Northwest Natural Holding (NWN) 10-Q 3 Nov 23 2023 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2023	Oct. 26, 2023
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Transition Report	false
Document Period End Date	Sep. 30, 2023
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		36,778,271
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Central Index Key	0001733998
Northwest Natural Gas Company [Member]
Document Information [Line Items]
Document Type	10-Q
Document Period End Date	Sep. 30, 2023
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	2023
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Central Index Key	0000073020

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Operating revenues [Abstract]
Operating revenues	$ 141,479,000	$ 116,839,000	$ 841,761,000	$ 662,100,000
Operating expenses:
Cost of gas	49,180,000	36,105,000	357,362,000	261,413,000
Operations and maintenance	61,524,000	50,745,000	200,160,000	161,405,000
Environmental remediation	1,032,000	980,000	8,547,000	7,950,000
General taxes	10,577,000	9,572,000	35,685,000	30,665,000
Revenue taxes	5,523,000	4,437,000	33,750,000	26,037,000
Depreciation	30,061,000	29,026,000	92,819,000	85,565,000
Other operating expenses	1,159,000	901,000	3,664,000	2,815,000
Total operating expenses	159,056,000	131,766,000	731,987,000	575,850,000
Income from operations	(17,577,000)	(14,927,000)	109,774,000	86,250,000
Other income (expense), net	5,004,000	1,636,000	13,228,000	908,000
Interest expense, net	19,406,000	13,054,000	56,676,000	36,156,000
Income (loss) before income taxes	(31,979,000)	(26,345,000)	66,326,000	51,002,000
Income tax expense (benefit)	(8,292,000)	(6,758,000)	17,098,000	12,635,000
Net income (loss)	(23,687,000)	(19,587,000)	49,228,000	38,367,000
Other comprehensive income (loss):
Amortization of non-qualified employee benefit plan liability, net of taxes	102,000	202,000	307,000	596,000
Derivative, Gain (Loss) on Derivative, Net	174,000	0	999,000	0
Comprehensive income (loss)	(23,411,000)	(19,385,000)	50,534,000	38,963,000
Supplemental Income Statement Elements [Abstract]
Amortization of non-qualified employee benefit plan liability, tax	37,000	$ 73,000	111,000	$ 215,000
Unrealized Loss on Derivative, tax	$ (62)		$ (359)
Average common shares outstanding:
Basic (in shares)	36,214	34,939	35,950	33,491
Diluted (in shares)	36,214	34,939	35,980	33,539
Earnings per share of common stock:
Basic (in dollars per share)	$ (0.65)	$ (0.56)	$ 1.37	$ 1.15
Diluted (in dollars per share)	$ (0.65)	$ (0.56)	$ 1.37	$ 1.14
Northwest Natural Gas Company [Member]
Operating revenues [Abstract]
Operating revenues	$ 129,942,000	$ 110,426,000	$ 812,803,000	$ 647,301,000
Operating expenses:
Cost of gas	49,235,000	36,164,000	357,530,000	261,584,000
Operations and maintenance	53,494,000	45,858,000	179,121,000	148,614,000
Environmental remediation	1,032,000	980,000	8,547,000	7,950,000
General taxes	10,328,000	9,467,000	34,925,000	30,328,000
Revenue taxes	5,425,000	4,375,000	33,559,000	25,907,000
Depreciation	28,446,000	28,201,000	88,470,000	83,166,000
Other operating expenses	397,000	675,000	1,636,000	2,370,000
Total operating expenses	148,357,000	125,720,000	703,788,000	559,919,000
Income from operations	(18,415,000)	(15,294,000)	109,015,000	87,382,000
Other income (expense), net	4,818,000	1,161,000	11,095,000	197,000
Interest expense, net	15,597,000	11,128,000	45,236,000	32,558,000
Income (loss) before income taxes	(29,194,000)	(25,261,000)	74,874,000	55,021,000
Income tax expense (benefit)	(7,707,000)	(6,455,000)	19,037,000	13,678,000
Net income (loss)	(21,487,000)	(18,806,000)	55,837,000	41,343,000
Other comprehensive income (loss):
Amortization of non-qualified employee benefit plan liability, net of taxes	102,000	202,000	307,000	596,000
Comprehensive income (loss)	(21,385,000)	(18,604,000)	56,144,000	41,939,000
Supplemental Income Statement Elements [Abstract]
Amortization of non-qualified employee benefit plan liability, tax	$ 37,000	$ 73,000	$ 111,000	$ 215,000

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022	Sep. 30, 2022
Current assets:
Cash and cash equivalents	$ 156,616	$ 29,270	$ 108,556
Accounts receivable	51,999	168,906	50,850
Accrued unbilled revenue	24,626	89,048	16,857
Allowance for uncollectible accounts	(2,312)	(3,296)	(2,171)
Regulatory assets	108,525	117,491	104,830
Derivative instruments	23,454	194,412	62,710
Inventories	94,585	87,096	98,725
Other current assets	49,947	61,286	41,414
Total current assets	507,440	744,213	481,771
Non-current assets:
Property, plant, and equipment	4,468,602	4,261,566	4,207,328
Less: Accumulated depreciation	1,189,968	1,147,166	1,166,150
Total property, plant, and equipment, net	3,278,634	3,114,400	3,041,178
Regulatory assets	312,665	340,432	301,660
Derivative instruments	6,188	5,045	8,008
Other investments	104,562	95,704	96,569
Operating lease right of use asset, net	71,477	73,429	73,145
Assets under sales-type leases	130,952	134,302	135,480
Goodwill	152,399	149,283	74,732
Other non-current assets	100,801	91,518	88,169
Total non-current assets	4,157,678	4,004,113	3,818,941
Total assets	4,665,118	4,748,326	4,300,712
Current liabilities:
Short-term debt	71,000	258,200	141,000
Current maturities of long-term debt	190,728	90,697	50,614
Accounts payable	99,326	180,667	118,274
Taxes accrued	17,120	15,625	18,080
Interest accrued	13,940	10,169	11,086
Regulatory liabilities	88,376	248,582	111,551
Derivative instruments	46,603	28,728	19,594
Operating lease liabilities	1,815	1,514	1,361
Other current liabilities	61,149	64,552	39,796
Total current liabilities	590,057	898,734	511,356
Long-term debt	1,424,572	1,246,167	1,287,006
Deferred credits and other non-current liabilities:
Deferred tax liabilities	375,917	366,022	349,633
Regulatory liabilities	683,262	689,578	663,547
Pension and other postretirement benefit liabilities	145,991	149,143	160,196
Derivative instruments	21,085	20,838	18,824
Operating lease liabilities	77,475	78,965	78,469
Other non-current liabilities	127,219	123,438	110,825
Total deferred credits and other non-current liabilities	1,430,949	1,427,984	1,381,494
Commitments and contingencies (Note 16)
Equity:
Common stock	$ 851,288	$ 805,253	$ 786,094
Shares Authorized (in shares)	100,000,000	100,000,000	100,000,000
Shares outstanding (in shares)	36,575,797	35,524,590	35,098,437
Shares issued (in shares)	36,575,797	35,524,590	35,098,437
Par Value (in dollars per share)	$ 0	$ 0	$ 0
Retained earnings	$ 373,231	$ 376,473	$ 345,570
Accumulated other comprehensive loss	(4,979)	(6,285)	(10,808)
Total equity	1,219,540	1,175,441	1,120,856
Total liabilities and equity	$ 4,665,118	4,748,326	4,300,712
Accounts Payable, Related Party, Type [Extensible Enumeration]	Affiliated Entity [Member]
Other Receivable, after Allowance for Credit Loss, Related Party, Type [Extensible Enumeration]	Affiliated Entity [Member]
Northwest Natural Gas Company [Member]
Current assets:
Cash and cash equivalents	$ 145,073	12,977	11,386
Accounts receivable	48,322	165,607	48,082
Accrued unbilled revenue	22,608	87,482	16,649
Other Receivables, Net, Current	2,195	634	221
Allowance for uncollectible accounts	(2,085)	(3,079)	(2,114)
Regulatory assets	108,525	117,491	104,830
Derivative instruments	22,679	194,236	62,710
Inventories	92,803	86,207	97,633
Other current assets	38,131	57,269	32,605
Total current assets	478,251	718,824	372,002
Non-current assets:
Property, plant, and equipment	4,328,477	4,148,547	4,124,488
Less: Accumulated depreciation	1,175,283	1,137,231	1,157,400
Total property, plant, and equipment, net	3,153,194	3,011,316	2,967,088
Regulatory assets	312,640	340,407	301,596
Derivative instruments	5,430	5,045	8,008
Other investments	87,753	80,110	80,871
Operating lease right of use asset, net	70,852	72,720	73,046
Assets under sales-type leases	130,952	134,302	135,480
Other non-current assets	99,131	89,994	86,661
Total non-current assets	3,859,952	3,733,894	3,652,750
Total assets	4,338,203	4,452,718	4,024,752
Current liabilities:
Short-term debt	0	170,200	53,000
Current maturities of long-term debt	39,997	89,942	49,938
Accounts payable	94,922	177,590	115,066
Accounts Payable, Other, Current	562	9,175	1,789
Taxes accrued	16,915	15,426	17,914
Interest accrued	13,368	8,900	10,533
Regulatory liabilities	88,326	248,553	111,526
Derivative instruments	46,603	28,728	19,594
Operating lease liabilities	1,658	1,363	1,298
Other current liabilities	59,101	62,019	38,998
Total current liabilities	361,452	811,896	419,656
Long-term debt	1,364,556	1,035,935	1,076,533
Deferred credits and other non-current liabilities:
Deferred tax liabilities	366,730	362,353	346,423
Regulatory liabilities	682,315	688,599	662,565
Pension and other postretirement benefit liabilities	145,991	149,143	160,196
Derivative instruments	21,085	20,838	18,824
Operating lease liabilities	77,041	78,345	78,436
Other non-current liabilities	116,930	114,527	109,304
Total deferred credits and other non-current liabilities	1,410,092	1,413,805	1,375,748
Commitments and contingencies (Note 16)
Equity:
Common stock	644,903	614,903	614,903
Retained earnings	563,307	582,593	548,720
Accumulated other comprehensive loss	(6,107)	(6,414)	(10,808)
Total equity	1,202,103	1,191,082	1,152,815
Total liabilities and equity	$ 4,338,203	$ 4,452,718	$ 4,024,752

Consolidated Statement of Share

Consolidated Statement of Shareholders' Equity - USD ($) $ in Thousands	Total	Northwest Natural Gas Company [Member]	Common Stock Including APIC [Member]	Common Stock Including APIC [Member] Northwest Natural Gas Company [Member]	Retained Earnings [Member]	Retained Earnings [Member] Northwest Natural Gas Company [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Accumulated Other Comprehensive Income (Loss) [Member] Northwest Natural Gas Company [Member]
Beginning Balance at Dec. 31, 2021	$ 935,146	$ 977,807	$ 590,771	$ 435,515	$ 355,779	$ 553,696	$ (11,404)	$ (11,404)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Capital contributions from parent		179,388		179,388
Net income	38,367	41,343			38,367	41,343
Dividends on common stock					(48,576)	(46,319)
Other comprehensive income	38,963	41,939					596	596
Stock-based compensation			2,695
Shares issued pursuant to equity based plans, net of shares withheld for taxes			1,958
Issuances of common stock, net of issuance costs			190,670
Ending Balance at Sep. 30, 2022	$ 1,120,856	1,152,815	786,094	614,903	345,570	548,720	(10,808)	(10,808)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends per share of common stock	$ 1.4475
Beginning Balance at Jun. 30, 2022	$ 1,138,779	1,173,676	767,826	601,032	381,963	583,654	(11,010)	(11,010)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Capital contributions from parent				13,871
Net income	(19,587)	(18,806)			(19,587)	(18,806)
Dividends on common stock					(16,806)	(16,128)
Other comprehensive income	(19,385)	(18,604)					202	202
Stock-based compensation			463
Shares issued pursuant to equity based plans, net of shares withheld for taxes			954
Issuances of common stock, net of issuance costs			16,851
Ending Balance at Sep. 30, 2022	$ 1,120,856	1,152,815	786,094	614,903	345,570	548,720	(10,808)	(10,808)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends per share of common stock	$ 0.4825
Beginning Balance at Dec. 31, 2022	$ 1,175,441	1,191,082	805,253	614,903	376,473	582,593	(6,285)	(6,414)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Capital contributions from parent		30,000		30,000
Net income	49,228	55,837			49,228	55,837
Dividends on common stock					(52,470)	(75,123)
Other comprehensive income	50,534	56,144					1,306	307
Stock-based compensation			3,257
Shares issued pursuant to equity based plans, net of shares withheld for taxes			1,883
Issuances of common stock, net of issuance costs			40,895
Ending Balance at Sep. 30, 2023	$ 1,219,540	1,202,103	851,288	644,903	373,231	563,307	(4,979)	(6,107)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends per share of common stock	$ 1.4550
Beginning Balance at Jun. 30, 2023	$ 1,240,278	1,210,296	831,135	614,903	414,398	601,602	(5,255)	(6,209)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Capital contributions from parent				30,000
Net income	(23,687)	(21,487)			(23,687)	(21,487)
Dividends on common stock					(17,480)	(16,808)
Other comprehensive income	(23,411)	(21,385)					276	102
Stock-based compensation			251
Shares issued pursuant to equity based plans, net of shares withheld for taxes			1,046
Issuances of common stock, net of issuance costs			18,856
Ending Balance at Sep. 30, 2023	$ 1,219,540	$ 1,202,103	$ 851,288	$ 644,903	$ 373,231	$ 563,307	$ (4,979)	$ (6,107)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends per share of common stock	$ 0.4850

Consolidated Statement of Cash

Consolidated Statement of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Operating activities:
Net income	$ 49,228	$ 38,367
Adjustments to reconcile net income to cash provided by operations:
Depreciation	92,819	85,565
Regulatory amortization of gas reserves	2,532	4,527
Deferred income taxes	6,678	7,759
Qualified defined benefit pension plan (benefit) expense	(1,823)	4,013
Deferred environmental expenditures, net	(14,887)	(14,437)
Environmental remediation expense	8,547	7,950
Asset optimization revenue sharing bill credits	(10,471)	(41,102)
Other	18,079	16,640
Changes in assets and liabilities:
Receivables, net	182,297	114,755
Inventories	(6,484)	(41,463)
Income and other taxes	8,770	19,447
Accounts payable	(39,695)	(30,010)
Deferred gas costs	(8,678)	(1,785)
Asset optimization revenue sharing	18,667	17,629
Decoupling mechanism	(12,328)	7,124
Change in Cloud-based software Assets	(12,316)	(17,332)
Other, net	20,568	(11,686)
Cash provided by operating activities	301,503	165,961
Investing activities:
Capital expenditures	(242,747)	(251,842)
Acquisitions, net of cash acquired	(3,248)	(2,352)
Other	(4,525)	(2,810)
Cash used in investing activities	(250,520)	(257,004)
Financing activities:
Proceeds from common stock issued, net	40,955	190,929
Long-term debt issued	330,000	290,000
Long-term debt retired	(50,000)	0
Changes in other short-term debt, net	(187,200)	(248,500)
Cash dividend payments on common stock	(50,114)	(46,434)
Other	(4,108)	(1,802)
Cash used in financing activities	79,533	184,193
Cash, cash equivalents and restricted cash	171,480	120,270
Increase (decrease) in cash, cash equivalents and restricted cash	130,516	93,150
Supplemental disclosure of cash flow information:
Interest paid, net of capitalization	51,970	31,774
Income taxes paid, net of refunds	18,963	2,106
Northwest Natural Gas Company [Member]
Operating activities:
Net income	55,837	41,343
Adjustments to reconcile net income to cash provided by operations:
Depreciation	88,470	83,166
Regulatory amortization of gas reserves	2,532	4,527
Deferred income taxes	1,411	7,013
Qualified defined benefit pension plan (benefit) expense	(1,823)	4,013
Deferred environmental expenditures, net	(14,887)	(14,437)
Environmental remediation expense	8,547	7,950
Asset optimization revenue sharing bill credits	(10,471)	(41,102)
Other	17,331	16,665
Changes in assets and liabilities:
Receivables, net	183,116	115,915
Inventories	(6,173)	(40,881)
Income and other taxes	6,942	17,412
Accounts payable	(43,315)	(32,023)
Deferred gas costs	(8,678)	(1,785)
Asset optimization revenue sharing	18,667	17,629
Decoupling mechanism	(12,328)	7,124
Change in Cloud-based software Assets	(12,316)	(17,332)
Other, net	21,306	(12,604)
Cash provided by operating activities	294,168	162,593
Investing activities:
Capital expenditures	(216,368)	(236,467)
Other	(3,524)	(2,810)
Cash used in investing activities	(219,892)	(239,277)
Financing activities:
Capital contributions from parent	30,000	179,388
Long-term debt issued	330,000	140,000
Long-term debt retired	(50,000)	0
Changes in other short-term debt, net	(170,200)	(192,500)
Cash dividend payments on common stock	(75,123)	(46,319)
Other	(3,713)	(1,617)
Cash used in financing activities	60,964	78,952
Cash, cash equivalents and restricted cash	159,911	23,100
Increase (decrease) in cash, cash equivalents and restricted cash	135,240	2,268
Supplemental disclosure of cash flow information:
Interest paid, net of capitalization	39,911	28,326
Income taxes paid, net of refunds	$ 27,745	$ 5,990

Organization and Principles of

Organization and Principles of Consolidation	9 Months Ended
	Sep. 30, 2023
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's regulated natural gas distribution activities are reported in the natural gas distribution (NGD) segment. The NGD segment is NW Natural's core operating business and serves residential, commercial, and industrial customers in Oregon and southwest Washington. The NGD segment is the only reportable segment for NW Holdings and NW Natural. All other activities, water and wastewater businesses, and other investments are aggregated and reported as other at their respective registrant. 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. NW Natural RNG Holding Company, LLC holds investments in Lexington Renewable Energy, LLC and Dakota City Renewable Energy LLC, which are also 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 2022 Annual Report on Form 10-K (2022 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. Certain reclassifications have been made to conform prior period information to the current presentation. The reclassifications did not have a material effect on our consolidated financial statements.

