. The adoption of this standard is not anticipated to have an impact on our results of operations, liquidity, or capital resources.

CODIFICATION IMPROVEMENTS. In December 2025, the FASB issued ASU 2025-12, which makes changes to the Codification that clarify, correct errors, or make minor improvements. The amendments make the Codification easier to understand and apply. The amendments in this ASU are varied in nature and may affect the application of guidance in cases in which the original guidance may have been unclear. ASU 2025-12 is effective for annual reporting periods beginning after December 15, 2026, and interim reporting periods within those annual reporting periods. The adoption of this standard is not anticipated to have an impact on our results of operations, liquidity, or capital resources.
v3.26.1
Significant Accounting Policies (Tables)
 3 Months Ended
Mar. 31, 2026
Accounting Policies [Abstract]  
Schedule of Regulatory Assets
Amounts deferred as regulatory assets and liabilities for NW Holdings and NW Natural were as follows:
Regulatory Assets
March 31,December 31,
In thousands202620252025
Current:
NW Natural:
Unrealized loss on derivatives(1)
$42,081 $26,122 $63,578 
Gas costs15,523 5,085 6,284 
Environmental costs(2)
12,271 10,819 12,148 
Decoupling(3)
22,136 351 11,631 
Pension balancing(4)
7,131 7,131 7,131 
Income taxes2,208 2,208 2,208 
Washington Climate Commitment Act compliance7,754 8,219 7,482 
Security and systems improvements1,391 2,182 1,771 
Industrial demand side management(5)
12,149 12,530 10,539 
Other(6)
23,302 13,951 20,363 
Total current - NW Natural145,946 88,598 143,135 
SiEnergy275 — 410 
NWN Water324 25 200 
Total current - NW Holdings$146,545 $88,623 $143,745 
Non-current:
NW Natural:
Unrealized loss on derivatives(1)
$17,318 $8,224 $14,039 
Pension balancing(4)
13,076 19,174 15,647 
Income taxes9,289 8,993 9,148 
Pension and other postretirement benefit liabilities93,773 108,970 96,008 
Environmental costs(2)
386,358 159,744 180,063 
Gas costs9,343 1,804 9,434 
Decoupling(3)
11,746 188 8,891 
Washington Climate Commitment Act compliance44,082 28,292 33,085 
Security and systems improvements8,158 8,452 8,234 
Industrial demand side management(5)
4,787 4,682 9,334 
Other(6)
34,124 21,105 35,964 
Total non-current - NW Natural632,054 369,628 419,847 
SiEnergy HB 4384 depreciation deferral3,288 — 2,095 
SiEnergy other1,427 876 1,412 
NWN Water794 754 840 
Total non-current - NW Holdings$637,563 $371,258 $424,194 
(1)Unrealized gains or losses on derivatives are non-cash items and therefore do not earn a rate of return or a carrying charge. These amounts are recoverable through NW Natural rates as part of the annual Purchased Gas Adjustment (PGA) mechanism when realized at settlement.
(2)Refer to the Environmental Cost Deferral and Recovery table in Note 17 for a description of environmental costs.
(3)This deferral represents the margin adjustment resulting from differences between actual and expected volumes. 
(4)Balance represents deferred net periodic benefit costs as approved by the OPUC.
(5)Energy efficiency program for industrial sales customers in Oregon to provide assistance with reducing their gas usage.
(6)Balances consist of deferrals and amortizations under approved regulatory mechanisms and typically earn a rate of return or carrying charge.
The following table presents information regarding the total regulatory asset deferred:
March 31,December 31,
In thousands202620252025
Deferred costs and interest (1)
$72,897 $65,526 $71,954 
Accrued site liabilities (2)
368,090 152,692 161,993 
Insurance proceeds and interest(42,358)(47,655)(41,736)
Total regulatory asset deferral(1)
398,629 170,563 192,211 
Current regulatory assets(3)
12,271 10,819 12,148 
Long-term regulatory assets(3)
386,358 159,744 180,063 
(1)    Includes pre-review and post-review deferred costs, amounts currently in amortization, and interest, net of amounts collected from customers.
(2)    Excludes 3.3% of the Front Street site liability as the OPUC only allows recovery of 96.7% of costs for those sites allocable to Oregon, including those that historically served only Oregon customers. Amounts excluded from regulatory assets were immaterial at March 31, 2026, March 31, 2025, and December 31, 2025.
(3)    Environmental costs relate to specific sites approved for regulatory deferral by the OPUC and WUTC. In Oregon, NW Natural earns a carrying charge on cash amounts paid, whereas amounts accrued but not yet paid do not earn a carrying charge until expended. It also accrues a carrying charge on insurance proceeds for amounts owed to customers. In Washington, neither the cash paid for insurance proceeds received accrue a carrying charge. Current environmental costs represent remediation costs management expects to collect from customers in the next 12 months. Amounts included in this estimate are still subject to a prudence and earnings test review by the OPUC and do not include the $5 million tariff rider. The amounts allocable to Oregon are recoverable through NW Natural rates, subject to an earnings test.
Schedule of Regulatory Liabilities
Regulatory Liabilities
March 31,December 31,
In thousands202620252025
Current:
NW Natural:
Gas costs$21,838 $33,864 $34,172 
Unrealized gain on derivatives(1)
2,719 4,339 3,922 
Decoupling(2)
2,738 8,177 5,181 
Income taxes5,406 4,726 5,406 
Asset optimization revenue sharing9,508 8,381 25,981 
Washington Climate Commitment Act compliance65,523 46,241 57,441 
Other(3)
5,996 5,128 5,805 
Total current - NW Natural113,728 110,856 137,908 
SiEnergy90 61 66 
NWN Water96 133 — 
Total current - NW Holdings$113,914 $111,050 $137,974 
Non-current:
NW Natural:
Gas costs$903 $9,168 $687 
Unrealized gain on derivatives(1)
459 858 366 
Decoupling(2)
— 2,538 — 
Income taxes(4)
154,830 160,975 159,176 
Accrued asset removal costs(5)
571,035 535,075 561,594 
Asset optimization revenue sharing— — 2,386 
Other(3)
25,175 20,525 24,637 
Total non-current - NW Natural752,402 729,139 748,846 
SiEnergy asset removal costs8,621 — 8,155 
NWN Water1,406 945 1,406 
Total non-current - NW Holdings$762,429 $730,084 $758,407 
(1)Unrealized gains or losses on derivatives are non-cash items and therefore do not earn a rate of return or a carrying charge. These amounts are recoverable through NW Natural rates as part of the annual Purchased Gas Adjustment (PGA) mechanism when realized at settlement.
(2)This deferral represents the margin adjustment resulting from differences between actual and expected volumes. 
(3)Balances consist of deferrals and amortizations under approved regulatory mechanisms and typically earn a rate of return or carrying charge.
(4)Balance represents excess deferred income tax benefits subject to regulatory flow-through. See Note 11.
(5)Estimated costs of removal on certain regulated properties are collected through rates.
Schedule of Cash Flow, Supplemental Disclosures
The following table provides a reconciliation of the cash, cash equivalents and restricted cash balances at NW Holdings as of March 31, 2026 and 2025 and December 31, 2025:
March 31,December 31,
In thousands202620252025
Cash and cash equivalents$34,945 $100,050 $36,673 
Restricted cash included in other current assets5,427 6,935 4,404 
Cash, cash equivalents and restricted cash$40,372 $106,985 $41,077 

The following table provides a reconciliation of the cash, cash equivalents and restricted cash balances at NW Natural as of March 31, 2026 and 2025 and December 31, 2025:
March 31,December 31,
In thousands202620252025
Cash and cash equivalents$24,274 $81,767 $29,347 
Restricted cash included in other current assets5,402 6,910 4,379 
Cash, cash equivalents and restricted cash$29,676 $88,677 $33,726 
Schedule of Accounts Receivable, Allowance for Credit Loss
The following table presents the activity related to the NW Holdings provision for uncollectible accounts by pool:

As ofAs of
December 31, 2025Three Months Ended March 31, 2026March 31, 2026
In thousandsBeginning BalanceProvision recorded, net of adjustmentsWrite-offs recognized, net of recoveriesEnding Balance
Allowance for uncollectible accounts:
Residential$2,280 $402 $(54)$2,628 
Commercial374 (27)(48)299 
Industrial46 10 — 56 
Accrued unbilled and other348 (49)3 302 
Total NW Natural3,048 336 (99)3,285 
Other - NW Holdings1,020 312 (107)1,225 
Total NW Holdings$4,068 $648 $(206)$4,510 
v3.26.1
Earnings Per Share (Tables)
 3 Months Ended
Mar. 31, 2026
Earnings Per Share [Abstract]  
Schedule of EPS Calculation
NW Holdings' diluted earnings or loss per share are calculated as follows:
Three Months Ended March 31,
In thousands, except per share data20262025
Net income$97,489 $87,916 
Average common shares outstanding - basic41,708 40,244 
Additional shares for stock-based compensation plans (See Note 8)
108 60 
Average common shares outstanding - diluted41,816 40,304 
Earnings per share of common stock:
Basic$2.34 $2.18 
Diluted2.33 2.18 
Additional information:
Anti-dilutive shares 13 10 
v3.26.1
Segment Information (Tables)
 3 Months Ended
Mar. 31, 2026
Segment Reporting [Abstract]  
Schedule of Segment Reporting Information, by Segment The following table presents summary financial information concerning the reportable segments and other:
Three Months Ended March 31,
In thousandsNW Natural
SiEnergy(2)
NWN WaterOtherNW Holdings
2026
Operating revenues$433,896 $31,695 $14,969 $9,843 $490,403 
Depreciation39,444 1,797 2,893 — 44,134 
Income from operations(1)
143,686 13,834 2,399 2,949 162,868 
Interest expense, net17,678 2,543 688 12,443 33,352 
Income tax expense (benefit)32,155 2,537 554 (2,707)32,539 
Capital expenditures79,615 24,944 9,097 — 113,656 
2025
Operating revenues$448,813 $22,666 $13,909 $8,896 $494,284 
Depreciation36,036 2,070 2,394 — 40,500 
Income from operations(1)
145,032 9,613 3,043 (3,334)154,354 
Interest expense, net15,580 2,257 792 10,766 29,395 
Income tax expense (benefit)35,664 1,944 631 (3,712)34,527 
Capital expenditures83,608 10,525 8,051 — 102,184 
(1)     Income from operations is not a financial measure used by the CODM for NW Natural or SiEnergy, but is included in the table above to enable the reconciliation of NW Natural and SiEnergy margin to consolidated income before taxes in accordance with ASU 2023-07.
(2)    SiEnergy was acquired by NW Holdings on January 7, 2025. Results for the period from January 7, 2025 to March 31, 2025 are presented in the table above. Prior to January 7, 2025, NW Holdings did not operate any assets that fall within its SiEnergy segment.
Schedule of NWN Gas Utility Margin
The following table presents additional segment information concerning NW Natural margin:
Three Months Ended March 31,
In thousands20262025
NW Natural margin calculation:
Distribution revenues$421,234 $435,908 
Regulated gas storage9,606 9,784 
Other revenue3,056 3,121 
Total operating revenues433,896 448,813 
Less: Cost of gas140,144 159,436 
          Environmental remediation6,325 6,253 
 Revenue taxes17,037 18,565 
NW Natural margin270,390 264,559 
Operations and maintenance70,530 67,766 
General taxes16,037 14,979 
Depreciation39,444 36,036 
Other Operating Expenses693 746 
NW Natural income from operations$143,686 $145,032 
Schedule of SiEnergy Gas Utility Margin
The following table presents additional segment information concerning SiEnergy margin:
Three Months Ended March 31,Three Months Ended March 31,
In thousands2026
2025(1)
SiEnergy margin calculation:
Distribution revenues$31,695 $22,666 
Total operating revenues31,695 22,666 
Less: Cost of gas12,279 8,303 
 Revenue taxes961 779 
SiEnergy margin18,455 13,584 
Operations and maintenance2,814 1,682 
General taxes10 219 
Depreciation1,797 2,070 
SiEnergy income from operations$13,834 $9,613 
(1)    SiEnergy was acquired by NW Holdings on January 7, 2025. Results for the period from January 7, 2025 to March 31, 2025 are presented in the table above. Prior to January 7, 2025, NW Holdings did not operate any assets that fall within its SiEnergy segment.
