Northwest Natural Holding (NWN) 10-K 24 Feb 23 2022 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2022	Feb. 16, 2023	Jun. 30, 2022
Document Information [Line Items]
Document Type	10-K
Document Period End Date	Dec. 31, 2022
Entity File Number	1-38681
Document Annual Report	true
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Central Index Key	0001733998
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Registrant Name	NORTHWEST NATURAL HOLDING COMPANY
Entity Voluntary Filers	No
Entity Well-known Seasoned Issuer	Yes
Entity Common Stock, Shares Outstanding		35,539,262
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	FY
Entity Public Float			$ 1,825,498,356
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Document Transition Report	false
Entity Incorporation, State or Country Code	OR
Entity Tax Identification Number	82-4710680
Entity Address, Address Line One	250 S.W. 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 Interactive Data Current	Yes
Entity Shell Company	false
Documents Incorporated by Reference [Text Block]	Portions of Northwest Natural Holding Company's Proxy Statement, to be filed in connection with the 2023 Annual Meeting of Shareholders, are incorporated by reference in Part III.
Northwest Natural Gas Company [Member]
Document Information [Line Items]
Document Type	10-K
Document Period End Date	Dec. 31, 2022
Entity File Number	1-15973
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Central Index Key	0000073020
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
Entity Registrant Name	NORTHWEST NATURAL GAS COMPANY
Entity Voluntary Filers	No
Entity Well-known Seasoned Issuer	No
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	FY
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	false
Entity Incorporation, State or Country Code	OR
Entity Tax Identification Number	93-0256722
Entity Address, Address Line One	250 S.W. 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 Interactive Data Current	Yes
Entity Shell Company	false

Audit Information

Audit Information	12 Months Ended
	Dec. 31, 2022
Auditor [Line Items]
Auditor Firm ID	238
Auditor Name	PricewaterhouseCoopers LLP
Auditor Location	Portland, Oregon
Northwest Natural Gas Company [Member]
Auditor [Line Items]
Auditor Firm ID	238
Auditor Name	PricewaterhouseCoopers LLP
Auditor Location	Portland, Oregon

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) shares in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Operating revenues [Abstract]
Operating revenues	$ 1,037,353,000	$ 860,400,000	$ 773,679,000
Operating expenses:
Cost of gas	429,635,000	292,314,000	262,755,000
Operations and maintenance	224,667,000	204,227,000	180,129,000
Environmental remediation	12,389,000	9,938,000	9,691,000
General taxes	41,031,000	38,633,000	35,078,000
Revenue taxes	41,826,000	34,740,000	30,291,000
Depreciation	116,707,000	113,534,000	103,683,000
Other operating expenses	3,621,000	3,897,000	3,701,000
Total operating expenses	869,876,000	697,283,000	625,328,000
Income from operations	167,477,000	163,117,000	148,351,000
Other income (expense), net	1,203,000	(12,559,000)	(13,944,000)
Interest expense, net	53,247,000	44,486,000	43,052,000
Income before income taxes	115,433,000	106,072,000	91,355,000
Income tax expense	29,130,000	27,406,000	21,082,000
Net income from continuing operations	86,303,000	78,666,000	70,273,000
Income from discontinued operations, net of tax	0	0	6,508,000
Net income	86,303,000	78,666,000	76,781,000
Other comprehensive income (loss):
Change in employee benefit plan liability, net of taxes	4,195,000	593,000	(2,848,000)
Amortization of non-qualified employee benefit plan liability, net of taxes	795,000	905,000	679,000
Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	129,000	0	0
Comprehensive income	91,422,000	80,164,000	74,612,000
Supplemental Income Statement Elements [Abstract]
Change in employee benefit plan liability, taxes	(1,511)	(219)	1,025
Amortization of non-qualified employee benefit plan liability, taxes	(286)	$ (320)	$ (244)
Unrealized Gain on Derivative, tax	$ (47)
Average common shares outstanding:
Basic (in shares)	33,934	30,702	30,541
Diluted (in shares)	33,984	30,752	30,599
Earnings from continuing operations per share of common stock:
Basic (in dollars per share)	$ 2.54	$ 2.56	$ 2.30
Diluted (in dollars per share)	2.54	2.56	2.30
Earnings from discontinued operations per share of common stock, basic
Basic (in dollars per share)	0	0	0.21
Earnings from discontinued operations per share of common stock, diluted
Diluted (in dollars per share)	0	0	0.21
Earnings per share of common stock:
Basic (in dollars per share)	2.54	2.56	2.51
Diluted (in dollars per share)	$ 2.54	$ 2.56	$ 2.51
Northwest Natural Gas Company [Member]
Operating revenues [Abstract]
Operating revenues	$ 1,014,339,000	$ 843,057,000	$ 758,748,000
Operating expenses:
Cost of gas	429,861,000	292,538,000	262,980,000
Utility Operations and maintenance	204,845,000	188,762,000	168,869,000
Environmental remediation	12,389,000	9,938,000	9,691,000
General taxes	40,151,000	38,150,000	34,459,000
Revenue taxes	41,627,000	34,600,000	30,291,000
Depreciation	112,957,000	110,504,000	101,586,000
Other operating expenses	3,135,000	3,332,000	3,232,000
Total operating expenses	844,965,000	677,824,000	611,108,000
Income from operations	169,374,000	165,233,000	147,640,000
Other income (expense), net	(436,000)	(12,745,000)	(15,116,000)
Interest expense, net	46,338,000	42,983,000	40,866,000
Income before income taxes	122,600,000	109,505,000	91,658,000
Income tax expense	31,036,000	28,333,000	21,095,000
Net income	91,564,000	81,172,000	70,563,000
Other comprehensive income (loss):
Change in employee benefit plan liability, net of taxes	4,195,000	593,000	(2,848,000)
Amortization of non-qualified employee benefit plan liability, net of taxes	795,000	905,000	679,000
Comprehensive income	96,554,000	82,670,000	68,394,000
Supplemental Income Statement Elements [Abstract]
Change in employee benefit plan liability, taxes	(1,511)	(219)	1,025
Amortization of non-qualified employee benefit plan liability, taxes	$ (286)	$ (320)	$ (244)

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) shares in Thousands, $ / shares in Thousands, $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 29,270	$ 18,559
Accounts receivable	168,906	101,495
Accrued unbilled revenue	89,048	82,169
Allowance for uncollectible accounts	(3,296)	(2,018)
Regulatory assets	117,491	72,391
Derivative instruments	194,412	48,130
Inventories	87,096	57,262
Other current assets	61,286	59,288
Total current assets	744,213	437,276
Non-current assets:
Property, plant, and equipment	4,261,566	3,997,243
Less: Accumulated depreciation	1,147,166	1,125,873
Total property, plant, and equipment, net	3,114,400	2,871,370
Regulatory Assets, Noncurrent	340,432	314,579
Derivative instruments	5,045	10,730
Other investments	95,704	89,278
Operating lease right of use asset	73,429	75,049
Assets under sales-type leases	134,302	138,995
Goodwill	149,283	70,570
Other non-current assets	91,518	56,757
Total non-current assets	4,004,113	3,627,328
Total assets	4,748,326	4,064,604
Current liabilities:
Short-term debt	258,200	389,500
Current maturities of long-term debt	90,697	345
Accounts payable	180,667	133,486
Taxes accrued	15,625	15,520
Interest accrued	10,169	7,503
Regulatory liabilities	248,582	112,281
Derivative instruments	28,728	10,402
Operating lease liabilities	1,514	1,296
Other current liabilities	64,552	54,432
Total current liabilities	898,734	724,765
Long-term debt	1,246,167	1,044,587
Deferred credits and other non-current liabilities:
Deferred Income Tax Liabilities, Net	366,022	340,231
Regulatory liabilities	689,578	658,332
Pension and other postretirement benefit liabilities	149,143	166,684
Derivative instruments	20,838	412
Operating lease liabilities	78,965	79,468
Other non-current liabilities	123,438	114,979
Total deferred credits and other non-current liabilities	1,427,984	1,360,106
Commitments and contingencies (see Note 16 and Note 17)
Equity:
Common stock - no par value	805,253	590,771
Retained earnings	376,473	355,779
Accumulated other comprehensive loss	(6,285)	(11,404)
Total equity	1,175,441	935,146
Total liabilities and equity	$ 4,748,326	$ 4,064,604
Par Value (in dollars per share)	$ 0	$ 0
Shares Authorized (in shares)	100,000	100,000
Shares issued (in shares)	35,525	31,129
Shares outstanding (in shares)	35,525	31,129
Northwest Natural Gas Company [Member]
Current assets:
Cash and cash equivalents	$ 12,977	$ 12,271
Accounts receivable	165,607	99,780
Accrued unbilled revenue	87,482	82,028
Receivables from affiliates	634	261
Allowance for uncollectible accounts	(3,079)	(1,962)
Regulatory assets	117,491	72,391
Derivative instruments	194,236	48,130
Inventories	86,207	56,752
Other current assets	57,269	47,378
Total current assets	718,824	417,029
Non-current assets:
Property, plant, and equipment	4,148,547	3,931,640
Less: Accumulated depreciation	1,137,231	1,119,361
Total property, plant, and equipment, net	3,011,316	2,812,279
Regulatory Assets, Noncurrent	340,407	314,539
Derivative instruments	5,045	10,730
Other investments	80,110	74,786
Operating lease right of use asset	72,720	74,987
Assets under sales-type leases	134,302	138,995
Other non-current assets	89,994	55,027
Total non-current assets	3,733,894	3,481,343
Total assets	4,452,718	3,898,372
Current liabilities:
Short-term debt	170,200	245,500
Current maturities of long-term debt	89,942	0
Accounts payable	177,590	131,475
Payables to affiliates	9,175	1,248
Taxes accrued	15,426	15,476
Interest accrued	8,900	7,296
Regulatory liabilities	248,553	112,281
Derivative instruments	28,728	10,402
Operating lease liabilities	1,363	1,273
Other current liabilities	62,019	53,591
Total current liabilities	811,896	578,542
Long-term debt	1,035,935	986,495
Deferred credits and other non-current liabilities:
Deferred Income Tax Liabilities, Net	362,353	337,717
Regulatory liabilities	688,599	657,350
Pension and other postretirement benefit liabilities	149,143	166,684
Derivative instruments	20,838	412
Operating lease liabilities	78,345	79,431
Other non-current liabilities	114,527	113,934
Total deferred credits and other non-current liabilities	1,413,805	1,355,528
Commitments and contingencies (see Note 16 and Note 17)
Equity:
Common stock - no par value	614,903	435,515
Retained earnings	582,593	553,696
Accumulated other comprehensive loss	(6,414)	(11,404)
Total equity	1,191,082	977,807
Total liabilities and equity	$ 4,452,718	$ 3,898,372

Consolidated Statement of Share

Consolidated Statement of Shareholders' Equity - USD ($) $ in Thousands	Total	Common Stock Including APIC [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Northwest Natural Gas Company [Member]	Northwest Natural Gas Company [Member] Northwest Natural Gas Company Consolidated [Member]	Northwest Natural Gas Company [Member] Common Stock Including APIC [Member]	Northwest Natural Gas Company [Member] Retained Earnings [Member]	Northwest Natural Gas Company [Member] Accumulated Other Comprehensive Income (Loss) [Member]
Beginning Balance at Dec. 31, 2019	$ 865,999	$ 558,282	$ 318,450	$ (10,733)		$ 822,196	$ 319,557	$ 513,372	$ (10,733)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income (loss)	74,612	0	76,781	(2,169)	$ 68,394	68,394	0	70,563	(2,169)
Dividends on common stock	(58,708)	0	(58,708)	0		(55,355)	0	(55,355)	0
Stockholders' Equity, Other						(51)	(51)	0	0
Shares issued pursuant to equity based plans	4,361	4,361	0	0
Capital contributions					0	116,009	116,009	0	0
Shares issued pursuant to equity based plans	2,469	(2,469)	0	0
Ending Balance at Dec. 31, 2020	$ 888,733	565,112	336,523	(12,902)		835,184	319,506	528,580	(12,902)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends on common stock (in dollars per share)	$ 1.91
Comprehensive income (loss)	$ 80,164	0	78,666	1,498	82,670	82,670	0	81,172	1,498
Dividends on common stock	(59,410)	0	(59,410)	0		(56,056)	0	(56,056)	0
Stock-based compensation	3,615	3,615	0	0
Shares issued pursuant to equity based plans	4,543	4,543	0	0
Capital contributions					116,009
Issuance of common stock, net of issuance costs	17,501	17,501	0	0
Ending Balance at Dec. 31, 2021	$ 935,146	590,771	355,779	(11,404)		977,807	435,515	553,696	(11,404)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends on common stock (in dollars per share)	$ 1.92
Comprehensive income (loss)	$ 91,422	0	86,303	5,119	96,554	96,554	0	91,564	4,990
Dividends on common stock	(65,609)	0	(65,609)	0		(62,667)	0	(62,667)	0
Stock-based compensation	3,228	3,228	0	0
Shares issued pursuant to equity based plans	2,978	2,978	0	0
Capital contributions					$ 179,388	179,388	179,388	0	0
Issuance of common stock, net of issuance costs	208,276	208,276	0	0
Ending Balance at Dec. 31, 2022	$ 1,175,441	$ 805,253	$ 376,473	$ (6,285)		$ 1,191,082	$ 614,903	$ 582,593	$ (6,414)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends on common stock (in dollars per share)	$ 1.93

Consolidated Statement of Cash

Consolidated Statement of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Operating activities:
Net income	$ 86,303	$ 78,666	$ 76,781
Adjustments to reconcile net income to cash provided by operations:
Depreciation	116,707	113,534	103,683
Regulatory amortization of gas reserves	5,589	13,897	17,779
Deferred income taxes	17,410	14,617	18,667
Qualified defined benefit pension plan expense	5,351	16,556	18,370
Contributions to qualified defined benefit pension plans	0	(9,590)	(28,980)
Deferred environmental expenditures, net	(18,160)	(18,187)	(27,871)
Environmental remediation expense	12,389	9,938	9,691
Gain on sale of discontinued operations, net of tax	0	0	(5,902)
Asset optimization revenue sharing bill credits	(41,102)	(9,053)	(16,970)
Other	21,558	20,622	10,028
Changes in assets and liabilities:
Receivables, net	(76,454)	(44,128)	(16,799)
Inventories	(29,269)	(14,571)	1,262
Income and other taxes	6,908	3,292	(10,710)
Accounts payable	24,508	12,118	(15,910)
Deferred gas costs	12,334	(40,541)	17,590
Asset optimization revenue sharing	28,937	44,458	(7,244)
Decoupling mechanism	10,922	(5,206)	2,884
Cloud-based software	(23,908)	(7,407)	(4,265)
Other, net	(12,351)	(18,662)	1,340
Discontinued operations	0	0	1,894
Cash provided by operating activities	147,672	160,353	145,318
Investing activities:
Capital expenditures	(338,602)	(293,892)	(273,016)
Acquisitions, net of cash acquired	(94,279)	(1,289)	(38,263)
Leasehold improvement expenditures	(761)	(1,364)	(7,878)
Proceeds from the sale of assets	870	3,926	8,149
Purchase of equity method investment	(1,000)	(14,450)	0
Proceeds from Sale of Equity Method Investments	0	7,000	7,000
Proceeds from sale of discontinued operations	0	0	12,500
Other	(1,688)	(54)	1,654
Discontinued operations	0	0	(4,423)
Cash used in investing activities	(435,460)	(300,123)	(294,277)
Financing activities:
Proceeds from common stock issued, net	208,561	17,501	0
Long-term debt issued	290,000	185,000	150,000
Long-term debt retired	0	(95,000)	(75,000)
Proceeds from term loan due within one year	0	100,000	150,000
Repayments of Short-term Debt	0	(100,000)	(150,000)
Proceeds from commercial paper, maturities greater than three months	0	0	195,025
Repayments of commercial paper, maturities greater than three months	0	(195,025)	0
Changes in other short-term debt, net	(131,300)	280,000	(39,600)
Cash dividend payments on common stock	(62,771)	(55,919)	(55,420)
Other	(2,858)	(5,121)	(3,228)
Cash provided by financing activities	301,632	131,436	171,777
Increase (decrease) in cash, cash equivalents and restricted cash	13,844	(8,334)	22,818
Cash, cash equivalents and restricted cash, beginning of period	18,559
Cash, cash equivalents and restricted cash, end of period	29,270	18,559
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	40,964	27,120	35,454
Supplemental disclosure of cash flow information:
Interest paid, net of capitalization	50,823	43,719	42,651
Income taxes paid, net of refunds	2,779	10,555	13,644
Northwest Natural Gas Company [Member]
Operating activities:
Net income	91,564	81,172	70,563
Adjustments to reconcile net income to cash provided by operations:
Depreciation	112,957	110,504	101,586
Regulatory amortization of gas reserves	5,589	13,897	17,779
Deferred income taxes	16,288	13,223	4,645
Qualified defined benefit pension plan expense	5,351	16,556	18,370
Contributions to qualified defined benefit pension plans	0	(9,590)	(28,980)
Deferred environmental expenditures, net	(18,160)	(18,187)	(27,871)
Environmental remediation expense	12,389	9,938	9,691
Asset optimization revenue sharing bill credits	(41,102)	(9,053)	(16,970)
Other	20,448	18,517	9,945
Changes in assets and liabilities:
Receivables, net	(75,177)	(43,030)	(16,540)
Inventories	(28,890)	(14,427)	1,539
Income and other taxes	6,729	(10,405)	10,832
Accounts payable	21,375	8,728	(18,909)
Deferred gas costs	12,334	(40,541)	17,590
Asset optimization revenue sharing	28,937	44,458	(7,244)
Decoupling mechanism	10,922	(5,206)	2,884
Cloud-based software	(23,908)	(7,407)	(4,265)
Other, net	(12,455)	(17,653)	3,872
Cash provided by operating activities	145,191	141,494	148,517
Investing activities:
Capital expenditures	(318,686)	(278,237)	(266,048)
Leasehold improvement expenditures	(761)	(1,364)	(7,878)
Proceeds from the sale of assets	870	3,926	8,149
Other	(1,688)	(54)	1,654
Cash used in investing activities	(320,265)	(275,729)	(264,123)
Financing activities:
Long-term debt issued	140,000	130,000	150,000
Long-term debt retired	0	(60,000)	(75,000)
Proceeds from term loan due within one year	0	100,000	150,000
Repayments of Short-term Debt	0	(100,000)	(150,000)
Proceeds from commercial paper, maturities greater than three months	0	0	195,025
Repayments of commercial paper, maturities greater than three months	0	(195,025)	0
Changes in other short-term debt, net	(75,300)	209,000	(88,600)
Cash contributions received from parent	179,388	116,009	0
Cash dividend payments on common stock	(62,667)	(56,056)	(55,355)
Other	(2,508)	(4,600)	(3,632)
Cash provided by financing activities	178,913	139,328	122,438
Increase (decrease) in cash, cash equivalents and restricted cash	3,839	5,093	6,832
Cash, cash equivalents and restricted cash, beginning of period	12,271
Cash, cash equivalents and restricted cash, end of period	12,977	12,271
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	24,671	20,832	15,739
Supplemental disclosure of cash flow information:
Interest paid, net of capitalization	44,813	42,395	40,624
Income taxes paid, net of refunds	$ 5,990	$ 26,451	$ 6,100

Pension and Other Postretiremen

Pension and Other Postretirement Benefits Costs - Schedule of Fair Value of Plan Assets - Pension Plan [Member] - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan Assets, Amount	$ 280,306	$ 399,217
Northwest Natural Gas Company [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan Assets, Amount	280,304	399,217
Total Pension Asset Investments Net Of Receivables And Payables	280,304	399,217
Accrued interest and dividend income	7,703	0
Total receivables	7,703	0
Due to broker for securities purchased	(7,701)	0
Northwest Natural Gas Company [Member] | United States Equity [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan Assets, Amount	68,729	121,090
Northwest Natural Gas Company [Member] | Non-U.S. equity [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan Assets, Amount	90,504	123,534
Northwest Natural Gas Company [Member] | Liability hedging [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan Assets, Amount	94,823	118,464
Northwest Natural Gas Company [Member] | Opportunistic [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan Assets, Amount	23,903	33,808
Northwest Natural Gas Company [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan Assets, Amount	2,345	2,321
Northwest Natural Gas Company [Member] | Level 1 [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Total Pension Asset Investments Net Of Receivables And Payables	26,677	35,456
Northwest Natural Gas Company [Member] | Level 1 [Member] | United States Equity [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan Assets, Amount	0	0
Northwest Natural Gas Company [Member] | Level 1 [Member] | Non-U.S. equity [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan Assets, Amount	26,677	35,456
Northwest Natural Gas Company [Member] | Level 1 [Member] | Liability hedging [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan Assets, Amount	0	0
Northwest Natural Gas Company [Member] | Level 1 [Member] | Opportunistic [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan Assets, Amount	0	0
Northwest Natural Gas Company [Member] | Level 1 [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan Assets, Amount	0	0
Northwest Natural Gas Company [Member] | Level 2 [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Total Pension Asset Investments Net Of Receivables And Payables	0	0
Northwest Natural Gas Company [Member] | Level 2 [Member] | United States Equity [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan Assets, Amount	0	0
Northwest Natural Gas Company [Member] | Level 2 [Member] | Non-U.S. equity [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan Assets, Amount	0	0
Northwest Natural Gas Company [Member] | Level 2 [Member] | Liability hedging [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan Assets, Amount	0	0
Northwest Natural Gas Company [Member] | Level 2 [Member] | Opportunistic [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan Assets, Amount	0	0
Northwest Natural Gas Company [Member] | Level 2 [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan Assets, Amount	0	0
Northwest Natural Gas Company [Member] | Level 3 [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Total Pension Asset Investments Net Of Receivables And Payables	0	0
Northwest Natural Gas Company [Member] | Level 3 [Member] | United States Equity [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan Assets, Amount	0	0
Northwest Natural Gas Company [Member] | Level 3 [Member] | Non-U.S. equity [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan Assets, Amount	0	0
Northwest Natural Gas Company [Member] | Level 3 [Member] | Liability hedging [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan Assets, Amount	0	0
Northwest Natural Gas Company [Member] | Level 3 [Member] | Opportunistic [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan Assets, Amount	0	0
Northwest Natural Gas Company [Member] | Level 3 [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan Assets, Amount	0	0
Northwest Natural Gas Company [Member] | Fair Value Measured at NAV [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Total Pension Asset Investments Net Of Receivables And Payables	253,627	363,761
Northwest Natural Gas Company [Member] | Fair Value Measured at NAV [Member] | United States Equity [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan Assets, Amount	68,729	121,090
Northwest Natural Gas Company [Member] | Fair Value Measured at NAV [Member] | Non-U.S. equity [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan Assets, Amount	63,827	88,078
Northwest Natural Gas Company [Member] | Fair Value Measured at NAV [Member] | Liability hedging [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan Assets, Amount	94,823	118,464
Northwest Natural Gas Company [Member] | Fair Value Measured at NAV [Member] | Opportunistic [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan Assets, Amount	23,903	33,808
Northwest Natural Gas Company [Member] | Fair Value Measured at NAV [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Plan Assets, Amount	$ 2,345	$ 2,321