Significant Accounting Policies

Significant Accounting Policies	9 Months Ended
	Sep. 30, 2023
Accounting Policies [Abstract]
Significant Accounting Policies	SIGNIFICANT ACCOUNTING POLICIES Significant accounting policies are described in Note 2 of the 2022 Form 10-K. There were no material changes to those accounting policies during the nine months ended September 30, 2023 other than those set forth in this Note 2. The following are current 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 and its other subsidiaries. NW Natural's principal business is the distribution of natural gas, which is regulated by the OPUC and WUTC. NW Natural also has natural gas storage services, which are regulated by the FERC, and to a certain extent by the OPUC and WUTC. Additionally, certain of NW Holdings' subsidiaries own water businesses, which are regulated by the public utility commission in the state in which the water utility is located, which is currently Oregon, Washington, Idaho, Texas and Arizona. Wastewater businesses, to the extent they are regulated, are generally regulated by the public utility commissions in the state in which the wastewater utility is located, which is currently Texas and Arizona. In applying regulatory accounting principles, NW Holdings and NW Natural capitalize or defer certain costs and revenues as regulatory assets and liabilities pursuant to orders of the applicable state public utility commission, which provide for the recovery of revenues or expenses from, or refunds to, utility customers in future periods, including a return or a carrying charge in certain cases. Amounts deferred as regulatory assets and liabilities for NW Holdings and NW Natural were as follows: Regulatory Assets September 30, December 31, In thousands 2023 2022 2022 NW Natural: Current: Unrealized loss on derivatives (1) $ 46,603 $ 19,594 $ 28,728 Gas costs 11,361 52,115 61,223 Environmental costs (2) 7,047 9,461 7,392 Decoupling (3) 3,480 114 — Pension balancing (4) 7,131 7,131 7,131 Income taxes 2,208 2,399 2,208 COVID-19 deferrals and expenses, net 11,127 — 789 Other (5) 19,568 14,016 10,020 Total current - NW Natural $ 108,525 $ 104,830 $ 117,491 Non-current: Unrealized loss on derivatives (1) $ 21,085 $ 18,824 $ 20,838 Pension balancing (4) 29,450 34,928 32,997 Income taxes 10,540 11,168 10,943 Pension and other postretirement benefit liabilities 101,413 107,722 101,413 Environmental costs (2) 108,941 82,667 104,253 Gas costs 718 3,369 22,355 Decoupling (3) 212 — — Washington Climate Commitment Act compliance 12,513 — — COVID-19 deferrals and expenses, net 1,811 15,147 14,555 Other (5) 25,957 27,771 33,053 Total non-current - NW Natural $ 312,640 $ 301,596 $ 340,407 Other (NW Holdings) 25 64 25 Total non-current - NW Holdings $ 312,665 $ 301,660 $ 340,432 Regulatory Liabilities September 30, December 31, In thousands 2023 2022 2022 NW Natural: Current: Gas costs $ 5,030 $ 944 $ 4,121 Unrealized gain on derivatives (1) 22,679 62,882 194,236 Decoupling (3) 8,616 13,272 14,026 Income taxes 5,946 7,318 7,166 Asset optimization revenue sharing 29,938 23,461 26,368 Washington Climate Commitment Act proceeds 9,365 — — Other (5) 6,752 3,649 2,636 Total current - NW Natural $ 88,326 $ 111,526 $ 248,553 Other (NW Holdings) 50 25 29 Total current - NW Holdings $ 88,376 $ 111,551 $ 248,582 Non-current: Gas costs $ 252 $ 50 $ 12,644 Unrealized gain on derivatives (1) 5,430 8,008 5,045 Decoupling (3) 588 884 3,814 Income taxes (6) 171,843 179,319 174,212 Accrued asset removal costs (7) 489,006 460,666 467,742 Asset optimization revenue sharing — — 8,401 Washington Climate Commitment Act proceeds 654 — — Other (5) 14,542 13,638 16,741 Total non-current - NW Natural $ 682,315 $ 662,565 $ 688,599 Other (NW Holdings) 947 982 979 Total non-current - NW Holdings $ 683,262 $ 663,547 $ 689,578 (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 NGD 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 16 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) Balances consist of deferrals and amortizations under approved regulatory mechanisms and typically earn a rate of return or carrying charge. (6) Balance represents excess deferred income tax benefits subject to regulatory flow-through. (7) Estimated costs of removal on certain regulated properties are collected through rates. We believe all costs incurred and deferred at September 30, 2023 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 September 30, 2023, the amount invested in money market funds was $132.6 million at NW Natural and NW Holdings. 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. The following table provides a reconciliation of the cash, cash equivalents and restricted cash balances at NW Holdings as of September 30, 2023 and 2022 and December 31, 2022: September 30, December 31, In thousands 2023 2022 2022 Cash and cash equivalents $ 156,616 $ 108,556 $ 29,270 Restricted cash included in other current and non-current assets 14,864 11,714 11,694 Cash, cash equivalents and restricted cash $ 171,480 $ 120,270 $ 40,964 The following table provides a reconciliation of the cash, cash equivalents and restricted cash balances at NW Natural as of September 30, 2023 and 2022 and December 31, 2022: September 30, December 31, In thousands 2023 2022 2022 Cash and cash equivalents $ 145,073 $ 11,386 $ 12,977 Restricted cash included in other current assets 14,838 11,714 11,694 Cash, cash equivalents and restricted cash $ 159,911 $ 23,100 $ 24,671 Intercompany Dividend In April 2023, NW Natural made a dividend to NW Holdings for $25.0 million, returning additional equity contributed from NW Holdings to NW Natural in 2022. Accounts Receivable and Allowance for Uncollectible Accounts Accounts receivable consist primarily of amounts due for natural gas sales and transportation services to NGD customers, plus amounts due for gas storage services. NW Holdings and NW Natural establish allowances for uncollectible accounts (allowance) for trade receivables, including accrued unbilled revenue, based on the aging of receivables, collection experience of past due account balances including payment plans, and historical trends of write-offs as a percent of revenues. A specific allowance is established and recorded for large individual customer receivables when amounts are identified as unlikely to be partially or fully recovered. Inactive accounts are written-off against the allowance after they are 120 days past due or when deemed uncollectible. 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 prices. The allowance for uncollectible accounts is adjusted quarterly, as necessary, based on information currently available. Allowance for Trade Receivables The payment term of our NGD receivables is generally 15 days. For these short-term receivables, it is not expected that forecasted economic conditions would significantly affect the loss estimates under stable economic conditions. For extreme situations like a financial crisis, natural disaster, and the economic slowdown caused by the COVID-19 pandemic, we enhanced our review and analysis. For the residential and commercial uncollectible provision, we primarily followed our standard methodology, which includes assessing historical write-off trends and current information on delinquent accounts. Beginning October 1, 2022, new collection rules from the OPUC applied to residential and commercial customers. This included enhanced protections for low-income customers, a return to pre-pandemic time payment arrangements terms, revised disconnection rules during the heating season, and other items. As a result of these Oregon rule changes and our recent collection process experience, we augmented our provision review for accounts in the following categories: closed or inactive accounts aged less than 120 days, accounts on payment plans, and all other open accounts not on payment plans. For industrial accounts, we continue to assess the provision on an account-by-account basis with specific reserves taken as necessary. NW Natural will continue to closely monitor and evaluate our accounts receivable and the provision for uncollectible accounts. The following table presents the activity related to the NW Holdings provision for uncollectible accounts by pool: As of As of December 31, 2022 Nine Months Ended September 30, 2023 September 30, 2023 In thousands Beginning Balance Provision recorded, net of adjustments Write-offs recognized, net of recoveries Ending Balance Allowance for uncollectible accounts: Residential $ 2,155 $ 1,802 $ (2,468) $ 1,489 Commercial 400 264 (372) 292 Industrial 188 (105) (1) 82 Accrued unbilled and other 336 2 (116) 222 Total NW Natural 3,079 1,963 (2,957) 2,085 Other - NW Holdings 217 10 — 227 Total NW Holdings $ 3,296 $ 1,973 $ (2,957) $ 2,312 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. Due to the nature of this service, PGE may recover the costs of the lease through general rate cases. Therefore, we expect the risk of loss due to the credit of this lessee to be remote. As such, no allowance for uncollectibility was recorded for our 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 NW Natural is subject to greenhouse gas (GHG) emission reduction requirements under the Oregon Climate Protection Program (CPP) regulations and the Washington Climate Commitment Act (CCA) regulations. Under Oregon's CPP, emission reduction compliance mechanisms include: 1) compliance instruments distributed by the state, 2) Community Climate Investment (CCI) Credits, which act similar to carbon offsets, and 3) supplying alternative gaseous fuels, such as renewable natural gas and hydrogen. 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 will account for all purchased Oregon CCI Credits and Washington allowances as inventory at the lower of cost or market. 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 September 30, 2023, NW Natural had $18.3 million of emissions allowances for compliance in Washington recorded as inventory and no CCI Credits in Oregon. The compliance programs allow for the sale of the 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. In September 2023, NW Natural consigned no-cost allowances to a Washington auction and received $10.0 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 CCI Credits or emission allowances NW Natural would need to purchase to satisfy the obligations. As of September 30, 2023, NW Natural has not recognized a liability under the Oregon program for the purchase of CCI Credits. Under the Washington program, NW Natural has recognized a $12.1 million liability as of September 30, 2023. We expect that the costs to comply with the Oregon and Washington programs will be recovered from utility customers through rates. As a result, NW Natural recognized $12.5 million of deferred costs as of September 30, 2023. New Accounting Standards NW Natural and NW Holdings consider the applicability and impact of all accounting standards updates (ASUs) issued by the Financial Accounting Standards Board (FASB). ASUs not listed below were assessed and determined to be either not applicable or are expected to have minimal impact on consolidated financial position or results of operations. Recently Issued Accounting Pronouncements JOINT VENTURE FORMATIONS. In August 2023, the FASB issued ASU 2023-05, which requires a joint venture to initially measure all contributions received upon its formation at fair value. The standard is effective for all joint venture entities with a formation date on or after January 1, 2025, with early adoption permitted. The adoption of this standard is not anticipated to have a material impact on our results of operations, liquidity or capital resources. Recent Securities and Exchange Commission (SEC) Final Rules INSIDER TRADING ARRANGEMENTS. In December 2022, the SEC adopted the final rule under SEC Release No. 33-11138, Insider Trading Arrangements and Related Disclosures, which requires new disclosures regarding insider trading policies and procedures, the use of certain insider trading plans and director and executive compensation regarding equity compensation awards made close in time to disclosure of material nonpublic information. The adoption of this final rule is not anticipated to have a material impact on our results of operations, liquidity or capital resources. SHARE REPURCHASES. In May 2023, the SEC adopted the final rule under SEC Release No. 34-97424, Share Repurchase Disclosure Modernization, requiring disclosures related to issuers’ share repurchases that will provide investors with enhanced information to assess the purposes and effects of the repurchases. The adoption of this final rule is not anticipated to have a material impact on our results of operations, liquidity or capital resources. CYBERSECURITY DISCLOSURES. In July 2023, the SEC issued a final rule that requires new disclosures regarding cybersecurity risk management, strategy, governance, and incidents. The disclosures are required beginning with our annual report for the year ending December 31, 2023. The adoption of this final rule is not anticipated to have a material impact on our results of operations, liquidity or capital resources.

Earnings Per Share

Earnings Per Share	9 Months Ended
	Sep. 30, 2023
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 September 30, Nine Months Ended September 30, In thousands, except per share data 2023 2022 2023 2022 Net income (loss) $ (23,687) $ (19,587) $ 49,228 $ 38,367 Average common shares outstanding - basic 36,214 34,939 35,950 33,491 Additional shares for stock-based compensation plans (See Note 8) — — 30 48 Average common shares outstanding - diluted 36,214 34,939 35,980 33,539 Earnings (loss) per share of common stock: Basic $ (0.65) $ (0.56) $ 1.37 $ 1.15 Diluted $ (0.65) $ (0.56) $ 1.37 $ 1.14 Additional information: Anti-dilutive shares 45 85 1 —

Segment Information

Segment Information	9 Months Ended
	Sep. 30, 2023
Segment Reporting [Abstract]
Segment Information	SEGMENT INFORMATION We primarily operate in one reportable business segment, which is NW Natural's local gas distribution business and is referred to as the NGD segment. NW Natural and NW Holdings also have investments and business activities not specifically related to the NGD segment, which are aggregated and reported as other and described below for each entity. Natural Gas Distribution NW Natural's local gas distribution segment is a regulated utility principally engaged in the purchase, sale, and delivery of natural gas and related services to customers in Oregon and southwest Washington. In addition to NW Natural's local gas distribution business, the NGD segment also includes the portion of the Mist underground storage facility used to serve NGD customers, the North Mist gas storage expansion in Oregon, NWN Gas Reserves, which is a wholly-owned subsidiary of Energy Corp, and NW Natural RNG Holding Company, LLC, a holding company established to invest in the development and procurement of regulated renewable natural gas for NW Natural. NW Natural NW Natural's activities in Other include Interstate Storage Services and third-party asset management services, appliance retail center operations, and corporate operating and non-operating revenues and expenses that cannot be allocated to NGD operations. Earnings from Interstate Storage Services assets are primarily related to firm storage capacity revenues. Earnings from third-party asset management services also include revenue, net of amounts shared with NGD customers, from management of NGD assets at Mist and upstream pipeline capacity when not needed to serve NGD customers. Under the Oregon sharing mechanism, NW Natural retains 80% of the pre-tax income from these services when the costs of the capacity were not included in NGD rates, or 10% of the pre-tax income when the costs have been included in these rates. The remaining 20% and 90%, respectively, are recorded to a deferred regulatory account for crediting back to NGD customers. NW Holdings NW Holdings' activities in Other include all remaining activities not associated with NW Natural, specifically: NW Natural Water Company, LLC (NW Natural Water or NWN Water), which consolidates the water and wastewater utility operations and is pursuing other investments in the water and wastewater sector through itself and wholly-owned subsidiaries; NW Natural Water's equity investment in Avion Water Company, Inc. ; NWN Gas Storage, a wholly-owned subsidiary of NWN Energ y; other pipeline assets in NNG Financial; and NW Natural Renewables Holdings, LLC (NW Natural Renewables) and its non-regulated renewable natural gas activities . Other a lso 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. The following table presents summary financial information concerning the reportable segment and other. Three Months Ended September 30, In thousands NGD Other NW Natural Other NW Holdings 2023 Operating revenues $ 124,624 $ 5,318 $ 129,942 $ 11,537 $ 141,479 Depreciation 28,169 277 28,446 1,615 30,061 Income (loss) from operations (22,192) 3,777 (18,415) 838 (17,577) Net income (loss) (24,160) 2,673 (21,487) (2,200) (23,687) Capital expenditures 86,017 1,053 87,070 10,814 97,884 2022 Operating revenues $ 103,295 $ 7,131 $ 110,426 $ 6,413 $ 116,839 Depreciation 27,937 264 28,201 825 29,026 Income (loss) from operations (20,910) 5,616 (15,294) 367 (14,927) Net income (loss) (23,016) 4,210 (18,806) (781) (19,587) Capital expenditures 79,847 431 80,278 3,868 84,146 Nine Months Ended September 30, In thousands NGD Other NW Natural Other NW Holdings 2023 Operating revenues $ 796,108 $ 16,695 $ 812,803 $ 28,958 $ 841,761 Depreciation 87,650 820 88,470 4,349 92,819 Income (loss) from operations 97,357 11,658 109,015 759 109,774 Net income (loss) 47,520 8,317 55,837 (6,609) 49,228 Capital expenditures 214,874 1,494 216,368 26,379 242,747 Total assets at September 30, 2023 4,285,309 52,894 4,338,203 326,915 4,665,118 2022 Operating revenues $ 629,327 $ 17,974 $ 647,301 $ 14,799 $ 662,100 Depreciation 82,372 794 83,166 2,399 85,565 Income (loss) from operations 75,328 12,054 87,382 (1,132) 86,250 Net income (loss) 32,531 8,812 41,343 (2,976) 38,367 Capital expenditures 235,249 1,218 236,467 15,375 251,842 Total assets at September 30, 2022 3,968,040 56,712 4,024,752 275,960 4,300,712 Total assets at December 31, 2022 4,392,699 60,019 4,452,718 295,608 4,748,326 Natural Gas Distribution Margin NGD margin is the primary financial measure used by the Chief Operating Decision Maker (CODM) , consisting of NGD operating revenues, reduced by the associated cost of gas, environmental remediation expense, and revenue taxes. The cost of gas purchased for NGD customers is generally a pass-through cost in the amount of revenues billed to regulated NGD customers. 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 NGD 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, environmental remediation expense, and revenue taxes from NGD operating revenues, NGD margin provides a key metric used by the CODM in assessing the performance of the NGD segment. The following table presents additional segment information concerning NGD margin: Three Months Ended September 30, Nine Months Ended September 30, In thousands 2023 2022 2023 2022 NGD margin calculation: NGD distribution revenues $ 119,892 $ 98,391 $ 781,941 $ 614,605 Other regulated services 4,732 4,904 14,167 14,722 Total NGD operating revenues 124,624 103,295 796,108 629,327 Less: NGD cost of gas 49,235 36,258 357,530 261,678 Environmental remediation 1,032 975 8,547 7,945 Revenue taxes 5,425 4,375 33,559 25,907 NGD margin $ 68,932 $ 61,687 $ 396,472 $ 333,797

Equity

Equity	9 Months Ended
	Sep. 30, 2023
Equity [Abstract]
Stockholders' Equity Note Disclosure	COMMON STOCK In August 2021, NW Holdings initiated an at-the-market (ATM) equity program by entering into an equity distribution agreement under which NW Holdings may issue and sell from time to time shares of common stock, no par value, having an aggregate gross sales price of up to $200 million. NW Holdings is under no obligation to offer and sell common stock under the ATM equity program, which expires in August 2024. Any shares of common stock offered under the ATM equity program are registered on NW Holdings’ universal shelf registration statement filed with the SEC. During the three months ended September 30, 2023, NW Holdings issued and sold 475,732 shares of common stock pursuant to the ATM equity program resulting in cash proceeds of $18.8 million, net of fees and commissions paid to agents of $0.3 million. During the nine months ended September 30, 2023, NW Holdings issued and sold 955,325 shares of common stock pursuant to the ATM equity program resulting in cash proceeds of $40.9 million, net of fees and commissions paid to agents of $0.7 million. As of September 30, 2023, NW Holdings had $69.5 million of equity available for issuance under the program. The ATM equity program was initiated to raise funds for general corporate purposes, including equity contributions to NW Holdings’ subsidiaries, NW Natural and NW Natural Water. We intend that contributions to NW Natural and NW Natural Water will be used for general corporate purposes. In October 2023, NW Holdings issued 184,832 shares of common stock in connection with business combinations.

Revenue

Revenue	9 Months Ended
	Sep. 30, 2023
Revenue from Contract with Customer [Abstract]
Revenue from Contract with Customer	REVENUE The following tables present disaggregated revenue: Three Months Ended September 30, In thousands NGD Other NW Natural Other NW Holdings 2023 Natural gas sales $ 117,004 $ — $ 117,004 $ — $ 117,004 Gas storage revenue, net — 3,014 3,014 — 3,014 Asset management revenue, net — 1,623 1,623 — 1,623 Appliance retail center revenue — 680 680 — 680 Other revenue 733 — 733 11,537 12,270 Revenue from contracts with customers 117,737 5,317 123,054 11,537 134,591 Alternative revenue 2,868 — 2,868 — 2,868 Leasing revenue 4,020 — 4,020 — 4,020 Total operating revenues $ 124,625 $ 5,317 $ 129,942 $ 11,537 $ 141,479 2022 Natural gas sales $ 95,784 $ — $ 95,784 $ — $ 95,784 Gas storage revenue, net — 2,882 2,882 — 2,882 Asset management revenue, net — 3,047 3,047 — 3,047 Appliance retail center revenue — 1,202 1,202 — 1,202 Other revenue 624 — 624 6,413 7,037 Revenue from contracts with customers 96,408 7,131 103,539 6,413 109,952 Alternative revenue 2,589 — 2,589 — 2,589 Leasing revenue 4,298 — 4,298 — 4,298 Total operating revenues $ 103,295 $ 7,131 $ 110,426 $ 6,413 $ 116,839 Nine Months Ended September 30, In thousands NGD Other NW Natural Other NW Holdings 2023 Natural gas sales $ 783,506 $ — $ 783,506 $ — $ 783,506 Gas storage revenue, net — 9,014 9,014 — 9,014 Asset management revenue, net — 4,879 4,879 — 4,879 Appliance retail center revenue — 2,802 2,802 — 2,802 Other revenue 2,195 — 2,195 28,958 31,153 Revenue from contracts with customers 785,701 16,695 802,396 28,958 831,354 Alternative revenue (1,623) — (1,623) — (1,623) Leasing revenue 12,030 — 12,030 — 12,030 Total operating revenues $ 796,108 $ 16,695 $ 812,803 $ 28,958 $ 841,761 2022 Natural gas sales $ 623,121 $ — $ 623,121 $ — $ 623,121 Gas storage revenue, net — 8,678 8,678 — 8,678 Asset management revenue, net — 4,941 4,941 — 4,941 Appliance retail center revenue — 4,355 4,355 — 4,355 Other revenue 1,882 — 1,882 14,799 16,681 Revenue from contracts with customers 625,003 17,974 642,977 14,799 657,776 Alternative revenue (8,571) — (8,571) — (8,571) Leasing revenue 12,895 — 12,895 — 12,895 Total operating revenues $ 629,327 $ 17,974 $ 647,301 $ 14,799 $ 662,100 NW Natural's revenue represents substantially all of NW Holdings' revenue and is recognized for both registrants 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, using the output method based on time elapsed, due to the continuous nature of the service provided. 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 and 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 NGD customers and remitted to taxing authorities. Natural Gas Distribution Natural Gas Sales NW Natural's primary source of revenue is providing natural gas to customers in the NGD service territory, which includes residential, commercial, industrial and transportation customers. NGD 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. Customer accounts are to be paid in full each month, and 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. We applied the significant financing practical expedient and have not adjusted the consideration NW Natural expects to receive from NGD customers for the effects of a significant financing component as all payment arrangements are settled annually. 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 (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 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 with 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 as such, profit upon commencement was deferred and will be amortized over the lease term. 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. See Note 7 for additional information. NW Natural Other Gas Storage Revenue NW Natural's other 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 NGD 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 NGD 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 September 30, 2023, u nrecognized revenue for the fixed component of the transaction price related to gas storage and asset management revenue was approximately $83.5 million. Of this amount, approximately $5.4 million will be recognized during the remainder of 2023, $19.9 million in 2024, $19.0 million in 2025, $14.9 million in 2026, $7.4 million in 2027 and $16.9 million thereafter. The amounts presented here are calculated using current contracted rates. Appliance Retail Center 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. NW Holdings Other Water and Wastewater Services NW Holdings' primary source of other revenue is providing 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. Customer accounts are to be paid in full each month, bi-monthly, or quarterly, and there is no right of return or warranty for services provided. We applied the significant financing practical expedient and have not adjusted the consideration we expect to receive from water distribution and wastewater collection customers for the effects of a significant financing component as all payment arrangements are settled annually. Due to the election of the right to invoice practical expedient, we do not disclose the value of unsatisfied performance obligations.