Significant Segment Expenses
Public entities are required to disclose significant segment expenses for each reportable segment if they are regularly provided to the CODM and included in the reported measure of segment profit/loss. This requirement does not necessitate additional disclosure for the NW Natural and SiEnergy segments, as all expense categories are presented above in the NW Natural margin table and SiEnergy margin table, respectively. Significant segment expenses for NWN Water are presented below.
Three Months Ended March 31,
In thousands20262025
Operating revenues$14,969 $13,909 
Operating expenses:
Operations and maintenance8,607 7,265 
Depreciation2,893 2,394 
Other operating expenses(1)
1,070 1,207 
Income from operations$2,399 $3,043 
(1) Other operating expenses include general and revenue taxes and other expenses.
v3.26.1
Revenue (Tables)
 3 Months Ended
Mar. 31, 2026
Revenue from Contract with Customer [Abstract]  
Schedule of Disaggregation of Revenue
The following tables present disaggregated revenue of NW Holdings:
Three Months Ended March 31,
In thousandsNW Natural
SiEnergy(1)
NWN WaterOtherNW Holdings
2026
Natural gas sales$399,119 $28,376 $— $1,378 $428,873 
Gas storage revenue, net4,365 — — — 4,365 
Asset management revenue, net1,747 — — — 1,747 
Water and wastewater revenue— — 14,969 — 14,969 
Gas appliance retail revenue1,309 — — — 1,309 
Renewable natural gas sales— — — 8,465 8,465 
Other revenue876 — — — 876 
    Revenue from contracts with customers407,416 28,376 14,969 9,843 460,604 
Alternative revenue22,027 3,319 — — 25,346 
Leasing revenue4,453 — — — 4,453 
    Total operating revenues$433,896 $31,695 $14,969 $9,843 $490,403 
2025
Natural gas sales$430,249 $22,327 $— $1,170 $453,746 
Gas storage revenue, net4,616 — — — 4,616 
Asset management revenue, net1,749 — — — 1,749 
Water and wastewater revenue— — 13,909 — 13,909 
Gas appliance retail revenue1,372 — — — 1,372 
Renewable natural gas sales— — — 7,726 7,726 
Other revenue952 — — — 952 
    Revenue from contracts with customers438,938 22,327 13,909 8,896 484,070 
Alternative revenue5,569 339 — — 5,908 
Leasing revenue4,306 — — — 4,306 
    Total operating revenues$448,813 $22,666 $13,909 $8,896 $494,284 
(1)    SiEnergy was acquired by NW Holdings on January 7, 2025. Results for the period from January 7, 2025 to March 31, 2025 are presented in the table above. Prior to January 7, 2025, NW Holdings did not operate any assets that fall within its SiEnergy segment.
Schedule of Lease Revenue
The components of lease revenue at NW Holdings and NW Natural were as follows:

In thousandsThree Months Ended March 31,
20262025
NW Natural:
Lease revenue
Operating leases$19 $21 
Sales-type leases4,434 4,285 
Total lease revenue$4,453 $4,306 
v3.26.1
Leases (Tables)
 3 Months Ended
Mar. 31, 2026
Leases [Abstract]  
Schedule of Lease Expense
The components of lease expense, a portion of which is capitalized, were as follows:
In thousandsThree Months Ended March 31,
20262025
NW Holdings:
Operating lease expense$2,252 $2,111 
Short-term lease expense 218 189 
NW Natural:
Operating lease expense$1,954 $1,867 
Short-term lease expense 120 189 

The Company’s lease arrangements are described in Note 7 to the consolidated financial statements included in the Company’s Annual Report on Form 10‑K, which should be read in conjunction with this Form 10‑Q. There have been no material changes to the Company’s lease portfolio during the current quarter.
Supplemental cash flow information related to leases was as follows:
In thousandsThree Months Ended March 31,
20262025
NW Holdings:
Cash paid for amounts included in the measurement of lease liabilities
Operating cash flows from operating leases$2,107 $1,918 
Right of use assets obtained in exchange for lease obligations
Operating leases$978 $2,647 
NW Natural:
Cash paid for amounts included in the measurement of lease liabilities
Operating cash flows from operating leases$1,931 $1,861 
Right of use assets obtained in exchange for lease obligations
Operating leases$250 $346 
Schedule of Operating Lease, Weighted Average Remaining Term and Discount Rates
The weighted-average remaining lease terms and weighted-average discount rates for the operating leases were as follows:
In thousandsMarch 31,December 31,
202620252025
NW Natural:
Weighted-average remaining lease term (years)14.015.014.3
Weighted-average discount rate7.3 %7.3 %7.3 %
v3.26.1
Debt (Tables)
 3 Months Ended
Mar. 31, 2026
Debt Disclosure [Abstract]  
Schedule of Short-Term Debt
NW Holdings' short-term debt consisted of the following:

March 31, 2026March 31, 2025December 31, 2025
In millionsBalance Outstanding
Weighted Average Interest Rate(1)
Balance Outstanding
Weighted Average Interest Rate(1)
Balance Outstanding
Weighted Average Interest Rate(1)
Commercial Paper Borrowings - NW Holdings(2)
$171.3 4.1 %$— — %$162.0 4.1 %
Commercial Paper Borrowings - NW Natural— — %— — %10.0 4.0 %
NW Holdings Credit Agreement Loans— — %81.1 5.5 %— — %
Total short-term debt$171.3 $81.1 $172.0 
(1) Weighted average interest rate on outstanding short-term debt
(2) NW Holdings initiated a commercial paper program in March 2025.
Schedule of Long-Term Debt Instruments
NW Holdings' long-term debt consisted of the following:

March 31, 2026March 31, 2025December 31, 2025
In millionsBalance Outstanding
Weighted Average Interest Rate(1)
Balance Outstanding
Weighted Average Interest Rate(1)
Balance Outstanding
Weighted Average Interest Rate(2)
NW Natural first mortgage bonds$1,544.7 4.7 %$1,374.7 4.6 %$1,544.7 4.7 %
SiEnergy term loan(3)
— — %149.6 6.1 %— — %
SiEnergy secured senior notes185.0 5.6 %— — %185.0 5.6 %
NWN Water term loan55.0 4.7 %55.0 4.7 %55.0 4.7 %
Other water debt3.9 5.0 4.0 
NW Holdings unsecured senior bonds285.0 5.7 %285.0 5.7 %285.0 5.7 %
NW Holdings term loan50.0 4.7 %50.0 5.3 %50.0 5.2 %
NW Holdings junior subordinated debentures325.0 7.0 %325.0 7.0 %325.0 7.0 %
Long-term debt, gross2,448.6 2,244.3 2,448.7 
Less: unamortized debt issuance costs15.5 14.4 15.9 
Less: current maturities160.7 36.8 160.6 
Total long-term debt$2,272.4 $2,193.1 $2,272.2 

(1)    Weighted average interest rate for the three months ended March 31, 2026 and March 31, 2025
(2)    Weighted average interest rate for the year ended December 31, 2025
(3)    On January 7, 2025, NW Holdings acquired SiEnergy. SiEnergy's subsidiary, Si Investment Co., had this existing term loan outstanding at the date of acquisition. In August 2025, the associated facilities were terminated and are no longer available for financing.
Schedule of Carrying Values and Estimated Fair Values of Debt Instruments
The following table provides an estimate of the fair value of long-term debt, including current maturities of long-term debt, using market prices in effect on the valuation date:
March 31,December 31,
In millions202620252025
NW Holdings:
Gross long-term debt$2,448.6 $2,244.3 $2,448.7 
Unamortized debt issuance costs(15.5)(14.4)(15.9)
Carrying amount$2,433.1 $2,229.9 $2,432.8 
Estimated fair value(1)
$2,281.4 $2,069.8 $2,317.1 
NW Natural:
Gross long-term debt$1,544.7 $1,374.7 $1,544.7 
Unamortized debt issuance costs(9.6)(9.1)(9.8)
Carrying amount$1,535.1 $1,365.6 $1,534.9 
Estimated fair value(1)
$1,360.8 $1,198.7 $1,383.1 
(1) Estimated fair value does not include unamortized debt issuance costs.