Organization and Principles of

Organization and Principles of Consolidation	12 Months Ended
	Dec. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block]	ORGANIZATION AND PRINCIPLES OF CONSOLIDATION The accompanying consolidated financial statements represent the respective, consolidated financial results of NW Holdings and 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 an investment in Lexington Renewable Energy, LLC, which is 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. In June 2018, NWN Gas Storage, a wholly-owned subsidiary of NW Natural at the time and now a wholly-owned subsidiary of NW Holdings, entered into a Purchase and Sale Agreement that provided for the sale of all of the membership interests in its wholly-owned subsidiary, Gill Ranch Storage, LLC (Gill Ranch). We concluded that the sale of Gill Ranch qualified as assets and liabilities held for sale and discontinued operations. As such, the results of Gill Ranch were presented as a discontinued operation for NW Holdings for all periods presented on the consolidated statements of comprehensive income and cash flows, and the assets and liabilities associated with Gill Ranch were classified as discontinued operations assets and liabilities on the NW Holdings consolidated balance sheet. The sale closed on December 4, 2020. See Note 18 for additional information. Notes to the consolidated financial statements reflect the activity of continuing operations 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	12 Months Ended
	Dec. 31, 2022
Accounting Policies [Abstract]
Significant Accounting Policies	SIGNIFICANT ACCOUNTING POLICIES Use of Estimates The preparation of financial statements in conformity with generally accepted accounting principles in the United States of America (U.S. GAAP) requires management to make estimates and assumptions that affect reported amounts in the consolidated financial statements and accompanying notes. Actual amounts could differ from those estimates, and changes would most likely be reported in future periods. Management believes the estimates and assumptions used are reasonable . 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. Accounting records and practices of the regulated businesses conform to the requirements and uniform system of accounts prescribed by these regulatory authorities in accordance with U.S. GAAP. The businesses in which customer rates are regulated by the OPUC, WUTC, IPUC, PUTC, ACC and FERC have approved cost-based rates which are intended to allow such businesses to earn a reasonable return on invested capital. In applying regulatory accounting principles, NW Holdings and NW Natural capitalize or defer certain costs and revenues as regulatory assets and liabilities pursuant to orders of the applicable state public utility commission, which provide for the recovery of revenues or expenses from, or refunds to, utility customers in future periods, including a return or a carrying charge in certain cases. Amounts NW Natural deferred as regulatory assets and liabilities were as follows: Regulatory Assets In thousands 2022 2021 NW Natural: Current: Unrealized loss on derivatives (1) $ 28,728 $ 10,402 Gas costs 61,223 35,641 Environmental costs (2) 7,392 6,694 Decoupling (3) — 969 Pension balancing (4) 7,131 7,131 Income taxes 2,208 2,568 Other (5) 10,809 8,986 Total current $ 117,491 $ 72,391 Non-current: Unrealized loss on derivatives (1) $ 20,838 $ 412 Pension balancing (4) 32,997 38,302 Income taxes 10,943 12,609 Pension and other postretirement benefit liabilities 101,413 116,440 Environmental costs (2) 104,253 94,636 Gas costs 22,355 15,477 Other (5) 47,608 36,663 Total non-current $ 340,407 $ 314,539 Other (NW Holdings) 25 40 Total non-current -NW Holdings $ 340,432 $ 314,579 Regulatory Liabilities In thousands 2022 2021 NW Natural: Current: Gas costs $ 4,121 $ 70 Unrealized gain on derivatives (1) 194,236 48,130 Decoupling (3) 14,026 4,475 Income taxes (6) 7,166 8,192 Asset optimization revenue sharing 26,368 45,124 Other (5) 2,636 6,290 Total current - NW Natural $ 248,553 $ 112,281 Other (NW Holdings) 29 — Total current - NW Holdings $ 248,582 $ 112,281 Non-current: Gas costs $ 12,644 $ 250 Unrealized gain on derivatives (1) 5,045 10,730 Decoupling (3) 3,814 3,412 Income taxes (6) 174,212 181,404 Accrued asset removal costs (7) 467,742 445,952 Asset optimization revenue sharing 8,401 1,810 Other (5) 16,741 13,792 Total non-current - NW Natural $ 688,599 $ 657,350 Other (NW Holdings) 979 982 Total non-current -NW Holdings $ 689,578 $ 658,332 (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 natural gas distribution rates as part of the annual Purchased Gas Adjustment (PGA) mechanism when realized at settlement. (2) Refer to the Environmental Cost Deferral and Recovery table in Note 17 for a description of environmental costs. (3) This deferral represents the margin adjustment resulting from differences between actual and expected volumes. (4) Refer to Note 10 for information regarding the deferral of pension expenses. (5) Balances consist of deferrals and amortizations under approved regulatory mechanisms and typically earn a rate of return or carrying charge. (6) This balance represents estimated amounts associated with the Tax Cuts and Jobs Act. See Note 11. (7) Estimated costs of removal on certain regulated properties are collected through rates. See "Accounting Policies— Plant, Property, and Accrued Asset Removal Costs " below. The amortization period for NW Natural's regulatory assets and liabilities ranges from less than one year to an indeterminable period. Regulatory deferrals for gas costs payable are generally amortized over 12 months beginning each November 1 following the gas contract year during which the deferred gas costs are recorded. Similarly, most other regulatory deferred accounts are amortized over 12 months. However, certain regulatory account balances, such as income taxes, environmental costs, pension liabilities, and accrued asset removal costs, are large and tend to be amortized over longer periods once NW Natural has agreed upon an amortization period with the respective regulatory agency. We believe all costs incurred and deferred at December 31, 2022 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 Natural would be required to write-off the net unrecoverable balances in the period such determination is made. Regulatory interest income of $7.0 million and $6.1 million and regulatory interest expense of $2.0 million and $1.3 million was recognized within other income (expense), net for the years ended December 31, 2022 and 2021, respectively. Environmental Regulatory Accounting See Note 17 for information about the SRRM and OPUC orders regarding implementation. COVID-19 Impact During 2020, our regulated utilities received approval in their respective jurisdictions to defer certain financial impacts associated with COVID-19 such as bad debt expense, financing costs to secure liquidity, lost revenues related to late fees and reconnection fees, and other COVID-19 related costs, net of offsetting direct expense reductions associated with COVID-19. As of December 31, 2022, we believe that approximately $18.7 million of the financial effects related to COVID-19 are recoverable. As part of the 2022 Oregon general rate case, NW Natural received approval from the OPUC to recover the 2020 and 2021 COVID-19 deferral beginning November 1, 2022. Approximately $10.9 million will be amortized over a two 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 Adopted Accounting Pronouncements REFERENCE RATE REFORM. In March 2020, the FASB issued ASU 2020-04, "Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting." The purpose of the amendment is to provide optional expedients and exceptions for applying generally accepted accounting principles (GAAP) to contracts, hedging relationships, and other transactions affected by reference rate reform if certain criteria are met. The amendments in this ASU apply only to contracts, hedging relationships, and other transactions that reference London Inter-Bank Offered Rate (LIBOR) or another reference rate expected to be discontinued because of reference rate reform. In January 2021, the FASB issued ASU 2021-01, "Reference Rate Reform (Topic 848): Scope." The purpose of the amendment is to clarify guidance on reference rate reform activities, specifically related to accounting for derivative contracts and certain hedging relationships affected by changes in the interest rates used for discounting, margining, and contract price alignment (the "discounting transition"). The amendments in ASUs 2020-04 and 2021-01 are effective for all entities as of March 12, 2020 through December 31, 2022. In December 2022, the FASB issued ASU 2022-06, "Reference Rate Reform (Topic 848): Deferral of the Sunset Date of Topic 848." The purpose of the amendment is to defer the sunset date of Topic 848 from December 31, 2022, to December 31, 2024, after which entities will no longer be permitted to apply the relief in Topic 848. The objective of the guidance in Topic 848 is to provide temporary relief during the transition period. The Board included a sunset provision within Topic 848 based on expectations of when the London Interbank Offered Rate (LIBOR) would cease being published. We do not expect the ASUs to materially affect the financial statements and disclosures of NW Holdings or NW Natural. LEASES. In July 2021, the FASB issued ASU 2021-05, "Leases (Topic 842), Lessors - Certain Leases with Variable Lease Payments." The purpose of the amendment is to require lessors to account for certain lease transactions that contain variable lease payments as operating leases. The amendments in this ASU are intended to eliminate the recognition of any day-one loss associated with certain sales-type and direct-financing lease transactions. The changes do not impact lessee accounting. The new guidance was effective on January 1, 2022 and adopted using a prospective approach. The adoption did not materially affect the financial statements and disclosures of NW Holdings or NW Natural. Accounting Policies The accounting policies discussed below apply to both NW Holdings and NW Natural. Plant, Property, and Accrued Asset Removal Costs Plant and property are stated at cost, including capitalized labor, materials, and overhead. In accordance with regulatory accounting standards, the cost of acquiring and constructing long-lived plant and property generally includes an allowance for funds used during construction (AFUDC) or capitalized interest. AFUDC represents the regulatory financing cost incurred when debt and equity funds are used for construction (see “ AFUDC ” below). When constructed assets are subject to market-based rates rather than cost-based rates, the financing costs incurred during construction are included in capitalized interest in accordance with U.S. GAAP, not as regulatory financing costs under AFUDC. In accordance with long-standing regulatory treatment, our depreciation rates consist of three components: one based on the average service life of the asset, a second based on the estimated salvage value of the asset, and a third based on the asset’s estimated cost of removal. We collect, through rates, the estimated cost of removal on certain regulated properties through depreciation expense, with a corresponding offset to accumulated depreciation. These removal costs are non-legal obligations as defined by regulatory accounting guidance. Therefore, we have included these costs as non-current regulatory liabilities rather than as accumulated depreciation on our consolidated balance sheets. In the rate setting process, the liability for removal costs is treated as a reduction to the net rate base on which the NGD business has the opportunity to earn its allowed rate of return. The costs of NGD plant retired or otherwise disposed of are removed from NGD plant and charged to accumulated depreciation for recovery or refund through future rates. Gains from the sale of regulated assets are generally deferred and refunded to customers. For assets not related to NGD, we record a gain or loss upon the disposal of the property, and the gain or loss is recorded in operating income or loss in the consolidated statements of comprehensive income. The provision for depreciation of NGD property, plant, and equipment is recorded under the group method on a straight-line basis with rates computed in accordance with depreciation studies approved by regulatory authorities. The weighted-average depreciation rate for NGD assets in service was approximately 3.0% for 2022, 2021 and 2020, reflecting the approximate weighted-average economic life of the property. This includes 2022 weighted-average depreciation rates for the following asset categories: 2.5% for transmission and distribution plant, 2.1% for gas storage facilities, 6.1% for general plant, and 6.7% for intangible and other fixed assets. AFUDC. Certain additions to NGD plant include AFUDC, which represents the net cost of debt and equity funds used during construction. AFUDC is calculated using actual interest rates for debt and authorized rates for ROE, if applicable. If short-term debt balances are less than the total balance of construction work in progress, then a composite AFUDC rate is used to represent interest on all debt funds, shown as a reduction to interest charges, and on ROE funds, shown as other income. While cash is not immediately recognized from recording AFUDC, it is realized in future years through rate recovery resulting from the higher NGD cost of service. Our composite AFUDC rate was 2.8% in 2022, 0.7% in 2021, and 1.9% in 2020. IMPAIRMENT OF LONG-LIVED ASSETS. We review the carrying value of long-lived assets whenever events or changes in circumstances indicate the carrying amount of the assets may not be recoverable. Factors that would necessitate an impairment assessment of long-lived assets include a significant adverse change in the extent or manner in which the asset is used, a significant adverse change in legal factors or business climate that could affect the value of the asset, or a significant decline in the observable market value or expected future cash flows of the asset, among others. When such factors are present, we assess the recoverability by determining whether the carrying value of the asset will be recovered through expected future cash flows. An asset is determined to be impaired when the carrying value of the asset exceeds the expected undiscounted future cash flows from the use and eventual disposition of the asset. If an impairment is indicated, we record an impairment loss for the difference between the carrying value and the fair value of the long-lived assets. Fair value is estimated using appropriate valuation methodologies, which may include an estimate of discounted cash flows. Cash and Cash Equivalents For purposes of reporting cash flows, cash and cash equivalents include cash on hand plus highly liquid investment accounts with original maturity dates of three months or less. At December 31, 2022, NW Holdings had outstanding checks of $5.8 million, substantially all of which is recorded at NW Natural, and at December 31, 2021, NW Holdings had no outstanding checks. These balances are included in accounts payable in the NW Holdings and NW Natural balance sheets. Restricted cash is primarily comprised of funds from public purpose charges for programs that assist low-income customers with bill payments or energy efficiency. These balances are included in other current assets in the NW Holdings and NW Natural balance sheets. There were no transfers between restricted cash and cash and cash equivalents during the years ended December 31, 2022 and 2021. Prior period amounts have been reclassified to conform prior period information to the current presentation. The following table provides a reconciliation of the cash, cash equivalents and restricted cash balances at NW Holdings as of December 31, 2022 and 2021: December 31, In thousands 2022 2021 Cash and cash equivalents $ 29,270 $ 18,559 Restricted cash included in other current assets 11,694 8,561 Cash, cash equivalents and restricted cash $ 40,964 $ 27,120 The following table provides a reconciliation of the cash, cash equivalents and restricted cash balances at NW Natural as of December 31, 2022 and 2021: December 31, In thousands 2022 2021 Cash and cash equivalents $ 12,977 $ 12,271 Restricted cash included in other current assets 11,694 8,561 Cash, cash equivalents and restricted cash $ 24,671 $ 20,832 Revenue Recognition and Accrued Unbilled Revenue Revenues, derived primarily from the sale and transportation of natural gas, are recognized upon delivery of gas or water, or service to customers. Revenues include accruals for gas or water delivered but not yet billed to customers based on estimates of deliveries from meter reading dates to month end (accrued unbilled revenue). Accrued unbilled revenue is dependent upon a number of factors that require management’s judgment, including total natural gas receipts and deliveries, customer use of natural gas or water by billing cycle, and weather factors. Accrued unbilled revenue is reversed the following month when actual billings occur. NW Holdings' accrued unbilled revenue at December 31, 2022 and 2021 was $89.0 million and $82.2 million, respectively, substantially all of which is accrued unbilled revenue at NW Natural. Revenues not related to NGD are derived primarily from Interstate Storage Services, asset management activities at the Mist gas storage facility, and other investments and business activities. At the Mist underground storage facility, revenues are primarily firm service revenues in the form of fixed monthly reservation charges. In addition, we also have asset management service revenue from an independent energy marketing company that optimizes commodity, storage, and pipeline capacity release transactions. Under this agreement, guaranteed asset management revenue is recognized using a straight-line, pro-rata methodology over the term of each contract. Revenues earned above the guaranteed amount are recognized as they are earned. Revenue Taxes Revenue-based taxes are primarily franchise taxes, which are collected from customers and remitted to taxing authorities. Revenue taxes are included in operating expenses in the statements of comprehensive income for NW Holdings and NW Natural. Revenue taxes at NW Holdings were $41.8 million, $34.7 million, and $30.3 million for 2022, 2021, and 2020, respectively. 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 2022 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 in the third and fourth quarter for Oregon 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, substantially all of which is related to NW Natural's accounts receivable: As of December 31, 2021 As of December 31, 2022 Year ended December 31, 2022 In thousands Beginning Balance Provision recorded, net of adjustments Write-offs recognized, net of recoveries Ending Balance Allowance for uncollectible accounts: Residential $ 1,460 $ 1,974 $ (1,062) $ 2,372 Commercial 178 546 (324) 400 Industrial 67 186 (65) 188 Accrued unbilled and other 313 185 (162) 336 Total $ 2,018 $ 2,891 $ (1,613) $ 3,296 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. Inventories NGD gas inventories, which consist of natural gas in storage for NGD customers, are stated at the lower of weighted-average cost or net realizable value. The regulatory treatment of these inventories provides for cost recovery in customer rates. NGD gas inventories injected into storage are priced in inventory based on actual purchase costs, and those withdrawn from storage are charged to cost of gas during the period they are withdrawn at the weighted-average inventory cost. Gas storage inventories mainly consist of natural gas received as fuel-in-kind from storage customers. Gas storage inventories are valued at the lower of average cost or net realizable value. Cushion gas is not included in inventory balances, is recorded at original cost, and is classified as a long-term plant asset. Materials and supplies inventories consist of inventories both related to and unrelated to NGD and are stated at the lower of average cost or net realizable value. NW Natural's NGD and gas storage inventories totaled $61.9 million and $37.4 million at December 31, 2022 and 2021, respectively. At December 31, 2022 and 2021, NW Holdings' materials and supplies inventories, which are comprised primarily of NW Natural's materials and supplies, totaled $23.5 million and $19.9 million, respectively. During 2022 and 2021, NW Natural entered into certain agreements to purchase renewable thermal certificates (RTCs). RTCs are initially recorded at cost and subsequently assessed for impairment based on the lower-of-cost or market model. NW Natural's RTCs inventory totaled $1.7 million at December 31, 2022, and all RTCs purchased during 2021 were retired or used on customers behalf prior to December 31, 2021. Gas Reserves Gas reserves are payments to acquire and produce natural gas reserves. Gas reserves are stated at cost, adjusted for regulatory amortization, with the associated deferred tax benefits recorded as liabilities on the balance sheet. The current portion is calculated based on expected gas deliveries within the next fiscal year. NW Natural recognizes regulatory amortization of this asset on a volumetric basis calculated using the estimated gas reserves and the estimated therms extracted and sold each month. The amortization of gas reserves is recorded to cost of gas along with gas production revenues and production costs. See Note 13. Derivatives NW Natural's derivatives are measured at fair value and recognized as either assets or liabilities on the balance sheet. Changes in the fair value of the derivatives are recognized in earnings unless specific regulatory or hedge accounting criteria are met. Accounting for derivatives and hedges provides an exception for contracts intended for normal purchases and normal sales for which physical delivery is probable. In addition, certain derivative contracts are approved by regulatory authorities for recovery or refund through customer rates. Accordingly, the changes in fair value of these approved contracts are deferred as regulatory assets or liabilities pursuant to regulatory accounting principles. NW Natural's financial derivatives generally qualify for deferral under regulatory accounting. NW Natural's index-priced physical derivative contracts also qualify for regulatory deferral accounting treatment. Derivative contracts entered into for NGD requirements after the annual PGA rate has been set and maturing during the PGA year are subject to the PGA incentive sharing mechanism. In Oregon, NW Natural participates in a PGA sharing mechanism under which it is required to select either an 80% or 90% deferral of higher or lower gas costs such that the impact on current earnings from the gas cost sharing is either 20% or 10% of gas cost differences compared to PGA prices, respectively. For each of the PGA years in Oregon beginning November 1, 2022, 2021, and 2020, NW Natural selected the 90% deferral of gas cost differences. In Washington, 100% of the differences between the PGA prices and actual gas costs are deferred. See Note 15. NW Holdings and NW Natural have financial derivative policies that set forth guidelines for using selected derivative products to support prudent risk management strategies within designated parameters. NW Natural's objective for using derivatives is to decrease the volatility of gas prices and cash flows without speculative risk. The use of derivatives is permitted only after the risk exposures have been identified, are determined to exceed acceptable tolerance levels, and are determined necessary to support normal business activities. NW Natural does not enter into derivative instruments for trading purposes. All commodity and foreign exchange derivatives are currently held at NW Natural, and interest rate swaps are held at NW Holdings and NWN Water. Fair Value In accordance with fair value accounting, we use the following fair value hierarchy for determining inputs for our debt, pension plan assets, and derivative fair value measurements: • Level 1: Valuation is based on quoted prices for identical instruments traded in active markets; • Level 2: Valuation is based on quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active, and model-based valuation techniques for which all significant assumptions are observable in the market; and • Level 3: Valuation is generated from model-based techniques that use significant assumptions not observable in the market. These unobservable assumptions reflect our own estimates of assumptions market participants would use in valuing the asset or liability. In addition, the fair value for certain pension trust investments is determined using Net Asset Value per share (NAV) as a practical expedient, and therefore they are not classified within the fair value hierarchy. These investments primarily consist of institutional investment products. When developing fair value measurements, it is our policy to use quoted market prices whenever available or to maximize the use of observable inputs and minimize the use of unobservable inputs when quoted market prices are not available. Fair values are primarily developed using industry-standard models that consider various inputs including: (a) quoted future prices for commodities; (b) forward currency prices; (c) time value; (d) volatility factors; (e) current market and contractual prices for underlying instruments; (f) market interest rates and yield curves; (g) credit spreads; and (h) other relevant economic measures. NW Natural considers liquid points for natural gas hedging to be those points for which there are regularly published prices in a nationally recognized publication or where the instruments are traded on an exchange. Goodwill and Business Combinations NW Holdings, through its wholly-owned subsidiary NWN Water and NWN Water's wholly-owned subsidiaries, has completed various acquisitions that resulted in the recognition of goodwill. Goodwill is measured as the excess of the acquisition-date fair value of the consideration transferred over the acquisition-date fair value of the net identifiable assets assumed. Adjustments are recorded during the measurement period to finalize the allocation of the purchase price. The carrying value of goodwill is reviewed annually during the fourth quarter, or whenever events or changes in circumstance indicate that such carrying values may not be recoverable. The goodwill assessment policy begins with a qualitative analysis in which events and circumstances are evaluated, including macroeconomic conditions, industry and market conditions, regulatory environments, and overall financial performance of the reporting unit. If the qualitative assessment indicates that the carrying value may be at risk of recoverability, a quantitative evaluation is performed to measure the carrying value of the goodwill against the fair value of the reporting unit. The reporting unit is determined primarily based on current operating segments and the level of review provided by the Chief Operating Decision Maker (CODM) and/or segment management on the operating segment's financial results. Reporting units are evaluated periodically for changes in the corporate environment. As of December 31, 2022 and 2021, NW Holdings had goodwill of $149.3 million and $70.6 million, respectively. All of NW Holdings' goodwill was acquired through the business combinations completed by NWN Water and its wholly-owned subsidiaries. No impairment charges were recorded as a result of the fourth quarter goodwill impairment assessment. Business combinations are accounted for using the acquisition method. The cost of an acquisition is measured as the aggregate of the consideration transferred, measured at fair value at the acquisition date, and the fair value of any non-controlling interest in the acquiree. Acquisition-related costs are expensed as incurred. When NW Natural acquires a business, it assesses the financial assets acquired and liabilities assumed for appropriate classification and designation in accordance with the contractual terms, economic circumstances and pertinent conditions as of the acquisition date. When there is substantial judgment or uncertainty around the fair value of acquired assets, we may engage a third party expert to assist in determining the fair values of certain assets or liabilities. Income Taxes We account for income taxes under the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements. Under this method, deferred tax assets and liabilities are determined on the basis of the differences between the financial statement and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. The effect of a change in tax rates on deferred tax assets and liabilities is recognized in income in the enact

Earnings Per Share

Earnings Per Share	12 Months Ended
	Dec. 31, 2022
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Earnings Per Share [Text Block]	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: In thousands, except per share data 2022 2021 2020 Net income from continuing operations $ 86,303 $ 78,666 $ 70,273 Income from discontinued operations, net of tax — — 6,508 Net income $ 86,303 $ 78,666 $ 76,781 Average common shares outstanding - basic 33,934 30,702 30,541 Additional shares for stock-based compensation plans (See Note 8) 50 50 58 Average common shares outstanding - diluted 33,984 30,752 30,599 Earnings from continuing operations per share of common stock: Basic $ 2.54 $ 2.56 $ 2.30 Diluted 2.54 2.56 2.30 Earnings from discontinued operations per share of common stock: Basic $ — $ — $ 0.21 Diluted — — 0.21 Earnings per share of common stock: Basic $ 2.54 $ 2.56 $ 2.51 Diluted 2.54 2.56 2.51 Additional information: Anti-dilutive shares 2 7 1

Segment Information

Segment Information	12 Months Ended
	Dec. 31, 2022
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. No individual customer accounts for over 10% of NW Holdings' or NW Natural's operating revenues. Natural Gas Distribution NW Natural's local gas distribution segment (NGD) 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. The NGD business is responsible for building and maintaining a safe and reliable pipeline distribution system, purchasing sufficient gas supplies from producers and marketers, contracting for firm and interruptible transportation of gas over interstate pipelines to bring gas from the supply basins into its service territory, and re-selling the gas to customers subject to rates, terms, and conditions approved by the OPUC or WUTC. NGD also includes taking customer-owned gas and transporting it from interstate pipeline connections, or city gates, to the customers’ end-use facilities for a fee, which is approved by the OPUC or WUTC. Approximately 88% of NGD customers are located in Oregon and 12% in Washington. On an annual basis, residential and commercial customers typically account for around 60% of total NGD volumes delivered and around 90% of NGD margin. Industrial customers largely account for the remaining volumes and NGD margin. A small amount of the margin is also derived from miscellaneous services, gains or losses from an incentive gas cost sharing mechanism, and other service fees. Industrial sectors served by the NGD business include: pulp, paper, and other forest products; the manufacture of electronic, electrochemical and electrometallurgical products; the processing of farm and food products; the production of various mineral products; metal fabrication and casting; the production of machine tools, machinery, and textiles; the manufacture of asphalt, concrete, and rubber; printing and publishing; nurseries; and government and educational institutions. 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 for the Mist facility in Oregon, 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 the Mist facility 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 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; NWN Water's equity investment in Avion Water Company, Inc.; NWN Gas Storage, a wholly-owned subsidiary of NWN Energy; NWN Energy's equity investment in Trail West Holdings, LLC (TWH) through August 6, 2020; other pipeline assets in NNG Financial; and NW Natural Renewables Holdings, LLC and its non-regulated renewable natural gas activities. For more information on the sale of TWH, see Note 13. Other also includes corporate revenues and expenses that cannot be allocated to other operations, including certain business development activities. Segment Information Summary Inter-segment transactions were immaterial for the periods presented. The following table presents summary financial information concerning the reportable segment and other for continuing operations. See Note 18 for information regarding discontinued operations for NW Holdings. In thousands NGD Other NW Natural Other NW Holdings 2022 Operating revenues $ 989,752 $ 24,587 $ 1,014,339 $ 23,014 $ 1,037,353 Depreciation 111,871 1,086 112,957 3,750 116,707 Income (loss) from operations 152,839 16,535 169,374 (1,897) 167,477 Net income (loss) from continuing operations 79,690 11,874 91,564 (5,261) 86,303 Capital expenditures 315,979 2,707 318,686 19,916 338,602 Total assets at December 31, 2022 4,392,699 60,019 4,452,718 295,608 4,748,326 2021 Operating revenues $ 816,887 $ 26,170 $ 843,057 $ 17,343 $ 860,400 Depreciation 109,475 1,029 110,504 3,030 113,534 Income (loss) from operations 147,902 17,331 165,233 (2,116) 163,117 Net income (loss) from continuing operations 68,988 12,184 81,172 (2,506) 78,666 Capital expenditures 275,267 2,970 278,237 15,655 293,892 Total assets at December 31, 2021 3,846,112 52,260 3,898,372 166,232 4,064,604 2020 Operating revenues $ 741,072 $ 17,676 $ 758,748 $ 14,931 $ 773,679 Depreciation 100,591 995 101,586 2,097 103,683 Income (loss) from operations 137,724 9,916 147,640 711 148,351 Net income (loss) from continuing operations 63,555 7,008 70,563 (290) 70,273 Capital expenditures 263,777 2,271 266,048 6,968 273,016 Total assets at December 31, 2020 3,549,868 49,468 3,599,336 157,043 3,756,379 Natural Gas Distribution Margin NGD margin is the primary financial measure used by the 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: In thousands 2022 2021 2020 NGD margin calculation: NGD operating revenues $ 970,124 $ 797,800 $ 721,950 Other regulated services 19,628 19,087 19,122 Total NGD operating revenues 989,752 816,887 741,072 Less: NGD cost of gas 429,861 292,538 262,980 Environmental remediation expense 12,389 9,938 9,691 Revenue taxes 41,627 34,600 30,291 NGD margin $ 505,875 $ 479,811 $ 438,110

Revenue Revenue

Revenue Revenue	12 Months Ended
	Dec. 31, 2022
Revenue from Contract with Customer [Abstract]
Revenue	REVENUE The following table presents disaggregated revenue from continuing operations: Year ended December 31, 2022 In thousands NGD Other NW Natural Other NW Holdings Natural gas sales $ 989,654 $ — $ 989,654 $ — $ 989,654 Gas storage revenue, net — 11,792 11,792 — 11,792 Asset management revenue, net — 6,965 6,965 — 6,965 Appliance retail center revenue — 5,830 5,830 — 5,830 Other revenue 2,510 — 2,510 23,014 25,524 Revenue from contracts with customers 992,164 24,587 1,016,751 23,014 1,039,765 Alternative revenue (19,605) — (19,605) — (19,605) Leasing revenue 17,193 — 17,193 — 17,193 Total operating revenues $ 989,752 $ 24,587 $ 1,014,339 $ 23,014 $ 1,037,353 Year ended December 31, 2021 In thousands NGD Other NW Natural Other NW Holdings Natural gas sales $ 783,027 $ — $ 783,027 $ — $ 783,027 Gas storage revenue, net — 10,830 10,830 — 10,830 Asset management revenue, net — 9,387 9,387 — 9,387 Appliance retail center revenue — 5,953 5,953 — 5,953 Other revenue 1,615 — 1,615 17,343 18,958 Revenue from contracts with customers 784,642 26,170 810,812 17,343 828,155 Alternative revenue 14,694 — 14,694 — 14,694 Leasing revenue 17,551 — 17,551 — 17,551 Total operating revenues $ 816,887 $ 26,170 $ 843,057 $ 17,343 $ 860,400 Year ended December 31, 2020 In thousands NGD Other NW Natural Other NW Holdings Natural gas sales $ 710,422 $ — $ 710,422 $ — $ 710,422 Gas storage revenue, net — 9,759 9,759 — 9,759 Asset management revenue, net — 2,532 2,532 — 2,532 Appliance retail center revenue — 5,385 5,385 — 5,385 Other revenue 1,337 — 1,337 14,931 16,268 Revenue from contracts with customers 711,759 17,676 729,435 14,931 744,366 Alternative revenue 10,870 — 10,870 — 10,870 Leasing revenue 18,443 — 18,443 — 18,443 Total operating revenues $ 741,072 $ 17,676 $ 758,748 $ 14,931 $ 773,679 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 Portland General Electric (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 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 December 31, 2022, unrecognized revenue for the fixed component of the transaction price related to gas storage and asset management revenue was approximately $81.4 million. Of this amount, approximately $20.3 million will be recognized in 2023, $16.2 million in 2024, $13.5 million in 2025, $9.4 million in 2026, and $22.0 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 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 state we operate. Customer accounts are to be paid in full each month, and there is no right of return or warranty for services provided.