Leases

Leases	9 Months Ended
	Sep. 30, 2023
Leases [Abstract]
Lessee, Operating Leases	LEASES Lease Revenue Leasing revenue primarily consists of NW Natural's North Mist natural gas storage agreement with PGE, which is billed under an OPUC-approved rate schedule and includes an initial 30-year term beginning May 2019 with options to extend, totaling up to an additional 50 years upon mutual agreement of the parties. Under U.S. GAAP, this agreement is classified as a sales-type lease and qualifies for regulatory accounting deferral treatment. The investment in the storage facility is included in rate base under a separately established cost-of-service tariff, with revenues recognized according to the tariff schedule. As such, the selling profit that was calculated upon commencement as part of the sale-type lease recognition 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 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. Our lessor portfolio also contains small leases of property owned by NW Natural and NW Holdings to third parties. These transactions are accounted for as operating leases and the revenue is recognized over the term of the lease agreement. The components of lease revenue at NW Natural were as follows: Three Months Ended September 30, Nine Months Ended September 30, In thousands 2023 2022 2023 2022 Lease revenue Operating leases $ 19 $ 19 $ 57 $ 56 Sales-type leases 4,001 4,279 11,973 12,839 Total lease revenue $ 4,020 $ 4,298 $ 12,030 $ 12,895 Additionally, lease revenue of $0.1 million and $0.3 million was recognized for the three months ended September 30, 2023 and 2022, respectively, and lease revenue of $0.5 million and $0.4 million was recognized for the nine months ended September 30, 2023 and 2022 related to operating leases associated with non-utility property rentals. Lease revenue related to these leases was presented in other income (expense), net on the consolidated statements of comprehensive income as it is non-operating income. Total future minimum lease payments to be received under non-cancelable leases at September 30, 2023 are as follows: In thousands Operating Sales-Type Total NW Natural: Remainder of 2023 $ 153 $ 4,100 $ 4,253 2024 603 15,867 16,470 2025 599 15,306 15,905 2026 36 14,901 14,937 2027 22 14,521 14,543 Thereafter — 222,299 222,299 Total minimum lease payments $ 1,413 $ 286,994 $ 288,407 Less: imputed interest 156,626 Total leases receivable $ 130,368 Other (NW Holdings): Remainder of 2023 $ 13 $ — $ 13 2024 52 — 52 2025 53 — 53 2026 56 — 56 2027 57 — 57 Thereafter 857 — 857 Total minimum lease payments $ 1,088 $ — $ 1,088 NW Holdings: Remainder of 2023 $ 166 $ 4,100 $ 4,266 2024 655 15,867 16,522 2025 652 15,306 15,958 2026 92 14,901 14,993 2027 79 14,521 14,600 Thereafter 857 222,299 223,156 Total minimum lease payments $ 2,501 $ 286,994 $ 289,495 Less: imputed interest 156,626 Total leases receivable $ 130,368 The total leases receivable above is reported under the NGD segment and the short- and long-term portions are included within other current assets and assets under sales-type leases on the consolidated balance sheets, respectively. The total amount of unguaranteed residual assets was $5.4 million, $5.0 million and $5.1 million at September 30, 2023 and 2022 and December 31, 2022, respectively, and is included in assets under sales-type leases on the consolidated balance sheets. Additionally, under regulatory accounting, the revenues and expenses associated with these agreements are presented on the consolidated statements of comprehensive income such that their presentation aligns with similar regulated activities at NW Natural. 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 3 months to 17 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: Three Months Ended September 30, Nine Months Ended September 30, In thousands 2023 2022 2023 2022 NW Natural: Operating lease expense $ 1,817 $ 1,767 $ 5,382 $ 5,235 Short-term lease expense 198 105 556 684 Other (NW Holdings): Operating lease expense $ 51 $ 7 $ 131 $ 22 NW Holdings: Operating lease expense $ 1,868 $ 1,774 $ 5,513 $ 5,257 Short-term lease expense 198 105 556 684 Supplemental balance sheet information related to operating leases as of September 30, 2023 and 2022 and December 31, 2022 is as follows: In thousands September 30, December 31, 2023 2022 2022 NW Natural: Operating lease right of use asset $ 70,852 $ 73,046 $ 72,720 Operating lease liabilities - current liabilities $ 1,658 $ 1,298 $ 1,363 Operating lease liabilities - non-current liabilities 77,041 78,436 78,345 Total operating lease liabilities $ 78,699 $ 79,734 $ 79,708 Other (NW Holdings): Operating lease right of use asset $ 625 $ 99 $ 709 Operating lease liabilities - current liabilities $ 157 $ 63 $ 151 Operating lease liabilities - non-current liabilities 434 33 620 Total operating lease liabilities $ 591 $ 96 $ 771 NW Holdings: Operating lease right of use asset $ 71,477 $ 73,145 $ 73,429 Operating lease liabilities - current liabilities $ 1,815 $ 1,361 $ 1,514 Operating lease liabilities - non-current liabilities 77,475 78,469 78,965 Total operating lease liabilities $ 79,290 $ 79,830 $ 80,479 The weighted-average remaining lease terms and weighted-average discount rates for the operating leases at NW Natural were as follows: In thousands September 30, December 31, 2023 2022 2022 Weighted-average remaining lease term (years) 16.5 17.5 17.2 Weighted-average discount rate 7.3 % 7.3 % 7.3 % Headquarters and Operations Center Lease NW Natural commenced a 20-year operating lease agreement in March 2020 for a new headquarters and operations center in Portland, Oregon. There is an option to extend the term of the lease for two additional periods of seven years. There is a material timing difference between the minimum lease payments and expense recognition as calculated under operating lease accounting rules. OPUC issued an order allowing us to align our expense recognition with cash payments for ratemaking purposes. We recorded the difference between the minimum lease payments and the aggregate of the imputed interest on the finance lease obligation and amortization of the right-of-use asset as a deferred regulatory asset on our balance sheet. The balance of the regulatory asset was $7.8 million, $6.6 million and $6.9 million as of September 30, 2023 and 2022 and December 31, 2022, respectively. Maturities of operating lease liabilities at September 30, 2023 were as follows: In thousands NW Natural Other NW Holdings Remainder of 2023 $ 1,801 $ 44 $ 1,845 2024 7,307 183 7,490 2025 7,193 176 7,369 2026 7,361 153 7,514 2027 7,538 107 7,645 Thereafter 108,991 12 109,003 Total lease payments 140,191 675 140,866 Less: imputed interest 61,492 84 61,576 Total lease obligations 78,699 591 79,290 Less: current obligations 1,658 157 1,815 Long-term lease obligations $ 77,041 $ 434 $ 77,475 Supplemental cash flow information related to leases was as follows: Three Months Ended September 30, Nine Months Ended September 30, In thousands 2023 2022 2023 2022 NW Natural: Cash paid for amounts included in the measurement of lease liabilities Operating cash flows from operating leases $ 1,809 $ 1,759 $ 5,374 $ 5,225 Finance cash flows from finance leases 196 92 369 474 Right of use assets obtained in exchange for lease obligations Operating leases $ — $ — $ 81 $ — Finance leases 196 6 369 226 Other (NW Holdings): Cash paid for amounts included in the measurement of lease liabilities Operating cash flows from operating leases $ 54 $ 12 $ 132 $ 24 Right of use assets obtained in exchange for lease obligations Operating leases $ — $ 61 $ — $ 61 Finance leases 11 — 101 — NW Holdings: Cash paid for amounts included in the measurement of lease liabilities Operating cash flows from operating leases $ 1,863 $ 1,771 $ 5,506 $ 5,249 Finance cash flows from finance leases 196 92 369 474 Right of use assets obtained in exchange for lease obligations Operating leases $ — $ 61 $ 81 $ 61 Finance leases 207 6 470 226 Finance Leases NW Natural also leases building storage spaces for use as a gas meter room in order to provide natural gas to multifamily or mixed use developments. These contracts are accounted for as finance leases and typically involve a one-time upfront payment with no remaining liability. The right of use assets for finance leases were $2.6 million, $2.3 million and $2.3 million at September 30, 2023 and 2022 and at December 31, 2022, respectively. As of September 30, 2023, December 31, 2022 and September 30, 2022, there were no finance lease liabilities at NW Natural.

Stock-Based Compensation

Stock-Based Compensation	9 Months Ended
	Sep. 30, 2023
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 2022 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 nine months ended September 30, 2023, the final performance factor under the 2021 LTIP was approved and 55,250 performance-based shares were granted under the 2021 LTIP for accounting purposes. As such, NW Natural and other subsidiaries began recognizing compensation expense. In February 2022 and 2023, LTIP shares were awarded to participants; however, the agreements allow 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 quarters of 2024 and 2025, respectively, there is not a mutual understanding of the awards' key terms and conditions between NW Holdings and the participants as of September 30, 2023, and therefore, no expense was recognized for the 2022 and 2023 awards. NW Holdings will calculate the grant date fair value and NW Natural will recognize expense over the remaining service period for each award once the final performance factor has been approved. For the 2022 and 2023 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 2022 and 2023 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 2022 and 2023 awards, NW Holdings would grant for accounting purposes 49,100 and 52,765 shares in the first quarters of 2024 and 2025, respectively. As of September 30, 2023, there was $0.1 million of unrecognized compensation cost associated with the 2021 LTIP grant, which is expected to be recognized through 2023. Restricted Stock Units During the nine months ended September 30, 2023, 45,532 RSUs were granted under the LTIP with a weighted-average grant date fair value of $48.24 per share. Generally, the RSUs awarded are forfeitable and include a performance-based threshold as well as a vesting period of four 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 September 30, 2023, there was $3.5 million of unrecognized compensation cost from grants of RSUs, which is expected to be recognized over a period extending through 2027.

Debt

Debt	9 Months Ended
	Sep. 30, 2023
Debt Disclosure [Abstract]
Debt	DEBT Short-Term Debt At September 30, 2023, September 30, 2022 and December 31, 2022, short-term debt consisted of the following: September 30, 2023 September 30, 2022 December 31, 2022 In millions Balance Outstanding Weighted Average Interest Rate (1) Balance Outstanding Weighted Average Interest Rate (1) Balance Outstanding Weighted Average Interest Rate (1) NW Natural: Commercial paper $ — — % $ 53.0 3.3 % $ 170.2 4.6 % Other (NW Holdings): Credit agreement 71.0 6.4 % 88.0 4.7 % 88.0 5.3 % NW Holdings $ 71.0 $ 141.0 $ 258.2 (1) Weighted average interest rate on outstanding short-term debt Long-Term Debt At September 30, 2023, September 30, 2022 and December 31, 2022, NW Holdings' long-term debt consisted of the following: September 30, 2023 September 30, 2022 December 31, 2022 In millions Balance 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 $ 1,414.7 4.7 % $ 1,134.7 4.5 % $ 1,134.7 4.5 % NW Holdings credit agreement 100.0 5.5 % 100.0 4.1 % 100.0 4.2 % NWN Water credit agreement 50.0 5.7 % 50.0 4.1 % 50.0 4.2 % NWN Water term loan 55.0 4.8 % 55.0 3.5 % 55.0 2.5 % Other long-term debt 5.8 6.3 6.2 Long-term debt, gross $ 1,625.5 $ 1,346.0 $ 1,345.9 Less: unamortized debt issuance costs 10.2 8.4 9.0 Less: current maturities 190.7 50.6 90.7 Total long-term debt $ 1,424.6 $ 1,287.0 $ 1,246.2 (1) Weighted average interest rate for the nine months ended September 30, 2023 and September 30, 2022 (2) Weighted average interest rate for the year ended December 31, 2022 NW Natural's first mortgage bonds (FMBs) have maturity dates ranging from 2023 through 2053 and interest rates ranging from 2.8% to 7.9%. The credit agreements at NW Holdings and NWN Water have maturity dates in 2024 and the NWN Water term loan is due in 2026. In August 2023, NW Natural retired $50.0 million of FMBs with an interest rate of 3.5%. An additional $40.0 million of FMBs with an interest rate of 5.6% are set to mature in November 2023. No other debt is scheduled to mature in the next 12 months as of September 30, 2023 at NW Natural. Issuance of Long-Term Debt In August 2023, NW Natural issued and sold $80.0 million aggregate principal amount of its FMBs, 5.18% Series and $50.0 million aggregate principal amount of its FMBs, 5.23% Series, to certain institutional investors pursuant to the Bond Purchase Agreement. The 5.18% Bonds bear interest at the rate of 5.18% per annum, payable semi-annually on February 4 and August 4 of each year, commencing February 4, 2024, and will mature on August 4, 2034. The 5.23% Bonds bear interest at the rate of 5.23% per annum, payable semi-annually on February 4 and August 4 of each year, commencing February 4, 2024, and will mature on August 4, 2038. In March 2023, NW Natural issued and sold $100.0 million aggregate principal amount of 5.75% Secured Medium-Term Notes, Series B due 2033 (the Notes). The Notes bear interest at the rate of 5.75% per annum, payable semi-annually on March 15 and September 15 of each year. In January 2023, NW Natural issued and sold $100.0 million aggregate principal amount of its FMBs, 5.43% Series due January 2053, to certain institutional investors pursuant to the Bond Purchase Agreement. The 5.43% Bonds bear interest at the rate of 5.43% per annum, payable semi-annually on January 6 and July 6 of each year, commencing July 6, 2023, and will mature on January 6, 2053. In September 2022, NW Holdings entered into an 18-month credit agreement for $100.0 million and borrowed the full amount. The interest rate is based on the Secured Overnight Financing Rate (SOFR). The loan is due and payable on March 15, 2024. The credit agreement prohibits NW Holdings from permitting consolidated indebtedness to be greater than 70% of total capitalization, each as defined therein and calculated as of the end of each fiscal quarter. Failure to comply with this financial covenant would entitle the lenders to accelerate the maturity of the amounts outstanding under the credit agreement. NW Holdings was in compliance with this financial covenant as of September 30, 2023. In December 2022, NW Holdings entered into a swap to fix the interest rate on this debt beginning in January 2023 through the loan's maturity. See "Interest Rate Swap Agreements" below for more detail. In September 2022, NWN Water entered into an 18-month credit agreement for $50.0 million and borrowed the full amount. The interest rate is based on the SOFR. The loan is due and payable on March 15, 2024. The credit agreement prohibits NWN Water and NW Holdings from permitting consolidated indebtedness to be greater than 70% of total capitalization, each as defined therein and calculated as of the end of each fiscal quarter. Failure to comply with this financial covenant would entitle the lenders to accelerate the maturity of the amounts outstanding under the credit agreement. NWN Water and NW Holdings were in compliance with this financial covenant as of September 30, 2023. Interest Rate Swap Agreements NW Holdings and NWN Water entered into interest rate swap agreements with major financial institutions that effectively converted variable-rate debt to a fixed rate. Interest payments made between the effective date and expiration date are hedged by the swap agreements. The notional amount, effective date, expiration date and benchmark rate of the swap agreements are shown in the table below: In millions Notional Amount Effective Date Expiration Date Fixed Rate NW Holdings $ 100.0 1/17/2023 3/15/2024 4.7 % NWN Water $ 55.0 1/19/2023 6/10/2026 3.8 % 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 2022 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: September 30, December 31, In thousands 2023 2022 2022 NW Natural: Gross long-term debt $ 1,414,700 $ 1,134,700 $ 1,134,700 Unamortized debt issuance costs (10,147) (8,229) (8,823) Carrying amount $ 1,404,553 $ 1,126,471 $ 1,125,877 Estimated fair value (1) $ 1,176,212 $ 927,372 $ 944,383 NW Holdings: Gross long-term debt $ 1,625,545 $ 1,345,968 $ 1,345,851 Unamortized debt issuance costs (10,245) (8,348) (8,987) Carrying amount $ 1,615,300 $ 1,337,620 $ 1,336,864 Estimated fair value (1) $ 1,385,144 $ 1,133,087 $ 1,148,395 (1) Estimated fair value does not include unamortized debt issuance costs.

Pension and Other Postretiremen

Pension and Other Postretirement Benefit Costs	9 Months Ended
	Sep. 30, 2023
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 September 30, Nine Months Ended September 30, Pension Benefits Other Postretirement Pension Benefits Other In thousands 2023 2022 2023 2022 2023 2022 2023 2022 Service cost $ 842 $ 1,022 $ 27 $ 34 $ 2,940 $ 4,450 $ 83 $ 145 Interest cost 5,283 4,260 247 213 15,719 10,945 743 543 Expected return on plan assets (6,421) (7,076) — — (19,292) (19,274) — — Amortization of prior service credit — — — (15) — — — (249) Amortization of net actuarial loss (gain) 139 (1,542) — 57 418 9,459 — 319 Net periodic benefit cost (credit) (157) (3,336) 274 289 (215) 5,580 826 758 Amount allocated to construction (326) (496) (9) (14) (1,239) (1,965) (29) (57) Net periodic benefit cost (credit) charged to expense (483) (3,832) 265 275 (1,454) 3,615 797 701 Amortization of regulatory balancing account 675 675 — — 4,757 4,757 — — Net amount charged to expense $ 192 $ (3,157) $ 265 $ 275 $ 3,303 $ 8,372 $ 797 $ 701 Net periodic benefit costs are reduced by amounts capitalized to NGD 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 September 30, Nine Months Ended September 30, In thousands 2023 2022 2023 2022 Beginning balance $ (6,209) $ (11,010) $ (6,414) $ (11,404) Amounts reclassified from AOCL: Amortization of actuarial losses 139 275 418 811 Total reclassifications before tax 139 275 418 811 Tax benefit (37) (73) (111) (215) Total reclassifications for the period 102 202 307 596 Ending balance $ (6,107) $ (10,808) $ (6,107) $ (10,808) Employer Contributions to Company-Sponsored Defined Benefit Pension Plans NW Natural made no cash contributions to its qualified defined benefit pension plans during the nine months ended September 30, 2023 or 2022. NW Natural does not expect to make any plan contributions during the remainder of 2023 as a result of adopting the American Rescue Plan Act. 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 $8.0 million and $7.4 million for the nine months ended September 30, 2023 and 2022, respectively. See Note 10 in the 2022 Form 10-K for more information concerning these retirement and other postretirement benefit plans.

Income Tax

Income Tax	9 Months Ended
	Sep. 30, 2023
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 September 30, NW Holdings NW Natural In thousands 2023 2022 2023 2022 Income tax at statutory rate (federal) $ (6,716) $ (5,533) $ (6,131) $ (5,305) State income tax (2,742) (2,376) (2,633) (2,306) Increase (decrease): Differences required to be flowed-through by regulatory commissions 1,015 1,232 1,018 1,232 Other, net 151 (81) 39 (76) Total benefit for income taxes $ (8,292) $ (6,758) $ (7,707) $ (6,455) Effective income tax rate 25.9 % 25.7 % 26.4 % 25.6 % Nine Months Ended September 30, NW Holdings NW Natural In thousands 2023 2022 2023 2022 Income tax at statutory rate (federal) $ 13,928 $ 10,710 $ 15,723 $ 11,554 State income tax 5,618 4,298 5,990 4,497 Increase (decrease): Differences required to be flowed-through by regulatory commissions (2,055) (2,003) (2,051) (2,003) Other, net (393) (370) (625) (370) Total provision for income taxes $ 17,098 $ 12,635 $ 19,037 $ 13,678 Effective income tax rate 25.8 % 24.8 % 25.4 % 24.9 % The NW Holdings and NW Natural effective income tax rates for the nine months ended September 30, 2023 compared to the same period in 2022 changed primarily as a result of changes in pre-tax income. See Note 11 in the 2022 Form 10-K for more detail on income taxes and effective tax rates.