v3.26.1
Pension and Other Postretirement Benefit Costs (Tables)
 3 Months Ended
Mar. 31, 2026
Pension and Other Postretirement Benefits Cost (Reversal of Cost) [Abstract]  
Schedule of Net Benefit Costs
The following table provides the components of net periodic benefit cost (credit) for the pension and other postretirement benefit plans:
 Three Months Ended March 31,
Pension BenefitsOther
Postretirement Benefits
In thousands2026202520262025
Service cost$855 $885 $26 $27 
Interest cost5,167 5,410 282 288 
Expected return on plan assets(5,591)(5,433)— — 
Amortization of net actuarial loss2,295 2,444 63 20 
Net periodic benefit cost 2,726 3,306 371 335 
Amount allocated to construction(405)(434)(11)(11)
Net periodic benefit cost charged to expense2,321 2,872 360 324 
Amortization of regulatory balancing account2,801 2,801 — — 
Net amount charged to expense$5,122 $5,673 $360 $324 
Schedule of Amounts Recognized in Other Comprehensive Income (Loss)
The following table presents amounts recognized in accumulated other comprehensive loss (AOCL) and the changes in AOCL related to non-qualified employee benefit plans:
Three Months Ended March 31,
In thousands20262025
Beginning balance$(4,705)$(7,052)
Amounts reclassified from AOCL:
Amortization of actuarial losses124 200 
Total reclassifications before tax124 200 
Tax benefit(33)(25)
Total reclassifications for the period91 175 
Ending balance$(4,614)$(6,877)
v3.26.1
Income Tax (Tables)
 3 Months Ended
Mar. 31, 2026
Income Tax Disclosure [Abstract]  
Schedule of Effective Income Tax Rate Reconciliation
Three Months Ended March 31,
NW HoldingsNW Natural
In thousands2026202520262025
Income tax at statutory rate (federal)$27,306 $25,713 $26,440 $26,608 
State income tax8,830 9,980 9,247 10,202 
Increase (decrease): 
Differences required to be flowed-through by regulatory commissions(1,954)(1,668)(1,954)(1,668)
Other, net(1,643)502 (1,578)522 
Total provision for income taxes$32,539 $34,527 $32,155 $35,664 
Effective income tax rate25.0 %28.2 %25.5 %28.1 %
v3.26.1
Property, Plant and Equipment (Tables)
 3 Months Ended
Mar. 31, 2026
Property, Plant and Equipment [Abstract]  
Schedule of Public Utility Property, Plant, and Equipment
The following table sets forth the major classifications of property, plant, and equipment and accumulated depreciation:
March 31,December 31,
In thousands202620252025
NW Holdings:
Plant in service$5,509,029 $5,091,181 $5,468,170 
Construction work in progress213,327 176,882 172,265 
Less: Accumulated depreciation1,300,897 1,266,222 1,288,422 
Total property, plant, and equipment, net$4,421,459 $4,001,841 $4,352,013 
Capital expenditures in accrued liabilities$51,572 $32,042 $57,762 
NW Natural:
Plant in service$4,891,650 $4,634,047 $4,879,816 
Construction work in progress155,212 146,433 120,513 
Less: Accumulated depreciation1,257,950 1,237,907 1,256,289 
Total property, plant, and equipment, net$3,788,912 $3,542,573 $3,744,040 
Capital expenditures in accrued liabilities$34,917 $23,457 $33,582 
v3.26.1
Investments (Tables)
 3 Months Ended
Mar. 31, 2026
Investments [Abstract]  
Schedule of Investment
Investments include gas reserves, financial investments in life insurance policies, and equity method investments. The following table summarizes other investments:
NW HoldingsNW Natural
March 31,December 31,March 31,December 31,
In thousands202620252025202620252025
Investments in life insurance policies$34,032 $45,936 $45,606 $34,032 $45,936 $45,606 
Investments in gas reserves, non-current14,789 17,500 15,443 14,789 17,500 15,443 
Investment in unconsolidated affiliates20,620 19,227 19,627 — — — 
Total other investments$69,441 $82,663 $80,676 $48,821 $63,436 $61,049 
Schedule Of Investments In Unconsolidated Affiliates NWN Water subsequently increased its ownership stake in Avion Water as follows:
In millionsAmountOwnership %
July 2022$1.0 40.3 %
June 2023$1.0 43.1 %
January 2024$1.0 45.6 %
February 2025$1.0 47.9 %
January 2026$1.0 50.0 %
v3.26.1
Business Combinations (Tables)
 3 Months Ended
Mar. 31, 2026
Business Combination, Asset Acquisition, Transaction between Entities under Common Control, and Joint Venture Formation [Abstract]  
Schedule of Business Combination, Recognized Asset Acquired and Liability Assumed
The following table summarizes the consideration transferred and the amounts of identified assets acquired and liabilities assumed as the acquisition date:
In thousands
Fair value of consideration transferred:
Cash$271,087 
Recognized amounts of identifiable assets acquired and liabilities assumed:
Current assets$16,770 
Property, plant and equipment262,697 
Non-current assets3,872 
Current liabilities(24,962)
Non-current liabilities(158,397)
Total identifiable net assets$99,980 
Goodwill$171,107 
The following table summarizes the consideration transferred and the amounts of identified assets acquired and liabilities assumed as of the acquisition date:
In thousands
Fair value of consideration transferred:
Cash$60,436 
Recognized amounts of identifiable assets acquired and liabilities assumed:
Current assets$2,032 
Property, plant and equipment43,497 
Non-current assets1,382 
Current liabilities(1,462)
Non-current liabilities(105)
Total identifiable net assets$45,344 
Goodwill$15,092 
Schedule of Business Combination, Pro Forma Information
The table below presents the unaudited pro forma revenues and earnings of NW Holdings as if the SiEnergy and Pines acquisitions had occurred as of January 1, 2025:
Three Months Ended March 31,Three Months Ended March 31,
In thousands20262025
Operating revenues$490,403 $500,064 
Net income$97,489 $91,671 
v3.26.1
Derivative Instruments (Tables)
 3 Months Ended
Mar. 31, 2026
Derivative Instruments and Hedging Activities Disclosure [Abstract]  
Schedule of Notional Amounts of Outstanding Derivative Positions
The following table presents the absolute notional amounts related to open positions on NW Natural derivative instruments:
March 31,December 31,
In thousands202620252025
Natural gas (in therms):
Financial544,690 611,200 757,895 
Physical487,775 401,750 692,275 
Foreign exchange (in dollars)$5,853 $10,132 $8,596 
Schedule of Income Statement Presentation of Derivative Instruments
The following table reflects the income statement presentation for the unrealized gains and losses from NW Natural's derivative instruments:
Three Months Ended March 31,
20262025
In thousandsNatural gas commodityForeign exchangeNatural gas commodityForeign exchange
Benefit (expense) to cost of gas$(15,029)$(114)$29,697 $(24)
Amounts deferred to regulatory accounts on balance sheet
15,029 114 (29,697)24 
Total gain (loss) in pre-tax earnings$— $— $— $— 
v3.26.1
Commitments and Contingencies (Tables)
 3 Months Ended
Mar. 31, 2026
Commitments and Contingencies Disclosure [Abstract]  
Schedule of Other Commitments
The guarantee specifies annual cap amounts on the aggregate liability covered by the Guarantee as follows:
In thousands2026
Cap Amount$21,113 
v3.26.1
Environmental Matters (Tables)
 3 Months Ended
Mar. 31, 2026
Environmental Remediation Obligations [Abstract]  
Schedule of Environmental Loss Contingencies by Site
The following table summarizes information regarding liabilities related to environmental sites, which are recorded in other current liabilities and other noncurrent liabilities in NW Natural's balance sheet:
Current LiabilitiesNon-Current Liabilities
March 31,December 31,March 31,December 31,
In thousands202620252025202620252025
Portland Harbor site:
Gasco Sediments$11,510 $10,816 $13,950 $42,755 $41,565 $43,247 
Other Portland Harbor3,189 3,109 3,669 12,132 11,657 12,770 
Gasco Upland site22,089 20,767 25,643 275,514 63,594 61,782 
Front Street site455 760 486 290 278 292 
Oregon Steel Mills— — — 179 179 179 
Total$37,243 $35,452 $43,748 $330,870 $117,273 $118,270 
Schedule of Regulatory Assets
Amounts deferred as regulatory assets and liabilities for NW Holdings and NW Natural were as follows:
Regulatory Assets
March 31,December 31,
In thousands202620252025
Current:
NW Natural:
Unrealized loss on derivatives(1)
$42,081 $26,122 $63,578 
Gas costs15,523 5,085 6,284 
Environmental costs(2)
12,271 10,819 12,148 
Decoupling(3)
22,136 351 11,631 
Pension balancing(4)
7,131 7,131 7,131 
Income taxes2,208 2,208 2,208 
Washington Climate Commitment Act compliance7,754 8,219 7,482 
Security and systems improvements1,391 2,182 1,771 
Industrial demand side management(5)
12,149 12,530 10,539 
Other(6)
23,302 13,951 20,363 
Total current - NW Natural145,946 88,598 143,135 
SiEnergy275 — 410 
NWN Water324 25 200 
Total current - NW Holdings$146,545 $88,623 $143,745 
Non-current:
NW Natural:
Unrealized loss on derivatives(1)
$17,318 $8,224 $14,039 
Pension balancing(4)
13,076 19,174 15,647 
Income taxes9,289 8,993 9,148 
Pension and other postretirement benefit liabilities93,773 108,970 96,008 
Environmental costs(2)
386,358 159,744 180,063 
Gas costs9,343 1,804 9,434 
Decoupling(3)
11,746 188 8,891 
Washington Climate Commitment Act compliance44,082 28,292 33,085 
Security and systems improvements8,158 8,452 8,234 
Industrial demand side management(5)
4,787 4,682 9,334 
Other(6)
34,124 21,105 35,964 
Total non-current - NW Natural632,054 369,628 419,847 
SiEnergy HB 4384 depreciation deferral3,288 — 2,095 
SiEnergy other1,427 876 1,412 
NWN Water794 754 840 
Total non-current - NW Holdings$637,563 $371,258 $424,194 
(1)Unrealized gains or losses on derivatives are non-cash items and therefore do not earn a rate of return or a carrying charge. These amounts are recoverable through NW Natural rates as part of the annual Purchased Gas Adjustment (PGA) mechanism when realized at settlement.
(2)Refer to the Environmental Cost Deferral and Recovery table in Note 17 for a description of environmental costs.
(3)This deferral represents the margin adjustment resulting from differences between actual and expected volumes. 
(4)Balance represents deferred net periodic benefit costs as approved by the OPUC.
(5)Energy efficiency program for industrial sales customers in Oregon to provide assistance with reducing their gas usage.
(6)Balances consist of deferrals and amortizations under approved regulatory mechanisms and typically earn a rate of return or carrying charge.
The following table presents information regarding the total regulatory asset deferred:
March 31,December 31,
In thousands202620252025
Deferred costs and interest (1)
$72,897 $65,526 $71,954 
Accrued site liabilities (2)
368,090 152,692 161,993 
Insurance proceeds and interest(42,358)(47,655)(41,736)
Total regulatory asset deferral(1)
398,629 170,563 192,211 
Current regulatory assets(3)
12,271 10,819 12,148 
Long-term regulatory assets(3)
386,358 159,744 180,063 
(1)    Includes pre-review and post-review deferred costs, amounts currently in amortization, and interest, net of amounts collected from customers.
(2)    Excludes 3.3% of the Front Street site liability as the OPUC only allows recovery of 96.7% of costs for those sites allocable to Oregon, including those that historically served only Oregon customers. Amounts excluded from regulatory assets were immaterial at March 31, 2026, March 31, 2025, and December 31, 2025.
(3)    Environmental costs relate to specific sites approved for regulatory deferral by the OPUC and WUTC. In Oregon, NW Natural earns a carrying charge on cash amounts paid, whereas amounts accrued but not yet paid do not earn a carrying charge until expended. It also accrues a carrying charge on insurance proceeds for amounts owed to customers. In Washington, neither the cash paid for insurance proceeds received accrue a carrying charge. Current environmental costs represent remediation costs management expects to collect from customers in the next 12 months. Amounts included in this estimate are still subject to a prudence and earnings test review by the OPUC and do not include the $5 million tariff rider. The amounts allocable to Oregon are recoverable through NW Natural rates, subject to an earnings test.