Leases (Notes)

Leases (Notes)	12 Months Ended
	Dec. 31, 2022
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 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: Year ended December 31, In thousands 2022 2021 2020 Lease revenue Operating leases $ 74 $ 80 $ 88 Sales-type leases 17,119 17,471 18,355 Total lease revenue $ 17,193 $ 17,551 $ 18,443 Additionally, lease revenue of $0.6 million, $0.5 million and $0.5 million was recognized for each of the years ended December 31, 2022, 2021, and 2020, respectively, 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 December 31, 2022 are as follows: In thousands Operating Sales-Type Total NW Natural: 2023 $ 621 $ 16,557 $ 17,178 2024 612 15,867 16,479 2025 603 15,306 15,909 2026 36 14,901 14,937 2027 22 14,521 14,543 Thereafter — 222,299 222,299 Total minimum lease payments $ 1,894 $ 299,451 $ 301,345 Less: imputed interest 165,272 Total leases receivable $ 134,179 Other NW Holdings: 2023 $ 51 $ — $ 51 2024 52 — 52 2025 53 — 53 2026 56 — 56 2027 57 — 57 Thereafter 857 — 857 Total minimum lease payments $ 1,126 $ — $ 1,126 NW Holdings: 2023 $ 672 $ 16,557 $ 17,229 2024 664 15,867 16,531 2025 656 15,306 15,962 2026 92 14,901 14,993 2027 79 14,521 14,600 Thereafter 857 222,299 223,156 Total minimum lease payments $ 3,020 $ 299,451 $ 302,471 Less: imputed interest 165,272 Total leases receivable $ 134,179 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 $5.1 million and $4.7 million at December 31, 2022 and 2021, 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 nine 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: Year ended December 31, 2022 In thousands NW Natural Other NW Holdings Operating lease expense $ 7,003 $ 31 $ 7,034 Short-term lease expense 880 — 880 Year ended December 31, 2021 In thousands NW Natural Other NW Holdings Operating lease expense $ 6,859 $ 58 $ 6,917 Short-term lease expense 1,220 — 1,220 Year ended December 31, 2020 In thousands NW Natural Other NW Holdings Operating lease expense $ 4,381 $ 125 $ 4,506 Short-term lease expense 1,010 — 1,010 Supplemental balance sheet information related to operating leases as of December 31, 2022 is as follows: In thousands NW Natural Other NW Holdings Operating lease right of use assets $ 72,720 $ 709 $ 73,429 Operating lease liabilities - current liabilities $ 1,363 $ 151 $ 1,514 Operating lease liabilities - non-current liabilities 78,345 620 78,965 Total operating lease liabilities $ 79,708 $ 771 $ 80,479 Supplemental balance sheet information related to operating leases as of December 31, 2021 is as follows: In thousands NW Natural Other NW Holdings Operating lease right of use assets $ 74,987 $ 62 $ 75,049 Operating lease liabilities - current liabilities $ 1,273 $ 23 $ 1,296 Operating lease liabilities - non-current liabilities 79,431 37 79,468 Total operating lease liabilities $ 80,704 $ 60 $ 80,764 The weighted-average remaining lease terms and weighted-average discount rates for the operating leases at NW Natural were as follows: 2022 2021 Weighted-average remaining lease term (years) 17.2 18.2 Weighted-average discount rate 7.3 % 7.2 % 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 regulatory asset on our balance sheet. The balance of the regulatory asset was $6.9 million and $5.7 million as of December 31, 2022 and 2021, respectively. Maturities of operating lease liabilities at December 31, 2022 were as follows: In thousands NW Natural Other NW Holdings 2023 $ 7,169 $ 195 $ 7,364 2024 7,299 196 7,495 2025 7,185 184 7,369 2026 7,353 140 7,493 2027 7,530 107 7,637 Thereafter 108,901 12 108,913 Total lease payments 145,437 834 146,271 Less: imputed interest 65,729 63 65,792 Total lease obligations 79,708 771 80,479 Less: current obligations 1,363 151 1,514 Long-term lease obligations $ 78,345 $ 620 $ 78,965 As of December 31, 2022, there were no finance lease liabilities at NW Natural. Cash Flow Information Supplemental cash flow information related to leases was as follows: Year ended December 31, 2022 In thousands NW Natural Other NW Holdings Cash paid for amounts included in the measurement of lease liabilities Operating cash flows from operating leases $ 6,993 $ 64 $ 7,057 Finance cash flows from finance leases 524 — 524 Right of use assets obtained in exchange for lease obligations Operating leases $ 309 $ 668 $ 977 Finance leases 270 — 270 Year ended December 31, 2021 In thousands NW Natural Other NW Holdings Cash paid for amounts included in the measurement of lease liabilities Operating cash flows from operating leases $ 6,840 $ 58 $ 6,898 Finance cash flows from finance leases 801 — 801 Right of use assets obtained in exchange for lease obligations Operating leases $ 223 $ — $ 223 Finance leases 314 — 314 Year ended December 31, 2020 In thousands NW Natural Other NW Holdings Cash paid for amounts included in the measurement of lease liabilities Operating cash flows from operating leases $ 4,466 $ 131 $ 4,597 Finance cash flows from finance leases 835 — 835 Right of use assets obtained in exchange for lease obligations Operating leases $ 78,539 $ 51 $ 78,590 Finance leases 1,386 — 1,386 Finance Leases 2.3 million 2.1 million

Stock-Based Compensation (Notes

Stock-Based Compensation (Notes)	12 Months Ended
	Dec. 31, 2022
Share-Based Payment Arrangement [Abstract]
Share-based Payment Arrangement [Text Block]	STOCK-BASED COMPENSATION Stock-based compensation plans are designed to promote stock ownership in NW Holdings by employees and officers of NW Holdings and its affiliates. These compensation plans include a Long Term Incentive Plan (LTIP) and an ESPP. Long Term Incentive Plan The LTIP is intended to provide a flexible, competitive compensation program for eligible officers and key employees. Under the LTIP, shares of NW Holdings common stock are authorized for equity incentive grants in the form of stock, restricted stock, restricted stock units, stock options, or performance shares. An aggregate of 1,100,000 shares were authorized for issuance as of December 31, 2022. Shares awarded under the LTIP may be purchased on the open market or issued as original shares. Of the 1,100,000 shares of common stock authorized for LTIP awards at December 31, 2022, there were 247,666 shares available for issuance under any type of award. This assumes market, performance, and service-based grants currently outstanding are awarded at the target level. There were no outstanding grants of restricted stock or stock options under the LTIP at December 31, 2022 or 2021. The LTIP stock awards are compensatory awards for which compensation expense is based on the fair value of stock awards, with expense being recognized over the performance and vesting period of the outstanding awards. Forfeitures are recognized as they occur. Performance Shares LTIP performance shares incorporate a combination of market, performance, and service-based factors. The following table summarizes performance share expense information: Dollars in thousands Shares (1) Expense During Award Year (2) Total Expense for Award Estimated award: 2020-2022 grant (3) 29,472 $ 888 $ 888 Actual award: 2019-2021 grant 37,430 $ 1,323 $ 1,323 2018-2020 grant 31,600 $ 2,137 $ 2,137 (1) In addition to common stock shares, a participant also receives a dividend equivalent cash payment equal to the number of shares of common stock received on the award payout multiplied by the aggregate cash dividends paid per share during the performance period. (2) Amount represents the expense recognized in the third year of the vesting period noted above. For the 2019-2021 and 2020-2022 grants, mutual understanding of the award's key terms was established in the third year of the vesting period, triggering full expense recognition in 2021 and 2022, respectively. (3) This represents the estimated number of shares to be awarded as of December 31, 2022 as certain performance share measures have been achieved. Amounts are subject to change with final payout amounts authorized by the Board of Directors in February 2023. The aggregate number of performance shares granted and outstanding at the target and maximum levels were as follows: Dollars in thousands Performance Share Awards Outstanding 2022 Performance Period Target Maximum Expense 2020-22 31,160 62,320 $ 888 2021-23 — — — 2022-24 — — — Total 31,160 62,320 $ 888 Performance share awards are based on the achievement of a three Compensation expense is recognized in accordance with accounting standards for stock-based compensation and calculated based on performance levels achieved and an estimated fair value using the Monte-Carlo method. Due to there not being a mutual understanding of the 2021-2023 and 2022-2024 awards' key terms and conditions as noted above, the grant date fair value has not yet been determined and no non-vested shares existed at December 31, 2022. The weighted-average grant date fair value of non-vested shares associated with the 2020-2022 awards was $38.63 per share at December 31, 2022. The weighted-average grant date fair value of shares vested during the year was $38.63 per share and there were no performance shares granted during the year and no unrecognized compensation expense for accounting purposes as of December 31, 2022. Restricted Stock Units In 2012, RSUs began being granted under the LTIP instead of stock options under the Restated SOP. 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. During 2022, total RSU expense was $2.1 million compared to $2.0 million in 2021 and $2.0 million in 2020. As of December 31, 2022, there was $3.5 million of unrecognized compensation cost from grants of RSUs, which is expected to be recognized over a period extending through 2026 . Information regarding the RSU activity is summarized as follows: Number of RSUs Weighted - Nonvested, December 31, 2019 79,733 $ 61.17 Granted 33,594 55.58 Vested (29,273) 59.29 Forfeited (1,590) 69.71 Nonvested, December 31, 2020 82,464 59.40 Granted 38,160 49.16 Vested (31,733) 60.06 Forfeited (1,164) 46.82 Nonvested, December 31, 2021 87,727 54.87 Granted 48,212 46.50 Vested (33,054) 55.90 Forfeited (3,037) 56.34 Nonvested, December 31, 2022 99,848 $ 50.44 Employee Stock Purchase Plan NW Holdings' ESPP allows employees of NW Holdings, NW Natural and certain designated subsidiaries to purchase common stock at 85% of the closing price on the trading day immediately preceding the initial offering date, which is set annually. For the 2022-2023 ESPP period, each eligible employee may purchase up to $21,223 worth of stock through payroll deductions over a period defined by the Board of Directors, with shares issued at the end of the subscription period. Stock-Based Compensation Expense Stock-based compensation expense is recognized as operations and maintenance expense or is capitalized as part of construction overhead at the entity at which the award recipient is employed. The following table summarizes the NW Holdings' financial statement impact, substantially all of which was recorded at NW Natural, of stock-based compensation under the LTIP and ESPP: In thousands 2022 2021 2020 Operations and maintenance expense, for stock-based compensation $ 2,877 $ 3,272 $ 3,525 Income tax benefit (762) (866) (933) Net stock-based compensation effect on net income 2,115 2,406 2,592 Amounts capitalized for stock-based compensation $ 351 $ 344 $ 841

Debt

Debt	12 Months Ended
	Dec. 31, 2022
Debt Disclosure [Abstract]
Debt [Text Block]	DEBT Short-Term Debt The primary source of short-term liquidity for NW Holdings is cash balances, dividends from its operating subsidiaries, in particular NW Natural, available cash from a multi-year credit facility, and short-term credit facilities it may enter into from time to time. The primary source of short-term liquidity for NW Natural is from the sale of commercial paper, available cash from a multi-year credit facility, and short-term credit facilities it may enter into from time to time. In addition to issuing commercial paper or entering into bank loans to meet working capital requirements, including seasonal requirements to finance gas purchases and accounts receivable, short-term debt may also be used to temporarily fund capital requirements. For NW Natural, commercial paper and bank loans are periodically refinanced through the sale of long-term debt or equity contributions from NW Holdings. Commercial paper, when outstanding, is sold through two commercial banks under an issuing and paying agency agreement and is supported by one or more unsecured revolving credit facilities. See “ Credit Agreements ” below. At December 31, 2022 and 2021, NW Natural's short-term debt consisted of the following: December 31, 2022 December 31, 2021 In millions Balance Outstanding Weighted Average Interest Rate (1) Balance Outstanding Weighted Average Interest Rate (1) NW Natural: Commercial paper $ 170.2 4.6 % $ 245.5 0.3 % Other (NW Holdings): Credit agreement 88.0 5.3 % 144.0 1.1 % NW Holdings $ 258.2 $ 389.5 (1) Weighted average interest rate on outstanding short-term debt The carrying cost of commercial paper approximates fair value using Level 2 inputs. See Note 2 for a description of the fair value hierarchy. At December 31, 2022, NW Natural's commercial paper had a maximum remaining maturity of 6 days and an average remaining maturity of 5 days. Credit Agreements NW Holdings In November 2021, NW Holdings entered into an amended and restated $200.0 million credit agreement, with a feature that allows NW Holdings to request increases in the total commitment amount, up to a maximum of $300.0 million. The maturity date of the agreement is November 3, 2026, with an available extension of commitments for two additional one The NW Holdings credit agreement permits the issuance of letters of credit in an aggregate amount of up to $40.0 million. The principal amount of borrowings under the credit agreement is due and payable on the maturity date. The credit agreement requires NW Holdings to maintain a consolidated indebtedness to total capitalization ratio of 70% or less. Failure to comply with this covenant would entitle the lenders to terminate their lending commitments and accelerate the maturity of all amounts outstanding. NW Holdings was in compliance with this covenant at December 31, 2022 and 2021. The NW Holdings credit agreement also requires NW Holdings to maintain debt ratings (which are defined by a formula using NW Natural's credit ratings in the event NW Holdings does not have a credit rating) with Standard & Poor's (S&P) and Moody's Investors Service, Inc. (Moody’s) and notify the lenders of any change in its senior unsecured debt ratings or senior secured debt ratings, as applicable, by such rating agencies. A change in NW Holdings' debt ratings by S&P or Moody’s is not an event of default, nor is the maintenance of a specific minimum level of debt rating a condition of drawing upon the credit agreement. Rather, interest rates on any loans outstanding under the credit agreements are tied to debt ratings and therefore, a change in the debt rating would increase or decrease the cost of any loans under the credit agreements when ratings are changed. NW Holdings does not currently maintain ratings with S&P or Moody's. There was $88.0 million and $144.0 million of outstanding balances under the NW Holdings agreement at December 31, 2022 and 2021, respectively. No letters of credit were issued or outstanding under the NW Holdings agreement at December 31, 2022 and 2021. NW Natural In November 2021, NW Natural entered into an amended and restated credit agreement for unsecured revolving loans totaling $400.0 million, with a feature that allows NW Natural to request increases in the total commitment amount, up to a maximum of $600.0 million. The maturity date of the agreement is November 3, 2026 with an available extension of commitments for two additional one aggregate amount of up to $60.0 million. The principal amount of borrowings under the credit agreement is due and payable on the maturity date. Interest charges on the NW Natural credit agreement were indexed to the LIBOR through January 31, 2023. The agreement was amended to replace LIBOR with the SOFR beginning February 2023. The SOFR is subject to a 10 basis point spread adjustment. NW Natural's credit agreement requires NW Natural to maintain a consolidated indebtedness to total capitalization ratio of 70% or less. Failure to comply with this covenant would entitle the lenders to terminate their lending commitments and accelerate the maturity of all amounts outstanding. NW Natural was in compliance with this covenant at December 31, 2022 and 2021. The NW Natural credit agreement also requires NW Natural to maintain credit ratings with S&P and Moody’s and notify the lenders of any change in NW Natural's senior unsecured debt ratings or senior secured debt ratings, as applicable, by such rating agencies. A change in NW Natural's debt ratings by S&P or Moody’s is not an event of default, nor is the maintenance of a specific minimum level of debt rating a condition of drawing upon the credit agreement. Rather, interest rates on any loans outstanding under the credit agreement are tied to debt ratings and therefore, a change in the debt rating would increase or decrease the cost of any loans under the credit agreement when ratings are changed. There were no outstanding balances under NW Natural's credit agreement and no letters of credit issued or outstanding at December 31, 2022 and 2021. In February 2023, NW Natural issued a $14 million letter of credit through its existing credit agreement. There were no other letters of credit outstanding under the credit agreement. Long-Term Debt NW Holdings At December 31, 2022 and 2021, NW Holdings long-term debt consisted of the following: December 31, 2022 December 31, 2021 In millions Balance Outstanding Weighted Average Interest Rate (1) Balance Outstanding Weighted Average Interest Rate (1) NW Natural first mortgage bonds $ 1,134.7 4.5 % $ 994.7 4.4 % NW Holdings credit agreement 100.0 4.2 % — — % NWN Water credit agreement 50.0 4.2 % — — % NWN Water term loan 55.0 2.5 % 55.0 0.8 % Other long-term debt 6.2 3.5 Long-term debt, gross $ 1,345.9 $ 1,053.2 Less: unamortized debt issuance costs 9.0 8.3 Less: current maturities 90.7 0.3 Total long-term debt $ 1,246.2 $ 1,044.6 (1) Weighted average interest rate for the years ended December 31, 2022 and 2021. Long-term debt at NWN Water is primarily comprised of a five one 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 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 December 31, 2022. 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 December 31, 2022. Interest Rate Swap Agreements NW Holdings and NWN Water entered into interest rate swap agreements with major financial institutions that effectively convert 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 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 % NW Natural NW Natural's issuance of First Mortgage Bonds (FMBs), which includes NW Natural's medium-term notes, under the Mortgage and Deed of Trust (Mortgage) is limited by eligible property, adjusted net earnings, and other provisions of the Mortgage. The Mortgage constitutes a first mortgage lien on certain gas properties owned from time to time by NW Natural, including substantially all of NW Natural's NGD property. In July 2022, NW Natural entered into a Bond Purchase Agreement between NW Natural and the institutional investors named as purchasers therein (the Bond Purchase Agreement). The Bond Purchase Agreement provides for the issuance of $140.0 million aggregate principal amount of NW Natural's FMBs due in 2052 (the Bonds). The Bonds were issued on September 30, 2022. The Bonds bear interest at the rate of 4.78% per annum, payable semi-annually on March 30 and September 30 of each year, commencing March 30, 2023, and will mature on September 30, 2052. The Bonds are subject to redemption prior to maturity at the option of NW Natural, in whole or in part, (i) at any time prior to March 30, 2052, at a redemption price equal to 100% of the principal amount thereof plus a “make-whole” premium and accrued and unpaid interest thereon to the date of redemption, and (ii) at any time on and after March 30, 2052, at 100% of the principal amount thereof plus accrued and unpaid interest thereon to the date of redemption. Maturities and Outstanding Long-Term Debt Retirement of long-term debt for each of the annual periods through December 31, 2027 and thereafter are as follows: In thousands Long-term debt maturities NW Natural: 2023 $ 90,000 2024 — 2025 30,000 2026 55,000 2027 64,700 Thereafter 895,000 Total $ 1,134,700 The following table presents debt outstanding as of December 31: In thousands 2022 2021 NW Natural: First Mortgage Bonds: 3.542% Series due 2023 50,000 50,000 5.620% Series due 2023 40,000 40,000 7.720% Series due 2025 20,000 20,000 6.520% Series due 2025 10,000 10,000 7.050% Series due 2026 20,000 20,000 3.211% Series due 2026 35,000 35,000 7.000% Series due 2027 20,000 20,000 2.822% Series due 2027 25,000 25,000 6.650% Series due 2027 19,700 19,700 6.650% Series due 2028 10,000 10,000 3.141% Series due 2029 50,000 50,000 7.740% Series due 2030 20,000 20,000 7.850% Series due 2030 10,000 10,000 5.820% Series due 2032 30,000 30,000 5.660% Series due 2033 40,000 40,000 5.250% Series due 2035 10,000 10,000 4.000% Series due 2042 50,000 50,000 4.136% Series due 2046 40,000 40,000 3.685% Series due 2047 75,000 75,000 4.110% Series due 2048 50,000 50,000 3.869% Series due 2049 90,000 90,000 3.600% Series due 2050 150,000 150,000 3.078% Series due 2051 130,000 130,000 4.780% Series due 2052 140,000 — Long-term debt, gross 1,134,700 994,700 Less: current maturities 90,000 — Total long-term debt $ 1,044,700 $ 994,700 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. Substantially all outstanding debt at NW Holdings is comprised of NW Natural debt. These valuations are based on Level 2 inputs as defined in the fair value hierarchy. See Note 2. 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 : December 31, In thousands 2022 2021 NW Natural: Gross long-term debt $ 1,134,700 $ 994,700 Unamortized debt issuance costs (8,823) (8,205) Carrying amount $ 1,125,877 $ 986,495 Estimated fair value (1) $ 944,383 $ 1,110,741 NW Holdings: Gross long-term debt $ 1,345,851 $ 1,053,241 Unamortized debt issuance costs (8,987) (8,309) Carrying amount $ 1,336,864 $ 1,044,932 Estimated fair value (1) $ 1,148,395 $ 1,174,500 (1) Estimated fair value does not include unamortized debt issuance costs.

Income Tax

Income Tax	12 Months Ended
	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Income Tax [Text Block]	INCOME TAX The following table provides a reconciliation between income taxes calculated at the statutory federal tax rate and the provision for income taxes reflected in the NW Holdings and NW Natural statements of comprehensive income or loss for December 31: NW Holdings NW Natural Dollars in thousands 2022 2021 2020 2022 2021 2020 Income taxes at federal statutory rate $ 24,241 $ 22,275 $ 19,185 $ 25,746 $ 22,996 $ 19,248 Increase (decrease): State income tax, net of federal 10,139 9,962 6,389 10,504 10,150 6,385 Differences required to be flowed-through by regulatory commissions (4,748) (4,655) (3,960) (4,746) (4,738) (3,960) Other, net (502) (176) (532) (468) (75) (578) Total provision for income taxes $ 29,130 $ 27,406 $ 21,082 $ 31,036 $ 28,333 $ 21,095 Effective tax rate 25.2% 25.8% 23.1% 25.3% 25.9% 23.0% The NW Holdings and NW Natural effective income tax rates for 2022 compared to 2021 changed primarily due to lower income tax amortization in 2022 of the 2020 Oregon Corporate Activity Tax (CAT), which was subject to regulatory deferral when it became effective on January 1, 2020 and then amortized in income tax expense as recovery began in late 2020, 2021, and 2022. The NW Holdings and NW Natural effective income tax rates for 2021 compared to 2020 changed primarily due to Oregon CAT, the majority of which is incurred because of Oregon regulated operations and for which rate recovery began on November 1, 2020. The provision for current and deferred income taxes consists of the following at December 31: NW Holdings NW Natural In thousands 2022 2021 2020 2022 2021 2020 Current Federal $ 5,172 $ 6,508 $ 10,106 $ 7,442 $ 7,570 $ 11,092 State 6,551 6,281 5,971 7,307 7,540 5,357 Total current income taxes 11,723 12,789 16,077 14,749 15,110 16,449 Deferred Federal 11,124 8,289 2,888 10,298 7,915 1,921 State 6,283 6,328 2,117 5,989 5,308 2,725 Total deferred income taxes 17,407 14,617 5,005 16,287 13,223 4,646 Income tax provision $ 29,130 $ 27,406 $ 21,082 $ 31,036 $ 28,333 $ 21,095 The following table summarizes the tax effect of significant items comprising NW Holdings and NW Natural's deferred income tax balances recorded at December 31: NW Holdings NW Natural In thousands 2022 2021 2022 2021 Deferred tax liabilities: Plant and property $ 326,326 $ 310,471 $ 320,121 $ 303,928 Leases receivable 36,873 38,123 36,873 38,123 Pension and postretirement obligations 22,973 23,097 22,973 23,097 Income tax regulatory asset 13,152 14,818 13,152 14,818 Lease right of use assets 21,272 21,362 21,084 21,350 Other 17,050 7,793 17,314 8,003 Total deferred income tax liabilities $ 437,646 $ 415,664 $ 431,517 $ 409,319 Deferred income tax assets: Income tax regulatory liability $ 48,270 $ 50,447 $ 48,018 $ 50,193 Lease liabilities 21,306 21,376 21,102 21,365 Other intangible assets 1,947 3,484 — — Net operating losses and credits carried forward 101 126 44 44 Total deferred income tax assets $ 71,624 $ 75,433 $ 69,164 $ 71,602 Total net deferred income tax liabilities $ 366,022 $ 340,231 $ 362,353 $ 337,717 At December 31, 2022 and 2021, regulatory income tax assets of $10.2 million and $12.4 million, respectively, were recorded by NW Natural, a portion of which is recorded in current assets. These regulatory income tax assets primarily represent future rate recovery of deferred tax liabilities, resulting from differences in NGD plant financial statement and tax bases and NGD plant removal costs, which were previously flowed through for rate making purposes and to take into account the additional future taxes, which will be generated by that recovery. These deferred tax liabilities, and the associated regulatory income tax assets, are currently being recovered through customer rates. At December 31, 2022 and 2021, regulatory income tax assets of $2.9 million and $2.4 million, respectively, were recorded by NW Natural, representing future recovery of deferred tax liabilities resulting from the equity portion of AFUDC. At December 31, 2021, a regulatory income tax asset of $0.4 million was recorded by NW Natural, representing future recovery of Oregon CAT that was deferred between January 1, 2020 and October 31,2020. In October 2020, the OPUC issued an order providing for recovery of deferred Oregon CAT as well as CAT incurred prospectively beginning November 1, 2020. This asset was fully recovered as of December 31, 2022. At December 31, 2022 and 2021, deferred tax assets of $48.0 million and $50.2 million, respectively, were recorded by NW Natural representing the future income tax benefit associated with the excess deferred income tax regulatory liability recorded as a result of the lower federal corporate income tax rate provided for by the TCJA. At December 31, 2022 and 2021, regulatory liability balances representing the benefit of the change in deferred taxes as a result of the TCJA of $181.4 million and $189.6 million, respectively, were recorded by NW Natural. NW Holdings and NW Natural assess the available positive and negative evidence to estimate if sufficient taxable income will be generated to utilize their respective existing deferred tax assets. Based upon this assessment, NW Holdings and NW Natural determined that it is more likely than not that all of their respective deferred tax assets recorded as of December 31, 2022 will be realized. The Company estimates it has net operating loss (NOL) carryforwards of $0.1 million for federal taxes and $0.1 million for state taxes at December 31, 2022. The federal NOLs do not expire and we anticipate fully utilizing the state NOL carryforward balances before they begin to expire in 2040. California alternative minimum tax (AMT) credits of $56 thousand are also available. The AMT credits do not expire. Uncertain tax positions are accounted for in accordance with accounting standards that require an assessment of the anticipated settlement outcome of material uncertain tax positions taken in a prior year, or planned to be taken in the current year. Until such positions are sustained, the uncertain tax benefits resulting from such positions would not be recognized. No reserves for uncertain tax positions were recorded as of December 31, 2022, 2021, or 2020. The federal income tax returns for tax years 2018 and earlier are closed by statute. The IRS Compliance Assurance Process (CAP) examination of the 2019 and 2020 tax years have been completed. There were no material changes to these returns as filed. The 2021 and 2022 tax years are currently under IRS CAP examination. The 2023 CAP application has been filed. Under the CAP program, NW Holdings and NW Natural work with the IRS to identify and resolve material tax matters before the tax return is filed each year. As of December 31, 2022, income tax years 2018 through 2021 remain open for examination by the State of California. Income tax years 2019 through 2021 are open for examination by the States of Oregon, Idaho, and Texas.

Property, Plant and Equipment

Property, Plant and Equipment	12 Months Ended
	Dec. 31, 2022
Public Utilities, Property, Plant and Equipment [Abstract]
Property, Plant and Equipment [Text Block]	PROPERTY, PLANT, AND EQUIPMENT The following table sets forth the major classifications of property, plant, and equipment and accumulated depreciation of continuing operations at December 31: In thousands 2022 2021 NW Natural: NGD plant in service $ 3,992,676 $ 3,721,939 NGD construction work in progress 78,897 135,398 Less: Accumulated depreciation 1,115,690 1,098,715 NGD plant, net 2,955,883 2,758,622 Other plant in service 70,368 69,332 Other construction work in progress 6,606 4,971 Less: Accumulated depreciation 21,541 20,646 Other plant, net 55,433 53,657 Total property, plant, and equipment $ 3,011,316 $ 2,812,279 Other (NW Holdings): Other plant in service $ 92,979 $ 57,184 Other construction work in progress 20,040 8,419 Less: Accumulated depreciation 9,935 6,512 Other plant, net 103,084 59,091 NW Holdings: Total property, plant, and equipment $ 3,114,400 $ 2,871,370 NW Natural: Capital expenditures in accrued liabilities $ 24,584 $ 37,537 NW Holdings: Capital expenditures in accrued liabilities $ 25,318 $ 38,333 Accumulated depreciation does not include the accumulated provision for asset removal costs of $467.7 million and $446.0 million at December 31, 2022 and 2021, respectively. These accrued asset removal costs are reflected on the balance sheet as regulatory liabilities. See Note 2. 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. NW Natural Other plant balances include non-utility gas storage assets at the Mist facility and other long-lived assets not related to NGD.