Property, Plant and Equipment

Property, Plant and Equipment	9 Months Ended
	Sep. 30, 2023
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment Disclosure [Text Block]	PROPERTY, PLANT, AND EQUIPMENT The following table sets forth the major classifications of property, plant, and equipment and accumulated depreciation: September 30, December 31, In thousands 2023 2022 2022 NW Natural: NGD plant in service $ 4,096,560 $ 3,888,092 $ 3,992,676 NGD construction work in progress 153,231 161,658 78,897 Less: Accumulated depreciation 1,152,952 1,135,965 1,115,690 NGD plant, net 3,096,839 2,913,785 2,955,883 Other plant in service 70,363 69,626 70,368 Other construction work in progress 8,323 5,112 6,606 Less: Accumulated depreciation 22,331 21,435 21,541 Other plant, net 56,355 53,303 55,433 Total property, plant, and equipment, net $ 3,153,194 $ 2,967,088 $ 3,011,316 Other (NW Holdings): Other plant in service $ 127,721 $ 66,208 $ 92,979 Other construction work in progress 12,404 16,632 20,040 Less: Accumulated depreciation 14,685 8,750 9,935 Other plant, net $ 125,440 $ 74,090 $ 103,084 NW Holdings: Total property, plant, and equipment, net $ 3,278,634 $ 3,041,178 $ 3,114,400 NW Natural: Capital expenditures in accrued liabilities $ 21,402 $ 43,954 $ 24,584 NW Holdings: Capital expenditures in accrued liabilities $ 22,686 $ 45,374 $ 25,318 NW Natural Other plant balances include non-utility gas storage assets at the Mist facility and other long-lived assets not related to NGD. NW Holdings Other plant balances include long-lived assets associated with water and wastewater operations and non-regulated activities not held by NW Natural or its subsidiaries.

Investments

Investments	9 Months Ended
	Sep. 30, 2023
Investments [Abstract]
Investments [Text Block]	INVESTMENTS Investments include gas reserves, financial investments in life insurance policies, and equity method investments. The following table summarizes other investments: NW Holdings NW Natural September 30, December 31, September 30, December 31, In thousands 2023 2022 2022 2023 2022 2022 Investments in life insurance policies $ 46,870 $ 49,043 $ 49,358 $ 46,870 $ 49,043 $ 49,358 Investments in gas reserves, non-current 21,439 23,770 22,970 21,439 23,770 22,970 Investment in unconsolidated affiliates 36,253 23,756 23,376 19,444 8,058 7,782 Total other investments $ 104,562 $ 96,569 $ 95,704 $ 87,753 $ 80,871 $ 80,110 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 2022 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 September 30, 2023. Gas reserves are stated at cost, net of regulatory amortization, with the associated deferred tax benefits of $4.4 million, $5.5 million, and $5.2 million, which are recorded as liabilities in the September 30, 2023, September 30, 2022, and December 31, 2022 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 $2.4 million, $3.7 million, and $3.4 million as of September 30, 2023, September 30, 2022, and December 31, 2022, respectively. See Note 13 in the 2022 Form 10-K. Investments in Unconsolidated Affiliates In December 2021, NW Natural Water purchased a 37.3% ownership stake in Avion Water Company, Inc. (Avion Water), an investor-owned water utility for $14.5 million. In July 2022, NW Natural Water increased its ownership stake in Avion Water to 40.3% for an additional $1.0 million. In June 2023, NW Natural Water increased its ownership stake in Avion Water to 43.1% for an additional $1.0 million. Avion Water operates in Bend, Oregon and the surrounding communities, serving approximately 15,000 customer connections and employing 35 people. The carrying value of the equity method investment is $8.8 million higher than the underlying equity in the net assets of the investee at September 30, 2023 due to equity method goodwill. NW Natural Water's share in the earnings (loss) of Avion Water is included in other income (expense), net. In 2020, NW Natural began a partnership with BioCarbN to invest in up to four separate renewable natural gas (RNG) development projects that are designed to access biogas derived from water treatment at Tyson Foods’ processing plants, subject to approval by all parties. During the construction phase of the projects, NW Natural determined it is the primary beneficiary and fully consolidates each entity. In January 2022, commissioning of the first project, Lexington Renewable Energy LLC (Lexington), was completed. NW Natural determined it was no longer the primary beneficiary, deconsolidated the variable interest entity and recorded the investment in Lexington as an equity method investment. As of September 30, 2023, NW Natural had an investment balance in Lexington of $7.8 million. NW Natural's share in the earnings (loss) of Lexington is included in cost of gas. In April 2023, commissioning of the second project, Dakota City Renewable Energy LLC (Dakota City), was completed. NW Natural determined it was no longer the primary beneficiary of Dakota City once the project was commissioned. The investment in the variable interest entity was deconsolidated and recorded as an equity method investment. NW Natural accounts for its interest in Dakota City using the equity method of accounting because NW Natural does not control but has the ability to exercise significant influence over Dakota City's operations after commissioning. There was no gain or loss recognized upon deconsolidation. NW Natural determined the fair value of the investment approximated the carrying value which was primarily comprised of cash and property, plant and equipment. As of September 30, 2023, NW Natural had an investment balance in Dakota City of $11.6 million. NW Natural's share in the earnings (loss) of Dakota City is included in cost of gas.

Business Combinations Business

Business Combinations Business Combinations	9 Months Ended
	Sep. 30, 2023
Business Combinations [Abstract]
Business Combination Disclosure	BUSINESS COMBINATIONS 2023 Business Combinations During the nine months ended September 30, 2023, NWN Water and its subsidiaries acquired the assets of two businesses qualifying as business combinations. The aggregate fair value of the preliminary consideration transferred for these acquisitions was $3.6 million, most of which was preliminarily allocated to property, plant, and equipment, and goodwill. These transactions align with NW Holdings' water and wastewater sector strategy as it continues to expand its water and wastewater service territories and included: • Pedersen Family, LLC in Washington • King Water Corporation in Washington In October 2023, NWN Water completed the acquisition of Rose Valley Water Company. Located in Peoria, Arizona, this water utility serves approximately 2,400 connections. Also in October 2023, NWN Water completed the water services business portion of the Hiland Water asset acquisition. This water and wastewater services business supports approximately 6,400 connections across Oregon. The preliminary allocation of consideration to the acquired assets and assumed liabilities based on their fair value is not yet complete as valuation procedures are pending. Acquisition costs were insignificant and were expensed as incurred. 2022 Business Combinations During 2022, NWN Water and its subsidiaries acquired the assets of seven businesses qualifying as business combinations. The aggregate fair value of the preliminary consideration transferred for these acquisitions was $105.7 million, most of which was preliminarily allocated to property, plant and equipment and goodwill. These transactions align with NW Holdings' water and wastewater sector strategy as it continues to expand its service territories and included: • Far West Water & Sewer, Inc. in Arizona • Belle Oaks Water and Sewer Co., Inc in Texas • Northwest Water Services, LLC in Washington • Aquarius Utilities, LLC in Washington • Valiant Idaho, LLC (The Idaho Club - Sewer) in Idaho • Caney Creek in Texas • Water Necessities, Inc. and Rural Water Co. in Texas As each of these acquisitions met the criteria of a business combination, a preliminary allocation of the consideration to the acquired net assets based on their estimated fair value as of the acquisition date was performed. The allocation for each of these business combinations is considered preliminary as of September 30, 2023. In accordance with U.S. GAAP, the fair value determination involves management judgment in determining the significant estimates and assumptions used and was made using existing regulatory conditions for net assets. These allocations are considered preliminary as of September 30, 2023, as facts and circumstances that existed as of the acquisition date may be discovered as we continue to integrate the acquired businesses. As a result, subsequent adjustments to the preliminary valuation of tangible assets, contract assets and liabilities, tax positions, and goodwill may be required. Subsequent adjustments are not expected to be significant, and any such adjustments are expected to be completed within the one-year measurement period for all acquisitions described above. 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, total goodwill was $152.4 million, $74.7 million, and $149.3 million as of September 30, 2023, September 30, 2022, and December 31, 2022, respectively. All of our goodwill is related to water and wastewater acquisitions and is included in the other category for segment reporting purposes. The annual impairment assessment of goodwill occurs in the fourth quarter of each year. There have been no impairments recognized to date.

Derivative Instruments

Derivative Instruments	9 Months Ended
	Sep. 30, 2023
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments	DERIVATIVE INSTRUMENTS NW Natural NW Natural enters into financial derivative contracts to hedge a portion of the NGD segment's natural gas sales requirements. These contracts include swaps, options, and option combinations. These derivative financial instruments are primarily used to manage commodity price variability. A small portion of NW Natural's derivative hedging strategy involves 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. The foreign currency forward contracts are used to hedge the fluctuation in foreign currency exchange rates 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 NGD 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: September 30, December 31, In thousands 2023 2022 2022 Natural gas (in therms): Financial 1,080,345 1,006,665 852,435 Physical 749,838 672,350 463,254 Foreign exchange $ 10,483 $ 9,905 $ 7,617 Purchased Gas Adjustment (PGA) Rates and hedging approaches may vary between states due to different rate structures and 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 reflected in the weighted-average cost of gas in the PGA filing. Hedge contracts entered into after the start of the PGA period 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 its Washington gas supplies. NW Natural entered the 2022-23 gas year with forecasted sales volume hedged at approximately 84% in total, including 67% in financial hedges and 17% in physical gas supplies.The total hedged for Oregon was approximately 85%, including 67% in financial hedges and 18% in physical gas supplies. The total hedged for Washington was approximately 79%, including 66% 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 September 30, 2023 2022 In thousands Natural gas commodity Foreign Exchange Natural gas commodity Foreign Exchange Benefit (expense) to cost of gas $ 14,516 $ (276) $ (11,626) $ (455) Operating revenues (expense) — — — — Amounts deferred to regulatory accounts on balance sheet (14,516) 276 11,626 455 Total gain (loss) in pre-tax earnings $ — $ — $ — $ — Nine Months Ended September 30, 2023 2022 In thousands Natural gas commodity Foreign exchange Natural gas commodity Foreign exchange Benefit (expense) to cost of gas $ (58,741) $ (95) $ 32,827 $ (528) Operating revenues (expense) — — — — Amounts deferred to regulatory accounts on balance sheet 58,741 95 (32,827) 528 Total gain (loss) in pre-tax earnings $ — $ — $ — $ — Unrealized Gain/Loss Outstanding derivative instruments related to regulated NGD 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 ne t losses of $7.5 million and net gains of $145.7 million for the three and nine months ended September 30, 2023, respectively, from the settlement of natural gas financial derivative contracts, whereas, net gains of $16.9 million and $74.0 million were realized for the three and nine months ended September 30, 2022, respectively. 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 September 30, 2023 or 2022. 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 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 2023 or 2022. 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. 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 o f $10.1 million and a liability of $48.1 million as of September 30, 2023, an asset of $40.8 million and a liability of $8.5 million as of September 30, 2022, and an asset of $153.3 million and a liability of $3.6 million as of December 31, 2022. 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 2022 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 $0.3 million, which decreased the liability at September 30, 2023. The net fair value was a liability of $38.0 million, an asset of $32.3 million, and an asset of $149.7 million as of September 30, 2023 and 2022, and December 31, 2022, respectively. No Level 3 inputs were used in our derivative valuations during the nine months ended September 30, 2023, and 2022. See Note 2 in the 2022 Form 10-K. NW Holdings NW Holdings and NWN Water entered into interest rate swap agreements with major financial institutions that effectively converted variable-rate debt to a fixed rate. Interest payments made between the effective date and expiration date are hedged by the swap agreements. The notional amount, effective date, expiration date and benchmark rate of the swap agreements are shown in the table below: In millions Notional Amount Effective Date Expiration Date Fixed Rate NW Holdings $ 100.0 1/17/2023 3/15/2024 4.7 % NWN Water $ 55.0 1/19/2023 6/10/2026 3.8 % Unrealized gains and losses related to these interest rate swap agreements are recorded in AOCI on the consolidated balance sheet and totaled $1.1 million and $0.1 million, net of tax, as of September 30, 2023 and December 31, 2022, respectively. There were no amounts reclassified from AOCI to net income during the nine months ended September 30, 2023.

Environmental Matters

Environmental Matters	9 Months Ended
	Sep. 30, 2023
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 at that time. 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 Liabilities Non-Current Liabilities September 30, December 31, September 30, December 31, In thousands 2023 2022 2022 2023 2022 2022 Portland Harbor site: Gasco/Siltronic Sediments $ 18,679 $ 5,556 $ 9,744 $ 41,392 $ 40,740 $ 42,120 Other Portland Harbor 3,524 2,430 2,634 9,580 8,135 11,270 Gasco/Siltronic Upland site 8,908 8,367 16,067 32,512 33,354 35,457 Front Street site 812 201 457 939 868 879 Oregon Steel Mills — — — 179 179 179 Total $ 31,923 $ 16,554 $ 28,902 $ 84,602 $ 83,276 $ 89,905 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 remediation 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. 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 and in the navigation channel. Siltronic Corporation is not a party to the amended order. In the second quarter of 2021, NW Natural began preliminary design discussions with the EPA for the Gasco sediments site. These preliminary design discussions did not include a cost estimate for cleanup. No design alternatives are more likely than the EE/CA alternatives at this time, and NW Natural expects further design discussion and iteration with 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 $60.1 million to $350 million. NW Natural has recorded a liability of $60.1 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. In September 2023, the EPA approved the In Situ Stabilization and Solidification (ISS) Work Plan for the ISS field pilot study scheduled for the fall of 2023. Field work on the pilot study is underway. Information obtained from the pilot study will be used to support remedial design of the Gasco sediments project. This resulted in an increase to the liability of $10.1 million. 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 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. NW Natural has recognized a liability for the remediation of the uplands portion of the site which is at the low end of the range of potential liability; the high end of the range cannot be reasonably estimated at this time. 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. 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 $1.8 million associated with long-term monitoring and post-construction work. OREGON STEEL MILLS SITE. Refer to " Legal Proceedings" below. 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 2022 Form 10-K for a description of SRRM and ECRM collection processes. The following table presents information regarding the total regulatory asset deferred: September 30, December 31, In thousands 2023 2022 2022 Deferred costs and interest (1) $ 49,899 $ 47,011 $ 47,666 Accrued site liabilities (2) 116,469 99,795 118,763 Insurance proceeds and interest (50,380) (54,678) (54,784) Total regulatory asset deferral (1) $ 115,988 $ 92,128 $ 111,645 Current regulatory assets (3) 7,047 9,461 7,392 Long-term regulatory assets (3) 108,941 82,667 104,253 (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 $57 thousand at September 30, 2023, $34 thousand at September 30, 2022, and $43 thousand at December 31, 2022. (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 $5.0 million tariff rider. The amounts allocable to Oregon are recoverable through NGD 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 $5.0 million tariff rider and $5.0 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 $10.0 million with those earnings that exceed its authorized ROE. Legal Proceedings NW Holdings is not currently party to any direct claims or litigation, though in the future it may be subject to claims and litigation arising in the ordinary course of business. NW Natural is 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". Oregon Steel Mills Site See Note 17 in the 2022 Form 10-K. For additional information regarding other commitments and contingencies, see Note 16 in the 2022 Form 10-K.

Significant Accounting Polici_2

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

Significant Accounting Polici_3

Significant Accounting Policies	9 Months Ended
	Sep. 30, 2023
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 September 30, December 31, In thousands 2023 2022 2022 NW Natural: Current: Unrealized loss on derivatives (1) $ 46,603 $ 19,594 $ 28,728 Gas costs 11,361 52,115 61,223 Environmental costs (2) 7,047 9,461 7,392 Decoupling (3) 3,480 114 — Pension balancing (4) 7,131 7,131 7,131 Income taxes 2,208 2,399 2,208 COVID-19 deferrals and expenses, net 11,127 — 789 Other (5) 19,568 14,016 10,020 Total current - NW Natural $ 108,525 $ 104,830 $ 117,491 Non-current: Unrealized loss on derivatives (1) $ 21,085 $ 18,824 $ 20,838 Pension balancing (4) 29,450 34,928 32,997 Income taxes 10,540 11,168 10,943 Pension and other postretirement benefit liabilities 101,413 107,722 101,413 Environmental costs (2) 108,941 82,667 104,253 Gas costs 718 3,369 22,355 Decoupling (3) 212 — — Washington Climate Commitment Act compliance 12,513 — — COVID-19 deferrals and expenses, net 1,811 15,147 14,555 Other (5) 25,957 27,771 33,053 Total non-current - NW Natural $ 312,640 $ 301,596 $ 340,407 Other (NW Holdings) 25 64 25 Total non-current - NW Holdings $ 312,665 $ 301,660 $ 340,432
Schedule of Regulatory Liabilities	Regulatory Liabilities September 30, December 31, In thousands 2023 2022 2022 NW Natural: Current: Gas costs $ 5,030 $ 944 $ 4,121 Unrealized gain on derivatives (1) 22,679 62,882 194,236 Decoupling (3) 8,616 13,272 14,026 Income taxes 5,946 7,318 7,166 Asset optimization revenue sharing 29,938 23,461 26,368 Washington Climate Commitment Act proceeds 9,365 — — Other (5) 6,752 3,649 2,636 Total current - NW Natural $ 88,326 $ 111,526 $ 248,553 Other (NW Holdings) 50 25 29 Total current - NW Holdings $ 88,376 $ 111,551 $ 248,582 Non-current: Gas costs $ 252 $ 50 $ 12,644 Unrealized gain on derivatives (1) 5,430 8,008 5,045 Decoupling (3) 588 884 3,814 Income taxes (6) 171,843 179,319 174,212 Accrued asset removal costs (7) 489,006 460,666 467,742 Asset optimization revenue sharing — — 8,401 Washington Climate Commitment Act proceeds 654 — — Other (5) 14,542 13,638 16,741 Total non-current - NW Natural $ 682,315 $ 662,565 $ 688,599 Other (NW Holdings) 947 982 979 Total non-current - NW Holdings $ 683,262 $ 663,547 $ 689,578 (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 NGD 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 16 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) Balances consist of deferrals and amortizations under approved regulatory mechanisms and typically earn a rate of return or carrying charge. (6) Balance represents excess deferred income tax benefits subject to regulatory flow-through.
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 September 30, 2023 and 2022 and December 31, 2022: September 30, December 31, In thousands 2023 2022 2022 Cash and cash equivalents $ 156,616 $ 108,556 $ 29,270 Restricted cash included in other current and non-current assets 14,864 11,714 11,694 Cash, cash equivalents and restricted cash $ 171,480 $ 120,270 $ 40,964 The following table provides a reconciliation of the cash, cash equivalents and restricted cash balances at NW Natural as of September 30, 2023 and 2022 and December 31, 2022: September 30, December 31, In thousands 2023 2022 2022 Cash and cash equivalents $ 145,073 $ 11,386 $ 12,977 Restricted cash included in other current assets 14,838 11,714 11,694 Cash, cash equivalents and restricted cash $ 159,911 $ 23,100 $ 24,671
Accounts Receivable, Allowance for Credit Loss [Table Text Block]	The following table presents the activity related to the NW Holdings provision for uncollectible accounts by pool: As of As of December 31, 2022 Nine Months Ended September 30, 2023 September 30, 2023 In thousands Beginning Balance Provision recorded, net of adjustments Write-offs recognized, net of recoveries Ending Balance Allowance for uncollectible accounts: Residential $ 2,155 $ 1,802 $ (2,468) $ 1,489 Commercial 400 264 (372) 292 Industrial 188 (105) (1) 82 Accrued unbilled and other 336 2 (116) 222 Total NW Natural 3,079 1,963 (2,957) 2,085 Other - NW Holdings 217 10 — 227 Total NW Holdings $ 3,296 $ 1,973 $ (2,957) $ 2,312

Earnings Per Share_2

Earnings Per Share	9 Months Ended
	Sep. 30, 2023
Earnings Per Share [Abstract]
EPS Calculation	NW Holdings' diluted earnings or loss per share are calculated as follows: Three Months Ended September 30, Nine Months Ended September 30, In thousands, except per share data 2023 2022 2023 2022 Net income (loss) $ (23,687) $ (19,587) $ 49,228 $ 38,367 Average common shares outstanding - basic 36,214 34,939 35,950 33,491 Additional shares for stock-based compensation plans (See Note 8) — — 30 48 Average common shares outstanding - diluted 36,214 34,939 35,980 33,539 Earnings (loss) per share of common stock: Basic $ (0.65) $ (0.56) $ 1.37 $ 1.15 Diluted $ (0.65) $ (0.56) $ 1.37 $ 1.14 Additional information: Anti-dilutive shares 45 85 1 —