v3.26.1
Organization and Principles of Consolidation - Additional Information (Details)
 3 Months Ended
Mar. 31, 2026
segment
NW Natural  
Segment Reporting Information [Line Items]  
Number of reportable segments 1
v3.26.1
Significant Accounting Policies - Schedule of Regulatory Asset Disclosure (Details) - USD ($)
$ in Thousands
Mar. 31, 2026
Dec. 31, 2025
Mar. 31, 2025
Regulatory Assets [Line Items]      
Regulatory assets, current $ 146,545 $ 143,745 $ 88,623
Regulatory assets, noncurrent 637,563 424,194 371,258
SiEnergy      
Regulatory Assets [Line Items]      
Regulatory assets, current 275 410 0
Regulatory assets, noncurrent 3,288 2,095 0
SiEnergy other      
Regulatory Assets [Line Items]      
Regulatory assets, noncurrent 1,427 1,412 876
NWN Water      
Regulatory Assets [Line Items]      
Regulatory assets, current 324 200 25
Regulatory assets, noncurrent 794 840 754
NW Natural      
Regulatory Assets [Line Items]      
Regulatory assets, current 145,946 143,135 88,598
Regulatory assets, noncurrent 632,054 419,847 369,628
NW Natural | Unrealized loss on derivatives      
Regulatory Assets [Line Items]      
Regulatory assets, current 42,081 63,578 26,122
Regulatory assets, noncurrent 17,318 14,039 8,224
NW Natural | Gas costs      
Regulatory Assets [Line Items]      
Regulatory assets, current 15,523 6,284 5,085
Regulatory assets, noncurrent 9,343 9,434 1,804
NW Natural | Environmental costs      
Regulatory Assets [Line Items]      
Regulatory assets, current 12,271 12,148 10,819
Regulatory assets, noncurrent 386,358 180,063 159,744
NW Natural | Decoupling      
Regulatory Assets [Line Items]      
Regulatory assets, current 22,136 11,631 351
Regulatory assets, noncurrent 11,746 8,891 188
NW Natural | Pension balancing      
Regulatory Assets [Line Items]      
Regulatory assets, current 7,131 7,131 7,131
Regulatory assets, noncurrent 13,076 15,647 19,174
NW Natural | Income taxes      
Regulatory Assets [Line Items]      
Regulatory assets, current 2,208 2,208 2,208
Regulatory assets, noncurrent 9,289 9,148 8,993
NW Natural | Pension and other postretirement benefit liabilities      
Regulatory Assets [Line Items]      
Regulatory assets, noncurrent 93,773 96,008 108,970
NW Natural | Washington Climate Commitment Act compliance      
Regulatory Assets [Line Items]      
Regulatory assets, current 7,754 7,482 8,219
Regulatory assets, noncurrent 44,082 33,085 28,292
NW Natural | Security and systems improvements      
Regulatory Assets [Line Items]      
Regulatory assets, current 1,391 1,771 2,182
Regulatory assets, noncurrent 8,158 8,234 8,452
NW Natural | Industrial demand side management      
Regulatory Assets [Line Items]      
Regulatory assets, current 12,149 10,539 12,530
Regulatory assets, noncurrent 4,787 9,334 4,682
NW Natural | Other      
Regulatory Assets [Line Items]      
Regulatory assets, current 23,302 20,363 13,951
Regulatory assets, noncurrent $ 34,124 $ 35,964 $ 21,105
v3.26.1
Significant Accounting Policies - Schedule of Regulatory Liability Disclosure (Details) - USD ($)
$ in Thousands
Mar. 31, 2026
Dec. 31, 2025
Mar. 31, 2025
Regulatory Liabilities [Line Items]      
Regulatory liability, current $ 113,914 $ 137,974 $ 111,050
Regulatory liability, noncurrent 762,429 758,407 730,084
SiEnergy      
Regulatory Liabilities [Line Items]      
Regulatory liability, current 90 66 61
Regulatory liability, noncurrent 8,621 8,155 0
NWN Water      
Regulatory Liabilities [Line Items]      
Regulatory liability, current 96 0 133
Regulatory liability, noncurrent 1,406 1,406 945
NW Natural      
Regulatory Liabilities [Line Items]      
Regulatory liability, current 113,728 137,908 110,856
Regulatory liability, noncurrent 752,402 748,846 729,139
NW Natural | Gas costs      
Regulatory Liabilities [Line Items]      
Regulatory liability, current 21,838 34,172 33,864
Regulatory liability, noncurrent 903 687 9,168
NW Natural | Deferred Derivative Gain (Loss)      
Regulatory Liabilities [Line Items]      
Regulatory liability, current 2,719 3,922 4,339
Regulatory liability, noncurrent 459 366 858
NW Natural | Decoupling      
Regulatory Liabilities [Line Items]      
Regulatory liability, current 2,738 5,181 8,177
Regulatory liability, noncurrent 0 0 2,538
NW Natural | Income taxes      
Regulatory Liabilities [Line Items]      
Regulatory liability, current 5,406 5,406 4,726
Regulatory liability, noncurrent 154,830 159,176 160,975
NW Natural | Asset optimization revenue sharing      
Regulatory Liabilities [Line Items]      
Regulatory liability, current 9,508 25,981 8,381
Regulatory liability, noncurrent 0 2,386 0
NW Natural | Washington Climate Commitment Act compliance      
Regulatory Liabilities [Line Items]      
Regulatory liability, current 65,523 57,441 46,241
NW Natural | Accrued asset removal costs      
Regulatory Liabilities [Line Items]      
Regulatory liability, noncurrent 571,035 561,594 535,075
NW Natural | Other      
Regulatory Liabilities [Line Items]      
Regulatory liability, current 5,996 5,805 5,128
Regulatory liability, noncurrent $ 25,175 $ 24,637 $ 20,525
v3.26.1
Significant Accounting Policies - Narrative (Details)
Mar. 31, 2026
USD ($)
lease
Mar. 31, 2025
USD ($)
Accounts Receivable, Noncurrent, Credit Quality Indicator [Line Items]    
Money market funds, at carrying value $ 2,500,000 $ 68,100,000
Number of net investments in sales-type leases | lease 2  
Sales-type lease, net investment in lease, allowance for credit loss $ 0  
NW Natural    
Accounts Receivable, Noncurrent, Credit Quality Indicator [Line Items]    
Money market funds, at carrying value $ 2,500,000 $ 68,100,000
v3.26.1
Significant Accounting Policies - Schedule of Supplemental Cash Flow (Details) - USD ($)
$ in Thousands
Mar. 31, 2026
Dec. 31, 2025
Mar. 31, 2025
Dec. 31, 2024
Restricted Cash and Cash Equivalent Item [Line Items]        
Cash and cash equivalents $ 34,945 $ 36,673 $ 100,050  
Restricted cash included in other current assets 5,427 4,404 6,935  
Cash, cash equivalents and restricted cash 40,372 41,077 106,985 $ 47,982
NW Natural        
Restricted Cash and Cash Equivalent Item [Line Items]        
Cash and cash equivalents 24,274 29,347 81,767  
Restricted cash included in other current assets 5,402 4,379 6,910  
Cash, cash equivalents and restricted cash $ 29,676 $ 33,726 $ 88,677 $ 29,428
v3.26.1
Significant Accounting Policies - Schedule of Credit Losses - ASU 2016-13 (Details)
$ in Thousands
 3 Months Ended
Mar. 31, 2026
USD ($)
NW Natural  
Accounts Receivable, Allowance for Credit Loss [Roll Forward]  
Beginning Balance $ 3,048
Provision recorded, net of adjustments 336
Write-offs recognized, net of recoveries 99
Ending Balance 3,285
Other - NW Holdings  
Accounts Receivable, Allowance for Credit Loss [Roll Forward]  
Beginning Balance 1,020
Provision recorded, net of adjustments 312
Write-offs recognized, net of recoveries 107
Ending Balance 1,225
Total NW Holdings  
Accounts Receivable, Allowance for Credit Loss [Roll Forward]  
Beginning Balance 4,068
Provision recorded, net of adjustments 648
Write-offs recognized, net of recoveries 206
Ending Balance 4,510
Residential | NW Natural  
Accounts Receivable, Allowance for Credit Loss [Roll Forward]  
Beginning Balance 2,280
Provision recorded, net of adjustments 402
Write-offs recognized, net of recoveries 54
Ending Balance 2,628
Commercial | NW Natural  
Accounts Receivable, Allowance for Credit Loss [Roll Forward]  
Beginning Balance 374
Provision recorded, net of adjustments (27)
Write-offs recognized, net of recoveries 48
Ending Balance 299
Industrial | NW Natural  
Accounts Receivable, Allowance for Credit Loss [Roll Forward]  
Beginning Balance 46
Provision recorded, net of adjustments 10
Write-offs recognized, net of recoveries 0
Ending Balance 56
Accrued unbilled and other | NW Natural  
Accounts Receivable, Allowance for Credit Loss [Roll Forward]  
Beginning Balance 348
Provision recorded, net of adjustments (49)
Write-offs recognized, net of recoveries 3
Ending Balance $ 302
v3.26.1
Significant Accounting Policies - Greenhouse Gas Allowances Narrative (Details) - USD ($)
$ in Thousands
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Dec. 31, 2025
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]      
CCI deferred costs $ 51,800 $ 36,000  
Increase (decrease) in cloud-based software capital expenditure 2,200 2,100  
Capitalized computer software, amortization 3,100 3,100  
Other current assets 57,895 46,275 $ 75,850
Prepaid Expenses and Other Current Assets      
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]      
Other current assets 36,000 31,900  
Natural Gas      
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]      
Other current assets 2,600 2,700  
NW Natural      
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]      
Other current assets 50,078 40,698 $ 61,024
NW Natural | Prepaid Expenses and Other Current Assets      
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]      
Other current assets 28,200 26,400  
Washington Climate Commitment Act compliance | NW Natural      
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]      
Regulatory liability 47,100    
Washington Climate Commitment Act Allowances      
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]      
Proceeds from other operating activity 47,100    
WASHINGTON      
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]      
Inventory, emissions allowances 80,400 49,000  
CCI credits liability $ 51,800 $ 36,000  
v3.26.1
Earnings Per Share (Details) - USD ($)
$ / shares in Units, shares in Thousands, $ in Thousands
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Earnings Per Share [Abstract]    
Net income $ 97,489 $ 87,916
Average common shares outstanding:    
Average common shares outstanding - basic (in shares) 41,708 40,244
Additional shares for stock-based compensation plans 108 60
Average common shares outstanding - diluted (in shares) 41,816 40,304
Earnings per share of common stock:    
Basic (in dollars per share) $ 2.34 $ 2.18
Diluted (in dollars per share) $ 2.33 $ 2.18
Antidilutive shares (in shares) 13 10
v3.26.1
Segment Information - Narrative (Details)
 3 Months Ended
Mar. 31, 2026
segment
Operating Segments  
Segment Reporting Information [Line Items]  
Number of reportable segments 3
NW Natural  
Segment Reporting Information [Line Items]  
Number of reportable segments 1
v3.26.1
Segment Information - Schedule of Summarized Financial Information by Segment (Details) - USD ($)
$ in Thousands
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Segment Reporting Information [Line Items]    
Operating revenues $ 490,403 $ 494,284
Depreciation 44,134 40,500
Income (loss) from operations 162,868 154,354
Interest expense, net (33,352) (29,395)
Income tax expense (benefit) 32,539 34,527
Parent Company    
Segment Reporting Information [Line Items]    
Operating revenues 490,403 494,284
Depreciation 44,134 40,500
Income (loss) from operations 162,868 154,354
Interest expense, net 33,352 29,395
Income tax expense (benefit) 32,539 34,527
Capital expenditures 113,656 102,184
Operating Segments | NW Natural    
Segment Reporting Information [Line Items]    
Operating revenues 433,896 448,813
Depreciation 39,444 36,036
Interest expense, net 17,678 15,580
Income tax expense (benefit) 32,155 35,664
Capital expenditures 79,615 83,608
Operating Segments | SiEnergy    
Segment Reporting Information [Line Items]    
Operating revenues 31,695 22,666
Depreciation 1,797 2,070
Income (loss) from operations 13,834 9,613
Interest expense, net 2,543 2,257
Income tax expense (benefit) 2,537 1,944
Capital expenditures 24,944 10,525
Operating Segments | NWN Water    
Segment Reporting Information [Line Items]    
Operating revenues 14,969 13,909
Depreciation 2,893 2,394