Business Combinations Business

Business Combinations Business Combinations	12 Months Ended
	Dec. 31, 2022
Business Combinations [Abstract]
Business Combinations	BUSINESS COMBINATIONS 2022 Business Combinations Far West Water & Sewer, Inc. On October 5, 2022, NWN Water completed the acquisition of the water and wastewater utilities of Far West Water & Sewer, Inc. (Far West), which has a combined approximately 25,000 connections in Yuma, Arizona. The acquisition-date fair value of the total consideration transferred, after closing adjustments, was approximately $97.0 million, of which $88.4 million was cash consideration transferred at closing, $8.1 million was contingent consideration, and $0.5 million was deferred consideration. The contingent consideration is an earnout payment in an amount equal to the product of (i) the amount, if any, by which the average annual System Operating Revenue for the 2026, 2027, and 2028 years exceeds $13.0 million (ii) multiplied by 4 but shall not exceed $12.0 million. As of the acquisition date, the contingent consideration had a fair value of $8.1 million and was included in other non-current liabilities. The fair value as of the acquisition date was determined using a scenario-based technique using management's best estimate of forecast revenue for the years 2026, 2027, and 2028 discounted to present value. The inputs to determine the fair value of the contingent consideration include estimated future revenue and a risk-adjusted discount rate. The fair value measurement is based on significant inputs that are not observable in the market and thus represents a fair value measurement categorized within Level 3 of the fair value hierarchy per ASC Topic 820. The Far West acquisition met the criteria of a business combination, and as such a preliminary allocation of the consideration to the acquired net assets based on their estimated fair value as of the acquisition date was performed. In accordance with U.S. GAAP, the fair value determination involves management judgment in determining the significant estimates and assumptions used and was made using existing regulatory conditions for net assets associated with Far West. This allocation is considered preliminary as of December 31, 2022, as facts and circumstances that existed as of the acquisition date may be discovered as we continue to integrate Far West. 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. The acquisition costs were expensed as incurred. Preliminary goodwill of $70.8 million was recognized from this acquisition. The goodwill recognized is attributable to Far West's regulated water utility service territory, experienced workforce, and the strategic benefits for both the water utility and wastewater services expected from growth in its service territory. No intangible assets aside from goodwill were recognized. The amount of goodwill that is expected to be deductible for income tax purposes is approximately $61.8 million The preliminary purchase price for the acquisition has been allocated to the net assets acquired as of the acquisition date and is as follows: In thousands December 31, 2022 Current assets $ 1,281 Property, plant and equipment 25,744 Goodwill 70,842 Non-current assets 684 Current liabilities (1,136) Non-current liabilities (9,011) Total net assets acquired $ 88,404 The amount of Far West revenues included in NW Holdings' consolidated statements of comprehensive income is $2.9 million for the year ended December 31, 2022. Earnings from Far West activities for the year ended December 31, 2022 were not material to the results of NW Holdings. Far West is referred to as Foothills Utilities following the closure of the acquisition. Other 2022 Business Combinations During the year ended December 31, 2022, NWN Water and its subsidiaries acquired the assets of six additional businesses qualifying as business combinations. The aggregate fair value of the preliminary consideration transferred for these acquisitions was $8.7 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 water and wastewater service territories and included: • 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 2021 Business Combinations During the year ended December 31, 2021, NWN Water and its subsidiaries completed four acquisitions qualifying as business combinations. The aggregate fair value of the consideration transferred for these acquisitions were not material and are not significant to NW Holdings' results of operations. 2020 Business Combinations During the year ended December 31, 2020, NWN Water and its subsidiaries completed two significant acquisitions qualifying as business combinations. The aggregate fair value of the total cash consideration transferred for these acquisitions was $38.1 million, most of which was allocated to property, plant and equipment and goodwill. These transactions align with NW Holdings' water sector strategy as it continues to expand its water services territories in the Pacific Northwest and beyond and included: • Suncadia Water Company, LLC and Suncadia Environmental Company, LLC which were acquired by NWN Water of Washington on January 31, 2020, and • T&W Water Service Company which was acquired by NWN Water of Texas on March 2, 2020. T&W Water Service Company is referred to as Blue Topaz Utilities following the closure of the acquisition. Other 2020 Business Combinations During the year ended December 31, 2020, NWN Water completed three additional acquisitions, comprised of four water systems and one wastewater system, which qualified as business combinations. The aggregate fair value of the consideration transferred for these acquisitions was approximately $1.5 million. These business combinations were not significant to NW Holdings' results of operations. 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 $149.3 million as of December 31, 2022 and $70.6 million as of December 31, 2021. The increase in the goodwill balance was primarily due to additions associated with our acquisitions in the water and wastewater sector. 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	12 Months Ended
	Dec. 31, 2022
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 combinations of option contracts. 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 as well as to hedge spot purchases of natural gas. 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. NW Natural also enters into exchange contracts related to the third-party asset management of its gas portfolio, some of which are derivatives that do not qualify for hedge accounting or only partial regulatory deferral, but are subject to NW Natural's regulatory sharing agreement. These derivatives are recognized in operating revenues, net of amounts shared with NGD customers. Notional Amounts The following table presents the absolute notional amounts related to open positions on NW Natural derivative instruments: At December 31, In thousands 2022 2021 Natural gas (in therms): Financial 852,435 618,815 Physical 463,254 431,628 Foreign exchange $ 7,617 $ 6,268 Purchased Gas Adjustment (PGA) 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. Rates and hedging approaches may vary between states due to different rate structures and mechanisms. In addition, as required with the Washington PGA filing, NW Natural incorporated and began implementing risk-responsive hedging strategies for its Washington gas supplies. Hedge contracts entered into after the start of the PGA period are subject to the PGA incentive sharing mechanism in Oregon. NW Natural entered the 2022-23 and 2021-22 gas years with forecasted sales volumes hedged at 67% and 60% in financial swap and option contracts, and 17% and 19% in physical gas supplies, respectively. Hedge contracts entered into prior to the PGA filing, in September 2022, were included in the PGA for the 2022-23 gas year. Hedge contracts entered into after the PGA filing, and related to subsequent gas years, may be included in future PGA filings and qualify for regulatory deferral. 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: December 31, 2022 December 31, 2021 In thousands Natural gas commodity Foreign exchange Natural gas commodity Foreign exchange Benefit (expense) to cost of gas $ 119,935 $ (165) $ 36,539 $ (26) Operating revenues (expense) — — (26) — Amounts deferred to regulatory accounts on balance sheet (119,935) 165 (36,517) 26 Total gain (loss) in pre-tax earnings $ — $ — $ (4) $ — 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 net gains of $ 107.8 million 50.9 million Credit Risk Management of Financial Derivatives Instruments No collateral was posted with or by NW Natural counterparties as of December 31, 2022 or 2021. 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 2022 or 2021. 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 counterparty, NW Natural's physical and financial derivative position would result in an asset of $153.3 million and a liability of $3.6 million as of December 31, 2022, and an asset of $51.8 million and a liability of $3.8 million as of December 31, 2021. NW Natural is exposed to derivative credit and liquidity risk primarily through securing fixed price natural gas commodity swaps with financial counterparties. NW Natural utilizes master netting arrangements through International Swaps and Derivatives Association contracts to minimize this risk along with collateral 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. NW Natural's financial derivatives policy requires counterparties to have an investment-grade credit rating at the time the derivative instrument is entered into, and specifies limits on the contract amount and duration based on each counterparty’s credit rating. NW Natural does not speculate in derivatives. Derivatives are used to reduce NW Natural's net market risk and hedge exposure above risk tolerance limits. It is required that increases in market risk created by the use of derivatives is offset by the exposures they modify. We actively monitor NW Natural's derivative credit exposure and place counterparties on hold for trading purposes or require other forms of credit assurance, such as letters of credit, cash collateral, or guarantees as circumstances warrant. The ongoing assessment of counterparty credit risk includes consideration of credit ratings, credit default swap spreads, bond market credit spreads, financial condition, government actions, and market news. A Monte Carlo simulation model is used to estimate the change in credit and liquidity risk from the volatility of natural gas prices. The results of the model are used to establish trading limits. NW Natural's outstanding financial derivatives at December 31, 2022 mature by November 1, 2025. We could become materially exposed to credit risk with one or more of our counterparties if natural gas prices experience a significant increase. If a counterparty were to become insolvent or fail to perform on its obligations, we could suffer a material loss; however, we would expect such a loss to be eligible for regulatory deferral and rate recovery, subject to a prudence review. All of our existing counterparties currently have investment-grade credit ratings. Fair Value

Commitments and Contigencies

Commitments and Contigencies	12 Months Ended
	Dec. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	COMMITMENTS AND CONTINGENCIES Gas Purchase and Pipeline Capacity Purchase and Release Commitments NW Natural has signed agreements providing for the reservation of firm pipeline capacity under which it is required to make fixed monthly payments for contracted capacity. The pricing component of the monthly payment is established, subject to change, by U.S. or Canadian regulatory bodies, or is established directly with private counterparties, as applicable. In addition, NW Natural has entered into long-term agreements to release firm pipeline capacity. NW Natural also enters into short-term and long-term gas purchase agreements. In November 2021, NW Natural and a subsidiary of Archaea Energy entered into a long-term RNG purchase and sale agreement. Under the agreement, NW Natural committed to purchase the environmental attributes generated by Archaea related to up to ten million therms of RNG annually from its portfolio of RNG production facilities for a fixed fee for a period of 21 years. The agreement commenced in 2022, with the full annual quantity beginning in 2025. The aggregate amounts of these agreements at NW Natural were as follows at December 31, 2022: In thousands Gas Purchase Agreements (1) Pipeline Pipeline 2023 $ 400,370 $ 81,691 $ 8,154 2024 6,376 77,327 7,474 2025 6,426 78,493 3,397 2026 12,003 66,782 — 2027 11,330 66,906 — Thereafter 189,050 432,464 — Total 625,555 803,663 19,025 Less: Amount representing interest 86,250 200,243 989 Total at present value $ 539,305 $ 603,420 $ 18,036 (1) Gas purchase agreements include environmental attributes of RNG. Total fixed charges under capacity purchase agreements were $90.2 million for 2022, $82.9 million for 2021, and $81.8 million for 2020, of which $8.3 million, $7.7 million, and $4.8 million, respectively, related to capacity releases. In addition, per-unit charges are required to be paid based on the actual quantities shipped under the agreements. In certain take-or-pay purchase commitments, annual deficiencies may be offset by prepayments subject to recovery over a longer term if future purchases exceed the minimum annual requirements. Leases Refer to Note 7 for a discussion of lease commitments and contingencies. Environmental Matters Refer to Note 17 for a discussion of environmental commitments and contingencies.

Environmental Matters

Environmental Matters	12 Months Ended
	Dec. 31, 2022
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 at December 31: Current Liabilities Non-Current Liabilities In thousands 2022 2021 2022 2021 Portland Harbor site: Gasco/Siltronic Sediments $ 9,744 $ 7,582 $ 42,120 $ 42,076 Other Portland Harbor 2,634 2,592 11,270 9,570 Gasco/Siltronic Upland site 16,067 15,711 35,457 36,215 Front Street site 457 1,100 879 811 Oregon Steel Mills — — 179 179 Total $ 28,902 $ 26,985 $ 89,905 $ 88,851 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 to provide the estimated 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 $51.9 million to $350 million. NW Natural has recorded a liability of $51.9 million for the Gasco sediment clean-up, which reflects the low end of the range. At this time, we believe sediments at the Gasco sediments site represent the largest portion of NW Natural's liability related to the Portland Harbor site discussed above. OTHER PORTLAND HARBOR. While we believe liabilities associated with the Gasco sediments site represent NW Natural's largest exposure, there are other potential exposures associated with the Portland Harbor ROD, including NRD costs and harborwide remedial design and cleanup costs (including downstream petroleum contamination), for which allocations among the PRPs have not yet been determined. NW Natural and other parties have signed a cooperative agreement with the Portland Harbor Natural Resource Trustee council to participate in a phased NRD assessment to estimate liabilities to support an early restoration-based settlement of NRD claims. One member of this Trustee council, the Yakama Nation, withdrew from the council in 2009, and in 2017, filed suit against NW Natural and 29 other parties seeking remedial costs and NRD assessment costs associated with the Portland Harbor site, set forth in the complaint. The complaint seeks recovery of alleged costs totaling $0.3 million in connection with the selection of a remedial action for the Portland Harbor site as well as declaratory judgment for unspecified future remedial action costs and for costs to assess the injury, loss or destruction of natural resources resulting from the release of hazardous substances at and from the Portland Harbor site. The Yakama Nation has filed two amended complaints addressing certain pleading defects and dismissing the State of Oregon. On the motion of NW Natural and certain other defendants the federal court has stayed the case pending the outcome of the non-binding allocation proceeding discussed above. NW Natural has recorded a liability for NRD claims which is at the low end of the range of the potential liability; the high end of the range cannot be reasonably estimated at this time. The NRD liability is not included in the aforementioned range of costs provided in the Portland Harbor ROD. Gasco Uplands Site A predecessor of NW Natural, Portland Gas and Coke Company, owned a former gas manufacturing plant that was closed in 1958 (Gasco site) and is adjacent to the Portland Harbor site described above. The Gasco site has been under investigation by NW Natural for environmental contamination under the ODEQ Voluntary Cleanup Program (VCP). It is not included in the range of remedial costs for the Portland Harbor site noted above. The Gasco site is managed in two parts, the uplands portion 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 first year of post-construction monitoring was completed in 2021 and demonstrated that the cap was intact and performing as designed. NW Natural has recognized an additional liability of $1.3 million for costs associated with the discovery during construction of World War II-era munitions, design costs, regulatory and permitting issues, 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. The following table presents information regarding the total regulatory asset deferred as of December 31: In thousands 2022 2021 Deferred costs and interest (1) $ 47,666 $ 45,122 Accrued site liabilities (2) 118,763 115,773 Insurance proceeds and interest (54,784) (59,564) Total regulatory asset deferral (1) $ 111,645 $ 101,331 Current regulatory assets (3) $ 7,392 $ 6,694 Long-term regulatory assets (3) $ 104,253 $ 94,636 (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 $43 thousand in 2022 and $62 thousand in 2021. (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 nor 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. See " Oregon SRRM " below. Oregon SRRM Collections From Oregon Customers Under the SRRM collection process, there are three types of deferred environmental remediation expense: • Pre-review - This class of costs represents remediation spend that has not yet been deemed prudent by the OPUC. Carrying costs on these remediation expenses are recorded at NW Natural's authorized cost of capital. NW Natural anticipates the prudence review for annual costs and approval of the earnings test prescribed by the OPUC to occur by the third quarter of the following year. • Post-review - This class of costs represents remediation spend that has been deemed prudent and allowed after applying the earnings test, but is not yet included in amortization. NW Natural earns a carrying cost on these amounts at a rate equal to the five-year treasury rate plus 100 basis points. • Amortization - This class of costs represents amounts included in current customer rates for collection and is generally calculated as one-fifth of the post-review deferred balance. NW Natural earns a carrying cost equal to the amortization rate determined annually by the OPUC, which approximates a short-term borrowing rate. In addition to the collection amount noted above, an order issued by the OPUC provides for the annual collection of $5.0 million from Oregon customers through a tariff rider. As NW Natural collects amounts from customers, it recognizes these collections as revenue and separately amortizes an equal and offsetting amount of its deferred regulatory asset balance through the environmental remediation operating expense line shown separately in the operating expense section of the income statement. NW Natural received total environmental insurance proceeds of approximately $150 million as a result of settlements from litigation that was dismissed in July 2014. Under a 2015 OPUC order which established the SRRM, one-third of the Oregon allocated proceeds were applied to costs deferred through 2012 with the remaining two-thirds applied to costs at a rate of $5.0 million per year plus interest over the following 20 years. NW Natural accrues interest on the Oregon allocated insurance proceeds in the customer’s favor at a rate equal to the five-year treasury rate plus 100 basis points. As of December 31, 2022, NW Natural has applied $95.0 million of insurance proceeds to prudently incurred remediation costs allocated to Oregon. 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. Washington ECRM Washington Deferral On October 21, 2019, the WUTC issued an order (WUTC Order) establishing the ECRM which allows for recovery of past deferred and future prudently incurred environmental remediation costs allocable to Washington customers through application of insurance proceeds and collections from customers. Environmental remediation expenses relating to sites that previously served both Oregon and Washington customers are allocated between states with Washington customers receiving 3.3% percent of the costs and insurance proceeds. In accordance with the WUTC Order, insurance proceeds were fully applied to costs incurred between December 2018 and June 2019 that were deemed prudent. Remaining insurance proceeds will be amortized over a 10.5 year period ending December 31, 2029. As of December 31, 2022 , approximately $3.9 million of proceeds have been applied to prudently incurred costs. On an annual basis, NW Natural files for a prudence determination and a request to amortize costs to the extent that remediation expenses exceed the insurance amortization. After insurance proceeds are fully amortized, if in a particular year the request to collect deferred amounts exceeds one percent of Washington normalized revenues, then the excess will be collected over three years with interest. 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 In 2004, NW Natural was served with a third-party complaint by the Port of Portland (the Port) in a Multnomah County Circuit Court case, Oregon Steel Mills, Inc. v. The Port of Portland. The Port alleges that in the 1940s and 1950s petroleum wastes generated by NW Natural's predecessor, Portland Gas & Coke Company, and 10 other third-party defendants, were disposed of in a waste oil disposal facility operated by the United States or Shaver Transportation Company on property then owned by the Port and now owned by Evraz Oregon Steel Mills. The complaint seeks contribution for unspecified past remedial action costs incurred by the Port regarding the former waste oil disposal facility as well as a declaratory judgment allocating liability for future remedial action costs. No date has been set for trial. In August 2017, the case was stayed pending the outcome of the Portland Harbor allocation process or other mediation. Although the final outcome of this proceeding cannot be predicted with certainty, NW Natural and NW Holdings do not expect the ultimate disposition of this matter will have a material effect on NW Natural's or NW Holdings' financial condition, results of operations, or cash flows. For additional information regarding other commitments and contingencies, see Note 16.

Discontinued Operations

Discontinued Operations	12 Months Ended
	Dec. 31, 2021
Discontinued Operations and Disposal Groups [Abstract]
Discontinued Operations	DISCONTINUED OPERATIONS NW Holdings On June 20, 2018, NWN Gas Storage, then a wholly-owned subsidiary of NW Natural, entered into a Purchase and Sale Agreement (the Agreement) that provided for the sale by NWN Gas Storage of all of the membership interests in Gill Ranch. Gill Ranch owns a 75% interest in the natural gas storage facility located near Fresno, California known as the Gill Ranch Gas Storage Facility. On December 4, 2020, NWN Gas Storage closed the sale of all of the membership interests in Gill Ranch and received payment of the initial cash purchase price of $13.5 million less the $1.0 million deposit previously paid. Furthermore, additional payments to NWN Gas Storage may be made subject to a maximum amount of $15.0 million in the aggregate (subject to a working capital adjustment) based on the economic performance of Gill Ranch for each full gas storage year (April 1 of one year through March 31 of the following year) occurring after the closing and the remaining portion of the 2020-2021 gas storage year and will continue until such time as the maximum amount has been paid. The fair value of this arrangement at the closing date was zero based on a discounted cash flow forecast. Subsequent changes in the fair value will be recorded in earnings. The completion of the sale resulted in an after-tax gain of $5.9 million for the year ended December 31, 2020. The following table presents the operating results of Gill Ranch and is presented net of tax on NW Holdings' consolidated statements of comprehensive income: NW Holdings Discontinued Operations In thousands 2020 Revenues $ 10,193 Expenses Operations and maintenance 7,931 General taxes 198 Depreciation 391 Other expenses and interest 848 Total expenses 9,368 Income from discontinued operations 825 Gain on sale of discontinued operations 8,027 Income from discontinued operations before income tax 8,852 Income tax expense (1) 2,344 Income from discontinued operations, net of tax $ 6,508 (1) Includes income tax expense of $2.1 million related to the sale of Gill Ranch for the year ended December 31, 2020. As a result of the disposition of the membership interests of Gill Ranch, there were no assets or liabilities classified as held for sale at December 31, 2020.

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2022
Subsequent Events [Abstract]
Subsequent Events [Text Block]	SUBSEQUENT EVENT On January 6, 2023, NW Natural issued and sold $100.0 million aggregate principal amount of its FMBs, 5.43% Series due January 6, 2053 (the Bonds), to certain institutional investors pursuant to a Bond Purchase Agreement dated December 13, 2022. The 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. The Bonds will be subject to redemption prior to maturity at the option of NW Natural, in whole or in part, (i) at any time prior to July 6, 2052, at a redemption price equal to 100% of the principal amount thereof plus a “make-whole” premium and accrued and unpaid interest thereon to the date of redemption, and (ii) at any time on and after July 6, 2052, at 100% of the principal amount thereof plus accrued and unpaid interest thereon to the date of redemption. The Bond Purchase Agreement also provides for the issuance of $80.0 million aggregate principal amount of NW Natural’s FMBs, 5.18% Series due 2034 (5.18% Bonds) and $50.0 million aggregate principal amount of NW Natural’s FMBs, 5.23% Series due 2038 (5.23% Bonds). The 5.18% Bonds and the 5.23% Bonds are expected to be issued on or about August 4, 2023.

Condensed Financials Standalone

Condensed Financials Standalone Holdco Condensed Financials Standalone Holdco (Notes)	12 Months Ended
	Dec. 31, 2022
Condensed Financial Statements, Captions [Line Items]
Condensed Financial Information of Parent Company Only Disclosure [Text Block]	SCHEDULE I - CONDENSED FINANCIAL INFORMATION OF NORTHWEST NATURAL HOLDING COMPANY

Valuation Allowances and Reserv

Valuation Allowances and Reserves	12 Months Ended
	Dec. 31, 2022
Entity Information [Line Items]
Schedule of Valuation and Qualifying Accounts	NORTHWEST NATURAL HOLDING COMPANY SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS AND RESERVES COLUMN A COLUMN B COLUMN C COLUMN D COLUMN E Additions Deductions In thousands (year ended December 31) Balance at beginning of period Charged to costs and expenses Charged to other accounts Net write-offs Balance at end of period 2022 Reserves deducted in balance sheet from assets to which they apply: Allowance for uncollectible accounts $ 2,018 $ 1,081 $ 1,810 $ 1,613 $ 3,296 2021 Reserves deducted in balance sheet from assets to which they apply: Allowance for uncollectible accounts $ 3,219 $ 724 $ (219) $ 1,706 $ 2,018 2020 Reserves deducted in balance sheet from assets to which they apply: Allowance for uncollectible accounts $ 673 $ 890 $ 2,333 $ 677 $ 3,219 NORTHWEST NATURAL GAS COMPANY SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS AND RESERVES COLUMN A COLUMN B COLUMN C COLUMN D COLUMN E Additions Deductions In thousands (year ended December 31) Balance at beginning of period Charged to costs and expenses Charged to other accounts Net write-offs Balance at end of period 2022 Reserves deducted in balance sheet from assets to which they apply: Allowance for uncollectible accounts $ 1,962 $ 920 $ 1,810 $ 1,613 $ 3,079 2021 Reserves deducted in balance sheet from assets to which they apply: Allowance for uncollectible accounts $ 3,107 $ 780 $ (219) $ 1,706 $ 1,962 2020 Reserves deducted in balance sheet from assets to which they apply: Allowance for uncollectible accounts $ 672 $ 779 $ 2,333 $ 677 $ 3,107