Segment Information_2

Segment Information	9 Months Ended
	Sep. 30, 2023
Segment Reporting [Abstract]
Schedule of Segment Reporting Information, by Segment	The following table presents summary financial information concerning the reportable segment and other. Three Months Ended September 30, In thousands NGD Other NW Natural Other NW Holdings 2023 Operating revenues $ 124,624 $ 5,318 $ 129,942 $ 11,537 $ 141,479 Depreciation 28,169 277 28,446 1,615 30,061 Income (loss) from operations (22,192) 3,777 (18,415) 838 (17,577) Net income (loss) (24,160) 2,673 (21,487) (2,200) (23,687) Capital expenditures 86,017 1,053 87,070 10,814 97,884 2022 Operating revenues $ 103,295 $ 7,131 $ 110,426 $ 6,413 $ 116,839 Depreciation 27,937 264 28,201 825 29,026 Income (loss) from operations (20,910) 5,616 (15,294) 367 (14,927) Net income (loss) (23,016) 4,210 (18,806) (781) (19,587) Capital expenditures 79,847 431 80,278 3,868 84,146 Nine Months Ended September 30, In thousands NGD Other NW Natural Other NW Holdings 2023 Operating revenues $ 796,108 $ 16,695 $ 812,803 $ 28,958 $ 841,761 Depreciation 87,650 820 88,470 4,349 92,819 Income (loss) from operations 97,357 11,658 109,015 759 109,774 Net income (loss) 47,520 8,317 55,837 (6,609) 49,228 Capital expenditures 214,874 1,494 216,368 26,379 242,747 Total assets at September 30, 2023 4,285,309 52,894 4,338,203 326,915 4,665,118 2022 Operating revenues $ 629,327 $ 17,974 $ 647,301 $ 14,799 $ 662,100 Depreciation 82,372 794 83,166 2,399 85,565 Income (loss) from operations 75,328 12,054 87,382 (1,132) 86,250 Net income (loss) 32,531 8,812 41,343 (2,976) 38,367 Capital expenditures 235,249 1,218 236,467 15,375 251,842 Total assets at September 30, 2022 3,968,040 56,712 4,024,752 275,960 4,300,712 Total assets at December 31, 2022 4,392,699 60,019 4,452,718 295,608 4,748,326
NGD Margin	The following table presents additional segment information concerning NGD margin: Three Months Ended September 30, Nine Months Ended September 30, In thousands 2023 2022 2023 2022 NGD margin calculation: NGD distribution revenues $ 119,892 $ 98,391 $ 781,941 $ 614,605 Other regulated services 4,732 4,904 14,167 14,722 Total NGD operating revenues 124,624 103,295 796,108 629,327 Less: NGD cost of gas 49,235 36,258 357,530 261,678 Environmental remediation 1,032 975 8,547 7,945 Revenue taxes 5,425 4,375 33,559 25,907 NGD margin $ 68,932 $ 61,687 $ 396,472 $ 333,797

Revenue_2

Revenue	3 Months Ended
	Sep. 30, 2023
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenue	The following tables present disaggregated revenue: Three Months Ended September 30, In thousands NGD Other NW Natural Other NW Holdings 2023 Natural gas sales $ 117,004 $ — $ 117,004 $ — $ 117,004 Gas storage revenue, net — 3,014 3,014 — 3,014 Asset management revenue, net — 1,623 1,623 — 1,623 Appliance retail center revenue — 680 680 — 680 Other revenue 733 — 733 11,537 12,270 Revenue from contracts with customers 117,737 5,317 123,054 11,537 134,591 Alternative revenue 2,868 — 2,868 — 2,868 Leasing revenue 4,020 — 4,020 — 4,020 Total operating revenues $ 124,625 $ 5,317 $ 129,942 $ 11,537 $ 141,479 2022 Natural gas sales $ 95,784 $ — $ 95,784 $ — $ 95,784 Gas storage revenue, net — 2,882 2,882 — 2,882 Asset management revenue, net — 3,047 3,047 — 3,047 Appliance retail center revenue — 1,202 1,202 — 1,202 Other revenue 624 — 624 6,413 7,037 Revenue from contracts with customers 96,408 7,131 103,539 6,413 109,952 Alternative revenue 2,589 — 2,589 — 2,589 Leasing revenue 4,298 — 4,298 — 4,298 Total operating revenues $ 103,295 $ 7,131 $ 110,426 $ 6,413 $ 116,839 Nine Months Ended September 30, In thousands NGD Other NW Natural Other NW Holdings 2023 Natural gas sales $ 783,506 $ — $ 783,506 $ — $ 783,506 Gas storage revenue, net — 9,014 9,014 — 9,014 Asset management revenue, net — 4,879 4,879 — 4,879 Appliance retail center revenue — 2,802 2,802 — 2,802 Other revenue 2,195 — 2,195 28,958 31,153 Revenue from contracts with customers 785,701 16,695 802,396 28,958 831,354 Alternative revenue (1,623) — (1,623) — (1,623) Leasing revenue 12,030 — 12,030 — 12,030 Total operating revenues $ 796,108 $ 16,695 $ 812,803 $ 28,958 $ 841,761 2022 Natural gas sales $ 623,121 $ — $ 623,121 $ — $ 623,121 Gas storage revenue, net — 8,678 8,678 — 8,678 Asset management revenue, net — 4,941 4,941 — 4,941 Appliance retail center revenue — 4,355 4,355 — 4,355 Other revenue 1,882 — 1,882 14,799 16,681 Revenue from contracts with customers 625,003 17,974 642,977 14,799 657,776 Alternative revenue (8,571) — (8,571) — (8,571) Leasing revenue 12,895 — 12,895 — 12,895 Total operating revenues $ 629,327 $ 17,974 $ 647,301 $ 14,799 $ 662,100

Leases_2

Leases	9 Months Ended
	Sep. 30, 2023
Leases [Abstract]
Lease Revenue	The components of lease revenue at NW Natural were as follows: Three Months Ended September 30, Nine Months Ended September 30, In thousands 2023 2022 2023 2022 Lease revenue Operating leases $ 19 $ 19 $ 57 $ 56 Sales-type leases 4,001 4,279 11,973 12,839 Total lease revenue $ 4,020 $ 4,298 $ 12,030 $ 12,895
Lessor, Operating Lease, Payments to be Received, Maturity	Total future minimum lease payments to be received under non-cancelable leases at September 30, 2023 are as follows: In thousands Operating Sales-Type Total NW Natural: Remainder of 2023 $ 153 $ 4,100 $ 4,253 2024 603 15,867 16,470 2025 599 15,306 15,905 2026 36 14,901 14,937 2027 22 14,521 14,543 Thereafter — 222,299 222,299 Total minimum lease payments $ 1,413 $ 286,994 $ 288,407 Less: imputed interest 156,626 Total leases receivable $ 130,368 Other (NW Holdings): Remainder of 2023 $ 13 $ — $ 13 2024 52 — 52 2025 53 — 53 2026 56 — 56 2027 57 — 57 Thereafter 857 — 857 Total minimum lease payments $ 1,088 $ — $ 1,088 NW Holdings: Remainder of 2023 $ 166 $ 4,100 $ 4,266 2024 655 15,867 16,522 2025 652 15,306 15,958 2026 92 14,901 14,993 2027 79 14,521 14,600 Thereafter 857 222,299 223,156 Total minimum lease payments $ 2,501 $ 286,994 $ 289,495 Less: imputed interest 156,626 Total leases receivable $ 130,368
Lease Expense	The components of lease expense, a portion of which is capitalized, were as follows: Three Months Ended September 30, Nine Months Ended September 30, In thousands 2023 2022 2023 2022 NW Natural: Operating lease expense $ 1,817 $ 1,767 $ 5,382 $ 5,235 Short-term lease expense 198 105 556 684 Other (NW Holdings): Operating lease expense $ 51 $ 7 $ 131 $ 22 NW Holdings: Operating lease expense $ 1,868 $ 1,774 $ 5,513 $ 5,257 Short-term lease expense 198 105 556 684
Operating Lease, Lease Asset and Liabilities	Supplemental balance sheet information related to operating leases as of September 30, 2023 and 2022 and December 31, 2022 is as follows: In thousands September 30, December 31, 2023 2022 2022 NW Natural: Operating lease right of use asset $ 70,852 $ 73,046 $ 72,720 Operating lease liabilities - current liabilities $ 1,658 $ 1,298 $ 1,363 Operating lease liabilities - non-current liabilities 77,041 78,436 78,345 Total operating lease liabilities $ 78,699 $ 79,734 $ 79,708 Other (NW Holdings): Operating lease right of use asset $ 625 $ 99 $ 709 Operating lease liabilities - current liabilities $ 157 $ 63 $ 151 Operating lease liabilities - non-current liabilities 434 33 620 Total operating lease liabilities $ 591 $ 96 $ 771 NW Holdings: Operating lease right of use asset $ 71,477 $ 73,145 $ 73,429 Operating lease liabilities - current liabilities $ 1,815 $ 1,361 $ 1,514 Operating lease liabilities - non-current liabilities 77,475 78,469 78,965 Total operating lease liabilities $ 79,290 $ 79,830 $ 80,479
Operating Lease, Weighted Average Remaining Term and Discount Rates [Table Text Block]	The weighted-average remaining lease terms and weighted-average discount rates for the operating leases at NW Natural were as follows: In thousands September 30, December 31, 2023 2022 2022 Weighted-average remaining lease term (years) 16.5 17.5 17.2 Weighted-average discount rate 7.3 % 7.3 % 7.3 %
Lessee, Operating Lease, Liability, Maturity	Maturities of operating lease liabilities at September 30, 2023 were as follows: In thousands NW Natural Other NW Holdings Remainder of 2023 $ 1,801 $ 44 $ 1,845 2024 7,307 183 7,490 2025 7,193 176 7,369 2026 7,361 153 7,514 2027 7,538 107 7,645 Thereafter 108,991 12 109,003 Total lease payments 140,191 675 140,866 Less: imputed interest 61,492 84 61,576 Total lease obligations 78,699 591 79,290 Less: current obligations 1,658 157 1,815 Long-term lease obligations $ 77,041 $ 434 $ 77,475
Lessee, Leases, Supplemental Cash Flow Information	Supplemental cash flow information related to leases was as follows: Three Months Ended September 30, Nine Months Ended September 30, In thousands 2023 2022 2023 2022 NW Natural: Cash paid for amounts included in the measurement of lease liabilities Operating cash flows from operating leases $ 1,809 $ 1,759 $ 5,374 $ 5,225 Finance cash flows from finance leases 196 92 369 474 Right of use assets obtained in exchange for lease obligations Operating leases $ — $ — $ 81 $ — Finance leases 196 6 369 226 Other (NW Holdings): Cash paid for amounts included in the measurement of lease liabilities Operating cash flows from operating leases $ 54 $ 12 $ 132 $ 24 Right of use assets obtained in exchange for lease obligations Operating leases $ — $ 61 $ — $ 61 Finance leases 11 — 101 — NW Holdings: Cash paid for amounts included in the measurement of lease liabilities Operating cash flows from operating leases $ 1,863 $ 1,771 $ 5,506 $ 5,249 Finance cash flows from finance leases 196 92 369 474 Right of use assets obtained in exchange for lease obligations Operating leases $ — $ 61 $ 81 $ 61 Finance leases 207 6 470 226

Debt_2

Debt	9 Months Ended
	Sep. 30, 2023
Debt Disclosure [Abstract]
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: September 30, December 31, In thousands 2023 2022 2022 NW Natural: Gross long-term debt $ 1,414,700 $ 1,134,700 $ 1,134,700 Unamortized debt issuance costs (10,147) (8,229) (8,823) Carrying amount $ 1,404,553 $ 1,126,471 $ 1,125,877 Estimated fair value (1) $ 1,176,212 $ 927,372 $ 944,383 NW Holdings: Gross long-term debt $ 1,625,545 $ 1,345,968 $ 1,345,851 Unamortized debt issuance costs (10,245) (8,348) (8,987) Carrying amount $ 1,615,300 $ 1,337,620 $ 1,336,864 Estimated fair value (1) $ 1,385,144 $ 1,133,087 $ 1,148,395 (1) Estimated fair value does not include unamortized debt issuance costs.

Pension and Other Postretirem_2

Pension and Other Postretirement Benefit Costs	9 Months Ended
	Sep. 30, 2023
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 September 30, Nine Months Ended September 30, Pension Benefits Other Postretirement Pension Benefits Other In thousands 2023 2022 2023 2022 2023 2022 2023 2022 Service cost $ 842 $ 1,022 $ 27 $ 34 $ 2,940 $ 4,450 $ 83 $ 145 Interest cost 5,283 4,260 247 213 15,719 10,945 743 543 Expected return on plan assets (6,421) (7,076) — — (19,292) (19,274) — — Amortization of prior service credit — — — (15) — — — (249) Amortization of net actuarial loss (gain) 139 (1,542) — 57 418 9,459 — 319 Net periodic benefit cost (credit) (157) (3,336) 274 289 (215) 5,580 826 758 Amount allocated to construction (326) (496) (9) (14) (1,239) (1,965) (29) (57) Net periodic benefit cost (credit) charged to expense (483) (3,832) 265 275 (1,454) 3,615 797 701 Amortization of regulatory balancing account 675 675 — — 4,757 4,757 — — Net amount charged to expense $ 192 $ (3,157) $ 265 $ 275 $ 3,303 $ 8,372 $ 797 $ 701
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 September 30, Nine Months Ended September 30, In thousands 2023 2022 2023 2022 Beginning balance $ (6,209) $ (11,010) $ (6,414) $ (11,404) Amounts reclassified from AOCL: Amortization of actuarial losses 139 275 418 811 Total reclassifications before tax 139 275 418 811 Tax benefit (37) (73) (111) (215) Total reclassifications for the period 102 202 307 596 Ending balance $ (6,107) $ (10,808) $ (6,107) $ (10,808)

Income Tax_2

Income Tax	9 Months Ended
	Sep. 30, 2023
Income Tax Disclosure [Abstract]
Schedule of Effective Income Tax Rate Reconciliation	The effective income tax rate varied from the federal statutory rate due to the following: Three Months Ended September 30, NW Holdings NW Natural In thousands 2023 2022 2023 2022 Income tax at statutory rate (federal) $ (6,716) $ (5,533) $ (6,131) $ (5,305) State income tax (2,742) (2,376) (2,633) (2,306) Increase (decrease): Differences required to be flowed-through by regulatory commissions 1,015 1,232 1,018 1,232 Other, net 151 (81) 39 (76) Total benefit for income taxes $ (8,292) $ (6,758) $ (7,707) $ (6,455) Effective income tax rate 25.9 % 25.7 % 26.4 % 25.6 % Nine Months Ended September 30, NW Holdings NW Natural In thousands 2023 2022 2023 2022 Income tax at statutory rate (federal) $ 13,928 $ 10,710 $ 15,723 $ 11,554 State income tax 5,618 4,298 5,990 4,497 Increase (decrease): Differences required to be flowed-through by regulatory commissions (2,055) (2,003) (2,051) (2,003) Other, net (393) (370) (625) (370) Total provision for income taxes $ 17,098 $ 12,635 $ 19,037 $ 13,678 Effective income tax rate 25.8 % 24.8 % 25.4 % 24.9 %

Property, Plant and Equipment_2

Property, Plant and Equipment	9 Months Ended
	Sep. 30, 2023
Property, Plant and Equipment [Abstract]
Public Utility Property, Plant, and Equipment [Table Text Block]	The following table sets forth the major classifications of property, plant, and equipment and accumulated depreciation: September 30, December 31, In thousands 2023 2022 2022 NW Natural: NGD plant in service $ 4,096,560 $ 3,888,092 $ 3,992,676 NGD construction work in progress 153,231 161,658 78,897 Less: Accumulated depreciation 1,152,952 1,135,965 1,115,690 NGD plant, net 3,096,839 2,913,785 2,955,883 Other plant in service 70,363 69,626 70,368 Other construction work in progress 8,323 5,112 6,606 Less: Accumulated depreciation 22,331 21,435 21,541 Other plant, net 56,355 53,303 55,433 Total property, plant, and equipment, net $ 3,153,194 $ 2,967,088 $ 3,011,316 Other (NW Holdings): Other plant in service $ 127,721 $ 66,208 $ 92,979 Other construction work in progress 12,404 16,632 20,040 Less: Accumulated depreciation 14,685 8,750 9,935 Other plant, net $ 125,440 $ 74,090 $ 103,084 NW Holdings: Total property, plant, and equipment, net $ 3,278,634 $ 3,041,178 $ 3,114,400 NW Natural: Capital expenditures in accrued liabilities $ 21,402 $ 43,954 $ 24,584 NW Holdings: Capital expenditures in accrued liabilities $ 22,686 $ 45,374 $ 25,318 NW Natural Other plant balances include non-utility gas storage assets at the Mist facility and other long-lived assets not related to NGD. NW Holdings Other plant balances include long-lived assets associated with water and wastewater operations and non-regulated activities not held by NW Natural or its subsidiaries.

Investments_2

Investments	9 Months Ended
	Sep. 30, 2023
Investments [Abstract]
Investment [Table Text Block]	Investments include gas reserves, financial investments in life insurance policies, and equity method investments. The following table summarizes other investments: NW Holdings NW Natural September 30, December 31, September 30, December 31, In thousands 2023 2022 2022 2023 2022 2022 Investments in life insurance policies $ 46,870 $ 49,043 $ 49,358 $ 46,870 $ 49,043 $ 49,358 Investments in gas reserves, non-current 21,439 23,770 22,970 21,439 23,770 22,970 Investment in unconsolidated affiliates 36,253 23,756 23,376 19,444 8,058 7,782 Total other investments $ 104,562 $ 96,569 $ 95,704 $ 87,753 $ 80,871 $ 80,110

Derivative Instruments_2

Derivative Instruments	9 Months Ended
	Sep. 30, 2023
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: September 30, December 31, In thousands 2023 2022 2022 Natural gas (in therms): Financial 1,080,345 1,006,665 852,435 Physical 749,838 672,350 463,254 Foreign exchange $ 10,483 $ 9,905 $ 7,617
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:

Environmental Matters_2

Environmental Matters	9 Months Ended
	Sep. 30, 2023
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 Liabilities Non-Current Liabilities September 30, December 31, September 30, December 31, In thousands 2023 2022 2022 2023 2022 2022 Portland Harbor site: Gasco/Siltronic Sediments $ 18,679 $ 5,556 $ 9,744 $ 41,392 $ 40,740 $ 42,120 Other Portland Harbor 3,524 2,430 2,634 9,580 8,135 11,270 Gasco/Siltronic Upland site 8,908 8,367 16,067 32,512 33,354 35,457 Front Street site 812 201 457 939 868 879 Oregon Steel Mills — — — 179 179 179 Total $ 31,923 $ 16,554 $ 28,902 $ 84,602 $ 83,276 $ 89,905
Environmental Regulatory Table	The following table presents information regarding the total regulatory asset deferred: September 30, December 31, In thousands 2023 2022 2022 Deferred costs and interest (1) $ 49,899 $ 47,011 $ 47,666 Accrued site liabilities (2) 116,469 99,795 118,763 Insurance proceeds and interest (50,380) (54,678) (54,784) Total regulatory asset deferral (1) $ 115,988 $ 92,128 $ 111,645 Current regulatory assets (3) 7,047 9,461 7,392 Long-term regulatory assets (3) 108,941 82,667 104,253 (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 $57 thousand at September 30, 2023, $34 thousand at September 30, 2022, and $43 thousand at December 31, 2022. (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 $5.0 million tariff rider. The amounts allocable to Oregon are recoverable through NGD rates, subject to an earnings test.