Income (loss) from operations 2,399 3,043
Interest expense, net 688 792
Income tax expense (benefit) 554 631
Capital expenditures 9,097 8,051
Operating Segments | Other    
Segment Reporting Information [Line Items]    
Operating revenues 9,843 8,896
Depreciation 0 0
Income (loss) from operations 2,949 (3,334)
Interest expense, net 12,443 10,766
Income tax expense (benefit) $ (2,707) (3,712)
Capital expenditures   $ 0
v3.26.1
Segment Information - Additional Segment Information (Details) - USD ($)
$ in Thousands
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Segment Reporting Information [Line Items]    
Total operating revenues $ 490,403 $ 494,284
Less: Cost of gas 158,149 172,991
Environmental remediation 6,325 6,253
General taxes 16,343 15,771
Depreciation 44,134 40,500
Other operating expenses 1,375 1,327
NW Natural income from operations 162,868 154,354
Operating Segments | NWN Gas Utility    
Segment Reporting Information [Line Items]    
Distribution revenues 421,234 435,908
Regulated gas storage 9,606 9,784
Other revenue 3,056 3,121
Total operating revenues 433,896 448,813
Less: Cost of gas 140,144 159,436
Environmental remediation 6,325 6,253
Revenue taxes 17,037 18,565
NW Natural margin 270,390 264,559
Operations and maintenance 70,530 67,766
General taxes 16,037 14,979
Depreciation 39,444 36,036
Other operating expenses 693 746
NW Natural income from operations 143,686 145,032
Operating Segments | SiEnergy    
Segment Reporting Information [Line Items]    
Distribution revenues 31,695 22,666
Total operating revenues 31,695 22,666
Less: Cost of gas 12,279 8,303
Revenue taxes 961 779
NW Natural margin 18,455 13,584
Operations and maintenance 2,814 1,682
General taxes 10 219
Depreciation 1,797 2,070
NW Natural income from operations 13,834 9,613
Operating Segments | NWN Water    
Segment Reporting Information [Line Items]    
Total operating revenues 14,969 13,909
Operations and maintenance 8,607 7,265
Depreciation 2,893 2,394
Other operating expenses 1,070 1,207
NW Natural income from operations $ 2,399 $ 3,043
v3.26.1
Common Stock (Details) - ATM Equity Program - USD ($)
$ in Millions
 1 Months Ended 3 Months Ended
Aug. 31, 2024
Mar. 31, 2026
Class of Stock [Line Items]    
Stock issued during period, shares, new issues   441,034
Sale of stock, consideration received on transaction   $ 22.2
Sale of stock, commissions and fees paid   0.3
Market equity program equity available for issuance   $ 75.2
Maximum | Scenario, Plan    
Class of Stock [Line Items]    
Cumulative proceeds received on all transactions $ 200.0  
v3.26.1
Revenue - Disaggregation of Revenue (Details) - USD ($)
$ in Thousands
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Disaggregation of Revenue [Line Items]    
Revenue from contract with customer, including assessed tax $ 460,604 $ 484,070
Revenues 490,403 494,284
Natural gas sales | Transferred over Time    
Disaggregation of Revenue [Line Items]    
Revenue from contract with customer, including assessed tax 428,873 453,746
Gas storage revenue, net | Transferred over Time    
Disaggregation of Revenue [Line Items]    
Revenue from contract with customer, including assessed tax 4,365 4,616
Asset management revenue, net | Transferred over Time    
Disaggregation of Revenue [Line Items]    
Revenue from contract with customer, including assessed tax 1,747 1,749
Water and wastewater revenue | Transferred over Time    
Disaggregation of Revenue [Line Items]    
Revenue from contract with customer, including assessed tax 14,969 13,909
Gas appliance retail revenue | Transferred at Point in Time    
Disaggregation of Revenue [Line Items]    
Revenue from contract with customer, including assessed tax 1,309 1,372
Renewable natural gas sales | Transferred over Time    
Disaggregation of Revenue [Line Items]    
Revenue from contract with customer, including assessed tax 8,465 7,726
Other revenue | Transferred over Time    
Disaggregation of Revenue [Line Items]    
Revenue from contract with customer, including assessed tax 876 952
Alternative revenue    
Disaggregation of Revenue [Line Items]    
Revenues 25,346 5,908
Leasing revenue    
Disaggregation of Revenue [Line Items]    
Operating leases 4,453 4,306
Operating Segments | NW Natural | NW Natural    
Disaggregation of Revenue [Line Items]    
Revenue from contract with customer, including assessed tax 407,416 438,938
Revenues 433,896 448,813
Operating Segments | NW Natural | NW Natural | Natural gas sales | Transferred over Time    
Disaggregation of Revenue [Line Items]    
Revenue from contract with customer, including assessed tax 399,119 430,249
Operating Segments | NW Natural | NW Natural | Gas storage revenue, net | Transferred over Time    
Disaggregation of Revenue [Line Items]    
Revenue from contract with customer, including assessed tax 4,365 4,616
Operating Segments | NW Natural | NW Natural | Asset management revenue, net | Transferred over Time    
Disaggregation of Revenue [Line Items]    
Revenue from contract with customer, including assessed tax 1,747 1,749
Operating Segments | NW Natural | NW Natural | Water and wastewater revenue | Transferred over Time    
Disaggregation of Revenue [Line Items]    
Revenue from contract with customer, including assessed tax 0 0
Operating Segments | NW Natural | NW Natural | Gas appliance retail revenue | Transferred at Point in Time    
Disaggregation of Revenue [Line Items]    
Revenue from contract with customer, including assessed tax 1,309 1,372
Operating Segments | NW Natural | NW Natural | Renewable natural gas sales | Transferred over Time    
Disaggregation of Revenue [Line Items]    
Revenue from contract with customer, including assessed tax 0 0
Operating Segments | NW Natural | NW Natural | Other revenue | Transferred over Time    
Disaggregation of Revenue [Line Items]    
Revenue from contract with customer, including assessed tax 876 952
Operating Segments | NW Natural | NW Natural | Alternative revenue    
Disaggregation of Revenue [Line Items]    
Revenues 22,027 5,569
Operating Segments | NW Natural | NW Natural | Leasing revenue    
Disaggregation of Revenue [Line Items]    
Operating leases 4,453 4,306
Operating Segments | SiEnergy | SiEnergy    
Disaggregation of Revenue [Line Items]    
Revenue from contract with customer, including assessed tax 28,376 22,327
Revenues 31,695 22,666
Operating Segments | SiEnergy | SiEnergy | Natural gas sales | Transferred over Time    
Disaggregation of Revenue [Line Items]    
Revenue from contract with customer, including assessed tax 28,376 22,327
Operating Segments | SiEnergy | SiEnergy | Gas storage revenue, net | Transferred over Time    
Disaggregation of Revenue [Line Items]    
Revenue from contract with customer, including assessed tax 0 0
Operating Segments | SiEnergy | SiEnergy | Asset management revenue, net | Transferred over Time    
Disaggregation of Revenue [Line Items]    
Revenue from contract with customer, including assessed tax 0 0
Operating Segments | SiEnergy | SiEnergy | Water and wastewater revenue | Transferred over Time    
Disaggregation of Revenue [Line Items]    
Revenue from contract with customer, including assessed tax 0 0
Operating Segments | SiEnergy | SiEnergy | Gas appliance retail revenue | Transferred at Point in Time    
Disaggregation of Revenue [Line Items]    
Revenue from contract with customer, including assessed tax 0 0
Operating Segments | SiEnergy | SiEnergy | Renewable natural gas sales | Transferred over Time    
Disaggregation of Revenue [Line Items]    
Revenue from contract with customer, including assessed tax 0 0
Operating Segments | SiEnergy | SiEnergy | Other revenue | Transferred over Time    
Disaggregation of Revenue [Line Items]    
Revenue from contract with customer, including assessed tax 0 0
Operating Segments | SiEnergy | SiEnergy | Alternative revenue    
Disaggregation of Revenue [Line Items]    
Revenues 3,319 339
Operating Segments | SiEnergy | SiEnergy | Leasing revenue    
Disaggregation of Revenue [Line Items]    
Operating leases 0 0
Operating Segments | NWN Water | NWN Water    
Disaggregation of Revenue [Line Items]    
Revenue from contract with customer, including assessed tax 14,969 13,909
Revenues 14,969 13,909
Operating Segments | NWN Water | NWN Water | Natural gas sales | Transferred over Time    
Disaggregation of Revenue [Line Items]    
Revenue from contract with customer, including assessed tax 0 0
Operating Segments | NWN Water | NWN Water | Gas storage revenue, net | Transferred over Time    
Disaggregation of Revenue [Line Items]    
Revenue from contract with customer, including assessed tax 0 0
Operating Segments | NWN Water | NWN Water | Asset management revenue, net | Transferred over Time    
Disaggregation of Revenue [Line Items]    
Revenue from contract with customer, including assessed tax 0 0
Operating Segments | NWN Water | NWN Water | Water and wastewater revenue | Transferred over Time    
Disaggregation of Revenue [Line Items]    
Revenue from contract with customer, including assessed tax 14,969 13,909
Operating Segments | NWN Water | NWN Water | Gas appliance retail revenue | Transferred at Point in Time    
Disaggregation of Revenue [Line Items]    
Revenue from contract with customer, including assessed tax 0 0
Operating Segments | NWN Water | NWN Water | Renewable natural gas sales | Transferred over Time    
Disaggregation of Revenue [Line Items]    
Revenue from contract with customer, including assessed tax 0 0
Operating Segments | NWN Water | NWN Water | Other revenue | Transferred over Time    
Disaggregation of Revenue [Line Items]    
Revenue from contract with customer, including assessed tax 0 0
Operating Segments | NWN Water | NWN Water | Alternative revenue    
Disaggregation of Revenue [Line Items]    
Revenues 0 0
Operating Segments | NWN Water | NWN Water | Leasing revenue    
Disaggregation of Revenue [Line Items]    
Operating leases 0 0
Operating Segments | Other    
Disaggregation of Revenue [Line Items]    
Revenues 9,843 8,896
Operating Segments | Other | Other    
Disaggregation of Revenue [Line Items]    
Revenue from contract with customer, including assessed tax 9,843 8,896
Revenues 9,843 8,896
Operating Segments | Other | Other | Natural gas sales | Transferred over Time    
Disaggregation of Revenue [Line Items]    
Revenue from contract with customer, including assessed tax 1,378 1,170
Operating Segments | Other | Other | Gas storage revenue, net | Transferred over Time    
Disaggregation of Revenue [Line Items]    
Revenue from contract with customer, including assessed tax 0 0
Operating Segments | Other | Other | Asset management revenue, net | Transferred over Time    
Disaggregation of Revenue [Line Items]    
Revenue from contract with customer, including assessed tax 0 0
Operating Segments | Other | Other | Water and wastewater revenue | Transferred over Time    
Disaggregation of Revenue [Line Items]    
Revenue from contract with customer, including assessed tax 0 0
Operating Segments | Other | Other | Gas appliance retail revenue | Transferred at Point in Time    
Disaggregation of Revenue [Line Items]    
Revenue from contract with customer, including assessed tax 0 0
Operating Segments | Other | Other | Renewable natural gas sales | Transferred over Time    
Disaggregation of Revenue [Line Items]    
Revenue from contract with customer, including assessed tax 8,465 7,726
Operating Segments | Other | Other | Other revenue | Transferred over Time    
Disaggregation of Revenue [Line Items]    
Revenue from contract with customer, including assessed tax 0 0
Operating Segments | Other | Other | Alternative revenue    
Disaggregation of Revenue [Line Items]    
Revenues 0 0
Operating Segments | Other | Other | Leasing revenue    