Significant Accounting Polici_2

Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2022
Accounting Policies [Abstract]
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with generally accepted accounting principles in the United States of America (U.S. GAAP) requires management to make estimates and assumptions that affect reported amounts in the consolidated financial statements and accompanying notes. Actual amounts could differ from those estimates, and changes would most likely be reported in future periods. Management believes the estimates and assumptions used are reasonable .
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. Accounting records and practices of the regulated businesses conform to the requirements and uniform system of accounts prescribed by these regulatory authorities in accordance with U.S. GAAP. The businesses in which customer rates are regulated by the OPUC, WUTC, IPUC, PUTC, ACC and FERC have approved cost-based rates which are intended to allow such businesses to earn a reasonable return on invested capital. In applying regulatory accounting principles, NW Holdings and NW Natural capitalize or defer certain costs and revenues as regulatory assets and liabilities pursuant to orders of the applicable state public utility commission, which provide for the recovery of revenues or expenses from, or refunds to, utility customers in future periods, including a return or a carrying charge in certain cases. Amounts NW Natural deferred as regulatory assets and liabilities were as follows: Regulatory Assets In thousands 2022 2021 NW Natural: Current: Unrealized loss on derivatives (1) $ 28,728 $ 10,402 Gas costs 61,223 35,641 Environmental costs (2) 7,392 6,694 Decoupling (3) — 969 Pension balancing (4) 7,131 7,131 Income taxes 2,208 2,568 Other (5) 10,809 8,986 Total current $ 117,491 $ 72,391 Non-current: Unrealized loss on derivatives (1) $ 20,838 $ 412 Pension balancing (4) 32,997 38,302 Income taxes 10,943 12,609 Pension and other postretirement benefit liabilities 101,413 116,440 Environmental costs (2) 104,253 94,636 Gas costs 22,355 15,477 Other (5) 47,608 36,663 Total non-current $ 340,407 $ 314,539 Other (NW Holdings) 25 40 Total non-current -NW Holdings $ 340,432 $ 314,579 Regulatory Liabilities In thousands 2022 2021 NW Natural: Current: Gas costs $ 4,121 $ 70 Unrealized gain on derivatives (1) 194,236 48,130 Decoupling (3) 14,026 4,475 Income taxes (6) 7,166 8,192 Asset optimization revenue sharing 26,368 45,124 Other (5) 2,636 6,290 Total current - NW Natural $ 248,553 $ 112,281 Other (NW Holdings) 29 — Total current - NW Holdings $ 248,582 $ 112,281 Non-current: Gas costs $ 12,644 $ 250 Unrealized gain on derivatives (1) 5,045 10,730 Decoupling (3) 3,814 3,412 Income taxes (6) 174,212 181,404 Accrued asset removal costs (7) 467,742 445,952 Asset optimization revenue sharing 8,401 1,810 Other (5) 16,741 13,792 Total non-current - NW Natural $ 688,599 $ 657,350 Other (NW Holdings) 979 982 Total non-current -NW Holdings $ 689,578 $ 658,332 (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 natural gas distribution rates as part of the annual Purchased Gas Adjustment (PGA) mechanism when realized at settlement. (2) Refer to the Environmental Cost Deferral and Recovery table in Note 17 for a description of environmental costs. (3) This deferral represents the margin adjustment resulting from differences between actual and expected volumes. (4) Refer to Note 10 for information regarding the deferral of pension expenses. (5) Balances consist of deferrals and amortizations under approved regulatory mechanisms and typically earn a rate of return or carrying charge. (6) This balance represents estimated amounts associated with the Tax Cuts and Jobs Act. See Note 11. (7) Estimated costs of removal on certain regulated properties are collected through rates. See "Accounting Policies— Plant, Property, and Accrued Asset Removal Costs " below. The amortization period for NW Natural's regulatory assets and liabilities ranges from less than one year to an indeterminable period. Regulatory deferrals for gas costs payable are generally amortized over 12 months beginning each November 1 following the gas contract year during which the deferred gas costs are recorded. Similarly, most other regulatory deferred accounts are amortized over 12 months. However, certain regulatory account balances, such as income taxes, environmental costs, pension liabilities, and accrued asset removal costs, are large and tend to be amortized over longer periods once NW Natural has agreed upon an amortization period with the respective regulatory agency. We believe all costs incurred and deferred at December 31, 2022 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 Natural would be required to write-off the net unrecoverable balances in the period such determination is made. Regulatory interest income of $7.0 million and $6.1 million and regulatory interest expense of $2.0 million and $1.3 million was recognized within other income (expense), net for the years ended December 31, 2022 and 2021, respectively. Environmental Regulatory Accounting
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 Adopted Accounting Pronouncements REFERENCE RATE REFORM. In March 2020, the FASB issued ASU 2020-04, "Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting." The purpose of the amendment is to provide optional expedients and exceptions for applying generally accepted accounting principles (GAAP) to contracts, hedging relationships, and other transactions affected by reference rate reform if certain criteria are met. The amendments in this ASU apply only to contracts, hedging relationships, and other transactions that reference London Inter-Bank Offered Rate (LIBOR) or another reference rate expected to be discontinued because of reference rate reform. In January 2021, the FASB issued ASU 2021-01, "Reference Rate Reform (Topic 848): Scope." The purpose of the amendment is to clarify guidance on reference rate reform activities, specifically related to accounting for derivative contracts and certain hedging relationships affected by changes in the interest rates used for discounting, margining, and contract price alignment (the "discounting transition"). The amendments in ASUs 2020-04 and 2021-01 are effective for all entities as of March 12, 2020 through December 31, 2022. In December 2022, the FASB issued ASU 2022-06, "Reference Rate Reform (Topic 848): Deferral of the Sunset Date of Topic 848." The purpose of the amendment is to defer the sunset date of Topic 848 from December 31, 2022, to December 31, 2024, after which entities will no longer be permitted to apply the relief in Topic 848. The objective of the guidance in Topic 848 is to provide temporary relief during the transition period. The Board included a sunset provision within Topic 848 based on expectations of when the London Interbank Offered Rate (LIBOR) would cease being published. We do not expect the ASUs to materially affect the financial statements and disclosures of NW Holdings or NW Natural. LEASES. In July 2021, the FASB issued ASU 2021-05, "Leases (Topic 842), Lessors - Certain Leases with Variable Lease Payments." The purpose of the amendment is to require lessors to account for certain lease transactions that contain variable lease payments as operating leases. The amendments in this ASU are intended to eliminate the recognition of any day-one loss
Property, Plant and Accrued Asset Removal Costs	Plant, Property, and Accrued Asset Removal Costs Plant and property are stated at cost, including capitalized labor, materials, and overhead. In accordance with regulatory accounting standards, the cost of acquiring and constructing long-lived plant and property generally includes an allowance for funds used during construction (AFUDC) or capitalized interest. AFUDC represents the regulatory financing cost incurred when debt and equity funds are used for construction (see “ AFUDC ” below). When constructed assets are subject to market-based rates rather than cost-based rates, the financing costs incurred during construction are included in capitalized interest in accordance with U.S. GAAP, not as regulatory financing costs under AFUDC. In accordance with long-standing regulatory treatment, our depreciation rates consist of three components: one based on the average service life of the asset, a second based on the estimated salvage value of the asset, and a third based on the asset’s estimated cost of removal. We collect, through rates, the estimated cost of removal on certain regulated properties through depreciation expense, with a corresponding offset to accumulated depreciation. These removal costs are non-legal obligations as defined by regulatory accounting guidance. Therefore, we have included these costs as non-current regulatory liabilities rather than as accumulated depreciation on our consolidated balance sheets. In the rate setting process, the liability for removal costs is treated as a reduction to the net rate base on which the NGD business has the opportunity to earn its allowed rate of return. The costs of NGD plant retired or otherwise disposed of are removed from NGD plant and charged to accumulated depreciation for recovery or refund through future rates. Gains from the sale of regulated assets are generally deferred and refunded to customers. For assets not related to NGD, we record a gain or loss upon the disposal of the property, and the gain or loss is recorded in operating income or loss in the consolidated statements of comprehensive income. The provision for depreciation of NGD property, plant, and equipment is recorded under the group method on a straight-line basis with rates computed in accordance with depreciation studies approved by regulatory authorities. The weighted-average depreciation rate for NGD assets in service was approximately 3.0% for 2022, 2021 and 2020, reflecting the approximate weighted-average economic life of the property. This includes 2022 weighted-average depreciation rates for the following asset categories: 2.5% for transmission and distribution plant, 2.1% for gas storage facilities, 6.1% for general plant, and 6.7% for intangible and other fixed assets. AFUDC. Certain additions to NGD plant include AFUDC, which represents the net cost of debt and equity funds used during construction. AFUDC is calculated using actual interest rates for debt and authorized rates for ROE, if applicable. If short-term debt balances are less than the total balance of construction work in progress, then a composite AFUDC rate is used to represent interest on all debt funds, shown as a reduction to interest charges, and on ROE funds, shown as other income. While cash is not immediately recognized from recording AFUDC, it is realized in future years through rate recovery resulting from the higher NGD cost of service. Our composite AFUDC rate was 2.8% in 2022, 0.7% in 2021, and 1.9% in 2020. IMPAIRMENT OF LONG-LIVED ASSETS. We review the carrying value of long-lived assets whenever events or changes in circumstances indicate the carrying amount of the assets may not be recoverable. Factors that would necessitate an impairment assessment of long-lived assets include a significant adverse change in the extent or manner in which the asset is used, a significant adverse change in legal factors or business climate that could affect the value of the asset, or a significant decline in the observable market value or expected future cash flows of the asset, among others. When such factors are present, we assess the recoverability by determining whether the carrying value of the asset will be recovered through expected future cash flows. An asset is determined to be impaired when the carrying value of the asset exceeds the expected undiscounted future cash flows from the use and eventual disposition of the asset. If an impairment is indicated, we record an impairment loss for the difference between the carrying value and the fair value of the long-lived assets. Fair value is estimated using appropriate valuation methodologies, which may include an estimate of discounted cash flows.
Cash and Cash Equivalents	Cash and Cash Equivalents For purposes of reporting cash flows, cash and cash equivalents include cash on hand plus highly liquid investment accounts with original maturity dates of three months or less. At December 31, 2022, NW Holdings had outstanding checks of $5.8 million, substantially all of which is recorded at NW Natural, and at December 31, 2021, NW Holdings had no outstanding checks. These balances are included in accounts payable in the NW Holdings and NW Natural balance sheets. Restricted cash is primarily comprised of funds from public purpose charges for programs that assist low-income customers with bill payments or energy efficiency. These balances are included in other current assets in the NW Holdings and NW Natural balance sheets. There were no transfers between restricted cash and cash and cash equivalents during the years ended December 31, 2022 and 2021. Prior period amounts have been reclassified to conform prior period information to the current presentation. The following table provides a reconciliation of the cash, cash equivalents and restricted cash balances at NW Holdings as of December 31, 2022 and 2021: December 31, In thousands 2022 2021 Cash and cash equivalents $ 29,270 $ 18,559 Restricted cash included in other current assets 11,694 8,561 Cash, cash equivalents and restricted cash $ 40,964 $ 27,120 The following table provides a reconciliation of the cash, cash equivalents and restricted cash balances at NW Natural as of December 31, 2022 and 2021: December 31, In thousands 2022 2021 Cash and cash equivalents $ 12,977 $ 12,271 Restricted cash included in other current assets 11,694 8,561 Cash, cash equivalents and restricted cash $ 24,671 $ 20,832
Revenue Recognition and Accrued Unbilled Revenue	Revenue Recognition and Accrued Unbilled Revenue Revenues, derived primarily from the sale and transportation of natural gas, are recognized upon delivery of gas or water, or service to customers. Revenues include accruals for gas or water delivered but not yet billed to customers based on estimates of deliveries from meter reading dates to month end (accrued unbilled revenue). Accrued unbilled revenue is dependent upon a number of factors that require management’s judgment, including total natural gas receipts and deliveries, customer use of natural gas or water by billing cycle, and weather factors. Accrued unbilled revenue is reversed the following month when actual billings occur. NW Holdings' accrued unbilled revenue at December 31, 2022 and 2021 was $89.0 million and $82.2 million, respectively, substantially all of which is accrued unbilled revenue at NW Natural.
Revenue Taxes	Revenue Taxes
Accounts Receivable and Allowance for Uncollectible Accounts	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 2022 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 in the third and fourth quarter for Oregon 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, substantially all of which is related to NW Natural's accounts receivable: As of December 31, 2021 As of December 31, 2022 Year ended December 31, 2022 In thousands Beginning Balance Provision recorded, net of adjustments Write-offs recognized, net of recoveries Ending Balance Allowance for uncollectible accounts: Residential $ 1,460 $ 1,974 $ (1,062) $ 2,372 Commercial 178 546 (324) 400 Industrial 67 186 (65) 188 Accrued unbilled and other 313 185 (162) 336 Total $ 2,018 $ 2,891 $ (1,613) $ 3,296 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.
Inventories	Inventories NGD gas inventories, which consist of natural gas in storage for NGD customers, are stated at the lower of weighted-average cost or net realizable value. The regulatory treatment of these inventories provides for cost recovery in customer rates. NGD gas inventories injected into storage are priced in inventory based on actual purchase costs, and those withdrawn from storage are charged to cost of gas during the period they are withdrawn at the weighted-average inventory cost. Gas storage inventories mainly consist of natural gas received as fuel-in-kind from storage customers. Gas storage inventories are valued at the lower of average cost or net realizable value. Cushion gas is not included in inventory balances, is recorded at original cost, and is classified as a long-term plant asset. Materials and supplies inventories consist of inventories both related to and unrelated to NGD and are stated at the lower of average cost or net realizable value. NW Natural's NGD and gas storage inventories totaled $61.9 million and $37.4 million at December 31, 2022 and 2021, respectively. At December 31, 2022 and 2021, NW Holdings' materials and supplies inventories, which are comprised primarily of NW Natural's materials and supplies, totaled $23.5 million and $19.9 million, respectively. During 2022 and 2021, NW Natural entered into certain agreements to purchase renewable thermal certificates (RTCs). RTCs are initially recorded at cost and subsequently assessed for impairment based on the lower-of-cost or market model. NW Natural's RTCs inventory totaled $1.7 million at December 31, 2022, and all RTCs purchased during 2021 were retired or used on customers behalf prior to December 31, 2021.
Gas Reserves	Gas Reserves Gas reserves are payments to acquire and produce natural gas reserves. Gas reserves are stated at cost, adjusted for regulatory amortization, with the associated deferred tax benefits recorded as liabilities on the balance sheet. The current portion is calculated based on expected gas deliveries within the next fiscal year. NW Natural recognizes regulatory amortization of this asset on a volumetric basis calculated using the estimated gas reserves and the estimated therms extracted and sold each month. The amortization of gas reserves is recorded to cost of gas along with gas production revenues and production costs. See Note 13.
Derivatives	Derivatives NW Natural's derivatives are measured at fair value and recognized as either assets or liabilities on the balance sheet. Changes in the fair value of the derivatives are recognized in earnings unless specific regulatory or hedge accounting criteria are met. Accounting for derivatives and hedges provides an exception for contracts intended for normal purchases and normal sales for which physical delivery is probable. In addition, certain derivative contracts are approved by regulatory authorities for recovery or refund through customer rates. Accordingly, the changes in fair value of these approved contracts are deferred as regulatory assets or liabilities pursuant to regulatory accounting principles. NW Natural's financial derivatives generally qualify for deferral under regulatory accounting. NW Natural's index-priced physical derivative contracts also qualify for regulatory deferral accounting treatment. Derivative contracts entered into for NGD requirements after the annual PGA rate has been set and maturing during the PGA year are subject to the PGA incentive sharing mechanism. In Oregon, NW Natural participates in a PGA sharing mechanism under which it is required to select either an 80% or 90% deferral of higher or lower gas costs such that the impact on current earnings from the gas cost sharing is either 20% or 10% of gas cost differences compared to PGA prices, respectively. For each of the PGA years in Oregon beginning November 1, 2022, 2021, and 2020, NW Natural selected the 90% deferral of gas cost differences. In Washington, 100% of the differences between the PGA prices and actual gas costs are deferred. See Note 15. NW Holdings and NW Natural have financial derivative policies that set forth guidelines for using selected derivative products to support prudent risk management strategies within designated parameters. NW Natural's objective for using derivatives is to decrease the volatility of gas prices and cash flows without speculative risk. The use of derivatives is permitted only after the risk exposures have been identified, are determined to exceed acceptable tolerance levels, and are determined necessary to support normal business activities. NW Natural does not enter into derivative instruments for trading purposes. All commodity and foreign exchange derivatives are currently held at NW Natural, and interest rate swaps are held at NW Holdings and NWN Water.
Fair Value	Fair Value In accordance with fair value accounting, we use the following fair value hierarchy for determining inputs for our debt, pension plan assets, and derivative fair value measurements: • Level 1: Valuation is based on quoted prices for identical instruments traded in active markets; • Level 2: Valuation is based on quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active, and model-based valuation techniques for which all significant assumptions are observable in the market; and • Level 3: Valuation is generated from model-based techniques that use significant assumptions not observable in the market. These unobservable assumptions reflect our own estimates of assumptions market participants would use in valuing the asset or liability. In addition, the fair value for certain pension trust investments is determined using Net Asset Value per share (NAV) as a practical expedient, and therefore they are not classified within the fair value hierarchy. These investments primarily consist of institutional investment products. When developing fair value measurements, it is our policy to use quoted market prices whenever available or to maximize the use of observable inputs and minimize the use of unobservable inputs when quoted market prices are not available. Fair values are primarily developed using industry-standard models that consider various inputs including: (a) quoted future prices for commodities; (b) forward currency prices; (c) time value; (d) volatility factors; (e) current market and contractual prices for underlying instruments; (f) market interest rates and yield curves; (g) credit spreads; and (h) other relevant economic measures. NW Natural considers liquid points for natural gas hedging to be those points for which there are regularly published prices in a nationally recognized publication or where the instruments are traded on an exchange.
Goodwill	Goodwill and Business Combinations NW Holdings, through its wholly-owned subsidiary NWN Water and NWN Water's wholly-owned subsidiaries, has completed various acquisitions that resulted in the recognition of goodwill. Goodwill is measured as the excess of the acquisition-date fair value of the consideration transferred over the acquisition-date fair value of the net identifiable assets assumed. Adjustments are recorded during the measurement period to finalize the allocation of the purchase price. The carrying value of goodwill is reviewed annually during the fourth quarter, or whenever events or changes in circumstance indicate that such carrying values may not be recoverable. The goodwill assessment policy begins with a qualitative analysis in which events and circumstances are evaluated, including macroeconomic conditions, industry and market conditions, regulatory environments, and overall financial performance of the reporting unit. If the qualitative assessment indicates that the carrying value may be at risk of recoverability, a quantitative evaluation is performed to measure the carrying value of the goodwill against the fair value of the reporting unit. The reporting unit is determined primarily based on current operating segments and the level of review provided by the Chief Operating Decision Maker (CODM) and/or segment management on the operating segment's financial results. Reporting units are evaluated periodically for changes in the corporate environment. As of December 31, 2022 and 2021, NW Holdings had goodwill of $149.3 million and $70.6 million, respectively. All of NW Holdings' goodwill was acquired through the business combinations completed by NWN Water and its wholly-owned subsidiaries. No impairment charges were recorded as a result of the fourth quarter goodwill impairment assessment.
Income Taxes	Income Taxes We account for income taxes under the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements. Under this method, deferred tax assets and liabilities are determined on the basis of the differences between the financial statement and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. The effect of a change in tax rates on deferred tax assets and liabilities is recognized in income in the enactment date period unless, for NW Natural, a regulatory order specifies deferral of the effect of the change in tax rates over a longer period of time. For NW Natural, deferred income tax assets and liabilities are also recognized for temporary differences where the deferred income tax benefits or expenses have previously been flowed through in the ratemaking process of the NGD business. Regulatory tax assets and liabilities are recorded on these deferred tax assets and liabilities to the extent it is believed they will be recoverable from or refunded to customers in future rates. Investment tax credits associated with rate regulated plant additions are deferred for financial statement purposes and amortized over the estimated useful lives of the related plant. NW Holdings files consolidated or combined income tax returns that include NW Natural. Income tax expense is allocated on a separate company basis incorporating certain consolidated return considerations. Subsidiary income taxes payable or receivable are generally settled with NW Holdings, the common agent for income tax matters.
Environmental Contingencies	Environmental Contingencies Loss contingencies are recorded as liabilities when it is probable a liability has been incurred and the amount of the loss is reasonably estimable in accordance with accounting standards for contingencies. Estimating probable losses requires an analysis of uncertainties that often depend upon judgments about potential actions by third parties. Accruals for loss contingencies are recorded based on an analysis of potential results. With respect to environmental liabilities and related costs, estimates are developed based on a review of information available from numerous sources, including completed studies and site specific negotiations. NW Natural's policy is to accrue the full amount of such liability when information is sufficient to reasonably estimate the amount of probable liability. When information is not available to reasonably estimate the probable liability, or when only the range of probable liabilities can be estimated and no amount within the range is more likely than another, it is our policy to accrue at the low end of the range. Accordingly, due to numerous uncertainties surrounding the course of environmental remediation and the preliminary nature of several site investigations, in some cases, it may not be possible to reasonably estimate the high end of the range of possible loss. In those cases, the nature of the potential loss and the fact that the high end of the range cannot be reasonably estimated is disclosed. See Note 17.
Subsequent Events	Subsequent Events We monitor significant events occurring after the balance sheet date and prior to the issuance of the financial statements to determine the impacts, if any, of events on the financial statements to be issued.

Significant Accounting Polici_3

Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2022
Accounting Policies [Abstract]
Schedule of Regulatory Assets	Amounts NW Natural deferred as regulatory assets and liabilities were as follows: Regulatory Assets In thousands 2022 2021 NW Natural: Current: Unrealized loss on derivatives (1) $ 28,728 $ 10,402 Gas costs 61,223 35,641 Environmental costs (2) 7,392 6,694 Decoupling (3) — 969 Pension balancing (4) 7,131 7,131 Income taxes 2,208 2,568 Other (5) 10,809 8,986 Total current $ 117,491 $ 72,391 Non-current: Unrealized loss on derivatives (1) $ 20,838 $ 412 Pension balancing (4) 32,997 38,302 Income taxes 10,943 12,609 Pension and other postretirement benefit liabilities 101,413 116,440 Environmental costs (2) 104,253 94,636 Gas costs 22,355 15,477 Other (5) 47,608 36,663 Total non-current $ 340,407 $ 314,539 Other (NW Holdings) 25 40 Total non-current -NW Holdings $ 340,432 $ 314,579
Schedule of Regulatory Liabilities	Regulatory Liabilities In thousands 2022 2021 NW Natural: Current: Gas costs $ 4,121 $ 70 Unrealized gain on derivatives (1) 194,236 48,130 Decoupling (3) 14,026 4,475 Income taxes (6) 7,166 8,192 Asset optimization revenue sharing 26,368 45,124 Other (5) 2,636 6,290 Total current - NW Natural $ 248,553 $ 112,281 Other (NW Holdings) 29 — Total current - NW Holdings $ 248,582 $ 112,281 Non-current: Gas costs $ 12,644 $ 250 Unrealized gain on derivatives (1) 5,045 10,730 Decoupling (3) 3,814 3,412 Income taxes (6) 174,212 181,404 Accrued asset removal costs (7) 467,742 445,952 Asset optimization revenue sharing 8,401 1,810 Other (5) 16,741 13,792 Total non-current - NW Natural $ 688,599 $ 657,350 Other (NW Holdings) 979 982 Total non-current -NW Holdings $ 689,578 $ 658,332 (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 natural gas distribution rates as part of the annual Purchased Gas Adjustment (PGA) mechanism when realized at settlement. (2) Refer to the Environmental Cost Deferral and Recovery table in Note 17 for a description of environmental costs. (3) This deferral represents the margin adjustment resulting from differences between actual and expected volumes. (4) Refer to Note 10 for information regarding the deferral of pension expenses. (5) Balances consist of deferrals and amortizations under approved regulatory mechanisms and typically earn a rate of return or carrying charge. (6) This balance represents estimated amounts associated with the Tax Cuts and Jobs Act. See Note 11. (7) Estimated costs of removal on certain regulated properties are collected through rates. See "Accounting Policies— Plant, Property, and Accrued Asset Removal Costs
Accounts Receivable, Allowance for Credit Loss	The following table presents the activity related to the NW Holdings provision for uncollectible accounts by pool, substantially all of which is related to NW Natural's accounts receivable: As of December 31, 2021 As of December 31, 2022 Year ended December 31, 2022 In thousands Beginning Balance Provision recorded, net of adjustments Write-offs recognized, net of recoveries Ending Balance Allowance for uncollectible accounts: Residential $ 1,460 $ 1,974 $ (1,062) $ 2,372 Commercial 178 546 (324) 400 Industrial 67 186 (65) 188 Accrued unbilled and other 313 185 (162) 336 Total $ 2,018 $ 2,891 $ (1,613) $ 3,296

Earnings Per Share (Tables)

Earnings Per Share (Tables)	12 Months Ended
	Dec. 31, 2022
Earnings Per Share [Abstract]
EPS Calculation [Table Text Block]	NW Holdings' diluted earnings or loss per share are calculated as follows: In thousands, except per share data 2022 2021 2020 Net income from continuing operations $ 86,303 $ 78,666 $ 70,273 Income from discontinued operations, net of tax — — 6,508 Net income $ 86,303 $ 78,666 $ 76,781 Average common shares outstanding - basic 33,934 30,702 30,541 Additional shares for stock-based compensation plans (See Note 8) 50 50 58 Average common shares outstanding - diluted 33,984 30,752 30,599 Earnings from continuing operations per share of common stock: Basic $ 2.54 $ 2.56 $ 2.30 Diluted 2.54 2.56 2.30 Earnings from discontinued operations per share of common stock: Basic $ — $ — $ 0.21 Diluted — — 0.21 Earnings per share of common stock: Basic $ 2.54 $ 2.56 $ 2.51 Diluted 2.54 2.56 2.51 Additional information: Anti-dilutive shares 2 7 1

Segment Information (Tables)

Segment Information (Tables)	12 Months Ended
	Dec. 31, 2022
Segment Reporting [Abstract]
Schedule of Segment Reporting Information, by Segment	The following table presents summary financial information concerning the reportable segment and other for continuing operations. See Note 18 for information regarding discontinued operations for NW Holdings. In thousands NGD Other NW Natural Other NW Holdings 2022 Operating revenues $ 989,752 $ 24,587 $ 1,014,339 $ 23,014 $ 1,037,353 Depreciation 111,871 1,086 112,957 3,750 116,707 Income (loss) from operations 152,839 16,535 169,374 (1,897) 167,477 Net income (loss) from continuing operations 79,690 11,874 91,564 (5,261) 86,303 Capital expenditures 315,979 2,707 318,686 19,916 338,602 Total assets at December 31, 2022 4,392,699 60,019 4,452,718 295,608 4,748,326 2021 Operating revenues $ 816,887 $ 26,170 $ 843,057 $ 17,343 $ 860,400 Depreciation 109,475 1,029 110,504 3,030 113,534 Income (loss) from operations 147,902 17,331 165,233 (2,116) 163,117 Net income (loss) from continuing operations 68,988 12,184 81,172 (2,506) 78,666 Capital expenditures 275,267 2,970 278,237 15,655 293,892 Total assets at December 31, 2021 3,846,112 52,260 3,898,372 166,232 4,064,604 2020 Operating revenues $ 741,072 $ 17,676 $ 758,748 $ 14,931 $ 773,679 Depreciation 100,591 995 101,586 2,097 103,683 Income (loss) from operations 137,724 9,916 147,640 711 148,351 Net income (loss) from continuing operations 63,555 7,008 70,563 (290) 70,273 Capital expenditures 263,777 2,271 266,048 6,968 273,016 Total assets at December 31, 2020 3,549,868 49,468 3,599,336 157,043 3,756,379
Utility Margin	The following table presents additional segment information concerning NGD margin: In thousands 2022 2021 2020 NGD margin calculation: NGD operating revenues $ 970,124 $ 797,800 $ 721,950 Other regulated services 19,628 19,087 19,122 Total NGD operating revenues 989,752 816,887 741,072 Less: NGD cost of gas 429,861 292,538 262,980 Environmental remediation expense 12,389 9,938 9,691 Revenue taxes 41,627 34,600 30,291 NGD margin $ 505,875 $ 479,811 $ 438,110

Common Stock (Tables)

Common Stock (Tables)	12 Months Ended
	Dec. 31, 2022
Common Stock [Abstract]
Summary Of Common Stock Shares Issued And Outstanding Table	The following table summarizes the changes in the number of shares of NW Holdings' common stock issued and outstanding: In thousands Shares Balance, December 31, 2019 30,472 Sales to employees under ESPP 3 Stock-based compensation 46 Sales to shareholders under DRPP 68 Balance, December 31, 2020 30,589 Sales to employees under ESPP 48 Stock-based compensation 49 Equity issuance 376 Sales to shareholders under DRPP 67 Balance, December 31, 2021 31,129 Sales to employees under ESPP 36 Stock-based compensation 42 Equity issuance 4,257 Sales to shareholders under DRPP 61 Balance, December 31, 2022 35,525

Revenue (Tables)

Revenue (Tables)	12 Months Ended
	Dec. 31, 2022
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenue	The following table presents disaggregated revenue from continuing operations: Year ended December 31, 2022 In thousands NGD Other NW Natural Other NW Holdings Natural gas sales $ 989,654 $ — $ 989,654 $ — $ 989,654 Gas storage revenue, net — 11,792 11,792 — 11,792 Asset management revenue, net — 6,965 6,965 — 6,965 Appliance retail center revenue — 5,830 5,830 — 5,830 Other revenue 2,510 — 2,510 23,014 25,524 Revenue from contracts with customers 992,164 24,587 1,016,751 23,014 1,039,765 Alternative revenue (19,605) — (19,605) — (19,605) Leasing revenue 17,193 — 17,193 — 17,193 Total operating revenues $ 989,752 $ 24,587 $ 1,014,339 $ 23,014 $ 1,037,353 Year ended December 31, 2021 In thousands NGD Other NW Natural Other NW Holdings Natural gas sales $ 783,027 $ — $ 783,027 $ — $ 783,027 Gas storage revenue, net — 10,830 10,830 — 10,830 Asset management revenue, net — 9,387 9,387 — 9,387 Appliance retail center revenue — 5,953 5,953 — 5,953 Other revenue 1,615 — 1,615 17,343 18,958 Revenue from contracts with customers 784,642 26,170 810,812 17,343 828,155 Alternative revenue 14,694 — 14,694 — 14,694 Leasing revenue 17,551 — 17,551 — 17,551 Total operating revenues $ 816,887 $ 26,170 $ 843,057 $ 17,343 $ 860,400 Year ended December 31, 2020 In thousands NGD Other NW Natural Other NW Holdings Natural gas sales $ 710,422 $ — $ 710,422 $ — $ 710,422 Gas storage revenue, net — 9,759 9,759 — 9,759 Asset management revenue, net — 2,532 2,532 — 2,532 Appliance retail center revenue — 5,385 5,385 — 5,385 Other revenue 1,337 — 1,337 14,931 16,268 Revenue from contracts with customers 711,759 17,676 729,435 14,931 744,366 Alternative revenue 10,870 — 10,870 — 10,870 Leasing revenue 18,443 — 18,443 — 18,443 Total operating revenues $ 741,072 $ 17,676 $ 758,748 $ 14,931 $ 773,679

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2022
Leases [Abstract]
Lessee, Leases, Supplemental Cash Flow Information [Table Text Block]	Supplemental cash flow information related to leases was as follows: Year ended December 31, 2022 In thousands NW Natural Other NW Holdings Cash paid for amounts included in the measurement of lease liabilities Operating cash flows from operating leases $ 6,993 $ 64 $ 7,057 Finance cash flows from finance leases 524 — 524 Right of use assets obtained in exchange for lease obligations Operating leases $ 309 $ 668 $ 977 Finance leases 270 — 270 Year ended December 31, 2021 In thousands NW Natural Other NW Holdings Cash paid for amounts included in the measurement of lease liabilities Operating cash flows from operating leases $ 6,840 $ 58 $ 6,898 Finance cash flows from finance leases 801 — 801 Right of use assets obtained in exchange for lease obligations Operating leases $ 223 $ — $ 223 Finance leases 314 — 314 Year ended December 31, 2020 In thousands NW Natural Other NW Holdings Cash paid for amounts included in the measurement of lease liabilities Operating cash flows from operating leases $ 4,466 $ 131 $ 4,597 Finance cash flows from finance leases 835 — 835 Right of use assets obtained in exchange for lease obligations Operating leases $ 78,539 $ 51 $ 78,590 Finance leases 1,386 — 1,386
Lessee, Operating Lease, Liability, Maturity [Table Text Block]	Maturities of operating lease liabilities at December 31, 2022 were as follows: In thousands NW Natural Other NW Holdings 2023 $ 7,169 $ 195 $ 7,364 2024 7,299 196 7,495 2025 7,185 184 7,369 2026 7,353 140 7,493 2027 7,530 107 7,637 Thereafter 108,901 12 108,913 Total lease payments 145,437 834 146,271 Less: imputed interest 65,729 63 65,792 Total lease obligations 79,708 771 80,479 Less: current obligations 1,363 151 1,514 Long-term lease obligations $ 78,345 $ 620 $ 78,965
Lease, Cost [Table Text Block]	The components of lease expense, a portion of which is capitalized, were as follows: Year ended December 31, 2022 In thousands NW Natural Other NW Holdings Operating lease expense $ 7,003 $ 31 $ 7,034 Short-term lease expense 880 — 880 Year ended December 31, 2021 In thousands NW Natural Other NW Holdings Operating lease expense $ 6,859 $ 58 $ 6,917 Short-term lease expense 1,220 — 1,220 Year ended December 31, 2020 In thousands NW Natural Other NW Holdings Operating lease expense $ 4,381 $ 125 $ 4,506 Short-term lease expense 1,010 — 1,010
Operating Lease, Lease Income [Table Text Block]	The components of lease revenue at NW Natural were as follows: Year ended December 31, In thousands 2022 2021 2020 Lease revenue Operating leases $ 74 $ 80 $ 88 Sales-type leases 17,119 17,471 18,355 Total lease revenue $ 17,193 $ 17,551 $ 18,443
Lessor, Operating Lease, Payments to be Received, Maturity [Table Text Block]	Total future minimum lease payments to be received under non-cancelable leases at December 31, 2022 are as follows: In thousands Operating Sales-Type Total NW Natural: 2023 $ 621 $ 16,557 $ 17,178 2024 612 15,867 16,479 2025 603 15,306 15,909 2026 36 14,901 14,937 2027 22 14,521 14,543 Thereafter — 222,299 222,299 Total minimum lease payments $ 1,894 $ 299,451 $ 301,345 Less: imputed interest 165,272 Total leases receivable $ 134,179 Other NW Holdings: 2023 $ 51 $ — $ 51 2024 52 — 52 2025 53 — 53 2026 56 — 56 2027 57 — 57 Thereafter 857 — 857 Total minimum lease payments $ 1,126 $ — $ 1,126 NW Holdings: 2023 $ 672 $ 16,557 $ 17,229 2024 664 15,867 16,531 2025 656 15,306 15,962 2026 92 14,901 14,993 2027 79 14,521 14,600 Thereafter 857 222,299 223,156 Total minimum lease payments $ 3,020 $ 299,451 $ 302,471 Less: imputed interest 165,272 Total leases receivable $ 134,179
Operating Lease, Lease Asset and Liabilities [Table Text Block]	Supplemental balance sheet information related to operating leases as of December 31, 2022 is as follows: In thousands NW Natural Other NW Holdings Operating lease right of use assets $ 72,720 $ 709 $ 73,429 Operating lease liabilities - current liabilities $ 1,363 $ 151 $ 1,514 Operating lease liabilities - non-current liabilities 78,345 620 78,965 Total operating lease liabilities $ 79,708 $ 771 $ 80,479 Supplemental balance sheet information related to operating leases as of December 31, 2021 is as follows: In thousands NW Natural Other NW Holdings Operating lease right of use assets $ 74,987 $ 62 $ 75,049 Operating lease liabilities - current liabilities $ 1,273 $ 23 $ 1,296 Operating lease liabilities - non-current liabilities 79,431 37 79,468 Total operating lease liabilities $ 80,704 $ 60 $ 80,764

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Table Text Block]	In thousands 2022 2021 2020 Operations and maintenance expense, for stock-based compensation $ 2,877 $ 3,272 $ 3,525 Income tax benefit (762) (866) (933) Net stock-based compensation effect on net income 2,115 2,406 2,592 Amounts capitalized for stock-based compensation $ 351 $ 344 $ 841
Share-based Payment Arrangement, Restricted Stock and Restricted Stock Unit, Activity [Table Text Block]	Number of RSUs Weighted - Nonvested, December 31, 2019 79,733 $ 61.17 Granted 33,594 55.58 Vested (29,273) 59.29 Forfeited (1,590) 69.71 Nonvested, December 31, 2020 82,464 59.40 Granted 38,160 49.16 Vested (31,733) 60.06 Forfeited (1,164) 46.82 Nonvested, December 31, 2021 87,727 54.87 Granted 48,212 46.50 Vested (33,054) 55.90 Forfeited (3,037) 56.34 Nonvested, December 31, 2022 99,848 $ 50.44
Share-based Payment Arrangement, Performance Shares, Outstanding Activity [Table Text Block]	The aggregate number of performance shares granted and outstanding at the target and maximum levels were as follows: Dollars in thousands Performance Share Awards Outstanding 2022 Performance Period Target Maximum Expense 2020-22 31,160 62,320 $ 888 2021-23 — — — 2022-24 — — — Total 31,160 62,320 $ 888
Long Term Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangements by Share-based Payment Award, Performance-Based Units, Vested and Expected to Vest [Table Text Block]	The following table summarizes performance share expense information: Dollars in thousands Shares (1) Expense During Award Year (2) Total Expense for Award Estimated award: 2020-2022 grant (3) 29,472 $ 888 $ 888 Actual award: 2019-2021 grant 37,430 $ 1,323 $ 1,323 2018-2020 grant 31,600 $ 2,137 $ 2,137 (1) In addition to common stock shares, a participant also receives a dividend equivalent cash payment equal to the number of shares of common stock received on the award payout multiplied by the aggregate cash dividends paid per share during the performance period. (2) Amount represents the expense recognized in the third year of the vesting period noted above. For the 2019-2021 and 2020-2022 grants, mutual understanding of the award's key terms was established in the third year of the vesting period, triggering full expense recognition in 2021 and 2022, respectively. (3) This represents the estimated number of shares to be awarded as of December 31, 2022 as certain performance share measures have been achieved. Amounts are subject to change with final payout amounts authorized by the Board of Directors in February 2023.