Significant Accounting Polici_4

Significant Accounting Policies - Regulatory Asset Disclosure - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022	Sep. 30, 2022
Regulatory Assets [Line Items]
Regulatory Assets, Current	$ 108,525	$ 117,491	$ 104,830
Regulatory Assets, Noncurrent	$ 312,665	340,432	301,660
Inactive Account, Period Outstanding Prior to Write-Off	120 days
General Payment Term of NGD Receivables	15 days
Age of Closed or Inactive Accounts	120 days
Other [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Noncurrent	$ 25	25	64
Northwest Natural Gas Company [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Current	108,525	117,491	104,830
Regulatory Assets, Noncurrent	312,640	340,407	301,596
Northwest Natural Gas Company [Member] | Deferred Derivative Gain (Loss) [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Current	46,603	28,728	19,594
Regulatory Assets, Noncurrent	21,085	20,838	18,824
Northwest Natural Gas Company [Member] | Pension balancing [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Current	7,131	7,131	7,131
Regulatory Assets, Noncurrent	29,450	32,997	34,928
Northwest Natural Gas Company [Member] | Income taxes [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Current	2,208	2,208	2,399
Regulatory Assets, Noncurrent	10,540	10,943	11,168
Northwest Natural Gas Company [Member] | Pension and other postretirement benefit liabilities [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Noncurrent	101,413	101,413	107,722
Northwest Natural Gas Company [Member] | Environmental costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Current	7,047	7,392	9,461
Regulatory Assets, Noncurrent	108,941	104,253	82,667
Northwest Natural Gas Company [Member] | Gas costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Current	11,361	61,223	52,115
Regulatory Assets, Noncurrent	718	22,355	3,369
Northwest Natural Gas Company [Member] | Decoupling [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Current	3,480	0	114
Regulatory Assets, Noncurrent	212	0	0
Northwest Natural Gas Company [Member] | Washington Climate Commitment Act compliance
Regulatory Assets [Line Items]
Regulatory Assets, Noncurrent	12,513	0	0
Northwest Natural Gas Company [Member] | Other [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Current	19,568	10,020	14,016
Regulatory Assets, Noncurrent	25,957	33,053	27,771
Northwest Natural Gas Company [Member] | COVID-19 Related Costs
Regulatory Assets [Line Items]
Regulatory Assets, Current	11,127	789	0
Regulatory Assets, Noncurrent	$ 1,811	$ 14,555	$ 15,147

Significant Accounting Polici_5

Significant Accounting Policies - Regulatory Liability Disclosure - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022	Sep. 30, 2022
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	$ 88,376	$ 248,582	$ 111,551
Regulatory Liability, Noncurrent	683,262	689,578	663,547
Other [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	50	29	25
Regulatory Liability, Noncurrent	947	979	982
Northwest Natural Gas Company [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	88,326	248,553	111,526
Regulatory Liability, Noncurrent	682,315	688,599	662,565
Northwest Natural Gas Company [Member] | Gas costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	5,030	4,121	944
Regulatory Liability, Noncurrent	252	12,644	50
Northwest Natural Gas Company [Member] | Deferred Derivative Gain (Loss) [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	22,679	194,236	62,882
Regulatory Liability, Noncurrent	5,430	5,045	8,008
Northwest Natural Gas Company [Member] | Decoupling [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	8,616	14,026	13,272
Regulatory Liability, Noncurrent	588	3,814	884
Northwest Natural Gas Company [Member] | Income taxes [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	5,946	7,166	7,318
Regulatory Liability, Noncurrent	171,843	174,212	179,319
Northwest Natural Gas Company [Member] | Other [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	6,752	2,636	3,649
Regulatory Liability, Noncurrent	14,542	16,741	13,638
Northwest Natural Gas Company [Member] | Accrued asset removal costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Noncurrent	489,006	467,742	460,666
Northwest Natural Gas Company [Member] | Asset Optimization Revenue Sharing
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	29,938	26,368	23,461
Regulatory Liability, Noncurrent	0	8,401	0
Northwest Natural Gas Company [Member] | Washington Climate Commitment Act compliance
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	9,365	0	0
Regulatory Liability, Noncurrent	654	$ 0	$ 0
Regulatory Liability	$ 10,000

Supplemental Cash Flow

Supplemental Cash Flow - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Dec. 31, 2022	Sep. 30, 2022	Dec. 31, 2021
Restricted Cash and Cash Equivalents Items [Line Items]
Cash and cash equivalents	$ 156,616	$ 29,270	$ 108,556
Restricted Cash	14,864	11,694	11,714
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	171,480	40,964	120,270	$ 27,120
Money Market Funds, at Carrying Value	132,600
Northwest Natural Gas Company [Member]
Restricted Cash and Cash Equivalents Items [Line Items]
Cash and cash equivalents	145,073	12,977	11,386
Restricted Cash	14,838	11,694	11,714
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	159,911	$ 24,671	$ 23,100	$ 20,832
Money Market Funds, at Carrying Value	132,600
Payments of Dividends	$ 25,000

Significant Accounting Polici_6

Significant Accounting Policies - Credit Losses - ASU 2016-13 $ in Thousands	9 Months Ended
	Sep. 30, 2023 USD ($) numberOfLeases	Dec. 31, 2022 USD ($)	Sep. 30, 2022 USD ($)
Accounts Receivable, Noncurrent, Credit Quality Indicator [Line Items]
Number of Net Investments in Sales-Type Leases | numberOfLeases	2
Sales-type Lease, Net Investment in Lease, Allowance for Credit Loss	$ 0
Regulatory Assets, Noncurrent	312,665	$ 340,432	$ 301,660
Other Northwest Holdings [Member]
Accounts Receivable, Noncurrent, Credit Quality Indicator [Line Items]
Accounts Receivable, Allowance for Credit Loss	227	217
Accounts Receivable, Allowance for Credit Loss, Period Increase (Decrease)	10
Accounts Receivable, Allowance for Credit Loss, Recovery	0
Northwest Holdings [Member]
Accounts Receivable, Noncurrent, Credit Quality Indicator [Line Items]
Accounts Receivable, Allowance for Credit Loss	2,312	3,296
Accounts Receivable, Allowance for Credit Loss, Period Increase (Decrease)	1,973
Accounts Receivable, Allowance for Credit Loss, Recovery	(2,957)
Northwest Natural Gas Company [Member]
Accounts Receivable, Noncurrent, Credit Quality Indicator [Line Items]
Accounts Receivable, Allowance for Credit Loss	2,085	3,079
Accounts Receivable, Allowance for Credit Loss, Period Increase (Decrease)	1,963
Accounts Receivable, Allowance for Credit Loss, Recovery	(2,957)
Regulatory Assets, Noncurrent	312,640	340,407	$ 301,596
Residential [Member] | Northwest Natural Gas Company [Member]
Accounts Receivable, Noncurrent, Credit Quality Indicator [Line Items]
Accounts Receivable, Allowance for Credit Loss	1,489	2,155
Accounts Receivable, Allowance for Credit Loss, Period Increase (Decrease)	1,802
Accounts Receivable, Allowance for Credit Loss, Recovery	(2,468)
Commercial [Member] | Northwest Natural Gas Company [Member]
Accounts Receivable, Noncurrent, Credit Quality Indicator [Line Items]
Accounts Receivable, Allowance for Credit Loss	292	400
Accounts Receivable, Allowance for Credit Loss, Period Increase (Decrease)	264
Accounts Receivable, Allowance for Credit Loss, Recovery	(372)
Industrial [Member] | Northwest Natural Gas Company [Member]
Accounts Receivable, Noncurrent, Credit Quality Indicator [Line Items]
Accounts Receivable, Allowance for Credit Loss	82	188
Accounts Receivable, Allowance for Credit Loss, Period Increase (Decrease)	(105)
Accounts Receivable, Allowance for Credit Loss, Recovery	(1)
Accrued unbilled and other [Member] | Northwest Natural Gas Company [Member]
Accounts Receivable, Noncurrent, Credit Quality Indicator [Line Items]
Accounts Receivable, Allowance for Credit Loss	222	$ 336
Accounts Receivable, Allowance for Credit Loss, Period Increase (Decrease)	2
Accounts Receivable, Allowance for Credit Loss, Recovery	$ (116)

Greenhouse Gas Allowances

Greenhouse Gas Allowances $ in Thousands	9 Months Ended
	Sep. 30, 2023 USD ($)
CCI Deferred Costs	$ 12,500
Washington Climate Commitment Act Allowances
Proceeds from Other Operating Activities	10,000
WASHINGTON
CCI Credits Liability	12,100
Inventory, Emissions Allowances	18,300
Oregon [Member]
Inventory, Emissions Allowances	$ 0

Earnings Per Share_2_3

Earnings Per Share - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Earnings Per Share [Abstract]
Net income	$ (23,687)	$ (19,587)	$ 49,228	$ 38,367
Average common shares outstanding:
Average common shares outstanding - basic (in shares)	36,214	34,939	35,950	33,491
Additional shares for stock-based compensation plans	0	0	30	48
Average common shares outstanding - diluted (in shares)	36,214	34,939	35,980	33,539
Earnings (loss) per share of common stock
Basic (in dollars per share)	$ (0.65)	$ (0.56)	$ 1.37	$ 1.15
Diluted (in dollars per share)	$ (0.65)	$ (0.56)	$ 1.37	$ 1.14
Antidilutive shares	45	85	1	0

Segment Information - Narrative

Segment Information - Narrative	9 Months Ended
	Sep. 30, 2023
Operating Segments [Member]
Segment Reporting Information [Line Items]
Number of Reportable Segments	1
Oregon [Member] | Northwest Holdings and Northwest Natural [Member] | Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Percent Of Pre Tax Income From Gas Storage Retained When The Costs Of The Capacity Are Not In Utility Rates	80%
Percent Of Pre Tax Income From Gas Storage Retained When The Costs Of The Capacity Are In Utility Rates	10%
Percent Of Pre Tax Income From Gas Storage Credited To Deferred Regulatory Account	20%
Percent Of Pre Tax Income From Gas Storage Credited To Deferred Regulatory Account When In Rates	90%

Segment Information - Schedule

Segment Information - Schedule of Summarized Financial Information by Segment - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Segment Reporting Information [Line Items]
Operating revenues	$ 141,479	$ 116,839	$ 841,761	$ 662,100
Depreciation	30,061	29,026	92,819	85,565
Income from operations	(17,577)	(14,927)	109,774	86,250
Total assets	4,665,118	4,300,712	4,665,118	4,300,712	$ 4,748,326
Natural Gas Distribution [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating revenues	124,624	103,295	796,108	629,327
Depreciation	28,169	27,937	87,650	82,372
Income from operations	(22,192)	(20,910)	97,357	75,328
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	(24,160)	(23,016)	47,520	32,531
Capital expenditures	86,017	79,847	214,874	235,249
Total assets	4,285,309	3,968,040	4,285,309	3,968,040	4,392,699
Other Northwest Natural [Member] | Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Operating revenues	5,318	7,131	16,695	17,974
Depreciation	277	264	820	794
Income from operations	3,777	5,616	11,658	12,054
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	2,673	4,210	8,317	8,812
Capital expenditures	1,053	431	1,494	1,218
Total assets	52,894	56,712	52,894	56,712	60,019
Northwest Natural Gas Company [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating revenues	129,942	110,426	812,803	647,301
Depreciation	28,446	28,201	88,470	83,166
Income from operations	(18,415)	(15,294)	109,015	87,382
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	(21,487)	(18,806)	55,837	41,343
Capital expenditures	87,070	80,278	216,368	236,467
Total assets	4,338,203	4,024,752	4,338,203	4,024,752	4,452,718
Other Northwest Holdings [Member] | Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Operating revenues	11,537	6,413	28,958	14,799
Depreciation	1,615	825	4,349	2,399
Income from operations	838	367	759	(1,132)
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	(2,200)	(781)	(6,609)	(2,976)
Capital expenditures	10,814	3,868	26,379	15,375
Total assets	326,915	275,960	326,915	275,960	295,608
Northwest Natural Gas Company [Member]
Segment Reporting Information [Line Items]
Operating revenues	129,942	110,426	812,803	647,301
Depreciation	28,446	28,201	88,470	83,166
Income from operations	(18,415)	(15,294)	109,015	87,382
Total assets	4,338,203	4,024,752	4,338,203	4,024,752	4,452,718
Northwest Natural Gas Company [Member] | Natural Gas Distribution [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating revenues	124,625	103,295	796,108	629,327
Northwest Natural Gas Company [Member] | Other Northwest Natural [Member] | Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Operating revenues	5,317	7,131	16,695	17,974
Northwest Natural Gas Company [Member] | Northwest Natural Gas Company [Member]
Segment Reporting Information [Line Items]
Operating revenues	129,942	110,426	812,803	647,301
Parent Company [Member]
Segment Reporting Information [Line Items]
Operating revenues	141,479	116,839	841,761	662,100
Depreciation	30,061	29,026	92,819	85,565
Income from operations	(17,577)	(14,927)	109,774	86,250
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	(23,687)	(19,587)	49,228	38,367
Capital expenditures	97,884	84,146	242,747	251,842
Total assets	$ 4,665,118	$ 4,300,712	$ 4,665,118	$ 4,300,712	$ 4,748,326

Segment Information - Additiona

Segment Information - Additional Segment Information - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Segment Reporting Information [Line Items]
Operating revenues	$ 141,479	$ 116,839	$ 841,761	$ 662,100
Cost of gas	49,180	36,105	357,362	261,413
Environmental remediation	1,032	980	8,547	7,950
Operating Segments [Member] | Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Natural Gas Distribution revenues	119,892	98,391	781,941	614,605
Other regulated services	4,732	4,904	14,167	14,722
Operating revenues	124,624	103,295	796,108	629,327
Cost of gas	49,235	36,258	357,530	261,678
Environmental remediation	1,032	975	8,547	7,945
Revenue taxes	5,425	4,375	33,559	25,907
NGD margin	$ 68,932	$ 61,687	$ 396,472	$ 333,797

Equity - Narrative

Equity - Narrative - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2023	Sep. 30, 2022	Oct. 02, 2023	Dec. 31, 2022
Class of Stock [Line Items]
Par Value (in dollars per share)	$ 0	$ 0	$ 0		$ 0
Shares issued (in shares)	36,575,797	36,575,797	35,098,437		35,524,590
Proceeds from common stock issued, net		$ 40,955	$ 190,929
Subsequent Event [Member]
Class of Stock [Line Items]
Shares, Issued				184,832
Shares, Issued				184,832
Avion Water | Other Northwest Holdings [Member]
Class of Stock [Line Items]
Investment balance in Avion					$ 14,500
ATM Equity Program
Class of Stock [Line Items]
Par Value (in dollars per share)	$ 0	$ 0
Sale of Stock, Consideration Received on Transaction	$ 18,800	$ 40,900
Sale of Stock, Commissions and Fees Paid	$ 300	$ 700
Stock Issued During Period, Shares, New Issues	475,732	955,325
nwn:AttheMarketEquityProgramEquityAvailableforIssuance	$ 69,500	$ 69,500
Maximum [Member] | Scenario, Plan | ATM Equity Program
Class of Stock [Line Items]
Cumulative Proceeds Received on All Transactions		$ 200,000

Revenue - Disaggregation of Rev

Revenue - Disaggregation of Revenue - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	$ 134,591	$ 109,952	$ 831,354	$ 657,776
Revenues	141,479	116,839	841,761	662,100
Natural Gas Sales [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	117,004	95,784	783,506	623,121
Gas Storage Revenue, Net of Regulatory Sharing [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	3,014	2,882	9,014	8,678
Asset Management Revenue, Net of Regulatory Sharing [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	1,623	3,047	4,879	4,941
Appliance Center Revenue [Member] | Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	680	1,202	2,802	4,355
Other revenue [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	12,270	7,037	31,153	16,681
Alternative revenue [Member]
Disaggregation of Revenue [Line Items]
Revenues	2,868	2,589	(1,623)	(8,571)
Leasing revenue [Member]
Disaggregation of Revenue [Line Items]
Operating leases	4,020	4,298	12,030	12,895
Northwest Natural Gas Company [Member]
Disaggregation of Revenue [Line Items]
Revenues	129,942	110,426	812,803	647,301
Operating leases	19	19	57	56
Northwest Natural Gas Company [Member] | Northwest Natural Gas Company [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	123,054	103,539	802,396	642,977
Revenues	129,942	110,426	812,803	647,301
Northwest Natural Gas Company [Member] | Northwest Natural Gas Company [Member] | Natural Gas Sales [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	117,004	95,784	783,506	623,121
Northwest Natural Gas Company [Member] | Northwest Natural Gas Company [Member] | Gas Storage Revenue, Net of Regulatory Sharing [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	3,014	2,882	9,014	8,678
Northwest Natural Gas Company [Member] | Northwest Natural Gas Company [Member] | Asset Management Revenue, Net of Regulatory Sharing [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	1,623	3,047	4,879	4,941
Northwest Natural Gas Company [Member] | Northwest Natural Gas Company [Member] | Appliance Center Revenue [Member] | Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	680	1,202	2,802	4,355
Northwest Natural Gas Company [Member] | Northwest Natural Gas Company [Member] | Other revenue [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	733	624	2,195	1,882
Northwest Natural Gas Company [Member] | Northwest Natural Gas Company [Member] | Alternative revenue [Member]
Disaggregation of Revenue [Line Items]
Revenues	2,868	2,589	(1,623)	(8,571)
Northwest Natural Gas Company [Member] | Northwest Natural Gas Company [Member] | Leasing revenue [Member]
Disaggregation of Revenue [Line Items]
Operating leases	4,020	4,298	12,030	12,895
Operating Segments [Member] | Natural Gas Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenues	124,624	103,295	796,108	629,327
Operating Segments [Member] | Natural Gas Distribution [Member] | Northwest Natural Gas Company [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	117,737	96,408	785,701	625,003
Revenues	124,625	103,295	796,108	629,327
Operating Segments [Member] | Natural Gas Distribution [Member] | Northwest Natural Gas Company [Member] | Natural Gas Sales [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	117,004	95,784	783,506	623,121
Operating Segments [Member] | Natural Gas Distribution [Member] | Northwest Natural Gas Company [Member] | Gas Storage Revenue, Net of Regulatory Sharing [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Operating Segments [Member] | Natural Gas Distribution [Member] | Northwest Natural Gas Company [Member] | Asset Management Revenue, Net of Regulatory Sharing [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Operating Segments [Member] | Natural Gas Distribution [Member] | Northwest Natural Gas Company [Member] | Appliance Center Revenue [Member] | Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Operating Segments [Member] | Natural Gas Distribution [Member] | Northwest Natural Gas Company [Member] | Other revenue [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	733	624	2,195	1,882
Operating Segments [Member] | Natural Gas Distribution [Member] | Northwest Natural Gas Company [Member] | Alternative revenue [Member]
Disaggregation of Revenue [Line Items]
Revenues	2,868	2,589	(1,623)	(8,571)
Operating Segments [Member] | Natural Gas Distribution [Member] | Northwest Natural Gas Company [Member] | Leasing revenue [Member]
Disaggregation of Revenue [Line Items]
Operating leases	4,020	4,298	12,030	12,895
Operating Segments [Member] | Northwest Natural Gas Company [Member]
Disaggregation of Revenue [Line Items]
Revenues	129,942	110,426	812,803	647,301
Corporate, Non-Segment [Member] | Other Northwest Natural [Member]
Disaggregation of Revenue [Line Items]
Revenues	5,318	7,131	16,695	17,974
Corporate, Non-Segment [Member] | Other Northwest Natural [Member] | Northwest Natural Gas Company [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	5,317	7,131	16,695	17,974
Revenues	5,317	7,131	16,695	17,974
Corporate, Non-Segment [Member] | Other Northwest Natural [Member] | Northwest Natural Gas Company [Member] | Natural Gas Sales [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0	0
Corporate, Non-Segment [Member] | Other Northwest Natural [Member] | Northwest Natural Gas Company [Member] | Gas Storage Revenue, Net of Regulatory Sharing [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	3,014	2,882	9,014	8,678
Corporate, Non-Segment [Member] | Other Northwest Natural [Member] | Northwest Natural Gas Company [Member] | Asset Management Revenue, Net of Regulatory Sharing [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	1,623	3,047	4,879	4,941
Corporate, Non-Segment [Member] | Other Northwest Natural [Member] | Northwest Natural Gas Company [Member] | Appliance Center Revenue [Member] | Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	680	1,202	2,802	4,355
Corporate, Non-Segment [Member] | Other Northwest Natural [Member] | Northwest Natural Gas Company [Member] | Other revenue [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0	0
Corporate, Non-Segment [Member] | Other Northwest Natural [Member] | Northwest Natural Gas Company [Member] | Alternative revenue [Member]
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Corporate, Non-Segment [Member] | Other Northwest Natural [Member] | Northwest Natural Gas Company [Member] | Leasing revenue [Member]
Disaggregation of Revenue [Line Items]
Operating leases	0	0	0	0
Corporate, Non-Segment [Member] | Other Northwest Holdings [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	11,537	6,413	28,958	14,799
Revenues	11,537	6,413	28,958	14,799
Corporate, Non-Segment [Member] | Other Northwest Holdings [Member] | Natural Gas Sales [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0	0
Corporate, Non-Segment [Member] | Other Northwest Holdings [Member] | Gas Storage Revenue, Net of Regulatory Sharing [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0	0
Corporate, Non-Segment [Member] | Other Northwest Holdings [Member] | Asset Management Revenue, Net of Regulatory Sharing [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0	0
Corporate, Non-Segment [Member] | Other Northwest Holdings [Member] | Appliance Center Revenue [Member] | Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0	0
Corporate, Non-Segment [Member] | Other Northwest Holdings [Member] | Other revenue [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	11,537	6,413	28,958	14,799
Corporate, Non-Segment [Member] | Other Northwest Holdings [Member] | Alternative revenue [Member]
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Corporate, Non-Segment [Member] | Other Northwest Holdings [Member] | Leasing revenue [Member]
Disaggregation of Revenue [Line Items]
Operating leases	$ 0	$ 0	$ 0	$ 0