Disaggregation of Revenue [Line Items]    
Operating leases $ 0 $ 0
v3.26.1
Revenue - Schedule of Lease Revenue (Details) - NW Natural - USD ($)
$ in Thousands
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Disaggregation of Revenue [Line Items]    
Operating leases $ 19 $ 21
Sales-type leases 4,434 4,285
Total lease revenue $ 4,453 $ 4,306
v3.26.1
Revenue - Narrative (Details)
 3 Months Ended
Mar. 31, 2026
USD ($)
performanceObligation
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Revenue, over time performance obligation, number | performanceObligation 1
Revenue, remaining performance obligation, amount $ 112,300,000
Lessor, sales-type lease, term of contract 30 years
Lessor, sales-type lease, renewal term 50 years
North Mist Lease  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Residual value of leased asset $ 0
Variable lease, payment 0
Other Immaterial Leases  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Residual value of leased asset 0
Variable lease, payment $ 0
Compressed Natural Gas Lease  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Lessor, sales-type lease, term of contract 10 years
NWN Gas Utility | NW Natural  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Contract with customer, refund liability $ 0
Other - NW Holdings  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Contract with customer, refund liability 0
Other | NW Natural  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Contract with customer, refund liability 0
SiEnergy  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Contract with customer, refund liability 0
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2026-04-01  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Revenue, remaining performance obligation, amount $ 23,000,000.0
Revenue, remaining performance obligation, expected timing of satisfaction, year 9 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2027-01-01  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Revenue, remaining performance obligation, amount $ 21,800,000
Revenue, remaining performance obligation, expected timing of satisfaction, year 1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2028-01-01  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Revenue, remaining performance obligation, amount $ 16,800,000
Revenue, remaining performance obligation, expected timing of satisfaction, year 1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2029-01-01  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Revenue, remaining performance obligation, amount $ 16,800,000
Revenue, remaining performance obligation, expected timing of satisfaction, year 1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2030-01-01  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Revenue, remaining performance obligation, amount $ 16,300,000
Revenue, remaining performance obligation, expected timing of satisfaction, year 1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2031-01-01  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Revenue, remaining performance obligation, amount $ 17,600,000
Revenue, remaining performance obligation, expected timing of satisfaction, year
v3.26.1
Leases - Narrative (Details)
Mar. 31, 2026
Lessee, Lease, Description [Line Items]  
Lessee, operating lease, maximum term of short-term leases not recorded on the balance sheet 12 months
Minimum  
Lessee, Lease, Description [Line Items]  
Lessee, operating lease, term of contract 2 months
Maximum  
Lessee, Lease, Description [Line Items]  
Lessee, operating lease, term of contract 14 years
v3.26.1
Leases - Lease Expenses (Details) - USD ($)
$ in Thousands
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Lessee, Lease, Description [Line Items]    
Operating lease expense $ 2,252 $ 2,111
Short-term lease expense 218 189
NW Natural    
Lessee, Lease, Description [Line Items]    
Operating lease expense 1,954 1,867
Short-term lease expense $ 120 $ 189
v3.26.1
Leases - weighted-Average Remaining Lease Terms and Weighted-Average Discount Rates (Details) - NW Natural
Mar. 31, 2026
Dec. 31, 2025
Mar. 31, 2025
Lessee, Lease, Description [Line Items]      
Weighted-average remaining lease term (years) 14 years 14 years 3 months 18 days 15 years
Weighted-average discount rate 7.30% 7.30% 7.30%
v3.26.1
Leases - Supplemental Cash Flow Information (Details) - USD ($)
$ in Thousands
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Lessee, Lease, Description [Line Items]    
Operating cash flows from operating leases $ 2,107 $ 1,918
Right of use assets obtained in exchange for lease obligations    
Operating leases 978 2,647
NW Natural    
Lessee, Lease, Description [Line Items]    
Operating cash flows from operating leases 1,931 1,861
Right of use assets obtained in exchange for lease obligations    
Operating leases $ 250 $ 346
v3.26.1
Stock-Based Compensation (Details) - Long Term Incentive Plan - USD ($)
 1 Months Ended 3 Months Ended
Feb. 28, 2026
Feb. 28, 2025
Mar. 31, 2029
Mar. 31, 2028
Mar. 31, 2026
Performance Shares          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Award vesting period         3 years
Unrecognized compensation costs         $ 1,500,000
ROIC performance period (in years)   3 years      
Cumulative EBITDA performance period (in years)   3 years      
Performance Shares | Minimum          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Conversion ratio, percent of target   0.00%      
Performance Shares | Maximum          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Conversion ratio, percent of target   200.00%      
Restricted Stock Units (RSUs)          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Award vesting period         3 years
Unrecognized compensation costs         $ 5,500,000
Number of RSUs granted in period (in shares)         59,349
Weighted-average grant date fair value (in dollars per share)         $ 49.99
2023-2025 Award | Performance Shares          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Number of shares granted (in shares)         52,178
2024-2026 Award | Performance Shares          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Share-based payment arrangement, expense         $ 0
2025-2027 Award | Performance Shares          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Number of shares granted (in shares) 6,135 8,675      
Share-based payment arrangement, expense         $ 0
Forecast | 2025-2027 Award | Performance Shares          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Share based compensation award target share (in shares)     65,240 73,640  
v3.26.1
DEBT - Short-Term Debt (Details) - USD ($)
$ in Thousands
Mar. 31, 2026
Dec. 31, 2025
Mar. 31, 2025
Short-term Debt [Line Items]      
Balance Outstanding $ 171,276 $ 171,989 $ 81,100
NW Natural      
Short-term Debt [Line Items]      
Balance Outstanding 0 9,990 0
Commercial Paper      
Short-term Debt [Line Items]      
Balance Outstanding $ 171,300 $ 162,000 $ 0
Weighted average interest rate (as percent) 4.10% 4.10% 0.00%
Commercial Paper | NW Natural      
Short-term Debt [Line Items]      
Balance Outstanding $ 0 $ 10,000 $ 0
Weighted average interest rate (as percent) 0.00% 4.00% 0.00%
Line of Credit      
Short-term Debt [Line Items]      
Balance Outstanding $ 0 $ 0 $ 81,100
Weighted average interest rate (as percent) 0.00% 0.00% 5.50%
v3.26.1
DEBT - Long-Term Debt (Details) - USD ($)
$ in Thousands
Mar. 31, 2026
Dec. 31, 2025
Mar. 31, 2025
Debt Instrument [Line Items]      
Balance Outstanding $ 2,448,600 $ 2,448,700 $ 2,244,300
Long-term debt 2,433,100    
Less: unamortized debt issuance costs 15,500 15,900 14,400
Current maturities of long-term debt 160,669 160,627 36,838
Long-term debt 2,272,444 2,272,202 2,193,071
NW Natural      
Debt Instrument [Line Items]      
Balance Outstanding 1,544,700 1,544,700 1,374,700
Long-term debt 1,535,100 1,534,900 1,365,600
Less: unamortized debt issuance costs 9,600 9,800 9,100
Current maturities of long-term debt 54,962 54,948 29,995
Long-term debt 1,480,109 1,479,942 1,335,572
NW Holdings      
Debt Instrument [Line Items]      
Balance Outstanding 2,448,600 2,448,700 2,244,300
Long-term debt 2,433,100 2,432,800 2,229,900
Less: unamortized debt issuance costs 15,500 15,900 14,400
Long-term debt $ 2,272,400 $ 2,272,200 $ 2,193,100
Delayed Draw Term Loan | SiEnergy      
Debt Instrument [Line Items]      
Weighted average interest rate (as percent) 0.00% 0.00% 6.10%
Long-term debt $ 0 $ 0 $ 149,600
Junior Subordinated Debt | Junior Subordinated Debentures      
Debt Instrument [Line Items]      
Balance Outstanding $ 325,000 $ 325,000 $ 325,000
Weighted average interest rate (as percent) 7.00% 7.00% 7.00%
Mortgages | Natural first mortgage bonds | NW Natural      
Debt Instrument [Line Items]      
Balance Outstanding $ 1,544,700 $ 1,544,700 $ 1,374,700
Weighted average interest rate (as percent) 4.70% 4.70% 4.60%
Secured Debt | SiEnergy secured senior notes | SiEnergy      
Debt Instrument [Line Items]      
Balance Outstanding $ 185,000 $ 185,000 $ 0
Weighted average interest rate (as percent) 5.60% 5.60% 0.00%
Secured Debt | NWN Water Term Loan Due 2026 | NWN Water      
Debt Instrument [Line Items]      
Balance Outstanding $ 55,000 $ 55,000 $ 55,000
Weighted average interest rate (as percent) 4.70% 4.70% 4.70%
Secured Debt | Other water debt | NWN Water      
Debt Instrument [Line Items]      
Balance Outstanding $ 3,900 $ 4,000 $ 5,000
Secured Debt | Term Loan      
Debt Instrument [Line Items]      
Balance Outstanding $ 50,000 $ 50,000 $ 50,000
Weighted average interest rate (as percent) 4.70% 5.20% 5.30%
Unsecured Debt | NW Holdings Unsecured Senior Bonds      
Debt Instrument [Line Items]      
Balance Outstanding $ 285,000 $ 285,000 $ 285,000
Weighted average interest rate (as percent) 5.70% 5.70% 5.70%
v3.26.1
DEBT - Narrative (Details) - USD ($)
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Dec. 31, 2025
Short-term Debt [Line Items]      
Long-term debt $ 2,433,100,000    
Less: unamortized debt issuance costs 15,500,000 $ 14,400,000 $ 15,900,000
Current maturities of long-term debt 160,669,000 36,838,000 160,627,000
Balance Outstanding 2,448,600,000 2,244,300,000 2,448,700,000
Long-term debt issued 0 375,000,000  
NW Natural      
Short-term Debt [Line Items]      
Long-term debt 1,535,100,000 1,365,600,000 1,534,900,000
Less: unamortized debt issuance costs 9,600,000 9,100,000 9,800,000
Current maturities of long-term debt 54,962,000 29,995,000 54,948,000
Long-term debt, current maturities 55,000,000.0    
Balance Outstanding 1,544,700,000 1,374,700,000 1,544,700,000
NWN Water      
Short-term Debt [Line Items]      
Long-term debt, current maturities 55,700,000    
Natural first mortgage bonds | NW Natural      
Short-term Debt [Line Items]      
Long-term debt issued 0    
Natural first mortgage bonds | Mortgages | NW Natural      
Short-term Debt [Line Items]      
Balance Outstanding 1,544,700,000 1,374,700,000 1,544,700,000
Repayments of debt 0    
Extinguishment of debt 0    
NW Holdings Unsecured Senior Bonds | Unsecured Debt      
Short-term Debt [Line Items]      
Balance Outstanding $ 285,000,000.0 285,000,000.0 285,000,000.0
Junior Subordinated Debt | Junior Subordinated Debt      
Short-term Debt [Line Items]      
Stated interest rate (as percent) 7.00%    
Term Loan | Secured Debt      
Short-term Debt [Line Items]      
Balance Outstanding $ 50,000,000.0 $ 50,000,000.0 $ 50,000,000.0
Minimum | Natural first mortgage bonds | Mortgages | NW Natural      
Short-term Debt [Line Items]      
Stated interest rate (as percent) 2.82%    
Minimum | SiEnergy secured senior notes | Secured Debt      
Short-term Debt [Line Items]      
Stated interest rate (as percent) 4.86%    