Debt (Tables)

Debt (Tables)	12 Months Ended
	Dec. 31, 2022
Debt Disclosure [Abstract]
Schedule of Maturities of Long-term Debt [Table Text Block]	Retirement of long-term debt for each of the annual periods through December 31, 2027 and thereafter are as follows: In thousands Long-term debt maturities NW Natural: 2023 $ 90,000 2024 — 2025 30,000 2026 55,000 2027 64,700 Thereafter 895,000 Total $ 1,134,700
Schedule of Debt [Table Text Block]	The following table presents debt outstanding as of December 31: In thousands 2022 2021 NW Natural: First Mortgage Bonds: 3.542% Series due 2023 50,000 50,000 5.620% Series due 2023 40,000 40,000 7.720% Series due 2025 20,000 20,000 6.520% Series due 2025 10,000 10,000 7.050% Series due 2026 20,000 20,000 3.211% Series due 2026 35,000 35,000 7.000% Series due 2027 20,000 20,000 2.822% Series due 2027 25,000 25,000 6.650% Series due 2027 19,700 19,700 6.650% Series due 2028 10,000 10,000 3.141% Series due 2029 50,000 50,000 7.740% Series due 2030 20,000 20,000 7.850% Series due 2030 10,000 10,000 5.820% Series due 2032 30,000 30,000 5.660% Series due 2033 40,000 40,000 5.250% Series due 2035 10,000 10,000 4.000% Series due 2042 50,000 50,000 4.136% Series due 2046 40,000 40,000 3.685% Series due 2047 75,000 75,000 4.110% Series due 2048 50,000 50,000 3.869% Series due 2049 90,000 90,000 3.600% Series due 2050 150,000 150,000 3.078% Series due 2051 130,000 130,000 4.780% Series due 2052 140,000 — Long-term debt, gross 1,134,700 994,700 Less: current maturities 90,000 — Total long-term debt $ 1,044,700 $ 994,700
Fair Value Of Long Term Debt Table [Text Block]	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 : December 31, In thousands 2022 2021 NW Natural: Gross long-term debt $ 1,134,700 $ 994,700 Unamortized debt issuance costs (8,823) (8,205) Carrying amount $ 1,125,877 $ 986,495 Estimated fair value (1) $ 944,383 $ 1,110,741 NW Holdings: Gross long-term debt $ 1,345,851 $ 1,053,241 Unamortized debt issuance costs (8,987) (8,309) Carrying amount $ 1,336,864 $ 1,044,932 Estimated fair value (1) $ 1,148,395 $ 1,174,500 (1) Estimated fair value does not include unamortized debt issuance costs.

Pension and Other Postretirem_2

Pension and Other Postretirement Benefits Costs (Tables)	12 Months Ended
	Dec. 31, 2022
Retirement Benefits [Abstract]
Schedule of Defined Benefit Plans Disclosures	The following table provides a reconciliation of the changes in NW Natural's benefit obligations and fair value of plan assets, as applicable, for NW Natural's pension and other postretirement benefit plans, excluding the Retirement K Savings Plan, and a summary of the funded status and amounts recognized in NW Holdings' and NW Natural's consolidated balance sheets as of December 31: Postretirement Benefit Plans Pension Benefits Other Benefits In thousands 2022 2021 2022 2021 Reconciliation of change in benefit obligation: Obligation at January 1 $ 542,618 $ 566,147 $ 27,223 $ 29,039 Service cost 5,933 6,982 193 238 Interest cost 14,593 13,447 724 684 Net actuarial gain (122,168) (18,587) (6,234) (688) Benefits paid (27,563) (25,371) (2,026) (2,050) Obligation at December 31 $ 413,413 $ 542,618 $ 19,880 $ 27,223 Reconciliation of change in plan assets: Fair value of plan assets at January 1 $ 399,217 $ 373,932 $ — $ — Actual return on plan assets (93,703) 38,712 — — Employer contributions 2,353 11,944 2,026 2,050 Benefits paid (27,563) (25,371) (2,026) (2,050) Fair value of plan assets at December 31 $ 280,304 $ 399,217 $ — $ — Funded status at December 31 $ (133,109) $ (143,401) $ (19,880) $ (27,223)
Schedule Of Amounts Recognized In Regulatory Assets Or Other Comprehensive Income Loss	The following table presents amounts realized through regulatory assets or in other comprehensive loss (income) for the years ended December 31: Regulatory Assets Other Comprehensive Loss (Income) Pension Benefits Other Postretirement Benefits Pension Benefits In thousands 2022 2021 2020 2022 2021 2020 2022 2021 2020 Net actuarial (gain) loss $ 2,833 $ (32,258) $ 16,170 $ (6,234) $ (688) $ 145 $ (5,706) $ (812) $ 3,873 Amortization of: Prior service credit — — — 333 468 468 — — — Actuarial loss (11,531) (21,250) (18,627) (426) (645) (607) (1,081) (1,225) (923) Total $ (8,698) $ (53,508) $ (2,457) $ (6,327) $ (865) $ 6 $ (6,787) $ (2,037) $ 2,950
Schedule Of Defined Benefit Plan Amounts In AOCL And Regulatory Assets	The following table presents amounts recognized in regulatory assets and accumulated other comprehensive loss (AOCL) at December 31: Regulatory Assets AOCL Pension Benefits Other Postretirement Benefits Pension Benefits In thousands 2022 2021 2022 2021 2022 2021 Prior service credit $ — $ — $ — $ (333) $ — $ — Net actuarial loss (gain) 102,240 112,182 (826) 5,834 8,717 15,399 Total $ 102,240 $ 112,182 $ (826) $ 5,501 $ 8,717 $ 15,399
Schedule of Amounts Recognized in Other Comprehensive Income (Loss)	The following table presents amounts recognized by NW Holdings and NW Natural in AOCL and the changes in AOCL related to NW Natural's non-qualified employee benefit plans: Year ended December 31, In thousands 2022 2021 Beginning balance $ (11,404) $ (12,902) Amounts reclassified to AOCL 5,706 812 Amounts reclassified from AOCL: Amortization of actuarial losses 1,081 1,225 Total reclassifications before tax 6,787 2,037 Tax benefit (1,797) (539) Total reclassifications for the period 4,990 1,498 Ending balance $ (6,414) $ (11,404)
Schedule of Allocation of Plan Assets	The following table presents the Pension Plan asset target allocation at December 31, 2022: Asset Category Target Allocation Long government/credit 20 % U.S. large cap equity 18 Non-U.S. equity 18 Absolute return strategies 12 U.S. small/mid cap equity 10 Real estate funds 7 High yield bonds 5 Emerging markets equity 5 Emerging market debt 5
Schedule of Net Benefit Costs	The following table provides the components of net periodic benefit cost for NW Natural's pension and other postretirement benefit plans for the years ended December 31: Pension Benefits Other Postretirement Benefits In thousands 2022 2021 2020 2022 2021 2020 Service cost $ 5,933 $ 6,981 $ 6,614 $ 193 $ 238 $ 258 Interest cost 14,593 13,448 16,161 724 684 905 Expected return on plan assets (25,698) (24,232) (21,865) — — — Amortization of prior service credit — — — (333) (468) (468) Amortization of net actuarial loss 12,612 22,475 19,550 426 645 607 Net periodic benefit cost 7,440 18,672 20,460 1,010 1,099 1,302 Amount allocated to construction (2,621) (3,015) (2,798) (76) (93) (98) Net periodic benefit cost charged to expense 4,819 15,657 17,662 934 1,006 1,204 Amortization of regulatory balancing account 7,131 7,131 7,131 — — — Net amount charged to expense $ 11,950 $ 22,788 $ 24,793 $ 934 $ 1,006 $ 1,204
Sensitivity Analysis Of Retirement Benefit Costs and Benefit Obligations	The following table provides the assumptions used in measuring periodic benefit costs and benefit obligations for the years ended December 31: Pension Benefits Other Postretirement Benefits 2022 2021 2020 2022 2021 2020 Assumptions for net periodic benefit cost: Weighted-average discount rate 2.71 % 2.40 % 3.18 % 2.72 % 2.34 % 3.11 % Rate of increase in compensation 3.50 % 3.50 % 3.50 % n/a n/a n/a Expected long-term rate of return 7.00 % 7.25 % 7.25 % n/a n/a n/a Assumptions for year-end funded status: Weighted-average discount rate 5.18 % 2.71 % 2.36 % 5.19 % 2.72 % 2.34 % Rate of increase in compensation (1) 4.00-6.00% 3.50 % 3.50-6.50% n/a n/a n/a Expected long-term rate of return 7.50 % 7.00 % 7.25 % n/a n/a n/a
Defined Benefit Plan Estimated Future Employer Contributions Benefit Payments and Estimated Future Payments	The following table provides information regarding employer contributions and benefit payments for NW Natural's Pension Plan, non-qualified pension plans, and other postretirement benefit plans for the years ended December 31, and estimated future contributions and payments: In thousands Pension Benefits Other Benefits Employer Contributions: 2021 $ 11,944 $ 2,050 2022 2,353 2,026 2023 (estimated) 2,333 1,586 Benefit Payments: 2020 25,073 1,837 2021 25,371 2,050 2022 27,563 2,026 Estimated Future Benefit Payments: 2023 26,499 1,586 2024 27,029 1,591 2025 27,541 1,586 2026 27,981 1,560 2027 36,485 1,552 2028-2032 145,486 7,345
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis	The following tables present the fair value of NW Natural's Pension Plan assets, including outstanding receivables and liabilities, of NW Natural's retirement trust fund In thousands December 31, 2022 Investments Level 1 Level 2 Level 3 Non-Published NAV (1) Total US equity $ — $ — $ — $ 68,729 $ 68,729 International / Global equity 26,677 — — 63,827 90,504 Liability hedging — — — 94,823 94,823 Opportunistic — — — 23,903 23,903 Cash and cash equivalents — — — 2,345 2,345 Total investments $ 26,677 $ — $ — $ 253,627 $ 280,304 December 31, 2021 Investments Level 1 Level 2 Level 3 Non-Published NAV (1) Total US equity $ — $ — $ — $ 121,090 $ 121,090 International / Global equity 35,456 — — 88,078 123,534 Liability hedging — — — 118,464 118,464 Opportunistic — — — 33,808 33,808 Cash and cash equivalents — — — 2,321 2,321 Total investments $ 35,456 $ — $ — $ 363,761 $ 399,217 December 31, 2022 2021 Receivables: Accrued interest and dividend income $ 7,703 $ — Total receivables 7,703 — Liabilities: Due to broker for securities purchased (7,701) — Total investment in retirement trust $ 280,306 $ 399,217 (1) The fair value for these investments is determined using Net Asset Value per share (NAV) as of December 31, as a practical expedient, and therefore they are not classified within the fair value hierarchy. These investments primarily consist of institutional investment products, for which the NAV is generally not publicly available.

Income Tax (Tables)

Income Tax (Tables)	12 Months Ended
	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]	The following table provides a reconciliation between income taxes calculated at the statutory federal tax rate and the provision for income taxes reflected in the NW Holdings and NW Natural statements of comprehensive income or loss for December 31: NW Holdings NW Natural Dollars in thousands 2022 2021 2020 2022 2021 2020 Income taxes at federal statutory rate $ 24,241 $ 22,275 $ 19,185 $ 25,746 $ 22,996 $ 19,248 Increase (decrease): State income tax, net of federal 10,139 9,962 6,389 10,504 10,150 6,385 Differences required to be flowed-through by regulatory commissions (4,748) (4,655) (3,960) (4,746) (4,738) (3,960) Other, net (502) (176) (532) (468) (75) (578) Total provision for income taxes $ 29,130 $ 27,406 $ 21,082 $ 31,036 $ 28,333 $ 21,095 Effective tax rate 25.2% 25.8% 23.1% 25.3% 25.9% 23.0%
Schedule of Components of Income Tax Expense (Benefit) [Table Text Block]	The provision for current and deferred income taxes consists of the following at December 31: NW Holdings NW Natural In thousands 2022 2021 2020 2022 2021 2020 Current Federal $ 5,172 $ 6,508 $ 10,106 $ 7,442 $ 7,570 $ 11,092 State 6,551 6,281 5,971 7,307 7,540 5,357 Total current income taxes 11,723 12,789 16,077 14,749 15,110 16,449 Deferred Federal 11,124 8,289 2,888 10,298 7,915 1,921 State 6,283 6,328 2,117 5,989 5,308 2,725 Total deferred income taxes 17,407 14,617 5,005 16,287 13,223 4,646 Income tax provision $ 29,130 $ 27,406 $ 21,082 $ 31,036 $ 28,333 $ 21,095
Schedule of Deferred Tax Assets and Liabilities [Table Text Block]	The following table summarizes the tax effect of significant items comprising NW Holdings and NW Natural's deferred income tax balances recorded at December 31: NW Holdings NW Natural In thousands 2022 2021 2022 2021 Deferred tax liabilities: Plant and property $ 326,326 $ 310,471 $ 320,121 $ 303,928 Leases receivable 36,873 38,123 36,873 38,123 Pension and postretirement obligations 22,973 23,097 22,973 23,097 Income tax regulatory asset 13,152 14,818 13,152 14,818 Lease right of use assets 21,272 21,362 21,084 21,350 Other 17,050 7,793 17,314 8,003 Total deferred income tax liabilities $ 437,646 $ 415,664 $ 431,517 $ 409,319 Deferred income tax assets: Income tax regulatory liability $ 48,270 $ 50,447 $ 48,018 $ 50,193 Lease liabilities 21,306 21,376 21,102 21,365 Other intangible assets 1,947 3,484 — — Net operating losses and credits carried forward 101 126 44 44 Total deferred income tax assets $ 71,624 $ 75,433 $ 69,164 $ 71,602 Total net deferred income tax liabilities $ 366,022 $ 340,231 $ 362,353 $ 337,717

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	12 Months Ended
	Dec. 31, 2022
Public Utilities, Property, Plant and Equipment [Abstract]
Major Classifications Of Property, Plant And Equipment And Accumulated Depreciation [Text Block]	The following table sets forth the major classifications of property, plant, and equipment and accumulated depreciation of continuing operations at December 31: In thousands 2022 2021 NW Natural: NGD plant in service $ 3,992,676 $ 3,721,939 NGD construction work in progress 78,897 135,398 Less: Accumulated depreciation 1,115,690 1,098,715 NGD plant, net 2,955,883 2,758,622 Other plant in service 70,368 69,332 Other construction work in progress 6,606 4,971 Less: Accumulated depreciation 21,541 20,646 Other plant, net 55,433 53,657 Total property, plant, and equipment $ 3,011,316 $ 2,812,279 Other (NW Holdings): Other plant in service $ 92,979 $ 57,184 Other construction work in progress 20,040 8,419 Less: Accumulated depreciation 9,935 6,512 Other plant, net 103,084 59,091 NW Holdings: Total property, plant, and equipment $ 3,114,400 $ 2,871,370 NW Natural: Capital expenditures in accrued liabilities $ 24,584 $ 37,537 NW Holdings: Capital expenditures in accrued liabilities $ 25,318 $ 38,333

Investments (Tables)

Investments (Tables)	12 Months Ended
	Dec. 31, 2022
Investments [Abstract]
Investment	The following table summarizes other investments at December 31: NW Holdings NW Natural In thousands 2022 2021 2022 2021 Investments in life insurance policies $ 49,358 $ 48,178 $ 49,358 $ 48,178 Investments in gas reserves, non-current 22,970 26,608 22,970 26,608 Investments in unconsolidated affiliates 23,376 14,492 7,782 — Total other investments $ 95,704 $ 89,278 $ 80,110 $ 74,786

Derivative Instruments (Tables)

Derivative Instruments (Tables)	12 Months Ended
	Dec. 31, 2022
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: At December 31, In thousands 2022 2021 Natural gas (in therms): Financial 852,435 618,815 Physical 463,254 431,628 Foreign exchange $ 7,617 $ 6,268
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: December 31, 2022 December 31, 2021 In thousands Natural gas commodity Foreign exchange Natural gas commodity Foreign exchange Benefit (expense) to cost of gas $ 119,935 $ (165) $ 36,539 $ (26) Operating revenues (expense) — — (26) — Amounts deferred to regulatory accounts on balance sheet (119,935) 165 (36,517) 26 Total gain (loss) in pre-tax earnings $ — $ — $ (4) $ —

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
Long-term Purchase Commitment	The aggregate amounts of these agreements at NW Natural were as follows at December 31, 2022: In thousands Gas Purchase Agreements (1) Pipeline Pipeline 2023 $ 400,370 $ 81,691 $ 8,154 2024 6,376 77,327 7,474 2025 6,426 78,493 3,397 2026 12,003 66,782 — 2027 11,330 66,906 — Thereafter 189,050 432,464 — Total 625,555 803,663 19,025 Less: Amount representing interest 86,250 200,243 989 Total at present value $ 539,305 $ 603,420 $ 18,036

Environmental Matters (Tables)

Environmental Matters (Tables)	12 Months Ended
	Dec. 31, 2022
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 at December 31: Current Liabilities Non-Current Liabilities In thousands 2022 2021 2022 2021 Portland Harbor site: Gasco/Siltronic Sediments $ 9,744 $ 7,582 $ 42,120 $ 42,076 Other Portland Harbor 2,634 2,592 11,270 9,570 Gasco/Siltronic Upland site 16,067 15,711 35,457 36,215 Front Street site 457 1,100 879 811 Oregon Steel Mills — — 179 179 Total $ 28,902 $ 26,985 $ 89,905 $ 88,851
Environmental Regulatory Table	The following table presents information regarding the total regulatory asset deferred as of December 31: In thousands 2022 2021 Deferred costs and interest (1) $ 47,666 $ 45,122 Accrued site liabilities (2) 118,763 115,773 Insurance proceeds and interest (54,784) (59,564) Total regulatory asset deferral (1) $ 111,645 $ 101,331 Current regulatory assets (3) $ 7,392 $ 6,694 Long-term regulatory assets (3) $ 104,253 $ 94,636 (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 $43 thousand in 2022 and $62 thousand in 2021. (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 nor 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. See " Oregon SRRM " below.

Discontinued Operations (Tables

Discontinued Operations (Tables)	12 Months Ended
	Dec. 31, 2022
Discontinued Operations and Disposal Groups [Abstract]
Disposal Groups, Including Discontinued Operations	The following table presents the operating results of Gill Ranch and is presented net of tax on NW Holdings' consolidated statements of comprehensive income: NW Holdings Discontinued Operations In thousands 2020 Revenues $ 10,193 Expenses Operations and maintenance 7,931 General taxes 198 Depreciation 391 Other expenses and interest 848 Total expenses 9,368 Income from discontinued operations 825 Gain on sale of discontinued operations 8,027 Income from discontinued operations before income tax 8,852 Income tax expense (1) 2,344 Income from discontinued operations, net of tax $ 6,508 (1) Includes income tax expense of $2.1 million related to the sale of Gill Ranch for the year ended December 31, 2020.

Condensed Financials Standalo_2

Condensed Financials Standalone Holdco NW Holdings Financial Statements (Tables)	12 Months Ended
	Dec. 31, 2022
Condensed Income Statements, Captions [Line Items]
Condensed Income Statement [Table Text Block]	NORTHWEST NATURAL HOLDING COMPANY CONDENSED STATEMENTS OF COMPREHENSIVE INCOME (PARENT COMPANY ONLY) Year Ended December 31, In thousands 2022 2021 2020 Operating expenses: Operations and maintenance $ 3,828 $ 4,837 $ 771 Total operating expenses 3,828 4,837 771 Loss from operations (3,828) (4,837) (771) Earnings from investment in subsidiaries, net of tax 92,727 83,072 78,450 Other income (expense), net 60 (143) 57 Interest expense, net 4,967 982 1,557 Income before income taxes 83,992 77,110 76,179 Income tax benefit (2,311) (1,556) (602) Net income 86,303 78,666 76,781 Other comprehensive income (loss) from subsidiaries, net of tax 5,108 1,498 (2,169) Unrealized gain on interest rate swap, net of tax 11 — — Comprehensive income $ 91,422 $ 80,164 $ 74,612 See Notes to Condensed Financial Statements
Condensed Balance Sheet [Table Text Block]	NORTHWEST NATURAL HOLDING COMPANY CONDENSED BALANCE SHEETS (PARENT COMPANY ONLY) As of December 31, In thousands 2022 2021 Assets: Current assets: Cash and cash equivalents $ 7,280 $ 265 Receivables from affiliates 9,967 2,180 Other current assets 2,895 11,348 Total current assets 20,142 13,793 Non-current assets: Investments in subsidiaries 1,357,599 1,080,949 Other investments 14 42 Deferred tax assets 520 383 Other non-current assets 486 613 Total non-current assets 1,358,619 1,081,987 Total assets $ 1,378,761 $ 1,095,780 Liabilities and equity: Current liabilities: Short-term debt $ 88,000 $ 144,000 Accounts payable 402 286 Payables to affiliates 14,665 16,105 Other current liabilities 295 243 Total current liabilities 103,362 160,634 Long-term debt 99,958 — Total equity 1,175,441 935,146 Total liabilities and equity $ 1,378,761 $ 1,095,780 See Notes to Condensed Financial Statements
Condensed Cash Flow Statement [Table Text Block]	NORTHWEST NATURAL HOLDING COMPANY CONDENSED STATEMENTS OF CASH FLOWS (PARENT COMPANY ONLY) Year Ended December 31, In thousands 2022 2021 2020 Operating activities: Net income $ 86,303 $ 78,666 $ 76,781 Adjustments to reconcile net income to cash used in operations: Equity in earnings of subsidiaries, net of tax (92,727) (83,072) (78,450) Cash dividends received from subsidiaries 62,710 56,057 55,387 Deferred income taxes (141) (212) 20 Other 142 119 65 Changes in assets and liabilities: Receivables from affiliates (7,787) 12,558 (12,788) Income and other taxes 8,161 1,299 (7,451) Accounts payable (2,499) 3,342 8,809 Interest accrued 156 57 77 Other, net (211) (313) (364) Cash provided by operating activities 54,107 68,501 42,086 Investing activities: Contributions to subsidiaries (241,497) (142,405) (47,194) Return of capital from subsidiaries — 26,000 19,000 Cash used in investing activities (241,497) (116,405) (28,194) Financing activities: Proceeds from common stock issued, net 208,561 17,501 — Long-term debt issued 100,000 — — Changes in other short-term debt, net (56,000) 71,000 49,000 Cash dividend payments on common stock (62,771) (55,919) (55,420) Other 4,615 4,320 3,676 Cash provided by (used in) financing activities 194,405 36,902 (2,744) Increase (decrease) in cash and cash equivalents 7,015 (11,002) 11,148 Cash, cash equivalents and restricted cash, beginning of period 265 11,267 119 Cash, cash equivalents and restricted cash, end of period $ 7,280 $ 265 $ 11,267 See Notes to Condensed Financial Statements

Valuation Allowances and Rese_2

Valuation Allowances and Reserves (Tables)	12 Months Ended
	Dec. 31, 2022
Entity Information [Line Items]
Summary of Valuation Allowance	NORTHWEST NATURAL HOLDING COMPANY SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS AND RESERVES COLUMN A COLUMN B COLUMN C COLUMN D COLUMN E Additions Deductions In thousands (year ended December 31) Balance at beginning of period Charged to costs and expenses Charged to other accounts Net write-offs Balance at end of period 2022 Reserves deducted in balance sheet from assets to which they apply: Allowance for uncollectible accounts $ 2,018 $ 1,081 $ 1,810 $ 1,613 $ 3,296 2021 Reserves deducted in balance sheet from assets to which they apply: Allowance for uncollectible accounts $ 3,219 $ 724 $ (219) $ 1,706 $ 2,018 2020 Reserves deducted in balance sheet from assets to which they apply: Allowance for uncollectible accounts $ 673 $ 890 $ 2,333 $ 677 $ 3,219
Northwest Natural Gas Company [Member]
Entity Information [Line Items]
Summary of Valuation Allowance	NORTHWEST NATURAL GAS COMPANY SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS AND RESERVES COLUMN A COLUMN B COLUMN C COLUMN D COLUMN E Additions Deductions In thousands (year ended December 31) Balance at beginning of period Charged to costs and expenses Charged to other accounts Net write-offs Balance at end of period 2022 Reserves deducted in balance sheet from assets to which they apply: Allowance for uncollectible accounts $ 1,962 $ 920 $ 1,810 $ 1,613 $ 3,079 2021 Reserves deducted in balance sheet from assets to which they apply: Allowance for uncollectible accounts $ 3,107 $ 780 $ (219) $ 1,706 $ 1,962 2020 Reserves deducted in balance sheet from assets to which they apply: Allowance for uncollectible accounts $ 672 $ 779 $ 2,333 $ 677 $ 3,107

- Narrative (Details)