Revenue - Revenue, Remaining Pe

Revenue - Revenue, Remaining Performance Obligation $ in Thousands	Sep. 30, 2023 USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Lessor, Sales-type Lease, Term of Contract	30 years
Lessor, Sales-type Lease, Renewal Term	50 years
Revenue, Remaining Performance Obligation, Amount	$ 83,500
Natural Gas Distribution [Member] | Northwest Natural Gas Company [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Contract with Customer, Refund Liability	0
Other Northwest Natural [Member] | Northwest Natural Gas Company [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Contract with Customer, Refund Liability	0
Other Northwest Holdings [Member]
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]: 2023-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Year	3 months
Revenue, Remaining Performance Obligation, Amount	$ 5,400
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Year	1 year
Revenue, Remaining Performance Obligation, Amount	$ 19,900
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Year	1 year
Revenue, Remaining Performance Obligation, Amount	$ 19,000
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2026-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Year	1 year
Revenue, Remaining Performance Obligation, Amount	$ 14,900
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, Expected Timing of Satisfaction, Year	1 year
Revenue, Remaining Performance Obligation, Amount	$ 7,400
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, Expected Timing of Satisfaction, Year	0 years
Revenue, Remaining Performance Obligation, Amount	$ 16,900

Leases - Lease Revenue

Leases - Lease Revenue - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Lessor, Lease, Description [Line Items]
Lessor, Sales-type Lease, Renewal Term	50 years		50 years
Lessor, Sales-type Lease, Term of Contract	30 years		30 years
Residual Value of Leased Asset	$ 5,400	$ 5,000	$ 5,400	$ 5,000	$ 5,100
Lease Revenue [Abstract]
Total lease revenue	100	300	500	400
Operating Leases Payment to be Received [Abstract]
Operating Lease, Payments to be Received, Remainder of Fiscal Year	166		166
Lessor, Operating Lease, Payment to be Received, Year One	655		655
Operating Lease, Payments to be Received, Two Years	652		652
Operating Lease, Payments to be Received, Three Years	92		92
Operating Lease, Payments to be Received, Four Years	79		79
Operating Lease, Payments to be Received, Thereafter	857		857
Total minimum lease payments	2,501		2,501
Total Lease Payments to be Received [Abstract]
Lease Payments to be Received, Remainder of Fiscal Year	4,266		4,266
Lease Payments to be Received, Two Years	16,522		16,522
Lease Payments to be Received, Three Years	15,958		15,958
Lease Payments to be Received, Four Years	14,993		14,993
Lease Payments to be Received, Five Years	14,600		14,600
Lease Payments to be Received, Thereafter	223,156		223,156
Total minimum lease payments	289,495		289,495
Northwest Natural Gas Company [Member]
Lease Revenue [Abstract]
Operating leases	19	19	57	56
Sales-type leases	4,001	4,279	11,973	12,839
Total lease revenue	4,020	$ 4,298	12,030	$ 12,895
Operating Leases Payment to be Received [Abstract]
Operating Lease, Payments to be Received, Remainder of Fiscal Year	153		153
Lessor, Operating Lease, Payment to be Received, Year One	603		603
Operating Lease, Payments to be Received, Two Years	599		599
Operating Lease, Payments to be Received, Three Years	36		36
Operating Lease, Payments to be Received, Four Years	22		22
Operating Lease, Payments to be Received, Thereafter	0		0
Total minimum lease payments	1,413		1,413
Total Lease Payments to be Received [Abstract]
Lease Payments to be Received, Remainder of Fiscal Year	4,253		4,253
Lease Payments to be Received, Two Years	16,470		16,470
Lease Payments to be Received, Three Years	15,905		15,905
Lease Payments to be Received, Four Years	14,937		14,937
Lease Payments to be Received, Five Years	14,543		14,543
Lease Payments to be Received, Thereafter	222,299		222,299
Total minimum lease payments	288,407		288,407
Other Northwest Holdings [Member]
Operating Leases Payment to be Received [Abstract]
Operating Lease, Payments to be Received, Remainder of Fiscal Year	13		13
Lessor, Operating Lease, Payment to be Received, Year One	52		52
Operating Lease, Payments to be Received, Two Years	53		53
Operating Lease, Payments to be Received, Three Years	56		56
Operating Lease, Payments to be Received, Four Years	57		57
Operating Lease, Payments to be Received, Thereafter	857		857
Total minimum lease payments	1,088		1,088
Total Lease Payments to be Received [Abstract]
Lease Payments to be Received, Remainder of Fiscal Year	13		13
Lease Payments to be Received, Two Years	52		52
Lease Payments to be Received, Three Years	53		53
Lease Payments to be Received, Four Years	56		56
Lease Payments to be Received, Five Years	57		57
Lease Payments to be Received, Thereafter	857		857
Total minimum lease payments	$ 1,088		$ 1,088
Compressed Natural Gas Lease [Member]
Lessor, Lease, Description [Line Items]
Lessor, Sales-type Lease, Term of Contract	10 years		10 years
Residual Value of Leased Asset	$ 0		$ 0
Variable Lease, Payment			0
North Mist Lease [Member]
Lessor, Lease, Description [Line Items]
Residual Value of Leased Asset	0		0
Variable Lease, Payment			0
Sales-type Lease [Member]
Sales-type Leases Payments to be Received [Abstract]
Sales-type Lease, Payments to be Received, Remainder of Fiscal Year	4,100		4,100
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year One	15,867		15,867
Sales-type Lease, Payments to be Received, Two Years	15,306		15,306
Sales-type Lease, Payments to be Received, Three Years	14,901		14,901
Sales-type Lease, Payments to be Received, Four Years	14,521		14,521
Sales-type Lease, Payments to be Received, Thereafter	222,299		222,299
Total minimum lease payments	286,994		286,994
Less: imputed interest	156,626		156,626
Total leases receivable	130,368		130,368
Sales-type Lease [Member] | Northwest Natural Gas Company [Member]
Sales-type Leases Payments to be Received [Abstract]
Sales-type Lease, Payments to be Received, Remainder of Fiscal Year	4,100		4,100
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year One	15,867		15,867
Sales-type Lease, Payments to be Received, Two Years	15,306		15,306
Sales-type Lease, Payments to be Received, Three Years	14,901		14,901
Sales-type Lease, Payments to be Received, Four Years	14,521		14,521
Sales-type Lease, Payments to be Received, Thereafter	222,299		222,299
Total minimum lease payments	286,994		286,994
Less: imputed interest	156,626		156,626
Total leases receivable	130,368		130,368
Sales-type Lease [Member] | Other Northwest Holdings [Member]
Sales-type Leases Payments to be Received [Abstract]
Sales-type Lease, Payments to be Received, Remainder of Fiscal Year	0		0
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year One	0		0
Sales-type Lease, Payments to be Received, Two Years	0		0
Sales-type Lease, Payments to be Received, Three Years	0		0
Sales-type Lease, Payments to be Received, Four Years	0		0
Sales-type Lease, Payments to be Received, Thereafter	0		0
Total minimum lease payments	$ 0		$ 0

Leases - Lease Expense

Leases - Lease Expense - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Lease Expense [Abstract]
Operating Lease, Expense	$ 1,868	$ 1,774	$ 5,513	$ 5,257
Short-term Lease, Cost	$ 198	105	$ 556	684
Lessee, Operating Lease, Maximum Term of Short-term Leases not recorded on the Balance Sheet	12 months		12 months
Minimum [Member]
Operating Lease Terms [Abstract]
Lessee, Operating Lease, Term of Contract	3 months		3 months
Maximum [Member]
Operating Lease Terms [Abstract]
Lessee, Operating Lease, Term of Contract	17 years		17 years
Northwest Natural Gas Company [Member]
Lease Expense [Abstract]
Operating Lease, Expense	$ 1,817	1,767	$ 5,382	5,235
Short-term Lease, Cost	198	105	556	684
Other Northwest Holdings [Member] | Corporate, Non-Segment [Member]
Lease Expense [Abstract]
Operating Lease, Expense	$ 51	$ 7	$ 131	$ 22

Leases - Lease Asset and Liabil

Leases - Lease Asset and Liabilities - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Operating Lease Asset and Liabilities [Abstract]
Operating lease right of use asset	$ 71,477	$ 73,145	$ 71,477	$ 73,145	$ 73,429
Operating lease liabilities current liabilities	1,815	1,361	1,815	1,361	1,514
Operating lease liabilities noncurrent liabilities	77,475	78,469	77,475	78,469	78,965
Total operating lease liabilities	$ 79,290	$ 79,830	$ 79,290	$ 79,830	$ 80,479
Operating Lease, Weighted Average Remaining Lease Term	16 years 6 months	17 years 6 months	16 years 6 months	17 years 6 months	17 years 2 months 12 days
Operating Lease, Weighted Average Discount Rate, Percent	7.30%	7.30%	7.30%	7.30%	7.30%
Commencement of Significant Lease [Abstract]
Lessee, Operating Lease, Liability, Payments, Due	$ 140,866		$ 140,866
Regulatory Assets, Noncurrent	312,665	$ 301,660	312,665	$ 301,660	$ 340,432
Maturity of Operating Lease Liabilities [Abstract]
Lessee, Operating Lease, Liability, Payments, Remainder of Fiscal Year	1,845		1,845
Lessee, Operating Lease, Liability, to be Paid, Year One	7,490		7,490
Lessee, Operating Lease, Liability, Payments, Due Year Two	7,369		7,369
Lessee, Operating Lease, Liability, Payments, Due Year Three	7,514		7,514
Lessee, Operating Lease, Liability, Payments, Due Year Four	7,645		7,645
Lessee, Operating Lease, Liability, Payments, Due after Year Five	109,003		109,003
Lessee, Operating Lease, Liability, Payments, Due	140,866		140,866
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	61,576		61,576
Total operating lease liabilities	79,290	79,830	79,290	79,830	80,479
Operating lease liabilities current liabilities	1,815	1,361	1,815	1,361	1,514
Operating lease liabilities noncurrent liabilities	77,475	78,469	77,475	78,469	78,965
Finance Lease, Liability, Payments, Due Next Twelve Months	0		0		0
Leases Cash Flow [Abstract]
Operating Lease, Payments	1,863	1,771	5,506	5,249
Finance Lease, Principal Payments	196	92	369	474
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	0	61	81	61
Right-of-Use Asset Obtained in Exchange for Finance Lease Liability	207	6	470	226
Finance Leases [Abstract]
Finance Lease, Liability	0		0
Finance Lease, Right-of-Use Asset	2,600	2,300	2,600	2,300	2,300
Other Northwest Holdings [Member] | Corporate, Non-Segment [Member]
Operating Lease Asset and Liabilities [Abstract]
Operating lease right of use asset	625	99	625	99	709
Operating lease liabilities current liabilities	157	63	157	63	151
Operating lease liabilities noncurrent liabilities	434	33	434	33	620
Total operating lease liabilities	591	96	591	96	771
Commencement of Significant Lease [Abstract]
Lessee, Operating Lease, Liability, Payments, Due	675		675
Maturity of Operating Lease Liabilities [Abstract]
Lessee, Operating Lease, Liability, Payments, Remainder of Fiscal Year	44		44
Lessee, Operating Lease, Liability, to be Paid, Year One	183		183
Lessee, Operating Lease, Liability, Payments, Due Year Two	176		176
Lessee, Operating Lease, Liability, Payments, Due Year Three	153		153
Lessee, Operating Lease, Liability, Payments, Due Year Four	107		107
Lessee, Operating Lease, Liability, Payments, Due after Year Five	12		12
Lessee, Operating Lease, Liability, Payments, Due	675		675
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	84		84
Total operating lease liabilities	591	96	591	96	771
Operating lease liabilities current liabilities	157	63	157	63	151
Operating lease liabilities noncurrent liabilities	434	33	434	33	620
Leases Cash Flow [Abstract]
Operating Lease, Payments	54	12	132	24
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	0	61	0	61
Northwest Natural Gas Company [Member]
Operating Lease Asset and Liabilities [Abstract]
Operating lease right of use asset	70,852	73,046	70,852	73,046	72,720
Operating lease liabilities current liabilities	1,658	1,298	1,658	1,298	1,363
Operating lease liabilities noncurrent liabilities	77,041	78,436	77,041	78,436	78,345
Total operating lease liabilities	78,699	79,734	78,699	79,734	79,708
Commencement of Significant Lease [Abstract]
Lessee, Operating Lease, Liability, Payments, Due	140,191		140,191
Regulatory Assets, Noncurrent	312,640	301,596	312,640	301,596	340,407
Maturity of Operating Lease Liabilities [Abstract]
Lessee, Operating Lease, Liability, Payments, Remainder of Fiscal Year	1,801		1,801
Lessee, Operating Lease, Liability, to be Paid, Year One	7,307		7,307
Lessee, Operating Lease, Liability, Payments, Due Year Two	7,193		7,193
Lessee, Operating Lease, Liability, Payments, Due Year Three	7,361		7,361
Lessee, Operating Lease, Liability, Payments, Due Year Four	7,538		7,538
Lessee, Operating Lease, Liability, Payments, Due after Year Five	108,991		108,991
Lessee, Operating Lease, Liability, Payments, Due	140,191		140,191
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	61,492		61,492
Total operating lease liabilities	78,699	79,734	78,699	79,734	79,708
Operating lease liabilities current liabilities	1,658	1,298	1,658	1,298	1,363
Operating lease liabilities noncurrent liabilities	77,041	78,436	77,041	78,436	78,345
Leases Cash Flow [Abstract]
Operating Lease, Payments	1,809	1,759	5,374	5,225
Finance Lease, Principal Payments	196	92	369	474
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	0	0	81	0
Right-of-Use Asset Obtained in Exchange for Finance Lease Liability	196	6	369	226
Other Northwest Holdings [Member] | Corporate, Non-Segment [Member]
Leases Cash Flow [Abstract]
Right-of-Use Asset Obtained in Exchange for Finance Lease Liability	$ 11		$ 101	0
New Headquarters Lease [Member]
Commencement of Significant Lease [Abstract]
Lessee, Operating Lease, Term of Contract	20 years		20 years
Regulatory Assets, Noncurrent	$ 7,800	$ 6,600	$ 7,800	$ 6,600	$ 6,900
New Headquarters Lease Renewal Term 2 of 2 [Member] | New Headquarters Lease [Member]
Commencement of Significant Lease [Abstract]
Lessee, Operating Lease, Renewal Term	7 years		7 years
New Headquarters Lease Renewal Term 1 of 2 [Member] | New Headquarters Lease [Member]
Commencement of Significant Lease [Abstract]
Lessee, Operating Lease, Renewal Term	7 years		7 years
Maximum [Member]
Commencement of Significant Lease [Abstract]
Lessee, Operating Lease, Term of Contract	17 years		17 years

Stock-Based Compensation_2

Stock-Based Compensation - Long Term Incentive Plan $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2023 USD ($) $ / shares shares
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares granted (in shares)	55,250
Award vesting period	3 years
Unrecognized compensation costs | $	$ 100
Performance Shares | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Conversion ratio, percent of target	0%
Performance Shares | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Conversion ratio, percent of target	200%
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	4 years
Number of RSUs granted in period (in shares)	45,532
Weighted-average grant date fair value (in dollars per share) | $ / shares	$ 48.24
Unrecognized compensation costs | $	$ 3,500
A 2021 and 2022 Award | Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Payment Arrangement, Expense | $	$ 0
Target Achieved [Member] | A 2021 Award | Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share Based Compensation Award Target Share	49,100
Target Achieved [Member] | A 2022 Award | Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share Based Compensation Award Target Share	52,765

Debt Short-term Debt

Debt Short-term Debt - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022	Sep. 30, 2022
Short-term Debt [Line Items]
Short-term debt	$ 71,000	$ 258,200	$ 141,000
Northwest Natural Gas Company [Member]
Short-term Debt [Line Items]
Short-term debt	0	170,200	53,000
Line of Credit [Member]
Short-term Debt [Line Items]
Short-term debt	$ 71,000	$ 88,000	$ 88,000
Debt, Weighted Average Interest Rate	6.40%	5.30%	4.70%
Commercial Paper [Member] | Northwest Natural Gas Company [Member]
Short-term Debt [Line Items]
Short-term debt	$ 0	$ 170,200	$ 53,000
Debt, Weighted Average Interest Rate	0%	4.60%	3.30%

Long-Term Debt

Long-Term Debt - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Mar. 31, 2023	Sep. 30, 2023	Sep. 30, 2022	Aug. 19, 2023	Aug. 04, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
Long-term Debt		$ 1,615,300	$ 1,337,620			$ 1,336,864
Other Long-Term Debt		5,800	6,300			6,200
Unamortized debt issuance costs		10,245	8,348			8,987
Long-term Debt, Gross		1,625,545	1,345,968			1,345,851
Long-term debt, Current Maturities, Gross		190,700	50,600			90,700
Long-term debt		1,424,572	1,287,006			1,246,167
Northwest Natural Gas Company [Member]
Debt Instrument [Line Items]
Long-term Debt		1,404,553	1,126,471			1,125,877
Unamortized debt issuance costs		$ 10,147	$ 8,229			$ 8,823
Weighted average interest rate		4.70%	4.50%			4.50%
Long-term Debt, Gross		$ 1,414,700	$ 1,134,700			$ 1,134,700
Long-term debt		$ 1,364,556	1,076,533			1,035,935
Northwest Natural Gas Company [Member] | Minimum [Member]
Debt Instrument [Line Items]
Stated interest rate		2.80%
Northwest Natural Gas Company [Member] | Maximum [Member]
Debt Instrument [Line Items]
Stated interest rate		7.90%
Northwest Holdings and Northwest Natural [Member]
Debt Instrument [Line Items]
Unamortized debt issuance costs		$ 10,200	$ 8,400			$ 9,000
18 Month Credit Agreement Due March 15, 2024
Debt Instrument [Line Items]
Weighted average interest rate		5.50%	4.10%			4.20%
Long-term Debt, Term		18 months
Proceeds from Issuance of Debt	$ 100,000	$ 100,000	$ 100,000
Debt Instrument Covenant Consolidated Indebtedness to Capitalization Ratio		70%
Derivative, Fixed Interest Rate		4.70%
18 Month Credit Agreement Due March 15, 2024 | NWN Water
Debt Instrument [Line Items]
Weighted average interest rate		5.70%	4.10%			4.20%
Long-term Debt, Term		18 months
Proceeds from Issuance of Debt	$ 50,000	$ 50,000	$ 50,000
Debt Instrument Covenant Consolidated Indebtedness to Capitalization Ratio		70%
NWN Water Term Loan Due 2026
Debt Instrument [Line Items]
Derivative, Fixed Interest Rate		3.80%
NWN Water Term Loan Due 2026 | Corporate, Non-Segment [Member] | Other Northwest Holdings [Member]
Debt Instrument [Line Items]
Long-term Debt		$ 55,000
NWN Water Term Loan Due 2026 | NWN Water
Debt Instrument [Line Items]
Long-term Debt		$ 55,000	$ 55,000			$ 55,000
Weighted average interest rate		4.80%	3.50%			2.50%
Note 5430 Series Due 2053 | Northwest Natural Gas Company [Member]
Debt Instrument [Line Items]
Stated interest rate		5.43%
Proceeds from Issuance of First Mortgage Bond		$ 100,000
Note 5750 | Northwest Natural Gas Company [Member]
Debt Instrument [Line Items]
Stated interest rate		5.75%
Proceeds from Issuance of Medium-term Notes		$ 100,000
Note 5180 due 2034
Debt Instrument [Line Items]
Stated interest rate					5.18%
Note 5180 due 2034 | Northwest Natural Gas Company [Member]
Debt Instrument [Line Items]
Proceeds from Issuance of Medium-term Notes		80,000
Note 5230 due 2038
Debt Instrument [Line Items]
Stated interest rate					5.23%
Note 5230 due 2038 | Northwest Natural Gas Company [Member]
Debt Instrument [Line Items]
Secured Debt					$ 50,000
Note 3540 due 2023
Debt Instrument [Line Items]
Stated interest rate				3.50%
Note 3540 due 2023 | Northwest Natural Gas Company [Member]
Debt Instrument [Line Items]
Repayments of First Mortgage Bond		50,000
Repayments of First Mortgage Bond		$ 50,000
Note 5620 due 2023
Debt Instrument [Line Items]
Stated interest rate		5.60%
Secured Debt, Current		$ 40,000
Secured Debt, Current		$ 40,000