Minimum | NW Holdings Unsecured Senior Bonds | Unsecured Debt      
Short-term Debt [Line Items]      
Stated interest rate (as percent) 5.52%    
Maximum | Natural first mortgage bonds | Mortgages | NW Natural      
Short-term Debt [Line Items]      
Stated interest rate (as percent) 7.85%    
Maximum | SiEnergy secured senior notes | Secured Debt      
Short-term Debt [Line Items]      
Stated interest rate (as percent) 6.04%    
Maximum | NW Holdings Unsecured Senior Bonds | Unsecured Debt      
Short-term Debt [Line Items]      
Stated interest rate (as percent) 5.86%    
v3.26.1
Debt - Fair Value of Long Term Debt (Details) - USD ($)
$ in Millions
Mar. 31, 2026
Dec. 31, 2025
Mar. 31, 2025
Debt Instrument [Line Items]      
Gross long-term debt $ 2,448.6 $ 2,448.7 $ 2,244.3
Unamortized debt issuance costs (15.5) (15.9) (14.4)
Long-term debt 2,433.1    
NW Holdings      
Debt Instrument [Line Items]      
Gross long-term debt 2,448.6 2,448.7 2,244.3
Unamortized debt issuance costs (15.5) (15.9) (14.4)
Long-term debt 2,433.1 2,432.8 2,229.9
Estimated fair value 2,281.4 2,317.1 2,069.8
NW Natural      
Debt Instrument [Line Items]      
Gross long-term debt 1,544.7 1,544.7 1,374.7
Unamortized debt issuance costs (9.6) (9.8) (9.1)
Long-term debt 1,535.1 1,534.9 1,365.6
Estimated fair value $ 1,360.8 $ 1,383.1 $ 1,198.7
v3.26.1
Pension and Other Postretirement Benefit Costs - Schedule of Net Benefit Costs (Details) - USD ($)
$ in Thousands
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Pension Benefits    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Service cost $ 855 $ 885
Interest cost 5,167 5,410
Expected return on plan assets (5,591) (5,433)
Amortization of net actuarial loss 2,295 2,444
Net periodic benefit cost 2,726 3,306
Amount allocated to construction (405) (434)
Net periodic benefit cost charged to expense 2,321 2,872
Amortization of regulatory balancing account 2,801 2,801
Net amount charged to expense 5,122 5,673
Other Postretirement Benefits    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Service cost 26 27
Interest cost 282 288
Expected return on plan assets 0 0
Amortization of net actuarial loss 63 20
Net periodic benefit cost 371 335
Amount allocated to construction (11) (11)
Net periodic benefit cost charged to expense 360 324
Amortization of regulatory balancing account 0 0
Net amount charged to expense $ 360 $ 324
v3.26.1
Pension and Other Postretirement Benefit Costs - Schedule of Amounts Recognized in Other Comprehensive Income (Loss) (Details) - USD ($)
$ in Thousands
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Accumulated Other Comprehensive Income Loss Net Of Tax [Roll Forward]    
Beginning balance $ 1,475,076  
Ending balance 1,576,901 $ 1,456,218
NW Natural    
Accumulated Other Comprehensive Income Loss Net Of Tax [Roll Forward]    
Beginning balance 1,508,244  
Ending balance 1,582,204 1,516,205
Non-Qualified Pension Plans, Defined Benefit | NW Natural    
Accumulated Other Comprehensive Income Loss Net Of Tax [Roll Forward]    
Beginning balance (4,705) (7,052)
Total reclassifications before tax 124 200
Tax benefit (33) (25)
Total reclassifications for the period 91 175
Ending balance (4,614) (6,877)
Non-Qualified Pension Plans, Defined Benefit | NW Natural | Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent    
Accumulated Other Comprehensive Income Loss Net Of Tax [Roll Forward]    
Total reclassifications before tax $ 124 $ 200
v3.26.1
Pension and Other Postretirement Benefit Costs - Narrative (Details) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Pension and Other Postretirement Benefits Cost (Reversal of Cost) [Abstract]    
Defined benefit pension plan cash contributions $ 2.9 $ 2.6
Employer contributions $ 4.3 $ 4.0
v3.26.1
Income Tax (Details) - USD ($)
$ in Thousands
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Effective Income Tax Rate Reconciliation, Amount [Abstract]    
Income tax at statutory rate (federal) $ 27,306 $ 25,713
State income tax 8,830 9,980
Differences required to be flowed-through by regulatory commissions (1,954) (1,668)
Other, net (1,643) 502
Total (benefit) expense for income taxes $ 32,539 $ 34,527
Effective income tax rate 25.00% 28.20%
NW Natural    
Effective Income Tax Rate Reconciliation, Amount [Abstract]    
Income tax at statutory rate (federal) $ 26,440 $ 26,608
State income tax 9,247 10,202
Differences required to be flowed-through by regulatory commissions (1,954) (1,668)
Other, net (1,578) 522
Total (benefit) expense for income taxes $ 32,155 $ 35,664
Effective income tax rate 25.50% 28.10%
v3.26.1
Property, Plant and Equipment (Details) - USD ($)
$ in Thousands
Mar. 31, 2026
Dec. 31, 2025
Mar. 31, 2025
Property, Plant and Equipment [Line Items]      
Property, plant, and equipment $ 5,722,356 $ 5,640,435 $ 5,268,063
Less: Accumulated depreciation 1,300,897 1,288,422 1,266,222
Total property, plant, and equipment, net 4,421,459 4,352,013 4,001,841
NW Natural      
Property, Plant and Equipment [Line Items]      
Property, plant, and equipment 5,046,862 5,000,329 4,780,480
Less: Accumulated depreciation 1,257,950 1,256,289 1,237,907
Total property, plant, and equipment, net 3,788,912 3,744,040 3,542,573
Parent Company      
Property, Plant and Equipment [Line Items]      
Less: Accumulated depreciation 1,300,897 1,288,422 1,266,222
Total property, plant, and equipment, net 4,421,459 4,352,013 4,001,841
Capital expenditures in accrued liabilities 51,572 57,762 32,042
Parent Company | Plant in service      
Property, Plant and Equipment [Line Items]      
Property, plant, and equipment 5,509,029 5,468,170 5,091,181
Parent Company | Construction work in progress      
Property, Plant and Equipment [Line Items]      
Construction work in progress 213,327 172,265 176,882
Subsidiaries | NW Natural      
Property, Plant and Equipment [Line Items]      
Less: Accumulated depreciation 1,257,950 1,256,289 1,237,907
Total property, plant, and equipment, net 3,788,912 3,744,040 3,542,573
Capital expenditures in accrued liabilities 34,917 33,582 23,457
Subsidiaries | NW Natural | Plant in service      
Property, Plant and Equipment [Line Items]      
Property, plant, and equipment 4,891,650 4,879,816 4,634,047
Subsidiaries | NW Natural | Construction work in progress      
Property, Plant and Equipment [Line Items]      
Construction work in progress $ 155,212 $ 120,513 $ 146,433
v3.26.1
Investments - Other Investments (Details) - USD ($)
$ in Thousands
Mar. 31, 2026
Dec. 31, 2025
Mar. 31, 2025
Schedule of Equity Method Investments [Line Items]      
Total other investments $ 69,441 $ 80,676 $ 82,663
Parent Company      
Schedule of Equity Method Investments [Line Items]      
Investments in life insurance policies 34,032 45,606 45,936
Investments in gas reserves, non-current 14,789 15,443 17,500
Investment in unconsolidated affiliates 20,620 19,627 19,227
Total other investments 69,441 80,676 82,663
Subsidiaries      
Schedule of Equity Method Investments [Line Items]      
Investments in life insurance policies 34,032 45,606 45,936
Investments in gas reserves, non-current 14,789 15,443 17,500
Investment in unconsolidated affiliates 0 0 0
Total other investments $ 48,821 $ 61,049 $ 63,436
v3.26.1
Investments - Narrative (Details)
$ in Millions
Mar. 31, 2026
USD ($)
connection
employee
Jan. 31, 2026
Dec. 31, 2025
USD ($)
Mar. 31, 2025
USD ($)
Feb. 28, 2025
Jan. 31, 2024
Jun. 30, 2023
Jul. 31, 2022
Dec. 31, 2021
USD ($)
Schedule of Equity Method Investments [Line Items]                  
Total cumulative gas reserves investment $ 188.0                
Deferred taxes related to gas reserves 1.5   $ 1.8 $ 2.6          
Gas reserves, current $ 2.6   $ 2.6 $ 2.7          
Avion Water | NWN Water                  
Schedule of Equity Method Investments [Line Items]                  
Ownership percentage of Avion   50.00%     47.90% 45.60% 43.10% 40.30% 37.30%
Equity method investment, underlying equity in net assets                 $ 14.5
Equity method investment, number of customer connections | connection 17,000                
Equity method investment, number of employees | employee 40                
Equity method investment, difference between carrying amount andunderlying equity $ 10.1                
v3.26.1
Investments - Investments in Unconsolidated Affiliates (Details) - Avion Water - NWN Water - USD ($)
$ in Thousands
Jan. 31, 2026
Feb. 28, 2025
Jan. 31, 2024
Jun. 30, 2023
Jul. 31, 2022
Dec. 31, 2021
Schedule of Equity Method Investments [Line Items]            
Amount $ 1,000 $ 1,000 $ 1,000 $ 1,000 $ 1,000  
Ownership percentage of Avion 50.00% 47.90% 45.60% 43.10% 40.30% 37.30%
v3.26.1
Business Combinations - Narrative (Details)
 3 Months Ended
Jun. 02, 2025
USD ($)
Jan. 07, 2025
USD ($)
Mar. 31, 2026
USD ($)
customer
business
Dec. 31, 2025
USD ($)
Sep. 30, 2025
USD ($)
Mar. 31, 2025
USD ($)
Business Combination [Line Items]            
Goodwill     $ 371,257,000 $ 370,815,000   $ 354,534,000
Goodwill, impairment loss     0      
SiEnergy            
Business Combination [Line Items]            
Goodwill     186,200,000 185,700,000   171,000,000.0
NWN Water            
Business Combination [Line Items]            
Goodwill     185,100,000 185,100,000   183,500,000
SiEnergy            
Business Combination [Line Items]            
Outstanding interest acquired, percentage   100.00%        
Cash   $ 271,087,000       271,100,000
Consideration transferred     $ 156,100,000      
Customers of business acquired | customer     85,000      
Business combination, acquisition cost         $ 5,300,000  
Goodwill   171,107,000        
Intangible asset, excluding goodwill     $ 0      
Business combination, goodwill, expected tax deductible, amount   $ 179,900,000        
Statutory tax rate     26.50%      
Pines Holdings, Inc.            
Business Combination [Line Items]            
Outstanding interest acquired, percentage 100.00%          
Cash $ 60,436,000   $ 60,400,000      
Customers of business acquired | customer     8,000      
Goodwill 15,092,000          
Intangible asset, excluding goodwill     $ 0      
Business combination, goodwill, expected tax deductible, amount $ 0          
Business combination, communities of business acquired     12      
Measurement period (in years) 1 year          
SiEnergy And Pines            
Business Combination [Line Items]            
Business combination, acquisition cost           5,300,000
Acquiree's revenue since acquisition date, actual     $ 31,700,000     22,700,000
Acquiree's earnings since acquisition date, actual     9,100,000     $ 5,500,000
Inline Utilities, LLC            
Business Combination [Line Items]            
Cash       $ 7,200,000    
Goodwill     1,000,000.0      
Business combination, goodwill, expected tax deductible, amount     4,300,000      
Other insignificant acquisitions            
Business Combination [Line Items]            
Cash     $ 1,600,000      
Number of businesses acquired | business     2      
v3.26.1
Business Combinations - Schedule of Recognized Identified Assets Acquired and Liabilities Assumed (Details) - USD ($)
$ in Thousands
 3 Months Ended
Jun. 02, 2025
Jan. 07, 2025
Mar. 31, 2026
Mar. 31, 2025
Dec. 31, 2025
Recognized amounts of identifiable assets acquired and liabilities assumed:          
Goodwill     $ 371,257 $ 354,534 $ 370,815
SiEnergy          
Fair value of consideration transferred:          
Cash   $ 271,087   $ 271,100  
Recognized amounts of identifiable assets acquired and liabilities assumed:          
Current assets   16,770      
Property, plant and equipment   262,697      
Non-current assets   3,872      
Current liabilities   (24,962)      
Non-current liabilities   (158,397)      
Total identifiable net assets   99,980      
Goodwill   $ 171,107      
Pines Holdings, Inc.          