- Narrative (Details) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2022 USD ($) numberOfLeases	Dec. 31, 2022 USD ($) numberOfLeases	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Industry Regulation [Abstract]
Regulatory Assets, Noncurrent	$ 340,432	$ 340,432	$ 314,579
COVID-19 Impact [Abstract]
Regulatory Assets, Noncurrent	340,432	$ 340,432	$ 314,579
Property, Plant and Accrued Asset Removal Costs [Abstract]
Weighted Average Depreciation Rates Transmission Distribution		2.50%
Weighted Average Depreciation Rates Gas Storage		2.10%
Weighted Average Depreciation Rates General Plant		6.10%
Weighted Average Depreciation Rates Intangible Other		6.70%
Public Utilities, AFUDC, Rate		2.80%	0.70%	1.90%
Cash and Cash Equivalents [Abstract]
Cash and cash equivalents	$ 29,270	$ 29,270	$ 18,559
Restricted Cash and Cash Equivalents, Current, Statement of Financial Position [Extensible Enumeration]	Other current assets	Other current assets	Other current assets
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	$ 40,964	$ 40,964	$ 27,120	$ 35,454	$ 12,636
Revenue Recognition [Abstract]
Accrued unbilled revenue	89,048	89,048	82,169
Revenue Taxes [Abstract]
Utilities Operating Expense, Taxes		41,826	34,740	30,291
Inventory Disclosure [Abstract]
Inventory, Raw Materials and Supplies, Net of Reserves	23,500	23,500	19,900
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	149,283	149,283	70,570
Goodwill and Intangible Asset Impairment	0
Allowance for Credit Loss [Abstract]
Accounts Receivable, Allowance for Credit Loss, Recovery		(1,613)
Accounts Receivable, Allowance for Credit Loss, Period Increase (Decrease)		2,891
Accounts Receivable, Allowance for Credit Loss	$ 3,296	$ 3,296	2,018
Number of Net Investments in Sales-Type Leases | numberOfLeases	2	2
Inactive Account, Period Outstanding Prior to Write-off	120 days	120 days
General Payment Term of NGD Receivables	15 days	15 days
Age of Closed or Inactive Accounts	120 days	120 days
Income Tax Disclosure [Abstract]
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued	$ 0	$ 0
Industrial
Allowance for Credit Loss [Abstract]
Accounts Receivable, Allowance for Credit Loss, Recovery		(65)
Accounts Receivable, Allowance for Credit Loss, Period Increase (Decrease)		186
Accounts Receivable, Allowance for Credit Loss	188	188	67
Accrued unbilled and other
Allowance for Credit Loss [Abstract]
Accounts Receivable, Allowance for Credit Loss, Recovery		(162)
Accounts Receivable, Allowance for Credit Loss, Period Increase (Decrease)		185
Accounts Receivable, Allowance for Credit Loss	336	336	313
Residential
Allowance for Credit Loss [Abstract]
Accounts Receivable, Allowance for Credit Loss, Recovery		(1,062)
Accounts Receivable, Allowance for Credit Loss, Period Increase (Decrease)		1,974
Accounts Receivable, Allowance for Credit Loss	2,372	2,372	1,460
Commercial
Allowance for Credit Loss [Abstract]
Accounts Receivable, Allowance for Credit Loss, Recovery		(324)
Accounts Receivable, Allowance for Credit Loss, Period Increase (Decrease)		546
Accounts Receivable, Allowance for Credit Loss	400	400	178
Accounts Payable [Member]
Cash and Cash Equivalents [Abstract]
Bank Overdrafts	5,800	5,800	0
COVID-19 Related Costs
Industry Regulation [Abstract]
Regulatory Assets, Noncurrent	18,700	18,700
COVID-19 Impact [Abstract]
Regulatory Assets, Noncurrent	18,700	$ 18,700
Northwest Natural Gas Company [Member]
Industry Regulation [Abstract]
Regulatory Liability, Amortization Period		12 months
Regulatory Asset, Amortization Period		12 months
Regulatory Assets, Noncurrent	340,407	$ 340,407	314,539
COVID-19 Impact [Abstract]
Regulatory Assets, Noncurrent	340,407	340,407	314,539
Cash and Cash Equivalents [Abstract]
Cash and cash equivalents	$ 12,977	$ 12,977	$ 12,271
Restricted Cash and Cash Equivalents, Current, Statement of Financial Position [Extensible Enumeration]	Other current assets	Other current assets	Other current assets
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	$ 24,671	$ 24,671	$ 20,832	15,739	$ 8,907
Revenue Recognition [Abstract]
Accrued unbilled revenue	87,482	87,482	82,028
Revenue Taxes [Abstract]
Utilities Operating Expense, Taxes		41,627	34,600	$ 30,291
Inventory Disclosure [Abstract]
Inventory - Gas	61,900	61,900	$ 37,400
Energy Related Inventory, Renewable Thermal Credits	$ 1,700	$ 1,700
Northwest Natural Gas Company [Member] | Oregon [Member]
Industry Regulation [Abstract]
Purchased Gas Adjustment Percentage		90%	90%	90%
Derivative Instruments and Hedging Activities Disclosure [Abstract]
PGA deferral rate		90%	90%	90%
Northwest Natural Gas Company [Member] | Oregon [Member] | Minimum [Member]
Industry Regulation [Abstract]
Purchased Gas Adjustment Percentage		80%
Derivative Instruments and Hedging Activities Disclosure [Abstract]
PGA deferral rate		80%
Impact on earnings from gas cost sharing		10%
Northwest Natural Gas Company [Member] | Oregon [Member] | Maximum [Member]
Industry Regulation [Abstract]
Purchased Gas Adjustment Percentage		90%
Derivative Instruments and Hedging Activities Disclosure [Abstract]
PGA deferral rate		90%
Impact on earnings from gas cost sharing		20%
Northwest Natural Gas Company [Member] | WASHINGTON
Industry Regulation [Abstract]
Purchased Gas Adjustment Percentage		100%	100%	100%
Derivative Instruments and Hedging Activities Disclosure [Abstract]
PGA deferral rate		100%	100%	100%
Asset Recoverable Gas Costs [Member] | Northwest Natural Gas Company [Member]
Industry Regulation [Abstract]
Regulatory Liability, Amortization Period		12 months
Sales-type Lease [Member]
Allowance for Credit Loss [Abstract]
Accounts Receivable, Allowance for Credit Loss, Period Increase (Decrease)		$ 0
Other Nonoperating Income (Expense) [Member]
Industry Regulation [Abstract]
Other Nonoperating Income		7,000	$ 6,100
Other Nonoperating Expense		$ 2,000	$ 1,300
Natural Gas Distribution [Member]
Property, Plant and Accrued Asset Removal Costs [Abstract]
Public Utilities, Property, Plant and Equipment, Disclosure of Composite Depreciation Rate for Plants in Service		3%	3%	3%
Weighted-average depreciation rate, assets in service		3%	3%	3%
Natural Gas Distribution [Member] | Operating Segments [Member]
Revenue Taxes [Abstract]
Utilities Operating Expense, Taxes		$ 41,627	$ 34,600	$ 30,291

Significant Accounting Polici_4

Significant Accounting Policies - Regulatory Asset Disclosure (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Regulatory Assets [Line Items]
Regulatory Assets, Current	$ 117,491	$ 72,391
Regulatory Assets, Noncurrent	340,432	314,579
Other [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Noncurrent	25	40
COVID-19 Related Costs
Regulatory Assets [Line Items]
Regulatory Assets, Noncurrent	18,700
Portion of COVID-19 Cost Approved for Recovery in 2022 OR Rate Case
Regulatory Assets [Line Items]
Regulatory Assets, Noncurrent	$ 10,900
Regulatory Asset, Amortization Period	2 years
Late Fee Portion of COVID-19 Cost Approved for Recovery in Future Periods
Regulatory Assets [Line Items]
Regulatory Assets, Noncurrent	$ 3,400
Northwest Natural Gas Company [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Current	117,491	72,391
Regulatory Assets, Noncurrent	$ 340,407	314,539
Regulatory Asset, Amortization Period	12 months
Northwest Natural Gas Company [Member] | Unrealized loss on derivatives [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Current	$ 28,728	10,402
Regulatory Assets, Noncurrent	20,838	412
Northwest Natural Gas Company [Member] | Gas costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Current	61,223	35,641
Regulatory Assets, Noncurrent	22,355	15,477
Northwest Natural Gas Company [Member] | Environmental costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Current	7,392	6,694
Regulatory Assets, Noncurrent	104,253	94,636
Northwest Natural Gas Company [Member] | Decoupling [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Current	0	969
Northwest Natural Gas Company [Member] | Income taxes [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Current	2,208	2,568
Regulatory Assets, Noncurrent	10,943	12,609
Northwest Natural Gas Company [Member] | Pension balancing [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Current	7,131	7,131
Regulatory Assets, Noncurrent	32,997	38,302
Northwest Natural Gas Company [Member] | Pension and other postretirement benefit liabilities [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Noncurrent	101,413	116,440
Northwest Natural Gas Company [Member] | Other [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Current	10,809	8,986
Regulatory Assets, Noncurrent	$ 47,608	$ 36,663

Significant Accounting Polici_5

Significant Accounting Policies - Regulatory Liability Disclosure (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	$ 248,582	$ 112,281
Regulatory Liability, Noncurrent	689,578	658,332
Other [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	29	0
Regulatory Liability, Noncurrent	979	982
Northwest Natural Gas Company [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	248,553	112,281
Regulatory Liability, Noncurrent	688,599	657,350
Northwest Natural Gas Company [Member] | Gas costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	4,121	70
Regulatory Liability, Noncurrent	12,644	250
Northwest Natural Gas Company [Member] | Unrealized gain on derivatives [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	194,236	48,130
Regulatory Liability, Noncurrent	5,045	10,730
Northwest Natural Gas Company [Member] | Decoupling [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	14,026	4,475
Regulatory Liability, Noncurrent	3,814	3,412
Northwest Natural Gas Company [Member] | Other [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	2,636	6,290
Regulatory Liability, Noncurrent	16,741	13,792
Northwest Natural Gas Company [Member] | Income taxes [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	7,166	8,192
Regulatory Liability, Noncurrent	174,212	181,404
Northwest Natural Gas Company [Member] | Accrued asset removal costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Noncurrent	467,742	445,952
Northwest Natural Gas Company [Member] | Asset Optimization Revenue Sharing
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	26,368	45,124
Regulatory Liability, Noncurrent	$ 8,401	$ 1,810

Significant Accounting Polici_6

Significant Accounting Policies Significant Accounting Policies - Leases ASU 2016-02 (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating Lease, Right-of-Use Asset	$ 73,429	$ 75,049
Northwest Natural Gas Company [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating Lease, Right-of-Use Asset	$ 72,720	$ 74,987

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Statement [Line Items]
Net income from continuing operations	$ 86,303	$ 78,666	$ 70,273
Income from discontinued operations, net of tax	0	0	6,508
Net income	$ 86,303	$ 78,666	$ 76,781
Average common shares outstanding:
Average common shares outstanding - basic (in shares)	33,934	30,702	30,541
Additional shares for stock-based compensation plans	50	50	58
Average common shares outstanding - diluted (in shares)	33,984	30,752	30,599
Earnings from continuing operations per share of common stock:
Basic (in dollars per share)	$ 2.54	$ 2.56	$ 2.30
Diluted (in dollars per share)	2.54	2.56	2.30
Earnings from discontinued operations per share of common stock, basic
Basic (in dollars per share)	0	0	0.21
Earnings from discontinued operations per share of common stock, diluted
Diluted (in dollars per share)	0	0	0.21
Earnings (loss) per share of common stock
Basic (in dollars per share)	2.54	2.56	2.51
Diluted (in dollars per share)	$ 2.54	$ 2.56	$ 2.51
Antidilutive shares	2	7	1
Discontinued Operations, Held-for-sale [Member] | Gill Ranch [Member]
Income Statement [Line Items]
Income from discontinued operations, net of tax	$ 6,508
Earnings from discontinued operations per share of common stock, basic
Basic (in dollars per share)	$ 0	$ 0	$ 0.21
Earnings from discontinued operations per share of common stock, diluted
Diluted (in dollars per share)	$ 0	$ 0	$ 0.21

Segment Information - Narrative

Segment Information - Narrative (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Segment Reporting Information [Line Items]
Assets	$ 4,748,326	$ 4,064,604
Operating Segments [Member]
Segment Reporting Information [Line Items]
Number of Reportable Segments	1
Operating Segments [Member] | Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Assets	$ 4,392,699	$ 3,846,112	$ 3,549,868
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%
Northwest Holdings and Northwest Natural [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Segment Reporting, Disclosure of Major Customers	No
Customer Total [Member] | Geographic Concentration Risk [Member] | Oregon [Member] | Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Concentration Risk, Percentage	88%
Customer Total [Member] | Geographic Concentration Risk [Member] | WASHINGTON | Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Concentration Risk, Percentage	12%
Volumes Delivered [Member] | Volumes Delivered [Member] | Residential and Commerical Customers [Member] | Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Concentration Risk, Percentage	60%
Gross Profit Margin [Member] | Residential and Commerical Customers [Member] | Residential and Commerical Customers [Member] | Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Concentration Risk, Percentage	90%

Segment Information - Schedule

Segment Information - Schedule of Summarized Financial Information by Segment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Segment Reporting Information [Line Items]
Operating revenues	$ 1,037,353	$ 860,400	$ 773,679
Depreciation	116,707	113,534	103,683
Income (loss) from operations	167,477	163,117	148,351
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	86,303	78,666	70,273
Capital expenditures	338,602	293,892	273,016
Total assets	4,748,326	4,064,604
Other Northwest Natural [Member] | Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Operating revenues	24,587	26,170	17,676
Depreciation	1,086	1,029	995
Income (loss) from operations	16,535	17,331	9,916
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	11,874	12,184	7,008
Capital expenditures	2,707	2,970	2,271
Total assets	60,019	52,260	49,468
Northwest Natural Gas Company [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating revenues	1,014,339	843,057	758,748
Depreciation	112,957	110,504	101,586
Income (loss) from operations	169,374	165,233	147,640
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	91,564	81,172	70,563
Capital expenditures	318,686	278,237	266,048
Total assets	4,452,718	3,898,372	3,599,336
Northwest Holdings Other [Member] | Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Operating revenues	23,014	17,343	14,931
Depreciation	3,750	3,030	2,097
Income (loss) from operations	(1,897)	(2,116)	711
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	(5,261)	(2,506)	(290)
Capital expenditures	19,916	15,655	6,968
Total assets	295,608	166,232	157,043
Natural Gas Distribution [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating revenues	989,752	816,887	741,072
Depreciation	111,871	109,475	100,591
Income (loss) from operations	152,839	147,902	137,724
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	79,690	68,988	63,555
Capital expenditures	315,979	275,267	263,777
Total assets	4,392,699	3,846,112	3,549,868
Northwest Natural Gas Company [Member]
Segment Reporting Information [Line Items]
Operating revenues	1,014,339	843,057	758,748
Depreciation	112,957	110,504	101,586
Income (loss) from operations	169,374	165,233	147,640
Capital expenditures	318,686	278,237	266,048
Total assets	4,452,718	3,898,372
Northwest Natural Gas Company [Member] | Other Northwest Natural [Member] | Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Operating revenues	24,587	26,170	17,676
Northwest Natural Gas Company [Member] | Northwest Natural Gas Company [Member]
Segment Reporting Information [Line Items]
Operating revenues	1,014,339	843,057	758,748
Northwest Natural Gas Company [Member] | Natural Gas Distribution [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating revenues	989,752	816,887	741,072
Parent Company [Member]
Segment Reporting Information [Line Items]
Operating revenues	1,037,353	860,400	773,679
Depreciation	116,707	113,534	103,683
Income (loss) from operations	167,477	163,117	148,351
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	86,303	78,666	70,273
Capital expenditures	338,602	293,892	273,016
Total assets	$ 4,748,326	$ 4,064,604	$ 3,756,379

Segment Information - Additiona

Segment Information - Additional Segment Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Segment Reporting Information [Line Items]
Operating revenues	$ 1,037,353	$ 860,400	$ 773,679
Cost of gas	429,635	292,314	262,755
Environmental remediation	12,389	9,938	9,691
Revenue taxes	41,826	34,740	30,291
Operating Segments [Member] | Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
NGD operating revenues	970,124	797,800	721,950
Other regulated services	19,628	19,087	19,122
Operating revenues	989,752	816,887	741,072
Cost of gas	429,861	292,538	262,980
Environmental remediation	12,389	9,938	9,691
Revenue taxes	41,627	34,600	30,291
NGD margin	$ 505,875	$ 479,811	$ 438,110

Common Stock - Narrative (Detai

Common Stock - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
	Apr. 01, 2022	Dec. 31, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares Authorized (in shares)		100,000,000	100,000,000
Equity issuance	2,875,000
Issuance of common stock, net of issuance costs		$ 208,276	$ 17,501
Par Value (in dollars per share)		$ 0	$ 0
Shares issued (in shares)		35,525,000	31,129,000
ATM Equity Program
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Par Value (in dollars per share)		$ 0
Sale of Stock, Cumulative Commissions and Fees Paid		$ 1,400
Cumulative Proceeds Received on All Transactions		$ 69,700
Shares issued (in shares)		1,381,728
nwn:AttheMarketEquityProgramEquityAvailableforIssuance		$ 111,100
ATM Equity Program | Maximum [Member] | Scenario, Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Cumulative Proceeds Received on All Transactions		$ 200,000
Stock Repurchase Plan [Member]
Stock Repurchase Program
Stock Repurchase Program, Number of Shares Authorized to be Repurchased		2,800,000
Stock Repurchase Program, Authorized Amount		$ 100,000
Treasury Stock, Shares, Acquired		0
Repurchases Since Plan Inception in Year 2000 [Member] | Stock Repurchase Plan [Member]
Stock Repurchase Program
Treasury Stock, Shares, Acquired		2,100,000
Treasury Stock, Value, Acquired, Cost Method		$ 83,300
Northwest Holdings [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Reserved Shares Dividend Reinvestment		394,102
Northwest Holdings [Member] | Employee Stock Purchase Plan Member [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common Stock, Capital Shares Reserved for Future Issuance		319,777
Northwest Natural Gas Company [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Repayments of Short-term Debt	$ 130,000

Common Stock - Schedule of Summ

Common Stock - Schedule of Summary of Changes in Common Stock (Details) - shares shares in Thousands		12 Months Ended
	Apr. 01, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Increase (Decrease) in Common Stock [Roll Forward]
Beginning Balance		31,129
Equity issuance	2,875
Ending Balance		35,525	31,129
Common Stock [Member]
Increase (Decrease) in Common Stock [Roll Forward]
Beginning Balance		31,129	30,589	30,472
Sales to employees under ESPP		36	48	3
Stock-based compensation		42	49	46
Equity issuance		4,257	376
Stock Issued During Period, Shares, Dividend Reinvestment Plan		61	67	68
Ending Balance		35,525	31,129	30,589

Revenue - Disaggregation of Rev

Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	$ 1,039,765	$ 828,155	$ 744,366
Operating revenues	1,037,353	860,400	773,679
Lease Income	17,193	17,551	18,443
Natural Gas Distribution [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	989,654	783,027	710,422
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	11,792	10,830	9,759
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	6,965	9,387	2,532
Appliance Center Revenue [Member] | Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	5,830	5,953	5,385
Other revenue [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	25,524	18,958	16,268
Alternative revenue [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	(19,605)	14,694	10,870
Leasing revenue [Member]
Disaggregation of Revenue [Line Items]
Lease Income	17,193	17,551	18,443
Operating Segments [Member] | Northwest Natural Gas Company [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	1,014,339	843,057	758,748
Operating Segments [Member] | Natural Gas Distribution [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	989,752	816,887	741,072
Corporate, Non-Segment [Member] | Other Northwest Natural [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	24,587	26,170	17,676
Corporate, Non-Segment [Member] | Northwest Holdings Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	23,014	17,343	14,931
Operating revenues	23,014	17,343	14,931
Corporate, Non-Segment [Member] | Northwest Holdings Other [Member] | Natural Gas Distribution [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0
Corporate, Non-Segment [Member] | Northwest Holdings Other [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
Corporate, Non-Segment [Member] | Northwest Holdings Other [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
Corporate, Non-Segment [Member] | Northwest Holdings Other [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
Corporate, Non-Segment [Member] | Northwest Holdings Other [Member] | Other revenue [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	23,014	17,343	14,931
Corporate, Non-Segment [Member] | Northwest Holdings Other [Member] | Alternative revenue [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	0	0	0
Corporate, Non-Segment [Member] | Northwest Holdings Other [Member] | Leasing revenue [Member]
Disaggregation of Revenue [Line Items]
Lease Income	0	0	0
Northwest Natural Gas Company [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	1,014,339	843,057	758,748
Northwest Natural Gas Company [Member] | Northwest Natural Gas Company [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	1,016,751	810,812	729,435
Operating revenues	1,014,339	843,057	758,748
Northwest Natural Gas Company [Member] | Northwest Natural Gas Company [Member] | Natural Gas Distribution [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	989,654	783,027	710,422
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	11,792	10,830	9,759
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	6,965	9,387	2,532
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	5,830	5,953	5,385
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	2,510	1,615	1,337
Northwest Natural Gas Company [Member] | Northwest Natural Gas Company [Member] | Alternative revenue [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	(19,605)	14,694	10,870
Northwest Natural Gas Company [Member] | Northwest Natural Gas Company [Member] | Leasing revenue [Member]
Disaggregation of Revenue [Line Items]
Lease Income	17,193	17,551	18,443
Northwest Natural Gas Company [Member] | Operating Segments [Member] | Natural Gas Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	992,164	784,642	711,759
Operating revenues	989,752	816,887	741,072
Northwest Natural Gas Company [Member] | Operating Segments [Member] | Natural Gas Distribution [Member] | Natural Gas Distribution [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	989,654	783,027	710,422
Northwest Natural Gas Company [Member] | Operating Segments [Member] | Natural Gas Distribution [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
Northwest Natural Gas Company [Member] | Operating Segments [Member] | Natural Gas Distribution [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
Northwest Natural Gas Company [Member] | Operating Segments [Member] | Natural Gas Distribution [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
Northwest Natural Gas Company [Member] | Operating Segments [Member] | Natural Gas Distribution [Member] | Other revenue [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	2,510	1,615	1,337
Northwest Natural Gas Company [Member] | Operating Segments [Member] | Natural Gas Distribution [Member] | Alternative revenue [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	(19,605)	14,694	10,870
Northwest Natural Gas Company [Member] | Operating Segments [Member] | Natural Gas Distribution [Member] | Leasing revenue [Member]
Disaggregation of Revenue [Line Items]
Lease Income	17,193	17,551	18,443
Northwest Natural Gas Company [Member] | Corporate, Non-Segment [Member] | Other Northwest Natural [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	24,587	26,170	17,676
Operating revenues	24,587	26,170	17,676
Northwest Natural Gas Company [Member] | Corporate, Non-Segment [Member] | Other Northwest Natural [Member] | Natural Gas Distribution [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0
Northwest Natural Gas Company [Member] | Corporate, Non-Segment [Member] | Other Northwest Natural [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	11,792	10,830	9,759
Northwest Natural Gas Company [Member] | Corporate, Non-Segment [Member] | Other Northwest Natural [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	6,965	9,387	2,532
Northwest Natural Gas Company [Member] | Corporate, Non-Segment [Member] | Other Northwest Natural [Member] | Appliance Center Revenue [Member] | Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	5,830	5,953	5,385
Northwest Natural Gas Company [Member] | Corporate, Non-Segment [Member] | Other Northwest Natural [Member] | Other revenue [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0
Northwest Natural Gas Company [Member] | Corporate, Non-Segment [Member] | Other Northwest Natural [Member] | Alternative revenue [Member]
Disaggregation of Revenue [Line Items]
Operating revenues	0	0	0
Northwest Natural Gas Company [Member] | Corporate, Non-Segment [Member] | Other Northwest Natural [Member] | Leasing revenue [Member]
Disaggregation of Revenue [Line Items]
Lease Income	$ 0	$ 0	$ 0

Revenue - Revenue, Remaining Pe

Revenue - Revenue, Remaining Performance Obligation (Details) $ in Thousands	Dec. 31, 2022 USD ($) performanceObligations
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	$ 81,400
Revenue, Over Time Performance Obligation, Number | performanceObligations	1
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
Northwest Holdings Other [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Contract with Customer, Refund Liability	0
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
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 20,300
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
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, Amount	$ 16,200
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
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, Amount	$ 13,500
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
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, Amount	$ 9,400
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2027-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 22,000
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	0 years

Leases - Lease Revenue (Details

Leases - Lease Revenue (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Lessor, Lease, Description [Line Items]
Lessor, Sales-type Lease, Term of Contract	30 years
Lessor, Sales-type Lease, Renewal Term	50 years
Residual Value of Leased Asset	$ 5,100,000	$ 4,700,000
Lease Revenue [Abstract]
Operating Lease, Lease Income, Statement of Income or Comprehensive Income [Extensible Enumeration]	Operating revenues	Operating revenues	Operating revenues
Sales-Type Lease, Lease Income, Statement of Income or Comprehensive Income [Extensible Enumeration]	Operating revenues	Operating revenues	Operating revenues
Lease Income	$ 17,193,000	$ 17,551,000	$ 18,443,000
Operating Leases Payment to be Received [Abstract]
Lessor, Operating Lease, Payments to be Received, Next Twelve Months	672,000
Lessor, Operating Lease, Payments to be Received, Two Years	664,000
Lessor, Operating Lease, Payments to be Received, Three Years	656,000
Lessor, Operating Lease, Payments to be Received, Four Years	92,000
Lessor, Operating Lease, Payments to be Received, Five Years	79,000
Lessor, Operating Lease, Payments to be Received, Thereafter	857,000
Lessor, Operating Lease, Payments to be Received	3,020,000
Total Lease Payments to be Received [Abstract]
Lease Payments to be Received, Next twelve months	17,229,000
Lease Payments to be Received, Two Years	16,531,000
Lease Payments to be Received, Three Years	15,962,000
Lease Payments to be Received, Four Years	14,993,000
Lease Payments to be Received, Five Years	14,600,000
Lease Payments to be Received, Thereafter	223,156,000
Lease Payments to be Received	302,471,000
Northwest Natural Gas Company [Member]
Operating Leases Payment to be Received [Abstract]
Lessor, Operating Lease, Payments to be Received, Next Twelve Months	621,000
Lessor, Operating Lease, Payments to be Received, Two Years	612,000
Lessor, Operating Lease, Payments to be Received, Three Years	603,000
Lessor, Operating Lease, Payments to be Received, Four Years	36,000
Lessor, Operating Lease, Payments to be Received, Five Years	22,000
Lessor, Operating Lease, Payments to be Received, Thereafter	0
Lessor, Operating Lease, Payments to be Received	1,894,000
Total Lease Payments to be Received [Abstract]
Lease Payments to be Received, Next twelve months	17,178,000
Lease Payments to be Received, Two Years	16,479,000
Lease Payments to be Received, Three Years	15,909,000
Lease Payments to be Received, Four Years	14,937,000
Lease Payments to be Received, Five Years	14,543,000
Lease Payments to be Received, Thereafter	222,299,000
Lease Payments to be Received	301,345,000
NWN Water
Operating Leases Payment to be Received [Abstract]
Lessor, Operating Lease, Payments to be Received, Next Twelve Months	51,000
Lessor, Operating Lease, Payments to be Received, Two Years	52,000
Lessor, Operating Lease, Payments to be Received, Three Years	53,000
Lessor, Operating Lease, Payments to be Received, Four Years	56,000
Lessor, Operating Lease, Payments to be Received, Five Years	57,000
Lessor, Operating Lease, Payments to be Received, Thereafter	857,000
Lessor, Operating Lease, Payments to be Received	1,126,000
Total Lease Payments to be Received [Abstract]
Lease Payments to be Received, Next twelve months	51,000
Lease Payments to be Received, Two Years	52,000
Lease Payments to be Received, Three Years	53,000
Lease Payments to be Received, Four Years	56,000
Lease Payments to be Received, Five Years	57,000
Lease Payments to be Received, Thereafter	857,000
Lease Payments to be Received	1,126,000
Sales-type Lease [Member]
Sales-type Leases Payments to be Received [Abstract]
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received, Next Twelve Months	16,557,000
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received, Two Years	15,867,000
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received, Three Years	15,306,000
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received, Four Years	14,901,000
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received, Five Years	14,521,000
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received, Thereafter	222,299,000
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received	299,451,000
Receivable with Imputed Interest, Discount	165,272,000
Receivable with Imputed Interest, Net Amount	134,179,000
Sales-type Lease [Member] | Northwest Natural Gas Company [Member]
Sales-type Leases Payments to be Received [Abstract]
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received, Next Twelve Months	16,557,000
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received, Two Years	15,867,000
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received, Three Years	15,306,000
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received, Four Years	14,901,000
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received, Five Years	14,521,000
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received, Thereafter	222,299,000
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received	299,451,000
Receivable with Imputed Interest, Discount	165,272,000
Receivable with Imputed Interest, Net Amount	134,179,000
Sales-type Lease [Member] | NWN Water
Sales-type Leases Payments to be Received [Abstract]
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received, Next Twelve Months	0
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received, Two Years	0
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received, Three Years	0
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received, Four Years	0
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received, Five Years	0
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received, Thereafter	0
Sales-type and Direct Financing Leases, Lease Receivable, Payments to be Received	0
North Mist Lease [Member]
Lessor, Lease, Description [Line Items]
Variable Lease, Payment	0
Residual Value of Leased Asset	$ 0
Compressed Natural Gas Lease [Member]
Lessor, Lease, Description [Line Items]
Lessor, Sales-type Lease, Term of Contract	10 years
Other Nonoperating Income (Expense) [Member]
Lease Revenue [Abstract]
Lease Income	$ 600,000	$ 500,000	$ 500,000