Debt Fair Value of Long Term De

Debt Fair Value of Long Term Debt - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022	Sep. 30, 2022
Debt Instrument [Line Items]
Gross long-term debt	$ 1,625,545	$ 1,345,851	$ 1,345,968
Unamortized debt issuance costs	(10,245)	(8,987)	(8,348)
Long-term Debt	1,615,300	1,336,864	1,337,620
Estimated fair value	1,385,144	1,148,395	1,133,087
Northwest Natural Gas Company [Member]
Debt Instrument [Line Items]
Gross long-term debt	1,414,700	1,134,700	1,134,700
Unamortized debt issuance costs	(10,147)	(8,823)	(8,229)
Long-term Debt	1,404,553	1,125,877	1,126,471
Estimated fair value	$ 1,176,212	$ 944,383	$ 927,372

Pension and Other Postretirem_3

Pension and Other Postretirement Benefit Costs - Net Periodic Benefit Cost - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Pension Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 842	$ 1,022	$ 2,940	$ 4,450
Interest cost	5,283	4,260	15,719	10,945
Expected return on plan assets	(6,421)	(7,076)	(19,292)	(19,274)
Amortization of net actuarial loss	0	0	0	0
Defined Benefit Plan, Amortization of Gain (Loss)	139	(1,542)	418	9,459
Net periodic benefit cost	(157)	(3,336)	(215)	5,580
Amount allocated to construction	(326)	(496)	(1,239)	(1,965)
Defined Benefit Plan Net Periodic Benefit Cost Charged To Expense	(483)	(3,832)	(1,454)	3,615
Amortization of Regulatory Balancing Account	675	675	4,757	4,757
Net amount charged to expense	192	(3,157)	3,303	8,372
Other Postretirement Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	27	34	83	145
Interest cost	247	213	743	543
Expected return on plan assets	0	0	0	0
Amortization of net actuarial loss	0	(15)	0	(249)
Defined Benefit Plan, Amortization of Gain (Loss)	0	57	0	319
Net periodic benefit cost	274	289	826	758
Amount allocated to construction	(9)	(14)	(29)	(57)
Defined Benefit Plan Net Periodic Benefit Cost Charged To Expense	265	275	797	701
Amortization of Regulatory Balancing Account	0	0	0	0
Net amount charged to expense	$ 265	$ 275	$ 797	$ 701

Pension and Other Postretirem_4

Pension and Other Postretirement Benefit Costs - Amounts Recognized in Accumulated Other Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]
Beginning balance			$ (6,285)
Ending balance	$ (4,979)	$ (10,808)	(4,979)	$ (10,808)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Accumulated other comprehensive loss	(4,979)	(10,808)	(4,979)	(10,808)
Northwest Natural Gas Company [Member]
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]
Beginning balance			(6,414)
Ending balance	(6,107)	(10,808)	(6,107)	(10,808)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Accumulated other comprehensive loss	(6,107)	(10,808)	(6,107)	(10,808)
Non-Qualified Pension Plans, Defined Benefit | Northwest Natural Gas Company [Member]
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]
Beginning balance	(6,209)	(11,010)	(6,414)	(11,404)
Amortization of actuarial losses	139	275	418	811
Total reclassifications before tax	139	275	418	811
Tax benefit	(37)	(73)	(111)	(215)
Total reclassifications for the period	102	202	307	596
Ending balance	(6,107)	(10,808)	(6,107)	(10,808)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Accumulated other comprehensive loss	(6,107)	(10,808)	(6,107)	(10,808)
Amortization of actuarial losses	139	275	418	811
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax	139	275	418	811
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, Tax, Attributable to Parent	37	73	111	215
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax	$ 102	$ 202	$ 307	$ 596

Pension and Other Postretirem_5

Pension and Other Postretirement Benefit Costs - Narrative - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Jun. 30, 2023	Dec. 31, 2022	Jun. 30, 2022	Dec. 31, 2021
Pension and Other Postretirement Benefits Cost (Reversal of Cost) [Abstract]
Defined benefit pension plan cash contributions			$ 0
Estimated future employer contributions in next fiscal year	$ 0		0
Employer contributions			8,000	$ 7,400
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Accumulated other comprehensive loss	(4,979)	$ (10,808)	(4,979)	(10,808)		$ (6,285)
Northwest Natural Gas Company [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Accumulated other comprehensive loss	(6,107)	(10,808)	(6,107)	(10,808)		(6,414)
Non-Qualified Pension Plans, Defined Benefit | Northwest Natural Gas Company [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Accumulated other comprehensive loss	(6,107)	(10,808)	(6,107)	(10,808)	$ (6,209)	$ (6,414)	$ (11,010)	$ (11,404)
Amortization of actuarial losses	139	275	418	811
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax	139	275	418	811
Tax benefit	(37)	(73)	(111)	(215)
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax	$ 102	$ 202	$ 307	$ 596

Income Tax_2_3

Income Tax - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Income taxes at statutory rates (federal and state)	$ (6,716)	$ (5,533)	$ 13,928	$ 10,710
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount	(2,742)	(2,376)	5,618	4,298
Differences required to be flowed-through by regulatory commissions	1,015	1,232	(2,055)	(2,003)
Other, net	151	(81)	(393)	(370)
Total provision for income taxes on continuing operations	$ (8,292)	$ (6,758)	$ 17,098	$ 12,635
Effective tax rate for continuing operations	25.90%	25.70%	25.80%	24.80%
Northwest Natural Gas Company [Member]
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Income taxes at statutory rates (federal and state)	$ (6,131)	$ (5,305)	$ 15,723	$ 11,554
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount	(2,633)	(2,306)	5,990	4,497
Differences required to be flowed-through by regulatory commissions	1,018	1,232	(2,051)	(2,003)
Other, net	39	(76)	(625)	(370)
Total provision for income taxes on continuing operations	$ (7,707)	$ (6,455)	$ 19,037	$ 13,678
Effective tax rate for continuing operations	26.40%	25.60%	25.40%	24.90%

Property, Plant and Equipment_3

Property, Plant and Equipment - USD ($)	Sep. 30, 2023	Dec. 31, 2022	Sep. 30, 2022
Property, Plant and Equipment [Line Items]
Property, plant, and equipment	$ 4,468,602,000	$ 4,261,566,000	$ 4,207,328,000
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	1,189,968,000	1,147,166,000	1,166,150,000
Total property, plant, and equipment, net	3,278,634,000	3,114,400,000	3,041,178,000
Natural Gas Distribution [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment	4,096,560,000	3,992,676,000	3,888,092,000
Public Utilities, Property, Plant and Equipment, Construction Work in Progress	153,231,000	78,897,000	161,658,000
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	1,152,952,000	1,115,690,000	1,135,965,000
Total property, plant, and equipment, net	3,096,839,000	2,955,883,000	2,913,785,000
Other Northwest Natural [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment	70,363,000	70,368,000	69,626,000
Public Utilities, Property, Plant and Equipment, Construction Work in Progress	8,323,000	6,606,000	5,112,000
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	22,331,000	21,541,000	21,435,000
Total property, plant, and equipment, net	56,355,000	55,433,000	53,303,000
Northwest Natural Gas Company [Member]
Property, Plant and Equipment [Line Items]
Total property, plant, and equipment, net	3,153,194,000	3,011,316,000	2,967,088,000
Property, Plant, Equipment non-cash	21,402,000	24,584,000	43,954,000
Other Northwest Holdings [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment	127,721,000	92,979,000	66,208,000
Public Utilities, Property, Plant and Equipment, Construction Work in Progress	12,404,000	20,040,000	16,632,000
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	14,685,000	9,935,000	8,750,000
Total property, plant, and equipment, net	125,440,000	103,084,000	74,090,000
Northwest Holdings [Member]
Property, Plant and Equipment [Line Items]
Property, Plant, Equipment non-cash	22,686,000	25,318,000	45,374,000
Northwest Natural Gas Company [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment	4,328,477,000	4,148,547,000	4,124,488,000
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	1,175,283,000	1,137,231,000	1,157,400,000
Total property, plant, and equipment, net	$ 3,153,194,000	$ 3,011,316,000	$ 2,967,088,000

Investments_2_3

Investments $ in Thousands	3 Months Ended
	Sep. 30, 2023 USD ($) numberOfProjects numberOfConnections employee	Dec. 31, 2022 USD ($)	Sep. 30, 2022 USD ($)	Jul. 31, 2022 USD ($)	Dec. 31, 2021
Schedule of Equity Method Investments [Line Items]
Life Insurance, Corporate or Bank Owned, Amount	$ 46,870	$ 49,358	$ 49,043
Gas reserves, noncurrent	21,439	22,970	23,770
Equity Method Investment, Aggregate Cost	36,253	23,376	23,756
Other investments	104,562	95,704	96,569
Total cumulative gas reserves investment	188,000
Deferred Taxes Related To Gas Reserves	4,400	5,200	5,500
Gas reserves, current	$ 2,400	3,400	3,700
Investments, Number of RNG Development Projects | numberOfProjects	4
Northwest Natural Gas Company [Member]
Schedule of Equity Method Investments [Line Items]
Life Insurance, Corporate or Bank Owned, Amount	$ 46,870	49,358	49,043
Gas reserves, noncurrent	21,439	22,970	23,770
Equity Method Investment, Aggregate Cost	19,444	7,782	8,058
Other investments	87,753	$ 80,110	$ 80,871
Lexington | Northwest Natural Gas Company [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Aggregate Cost	7,800
Dakota City | Northwest Natural Gas Company [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Aggregate Cost	11,600
Deconsolidation, Gain (Loss), Amount	$ 0
Other Northwest Holdings [Member] | Avion Water
Schedule of Equity Method Investments [Line Items]
Ownership percentage of Avion	43.10%	40.30%			37.30%
Investment balance in Avion		$ 14,500
Equity Method Investment, Number of Customer Connections | numberOfConnections	15,000
Equity Method Investment, Number of Employees | employee	35
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity	$ 8,800
Equity Method Investment, Additional Underlying Equity in Net Assets	$ 1,000			$ 1,000

Business Combinations Busines_2

Business Combinations Business Combinations	9 Months Ended	12 Months Ended
	Sep. 30, 2023 USD ($) numberOfConnections	Dec. 31, 2022 USD ($)	Dec. 31, 2021	Sep. 30, 2022 USD ($)
Business Acquisition [Line Items]
Goodwill	$ 152,399,000	$ 149,283,000		$ 74,732,000
Goodwill, Impairment Loss	0
Business Combination, Consideration Transferred	3,600,000	105,700,000
Business Combination, Consideration Transferred	$ 3,600,000	$ 105,700,000
Other insignificant acquisitions [Member]
Business Acquisition [Line Items]
Number of Businesses Acquired	7		2

Derivative Instruments Notional

Derivative Instruments Notional Amounts - Northwest Natural Gas Company [Member] therm in Thousands, $ in Thousands	Sep. 30, 2023 USD ($) therm	Dec. 31, 2022 USD ($) therm	Sep. 30, 2022 USD ($) therm
Gas Year 2021-2022
Derivative [Line Items]
TargetHedgeAchieved	84%
Gas Year 2021-2022 | Oregon [Member]
Derivative [Line Items]
TargetHedgeAchieved	85%
Gas Year 2021-2022 | WASHINGTON
Derivative [Line Items]
TargetHedgeAchieved	79%
Financial [Member] | Gas Year 2021-2022
Derivative [Line Items]
TargetHedgeAchieved	67%
Financial [Member] | Gas Year 2021-2022 | Oregon [Member]
Derivative [Line Items]
TargetHedgeAchieved	67%
Financial [Member] | Gas Year 2021-2022 | WASHINGTON
Derivative [Line Items]
TargetHedgeAchieved	66%
Physical [Member] | Gas Year 2021-2022
Derivative [Line Items]
TargetHedgeAchieved	17%
Physical [Member] | Gas Year 2021-2022 | Oregon [Member]
Derivative [Line Items]
TargetHedgeAchieved	18%
Physical [Member] | Gas Year 2021-2022 | WASHINGTON
Derivative [Line Items]
TargetHedgeAchieved	13%
Natural Gas Therms [Member] | Financial [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	1,080,345	852,435	1,006,665
Natural Gas Therms [Member] | Physical [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	749,838	463,254	672,350
Foreign Exchange Contract [Member]
Derivative [Line Items]
Derivative, Notional Amount | $	$ 10,483	$ 7,617	$ 9,905

Unrealized and Realized Gain_Lo

Unrealized and Realized Gain/Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Derivative [Line Items]
Derivative, Gain on Derivative	$ 16,900		$ 145,700	$ 74,000
Derivative, Gain (Loss) on Derivative, Net	174	$ 0	999	0
Derivative, Loss on Derivative	7,500
Financial [Member]
Derivative [Line Items]
Incremental Cost or Benefit to Collect or Refund to Customers			0
Northwest Holdings and Northwest Natural [Member] | Natural gas commodity
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	0	0	0	0
Northwest Holdings and Northwest Natural [Member] | Foreign exchange
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	0	0	0	0
Northwest Holdings and Northwest Natural [Member] | Benefit (expense) to cost of gas | Natural gas commodity
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	14,516	11,626	(58,741)	(32,827)
Northwest Holdings and Northwest Natural [Member] | Benefit (expense) to cost of gas | Foreign exchange
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	(276)	(455)	(95)	(528)
Northwest Holdings and Northwest Natural [Member] | Sales [Member] | Natural gas commodity
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	0	0	0	0
Northwest Holdings and Northwest Natural [Member] | Sales [Member] | Foreign exchange
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	0	0	0	0
Deferred Derivative Gain (Loss) [Member] | Northwest Holdings and Northwest Natural [Member] | Natural gas commodity
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	(14,516)	11,626	58,741	(32,827)
Deferred Derivative Gain (Loss) [Member] | Northwest Holdings and Northwest Natural [Member] | Foreign exchange
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	$ 276	$ 455	$ 95	$ 528

Derivative Instruments Credit R

Derivative Instruments Credit Rating - USD ($)	Sep. 30, 2023	Dec. 31, 2022	Sep. 30, 2022
Collateral Posted with NW Natural Counterparties [Member]
Derivative [Line Items]
Additional Collateral, Aggregate Fair Value	$ 0		$ 0
Northwest Natural Gas Company [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	10,100,000	$ 153,300,000	40,800,000
Derivative liability	$ 48,100,000	$ 3,600,000	$ 8,500,000

Derivative Instruments Fair Val

Derivative Instruments Fair Value - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Dec. 31, 2022	Sep. 30, 2022
Derivative [Line Items]
Derivative, Fair Value, Net	$ (38,000)	$ 149,700	$ 32,300
AOCI, Cash Flow Hedge, Cumulative Gain (Loss), after Tax	1,100	$ 100
Derivative Instruments, Gain Reclassified from Accumulated OCI into Income, Effective Portion	0
Derivative Credit Risk Valuation Adjustment, Derivative Liabilities	$ 300

Environmental Matters_2_3

Environmental Matters $ in Thousands	Sep. 30, 2023 USD ($)
Oregon [Member]
Site Contingency [Line Items]
Remediation Recovery Percentage	96.70%
Inventory, Emissions Allowances	$ 0
WASHINGTON
Site Contingency [Line Items]
Remediation Recovery Percentage	3.30%
Inventory, Emissions Allowances	$ 18,300

Environmental Matters - Environ

Environmental Matters - Environmental Sites $ in Thousands	1 Months Ended	3 Months Ended	9 Months Ended
	Jan. 31, 2017 USD ($)	Sep. 30, 2023 USD ($) property party	Sep. 30, 2023 USD ($) party property	Dec. 31, 2022 USD ($)	Sep. 30, 2022 USD ($)
Site Contingency [Line Items]
Current Liabilities		$ 31,923	$ 31,923	$ 28,902	$ 16,554
Non-Current Liabilities		84,602	84,602	89,905	83,276
Gasco/Siltronic Sediments
Site Contingency [Line Items]
Current Liabilities		18,679	18,679	9,744	5,556
Non-Current Liabilities		41,392	41,392	42,120	40,740
Site Contingency, Environmental Remediation Costs Recognized		60,100	60,100
Accrual for Environmental Loss Contingencies, Period Increase (Decrease)		10,100
Gasco/Siltronic Sediments | Minimum [Member]
Site Contingency [Line Items]
Environmental Exit Costs, Anticipated Cost			60,100
Gasco/Siltronic Sediments | Maximum [Member]
Site Contingency [Line Items]
Environmental Exit Costs, Anticipated Cost			350,000
Portland Harbor Other [Member]
Site Contingency [Line Items]
Current Liabilities		3,524	3,524	2,634	2,430
Non-Current Liabilities		$ 9,580	$ 9,580	11,270	8,135
Gasco Uplands [Member]
Site Contingency [Line Items]
Site contingency: number of management pieces		2	2
Gasco/Siltronic Upland [Member]
Site Contingency [Line Items]
Current Liabilities		$ 8,908	$ 8,908	16,067	8,367
Non-Current Liabilities		32,512	32,512	35,457	33,354
Front Street [Member]
Site Contingency [Line Items]
Current Liabilities		812	812	457	201
Non-Current Liabilities		939	939	879	868
Additional studies and design costs			1,800
Oregon Steel Mills [Member]
Site Contingency [Line Items]
Current Liabilities		0	0	0	0
Non-Current Liabilities		$ 179	$ 179	$ 179	$ 179
Portland Harbor [Member]
Site Contingency [Line Items]
Number of potentially responsible parties (more than) | party		100	100
EPA final feasibility study and proposed remediation plan, clean-up costs, portland harbor	$ 1,050,000
Number of remediation projects | property		2	2
Portland Harbor [Member] | Minimum [Member]
Site Contingency [Line Items]
Percentage of clean-up costs	(30.00%)
Portland Harbor [Member] | Maximum [Member]
Site Contingency [Line Items]
Percentage of clean-up costs	50%
Yakama Nation [Member] | Portland Harbor Other [Member]
Site Contingency [Line Items]
Trustee Council Members - Number of Claimants			1
Site Contingency, Number of Other Third-Party Defendants		29	29
NRD liability claim yakama nation		$ 300	$ 300
Number of Amended Complaints Filed			2

Environmental Matters - Regulat

Environmental Matters - Regulatory Deferred Assets - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Dec. 31, 2022	Sep. 30, 2022
Site Contingency [Line Items]
Regulatory Assets, Current	$ 108,525	$ 117,491	$ 104,830
Regulatory Assets, Noncurrent	$ 312,665	$ 340,432	$ 301,660
Remediation Non-recovery Percentage	3.30%	3.30%	3.30%
Annual tariff rider collection	$ 5,000
Annual insurance proceeds to apply against remediation costs	5,000
Total annual remediation expense and interest	$ 10,000
Oregon [Member]
Site Contingency [Line Items]
Remediation Recovery Percentage	96.70%
Front Street [Member] | Environmental costs [Member]
Site Contingency [Line Items]
Accrued site liabilities	$ 57	$ 43	$ 34
Northwest Natural Gas Company [Member]
Site Contingency [Line Items]
Regulatory Assets, Current	108,525	117,491	104,830
Regulatory Assets, Noncurrent	312,640	340,407	301,596
Northwest Natural Gas Company [Member] | Environmental costs [Member]
Site Contingency [Line Items]
Deferred costs and interest	49,899	47,666	47,011
Accrued site liabilities	116,469	118,763	99,795
Insurance proceeds and interest	(50,380)	(54,784)	(54,678)
Regulatory Assets	115,988	111,645	92,128
Regulatory Assets, Current	7,047	7,392	9,461
Regulatory Assets, Noncurrent	$ 108,941	$ 104,253	$ 82,667

Subsequent Events

Subsequent Events - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2023	Dec. 31, 2022
Subsequent Event [Line Items]
Business Combination, Consideration Transferred	$ 3,600	$ 105,700