Fair value of consideration transferred:          
Cash $ 60,436   $ 60,400    
Recognized amounts of identifiable assets acquired and liabilities assumed:          
Current assets 2,032        
Property, plant and equipment 43,497        
Non-current assets 1,382        
Current liabilities (1,462)        
Non-current liabilities (105)        
Total identifiable net assets 45,344        
Goodwill $ 15,092        
v3.26.1
Business Combinations - Unaudited Pro Forma Revenues And Earnings (Details) - SiEnergy And Pines - USD ($)
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Business Combination [Line Items]    
Operating revenues $ 490,403,000 $ 500,064,000
Net income $ 97,489,000 $ 91,671,000
v3.26.1
Derivative Instruments - Schedule of Notional Amounts of Outstanding Derivative Positions (Details) - NW Natural
therm in Thousands, $ in Thousands
Mar. 31, 2026
USD ($)
therm
Dec. 31, 2025
USD ($)
therm
Mar. 31, 2025
USD ($)
therm
Foreign Exchange      
Derivative [Line Items]      
Foreign exchange | $ $ 5,853 $ 8,596 $ 10,132
Financial | Natural Gas Therms      
Derivative [Line Items]      
Natural gas (in therms) 544,690 757,895 611,200
Physical | Natural Gas Therms      
Derivative [Line Items]      
Natural gas (in therms) 487,775 692,275 401,750
v3.26.1
Derivative Instruments - Narrative (Details) - USD ($)
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Dec. 31, 2025
Jan. 31, 2023
Derivative [Line Items]        
Derivative credit risk valuation adjustment, derivative liabilities $ 200,000      
Derivative, fair value, net (56,200,000) $ (29,100,000) $ (73,300,000)  
Long-term debt 2,433,100,000      
AOCI, cash flow hedge, cumulative gain (Loss), after tax 0 0    
Reclassification out of Accumulated Other Comprehensive Income        
Derivative [Line Items]        
Other comprehensive income (loss), cash flow hedge, gain (loss), reclassification, after tax   100,000    
Amounts reclassified to AOCL 0      
NWN Water Term Loan Due 2026        
Derivative [Line Items]        
Derivative, fixed interest rate       3.80%
Corporate Nonsegment | NWN Water Term Loan Due 2026 | NWN Water        
Derivative [Line Items]        
Long-term debt       $ 55,000,000.0
Collateral Posted with NW Natural Counterparties        
Derivative [Line Items]        
Additional collateral, aggregate fair value 0 0    
Financial        
Derivative [Line Items]        
Incremental cost or benefit to collect or refund to customers 0      
NW Natural        
Derivative [Line Items]        
Derivative, loss on derivative 41,500,000 46,200,000    
Derivative asset, fair value, amount not off set against collateral 2,600,000 2,600,000 2,800,000  
Derivative liability 58,800,000 31,700,000 76,100,000  
Long-term debt $ 1,535,100,000 $ 1,365,600,000 $ 1,534,900,000  
Gas Year 2024 - 2025 | NW Natural        
Derivative [Line Items]        
Target hedge achieved 79.00%      
Gas Year 2024 - 2025 | NW Natural | Oregon        
Derivative [Line Items]        
Target hedge achieved 84.00%      
Gas Year 2024 - 2025 | NW Natural | WASHINGTON        
Derivative [Line Items]        
Target hedge achieved 33.00%      
Gas Year 2024 - 2025 | NW Natural | Financial        
Derivative [Line Items]        
Target hedge achieved 64.00%      
Gas Year 2024 - 2025 | NW Natural | Financial | Oregon        
Derivative [Line Items]        
Target hedge achieved 69.00%      
Gas Year 2024 - 2025 | NW Natural | Financial | WASHINGTON        
Derivative [Line Items]        
Target hedge achieved 20.00%      
Gas Year 2024 - 2025 | NW Natural | Physical        
Derivative [Line Items]        
Target hedge achieved 15.00%      
Gas Year 2024 - 2025 | NW Natural | Physical | Oregon        
Derivative [Line Items]        
Target hedge achieved 15.00%      
Gas Year 2024 - 2025 | NW Natural | Physical | WASHINGTON        
Derivative [Line Items]        
Target hedge achieved 13.00%      
v3.26.1
Derivative Instruments - Schedule of Income Statement Presentation of Derivative Instruments (Details) - Northwest Holdings and Northwest Natural - USD ($)
$ in Thousands
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Natural gas commodity    
Derivative [Line Items]    
Total gain (loss) in pre-tax earnings $ 0 $ 0
Natural gas commodity | Amounts deferred to regulatory accounts on balance sheet    
Derivative [Line Items]    
Total gain (loss) in pre-tax earnings 15,029 (29,697)
Natural gas commodity | Benefit (expense) to cost of gas    
Derivative [Line Items]    
Total gain (loss) in pre-tax earnings (15,029) 29,697
Foreign Exchange    
Derivative [Line Items]    
Total gain (loss) in pre-tax earnings 0 0
Foreign Exchange | Amounts deferred to regulatory accounts on balance sheet    
Derivative [Line Items]    
Total gain (loss) in pre-tax earnings 114 24
Foreign Exchange | Benefit (expense) to cost of gas    
Derivative [Line Items]    
Total gain (loss) in pre-tax earnings $ (114) $ (24)
v3.26.1
Commitments and Contingencies - Narrative (Details)
$ in Thousands
 3 Months Ended 9 Months Ended 12 Months Ended
Mar. 31, 2026
USD ($)
facilty
Sep. 30, 2024
USD ($)
Dec. 31, 2025
Dec. 31, 2024
USD ($)
Dec. 31, 2026
USD ($)
Other Commitments [Line Items]          
Number of production facilities | facilty 2        
Increase (decrease) in RNG Facility prepaid operating assets   $ 26,000   $ 25,400  
Term (in years) 11 months   20 years    
Year one $ 31,400        
Year two 31,600        
Year three 30,800        
Year four 31,400        
Thereafter 599,300        
Unrecorded unconditional purchase obligation, including lease not yet commenced, to be paid, total amount 4,100        
Unrecorded unconditional purchase obligation, purchases $ 20,900        
Guarantor obligations, percent of contracted therms 75.00%        
Forecast          
Other Commitments [Line Items]          
Cap Amount         $ 21,113
Forecast | 2025 - 2042 Guarantee          
Other Commitments [Line Items]          
Cap Amount         $ 2,000
v3.26.1
Commitments and Contingencies - Other Commitments (Details)
$ in Thousands
Dec. 31, 2026
USD ($)
Forecast  
Other Commitments [Line Items]  
Cap Amount $ 21,113
v3.26.1
Environmental Matters - Narrative (Details)
$ in Millions
 1 Months Ended 3 Months Ended
Jan. 31, 2017
Mar. 31, 2026
USD ($)
complaint
party
property
mi
Oct. 14, 2024
Site Contingency [Line Items]      
Annual tariff rider collection   $ 5.0  
Annual insurance proceeds to apply against remediation costs   5.0  
Total annual remediation expense and interest   $ 10.0  
Enrolled customers during time period (in years)     6 years
Portland Harbor      
Site Contingency [Line Items]      
Number of miles | mi   10  
Number of potentially responsible parties (more than) | party   100  
EPA final feasibility study and proposed remediation plan, clean-up costs, portland harbor   $ 1,050.0  
Number of remediation projects | property   2  
Portland Harbor | Minimum      
Site Contingency [Line Items]      
Percentage of clean-up costs (30.00%)    
Portland Harbor | Maximum      
Site Contingency [Line Items]      
Percentage of clean-up costs 50.00%    
Gasco Sediments      
Site Contingency [Line Items]      
Site contingency, environmental remediation costs recognized   $ 54.0  
Gasco Sediments | Minimum      
Site Contingency [Line Items]      
Environmental exit costs, anticipated cost   54.0  
Gasco Sediments | Maximum      
Site Contingency [Line Items]      
Environmental exit costs, anticipated cost   $ 350.0  
Other Portland Harbor | Yakama Nation      
Site Contingency [Line Items]      
Trustee council members - number of claimants   1  
Site contingency, number of other third-party defendants   29  
NRD liability claim yakama nation   $ 0.3  
Number of amended complaints filed | complaint   2  
Gasco Uplands      
Site Contingency [Line Items]      
Site contingency number of management pieces   2  
Gasco Uplands | Minimum      
Site Contingency [Line Items]      
Environmental exit costs, anticipated cost   $ 288.0  
Gasco Uplands | Maximum      
Site Contingency [Line Items]      
Environmental exit costs, anticipated cost   $ 950.0  
Gasco Upland Site      
Site Contingency [Line Items]      
Undiscounted monitoring costs (in years)   30 years  
Gasco Upland Site | Minimum      
Site Contingency [Line Items]      
Environmental exit costs, anticipated cost   $ 230.0  
Gasco Upland Site | Maximum      
Site Contingency [Line Items]      
Environmental exit costs, anticipated cost   250.0  
Gasco Uplands IRAM | Minimum      
Site Contingency [Line Items]      
Environmental exit costs, anticipated cost   10.0  
Gasco Uplands IRAM | Maximum      
Site Contingency [Line Items]      
Environmental exit costs, anticipated cost   78.0  
Front Street site      
Site Contingency [Line Items]      
Additional studies and design costs   $ 0.7  
Oregon      
Site Contingency [Line Items]      
Remediation recovery percentage   96.70%  
WASHINGTON      
Site Contingency [Line Items]      
Remediation recovery percentage   3.30%  
v3.26.1
Environmental Matters - Environmental Loss Contingencies by Site (Details) - USD ($)
$ in Thousands
Mar. 31, 2026
Dec. 31, 2025
Mar. 31, 2025
Site Contingency [Line Items]      
Current Liabilities $ 37,243 $ 43,748 $ 35,452
Non-Current Liabilities 330,870 118,270 117,273
Gasco Sediments      
Site Contingency [Line Items]      
Current Liabilities 11,510 13,950 10,816
Non-Current Liabilities 42,755 43,247 41,565
Other Portland Harbor      
Site Contingency [Line Items]      
Current Liabilities 3,189 3,669 3,109
Non-Current Liabilities 12,132 12,770 11,657
Gasco Upland site      
Site Contingency [Line Items]      
Current Liabilities 22,089 25,643 20,767
Non-Current Liabilities 275,514 61,782 63,594
Front Street site      
Site Contingency [Line Items]      
Current Liabilities 455 486 760
Non-Current Liabilities 290 292 278
Oregon Steel Mills      
Site Contingency [Line Items]      
Current Liabilities 0 0 0
Non-Current Liabilities $ 179 $ 179 $ 179
v3.26.1
Environmental Matters - Regulatory Assets (Details) - USD ($)
$ in Thousands
 3 Months Ended
Mar. 31, 2026
Dec. 31, 2025
Mar. 31, 2025
Site Contingency [Line Items]      
Current regulatory assets $ 146,545 $ 143,745 $ 88,623
Long-term regulatory assets $ 637,563 $ 424,194 $ 371,258
Remediation non-recovery Percentage 3.30% 3.30% 3.30%
Annual tariff rider collection $ 5,000    
Oregon      
Site Contingency [Line Items]      
Remediation recovery percentage 96.70%    
NW Natural      
Site Contingency [Line Items]      
Current regulatory assets $ 145,946 $ 143,135 $ 88,598
Long-term regulatory assets 632,054 419,847 369,628
NW Natural | Environmental costs      
Site Contingency [Line Items]      
Deferred costs and interest 72,897 71,954 65,526
Accrued site liabilities 368,090 161,993 152,692
Insurance proceeds and interest (42,358) (41,736) (47,655)
Total regulatory asset deferral 398,629 192,211 170,563
Current regulatory assets 12,271 12,148 10,819
Long-term regulatory assets $ 386,358 $ 180,063 $ 159,744
v3.26.1
Subsequent Events (Details)
May 01, 2026
USD ($)
Subsequent Event | NW Natural | LC Reimbursement Agreement | Letter of Credit  
Subsequent Event [Line Items]  
Line of credit facility, maximum borrowing capacity $ 100,000,000