Leases - Lease Expense (Details

Leases - Lease Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Lessee, Lease, Description [Line Items]
Short-term Lease, Cost	$ 880	$ 1,220	$ 1,010
Lessor, Operating Lease, Payments to be Received, Two Years	$ 664
Operating Lease, Weighted Average Remaining Lease Term	17 years 2 months 12 days	18 years 2 months 12 days
Lessee, Operating Lease, Liability, Payments, Due	$ 146,271
Regulatory Assets, Noncurrent	340,432	$ 314,579
Operating Lease, Expense	$ 7,034	6,917	4,506
New Headquarters Lease [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Term of Contract	20 years
Lessee, Operating Lease, Term of Contract	20 years
New Headquarters Lease [Member]
Lessee, Lease, Description [Line Items]
Regulatory Assets, Noncurrent	$ 6,900	5,700
New Headquarters Lease [Member] | New Headquarters Lease Renewal Term 1 of 2 [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Term of Contract	7 years
Lessee, Operating Lease, Term of Contract	7 years
New Headquarters Lease [Member] | New Headquarters Lease 1st Renewal Period [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Term of Contract	7 years
Lessee, Operating Lease, Term of Contract	7 years
Short Term Leases
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Term of Contract	12 months
Lessee, Operating Lease, Term of Contract	12 months
Minimum [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Term of Contract	9 months
Lessee, Operating Lease, Term of Contract	9 months
Maximum [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Term of Contract	17 years
Lessee, Operating Lease, Term of Contract	17 years
Northwest Natural Gas Company [Member]
Lessee, Lease, Description [Line Items]
Short-term Lease, Cost	$ 880	$ 1,220	1,010
Lessor, Operating Lease, Payments to be Received, Two Years	$ 612
Operating Lease, Weighted Average Discount Rate, Percent	7.30%	7.20%
Lessee, Operating Lease, Liability, Payments, Due	$ 145,437
Regulatory Assets, Noncurrent	340,407	$ 314,539
Operating Lease, Expense	7,003	6,859	4,381
Northwest Holdings Other [Member] | Corporate, Non-Segment [Member]
Lessee, Lease, Description [Line Items]
Short-term Lease, Cost	0	0	0
Lessee, Operating Lease, Liability, Payments, Due	834
Operating Lease, Expense	$ 31	$ 58	$ 125

Leases - Lease Asset and Liabil

Leases - Lease Asset and Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Operating Lease Asset and Liabilities [Abstract]
Operating Lease, Right-of-Use Asset	$ 73,429	$ 75,049
Operating Lease, Liability, Current	1,514	1,296
Operating Lease, Liability, Noncurrent	78,965	79,468
Operating Lease, Liability	$ 80,479	$ 80,764
Operating Lease, Weighted Average Remaining Lease Term	17 years 2 months 12 days	18 years 2 months 12 days
Maturity of Operating Lease Liabilities [Abstract]
Lessee, Operating Lease, Liability, Payments, Due Next Twelve Months	$ 7,364
Lessee, Operating Lease, Liability, Payments, Due Year Two	7,495
Lessee, Operating Lease, Liability, Payments, Due Year Three	7,369
Lessee, Operating Lease, Liability, Payments, Due Year Four	7,493
Lessee, Operating Lease, Liability, Payments, Due Year Five	7,637
Lessee, Operating Lease, Liability, Payments, Due after Year Five	108,913
Lessee, Operating Lease, Liability, Payments, Due	146,271
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	65,792
Operating Lease, Liability	80,479	$ 80,764
Operating Lease, Liability, Current	1,514	1,296
Operating Lease, Liability, Noncurrent	78,965	79,468
Lease Not Yet Commenced [Abstract]
Lessee, Operating Lease, Liability, Payments, Due	146,271
Leases Cash Flow [Abstract]
Operating Lease, Payments	7,057	6,898	$ 4,597
Finance Lease, Principal Payments	524	801	835
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	977	223	78,590
Right-of-Use Asset Obtained in Exchange for Finance Lease Liability	$ 270	$ 314	1,386
Finance Leases [Abstract]
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]	Total property, plant, and equipment, net	Total property, plant, and equipment, net
Prior Period Disclosures [Abstract]
Lessee, Operating Lease, Liability, Payments, Due Next Twelve Months	$ 7,364
Lessee, Operating Lease, Liability, Payments, Due Year Two	7,495
Lessee, Operating Lease, Liability, Payments, Due Year Three	7,369
Lessee, Operating Lease, Liability, Payments, Due Year Four	7,493
Lessee, Operating Lease, Liability, Payments, Due Year Five	7,637
Lessee, Operating Lease, Liability, Payments, Due after Year Five	108,913
Lessee, Operating Lease, Liability, Payments, Due	146,271
Regulatory Assets, Noncurrent	340,432	$ 314,579
Finance Lease, Liability, to be Paid	0
Northwest Natural Gas Company [Member]
Operating Lease Asset and Liabilities [Abstract]
Operating Lease, Right-of-Use Asset	72,720	74,987
Operating Lease, Liability, Current	1,363	1,273
Operating Lease, Liability, Noncurrent	78,345	79,431
Operating Lease, Liability	$ 79,708	$ 80,704
Operating Lease, Weighted Average Discount Rate, Percent	7.30%	7.20%
Maturity of Operating Lease Liabilities [Abstract]
Lessee, Operating Lease, Liability, Payments, Due Next Twelve Months	$ 7,169
Lessee, Operating Lease, Liability, Payments, Due Year Two	7,299
Lessee, Operating Lease, Liability, Payments, Due Year Three	7,185
Lessee, Operating Lease, Liability, Payments, Due Year Four	7,353
Lessee, Operating Lease, Liability, Payments, Due Year Five	7,530
Lessee, Operating Lease, Liability, Payments, Due after Year Five	108,901
Lessee, Operating Lease, Liability, Payments, Due	145,437
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	65,729
Operating Lease, Liability	79,708	$ 80,704
Operating Lease, Liability, Current	1,363	1,273
Operating Lease, Liability, Noncurrent	78,345	79,431
Lease Not Yet Commenced [Abstract]
Lessee, Operating Lease, Liability, Payments, Due	145,437
Leases Cash Flow [Abstract]
Operating Lease, Payments	6,993	6,840	4,466
Finance Lease, Principal Payments	524	801	835
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	309	223	78,539
Right-of-Use Asset Obtained in Exchange for Finance Lease Liability	270	314	1,386
Prior Period Disclosures [Abstract]
Lessee, Operating Lease, Liability, Payments, Due Next Twelve Months	7,169
Lessee, Operating Lease, Liability, Payments, Due Year Two	7,299
Lessee, Operating Lease, Liability, Payments, Due Year Three	7,185
Lessee, Operating Lease, Liability, Payments, Due Year Four	7,353
Lessee, Operating Lease, Liability, Payments, Due Year Five	7,530
Lessee, Operating Lease, Liability, Payments, Due after Year Five	108,901
Lessee, Operating Lease, Liability, Payments, Due	145,437
Regulatory Assets, Noncurrent	340,407	314,539
Corporate, Non-Segment [Member] | Northwest Holdings Other [Member]
Operating Lease Asset and Liabilities [Abstract]
Operating Lease, Right-of-Use Asset	709	62
Operating Lease, Liability, Current	151	23
Operating Lease, Liability, Noncurrent	620	37
Operating Lease, Liability	771	60
Maturity of Operating Lease Liabilities [Abstract]
Lessee, Operating Lease, Liability, Payments, Due Next Twelve Months	195
Lessee, Operating Lease, Liability, Payments, Due Year Two	196
Lessee, Operating Lease, Liability, Payments, Due Year Three	184
Lessee, Operating Lease, Liability, Payments, Due Year Four	140
Lessee, Operating Lease, Liability, Payments, Due Year Five	107
Lessee, Operating Lease, Liability, Payments, Due after Year Five	12
Lessee, Operating Lease, Liability, Payments, Due	834
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	63
Operating Lease, Liability	771	60
Operating Lease, Liability, Current	151	23
Operating Lease, Liability, Noncurrent	620	37
Lease Not Yet Commenced [Abstract]
Lessee, Operating Lease, Liability, Payments, Due	834
Leases Cash Flow [Abstract]
Operating Lease, Payments	64	58	131
Finance Lease, Principal Payments	0	0	0
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	668	0	51
Right-of-Use Asset Obtained in Exchange for Finance Lease Liability	0	$ 0	$ 0
Prior Period Disclosures [Abstract]
Lessee, Operating Lease, Liability, Payments, Due Next Twelve Months	195
Lessee, Operating Lease, Liability, Payments, Due Year Two	196
Lessee, Operating Lease, Liability, Payments, Due Year Three	184
Lessee, Operating Lease, Liability, Payments, Due Year Four	140
Lessee, Operating Lease, Liability, Payments, Due Year Five	107
Lessee, Operating Lease, Liability, Payments, Due after Year Five	12
Lessee, Operating Lease, Liability, Payments, Due	$ 834
Maximum [Member]
Prior Period Disclosures [Abstract]
Lessee, Operating Lease, Term of Contract	17 years

Stock-Based Compensation - Long

Stock-Based Compensation - Long Term Incentive Plan (Details) - USD ($)	12 Months Ended			36 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Restricted Stock Units [Abstract]
Return on Invested Capital Threshold, Performance Shares	3 years
Long Term Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized	1,100,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant, Any Award Type	247,666
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	0	0		0
Restricted Stock Units (RSUs) [Member] | Long Term Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	99,848	87,727	82,464	87,727	82,464	79,733
Performance Shares [Abstract]
Share-based Payment Arrangement, Expense	$ 2,100,000	$ 2,000,000	$ 2,000,000
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount	$ 3,500,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value	$ 50.44	$ 54.87	$ 59.40	$ 54.87	$ 59.40	$ 61.17
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value	$ 55.90	$ 60.06	$ 59.29
Restricted Stock Units [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	4 years
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period	(33,054)	(31,733)	(29,273)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	48,212	38,160	33,594
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 46.50	$ 49.16	$ 55.58
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period	(3,037)	(1,164)	(1,590)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value	$ 56.34	$ 46.82	$ 69.71
Performance Shares [Member] | Long Term Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share Based Compensation Award Target Share	31,160
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	0
Performance Shares [Abstract]
Share-based Payment Arrangement, Expense	$ 888,000
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount	$ 0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value	$ 38.63
Performance Shares [Member] | A 2021 Award | Long Term Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share Based Compensation Award Target Share	0
Performance Shares [Abstract]
Share-based Payment Arrangement, Expense	$ 0
Performance Shares [Member] | A 2020 Award | Long Term Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share Based Compensation Award Target Share	0
Performance Shares [Abstract]
Share-based Payment Arrangement, Expense	$ 0
Performance Shares [Member] | A 2019 Award [Member] | Long Term Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share Based Compensation Award Target Share	31,160
Performance Shares [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Granted	29,472
Share-based Payment Arrangement, Expense	$ 888,000			$ 888,000
Performance Shares [Member] | A 2018 Award [Member] | Long Term Incentive Plan [Member]
Performance Shares [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Granted		37,430
Share-based Payment Arrangement, Expense		$ 1,323,000			$ 1,323,000
Performance Shares [Member] | A 2017 Award [Member] | Long Term Incentive Plan [Member]
Performance Shares [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Granted			31,600
Share-based Payment Arrangement, Expense			$ 2,137,000			$ 2,137,000
Maximum [Member] | Performance Shares [Member] | Long Term Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share Based Compensation Award Target Share	62,320
Maximum [Member] | Performance Shares [Member] | A 2021 Award | Long Term Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share Based Compensation Award Target Share	0
Maximum [Member] | Performance Shares [Member] | A 2020 Award | Long Term Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share Based Compensation Award Target Share	0
Maximum [Member] | Performance Shares [Member] | A 2019 Award [Member] | Long Term Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share Based Compensation Award Target Share	62,320
Target Achieved [Member] | Performance Shares [Member] | A 2021 Award | Long Term Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share Based Compensation Award Target Share	55,870
Target Achieved [Member] | Performance Shares [Member] | A 2020 Award | Long Term Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share Based Compensation Award Target Share	55,250

Stock-Based Compensation - Rest

Stock-Based Compensation - Restated Stock Option Plan (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Payment Arrangement, Expense, Tax Benefit	$ 762	$ 866	$ 933

Stock-Based Compensation - Empl

Stock-Based Compensation - Employee Stock Purchase Plan (Details) - Employee Stock Purchase Plan [Member]	12 Months Ended
	Dec. 31, 2022 USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price of Common Stock, Percent	85%
Maximum Value Of Stock Employees Are Allowed To Purchase	$ 21,223

Stock-Based Compensation - Stoc

Stock-Based Compensation - Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Payment Arrangement, Expense, Tax Benefit	$ (762)	$ (866)	$ (933)
Share-based Payment Arrangement, Expense, after Tax	2,115	2,406	2,592
Share-based Payment Arrangement, Amount Capitalized	351	344	841
Operations and Maintenance Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Payment Arrangement, Expense	$ 2,877	$ 3,272	$ 3,525

Debt (Details)

Debt (Details) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2022	Dec. 31, 2022	Dec. 31, 2021	Feb. 23, 2023
Debt Instruments [Abstract]
Long-Term Debt, Current Maturities, Gross		$ 90,700,000	$ 300,000
Ratio of Indebtedness to Net Capital		0.576	0.605
Liabilities, Fair Value Disclosure [Abstract]
Long-term Debt		$ 1,336,864,000	$ 1,044,932,000
Other Long-Term Debt		6,200,000	3,500,000
Unamortized Debt Issuance Expense		8,987,000	8,309,000
Debt Instrument, Fair Value Disclosure		1,148,395,000	1,174,500,000
Long-term Debt, Gross		1,345,851,000	1,053,241,000
Short-term Debt, Other Disclosures [Abstract]
Short-term debt		$ 258,200,000	$ 389,500,000
Short-term Debt, Weighted Average Interest Rate, at Point in Time		5.30%	1.10%
Commercial Paper, Maximum Maturity		6 days
Commercial Paper, Average Maturity		5 days
Short-term Debt, Weighted Average Interest Rate, at Point in Time		5.30%	1.10%
Long-term debt		$ 1,246,167,000	$ 1,044,587,000
Debt [Text Block]		DEBT Short-Term Debt The primary source of short-term liquidity for NW Holdings is cash balances, dividends from its operating subsidiaries, in particular NW Natural, available cash from a multi-year credit facility, and short-term credit facilities it may enter into from time to time. The primary source of short-term liquidity for NW Natural is from the sale of commercial paper, available cash from a multi-year credit facility, and short-term credit facilities it may enter into from time to time. In addition to issuing commercial paper or entering into bank loans to meet working capital requirements, including seasonal requirements to finance gas purchases and accounts receivable, short-term debt may also be used to temporarily fund capital requirements. For NW Natural, commercial paper and bank loans are periodically refinanced through the sale of long-term debt or equity contributions from NW Holdings. Commercial paper, when outstanding, is sold through two commercial banks under an issuing and paying agency agreement and is supported by one or more unsecured revolving credit facilities. See “ Credit Agreements ” below. At December 31, 2022 and 2021, NW Natural's short-term debt consisted of the following: December 31, 2022 December 31, 2021 In millions Balance Outstanding Weighted Average Interest Rate (1) Balance Outstanding Weighted Average Interest Rate (1) NW Natural: Commercial paper $ 170.2 4.6 % $ 245.5 0.3 % Other (NW Holdings): Credit agreement 88.0 5.3 % 144.0 1.1 % NW Holdings $ 258.2 $ 389.5 (1) Weighted average interest rate on outstanding short-term debt The carrying cost of commercial paper approximates fair value using Level 2 inputs. See Note 2 for a description of the fair value hierarchy. At December 31, 2022, NW Natural's commercial paper had a maximum remaining maturity of 6 days and an average remaining maturity of 5 days. Credit Agreements NW Holdings In November 2021, NW Holdings entered into an amended and restated $200.0 million credit agreement, with a feature that allows NW Holdings to request increases in the total commitment amount, up to a maximum of $300.0 million. The maturity date of the agreement is November 3, 2026, with an available extension of commitments for two additional one The NW Holdings credit agreement permits the issuance of letters of credit in an aggregate amount of up to $40.0 million. The principal amount of borrowings under the credit agreement is due and payable on the maturity date. The credit agreement requires NW Holdings to maintain a consolidated indebtedness to total capitalization ratio of 70% or less. Failure to comply with this covenant would entitle the lenders to terminate their lending commitments and accelerate the maturity of all amounts outstanding. NW Holdings was in compliance with this covenant at December 31, 2022 and 2021. The NW Holdings credit agreement also requires NW Holdings to maintain debt ratings (which are defined by a formula using NW Natural's credit ratings in the event NW Holdings does not have a credit rating) with Standard & Poor's (S&P) and Moody's Investors Service, Inc. (Moody’s) and notify the lenders of any change in its senior unsecured debt ratings or senior secured debt ratings, as applicable, by such rating agencies. A change in NW Holdings' debt ratings by S&P or Moody’s is not an event of default, nor is the maintenance of a specific minimum level of debt rating a condition of drawing upon the credit agreement. Rather, interest rates on any loans outstanding under the credit agreements are tied to debt ratings and therefore, a change in the debt rating would increase or decrease the cost of any loans under the credit agreements when ratings are changed. NW Holdings does not currently maintain ratings with S&P or Moody's. There was $88.0 million and $144.0 million of outstanding balances under the NW Holdings agreement at December 31, 2022 and 2021, respectively. No letters of credit were issued or outstanding under the NW Holdings agreement at December 31, 2022 and 2021. NW Natural In November 2021, NW Natural entered into an amended and restated credit agreement for unsecured revolving loans totaling $400.0 million, with a feature that allows NW Natural to request increases in the total commitment amount, up to a maximum of $600.0 million. The maturity date of the agreement is November 3, 2026 with an available extension of commitments for two additional one aggregate amount of up to $60.0 million. The principal amount of borrowings under the credit agreement is due and payable on the maturity date. Interest charges on the NW Natural credit agreement were indexed to the LIBOR through January 31, 2023. The agreement was amended to replace LIBOR with the SOFR beginning February 2023. The SOFR is subject to a 10 basis point spread adjustment. NW Natural's credit agreement requires NW Natural to maintain a consolidated indebtedness to total capitalization ratio of 70% or less. Failure to comply with this covenant would entitle the lenders to terminate their lending commitments and accelerate the maturity of all amounts outstanding. NW Natural was in compliance with this covenant at December 31, 2022 and 2021. The NW Natural credit agreement also requires NW Natural to maintain credit ratings with S&P and Moody’s and notify the lenders of any change in NW Natural's senior unsecured debt ratings or senior secured debt ratings, as applicable, by such rating agencies. A change in NW Natural's debt ratings by S&P or Moody’s is not an event of default, nor is the maintenance of a specific minimum level of debt rating a condition of drawing upon the credit agreement. Rather, interest rates on any loans outstanding under the credit agreement are tied to debt ratings and therefore, a change in the debt rating would increase or decrease the cost of any loans under the credit agreement when ratings are changed. There were no outstanding balances under NW Natural's credit agreement and no letters of credit issued or outstanding at December 31, 2022 and 2021. In February 2023, NW Natural issued a $14 million letter of credit through its existing credit agreement. There were no other letters of credit outstanding under the credit agreement. Long-Term Debt NW Holdings At December 31, 2022 and 2021, NW Holdings long-term debt consisted of the following: December 31, 2022 December 31, 2021 In millions Balance Outstanding Weighted Average Interest Rate (1) Balance Outstanding Weighted Average Interest Rate (1) NW Natural first mortgage bonds $ 1,134.7 4.5 % $ 994.7 4.4 % NW Holdings credit agreement 100.0 4.2 % — — % NWN Water credit agreement 50.0 4.2 % — — % NWN Water term loan 55.0 2.5 % 55.0 0.8 % Other long-term debt 6.2 3.5 Long-term debt, gross $ 1,345.9 $ 1,053.2 Less: unamortized debt issuance costs 9.0 8.3 Less: current maturities 90.7 0.3 Total long-term debt $ 1,246.2 $ 1,044.6 (1) Weighted average interest rate for the years ended December 31, 2022 and 2021. Long-term debt at NWN Water is primarily comprised of a five one 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 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 December 31, 2022. 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 December 31, 2022. Interest Rate Swap Agreements NW Holdings and NWN Water entered into interest rate swap agreements with major financial institutions that effectively convert 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 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 % NW Natural NW Natural's issuance of First Mortgage Bonds (FMBs), which includes NW Natural's medium-term notes, under the Mortgage and Deed of Trust (Mortgage) is limited by eligible property, adjusted net earnings, and other provisions of the Mortgage. The Mortgage constitutes a first mortgage lien on certain gas properties owned from time to time by NW Natural, including substantially all of NW Natural's NGD property. In July 2022, NW Natural entered into a Bond Purchase Agreement between NW Natural and the institutional investors named as purchasers therein (the Bond Purchase Agreement). The Bond Purchase Agreement provides for the issuance of $140.0 million aggregate principal amount of NW Natural's FMBs due in 2052 (the Bonds). The Bonds were issued on September 30, 2022. The Bonds bear interest at the rate of 4.78% per annum, payable semi-annually on March 30 and September 30 of each year, commencing March 30, 2023, and will mature on September 30, 2052. The Bonds are subject to redemption prior to maturity at the option of NW Natural, in whole or in part, (i) at any time prior to March 30, 2052, at a redemption price equal to 100% of the principal amount thereof plus a “make-whole” premium and accrued and unpaid interest thereon to the date of redemption, and (ii) at any time on and after March 30, 2052, at 100% of the principal amount thereof plus accrued and unpaid interest thereon to the date of redemption. Maturities and Outstanding Long-Term Debt Retirement of long-term debt for each of the annual periods through December 31, 2027 and thereafter are as follows: In thousands Long-term debt maturities NW Natural: 2023 $ 90,000 2024 — 2025 30,000 2026 55,000 2027 64,700 Thereafter 895,000 Total $ 1,134,700 The following table presents debt outstanding as of December 31: In thousands 2022 2021 NW Natural: First Mortgage Bonds: 3.542% Series due 2023 50,000 50,000 5.620% Series due 2023 40,000 40,000 7.720% Series due 2025 20,000 20,000 6.520% Series due 2025 10,000 10,000 7.050% Series due 2026 20,000 20,000 3.211% Series due 2026 35,000 35,000 7.000% Series due 2027 20,000 20,000 2.822% Series due 2027 25,000 25,000 6.650% Series due 2027 19,700 19,700 6.650% Series due 2028 10,000 10,000 3.141% Series due 2029 50,000 50,000 7.740% Series due 2030 20,000 20,000 7.850% Series due 2030 10,000 10,000 5.820% Series due 2032 30,000 30,000 5.660% Series due 2033 40,000 40,000 5.250% Series due 2035 10,000 10,000 4.000% Series due 2042 50,000 50,000 4.136% Series due 2046 40,000 40,000 3.685% Series due 2047 75,000 75,000 4.110% Series due 2048 50,000 50,000 3.869% Series due 2049 90,000 90,000 3.600% Series due 2050 150,000 150,000 3.078% Series due 2051 130,000 130,000 4.780% Series due 2052 140,000 — Long-term debt, gross 1,134,700 994,700 Less: current maturities 90,000 — Total long-term debt $ 1,044,700 $ 994,700 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. Substantially all outstanding debt at NW Holdings is comprised of NW Natural debt. These valuations are based on Level 2 inputs as defined in the fair value hierarchy. See Note 2. 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 : December 31, In thousands 2022 2021 NW Natural: Gross long-term debt $ 1,134,700 $ 994,700 Unamortized debt issuance costs (8,823) (8,205) Carrying amount $ 1,125,877 $ 986,495 Estimated fair value (1) $ 944,383 $ 1,110,741 NW Holdings: Gross long-term debt $ 1,345,851 $ 1,053,241 Unamortized debt issuance costs (8,987) (8,309) Carrying amount $ 1,336,864 $ 1,044,932 Estimated fair value (1) $ 1,148,395 $ 1,174,500 (1) Estimated fair value does not include unamortized debt issuance costs.
NWN Water Term Loan Due 2026
Short-term Debt, Other Disclosures [Abstract]
Derivative, Fixed Interest Rate		3.80%
18 Month Credit Agreement Due March 15, 2024
Credit Agreements [Abstract]
Debt Instrument Covenant Consolidated Indebtedness To Capitalization Ratio	70%	7,000%
Debt Outstanding
Proceeds from Issuance of Debt		$ 100,000,000	$ 0
Short-term Debt, Other Disclosures [Abstract]
Long-term Debt, Term	18 months
Long-Term Debt, Weighted Average Interest Rate, at Point in Time		4.20%	0%
Derivative, Fixed Interest Rate		4.70%
Northwest Natural Gas Company [Member]
Maturities of Long-term Debt [Abstract]
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months		$ 90,000,000
Long-term Debt, Maturities, Repayments of Principal in Year Two		0
Long-term Debt, Maturities, Repayments of Principal in Year Three		30,000,000
Long-term Debt, Maturities, Repayments of Principal in Year Four		55,000,000
Long-term Debt, Maturities, Repayments of Principal in Year Five		64,700,000
Long-term Debt, Maturities, Repayments of Principal after Year Five		895,000,000
Debt Instruments [Abstract]
Long-Term Debt, Current Maturities, Gross		90,000,000	$ 0
Long-term Debt, Excluding Current Maturities, Gross		1,044,700,000
Liabilities, Fair Value Disclosure [Abstract]
Long-term Debt		1,125,877,000	986,495,000
Unamortized Debt Issuance Expense		8,823,000	8,205,000
Debt Instrument, Fair Value Disclosure		944,383,000	1,110,741,000
Long-term Debt, Gross		1,134,700,000	994,700,000
Short-term Debt, Other Disclosures [Abstract]
Short-term debt		$ 170,200,000	$ 245,500,000
Short-term Debt, Weighted Average Interest Rate, at Point in Time		4.60%	0.30%
Long-Term Debt, Weighted Average Interest Rate, at Point in Time		4.50%	4.40%
Short-term Debt, Weighted Average Interest Rate, at Point in Time		4.60%	0.30%
Long-term debt		$ 1,035,935,000	$ 986,495,000
Northwest Natural Gas Company [Member] | Note 3600 Series Due 2050
Debt Instruments [Abstract]
Secured Debt		$ 150,000,000	$ 150,000,000
Short-term Debt, Other Disclosures [Abstract]
Debt Instrument, Interest Rate, Stated Percentage		3.60%	3.60%
Northwest Natural Gas Company [Member] | Note 3869 Series Due 2049 [Member]
Debt Instruments [Abstract]
Secured Debt		$ 90,000,000	$ 90,000,000
Short-term Debt, Other Disclosures [Abstract]
Debt Instrument, Interest Rate, Stated Percentage		3.869%	3.869%
Northwest Natural Gas Company [Member] | Note 4110 Series Due 2048 [Member]
Debt Instruments [Abstract]
Secured Debt		$ 50,000,000	$ 50,000,000
Short-term Debt, Other Disclosures [Abstract]
Debt Instrument, Interest Rate, Stated Percentage		4.11%	4.11%
Northwest Natural Gas Company [Member] | Note 3685 Series Due 2047 [Member]
Debt Instruments [Abstract]
Secured Debt		$ 75,000,000	$ 75,000,000
Short-term Debt, Other Disclosures [Abstract]
Debt Instrument, Interest Rate, Stated Percentage		3.685%	3.685%
Northwest Natural Gas Company [Member] | Note 4136 Series Due 2046 [Member]
Debt Instruments [Abstract]
Secured Debt		$ 40,000,000	$ 40,000,000
Short-term Debt, Other Disclosures [Abstract]
Debt Instrument, Interest Rate, Stated Percentage		4.136%	4.136%
Northwest Natural Gas Company [Member] | Note 4000 Series Due 2042 [Member]
Debt Instruments [Abstract]
Secured Debt		$ 50,000,000	$ 50,000,000
Short-term Debt, Other Disclosures [Abstract]
Debt Instrument, Interest Rate, Stated Percentage		4%	4%
Northwest Natural Gas Company [Member] | Note 5250 Series Due 2035 [Member]
Debt Instruments [Abstract]
Secured Debt		$ 10,000,000	$ 10,000,000
Short-term Debt, Other Disclosures [Abstract]
Debt Instrument, Interest Rate, Stated Percentage		5.25%	5.25%
Northwest Natural Gas Company [Member] | Note 5660 Series Due 2033 [Member]
Debt Instruments [Abstract]
Secured Debt		$ 40,000,000	$ 40,000,000
Short-term Debt, Other Disclosures [Abstract]
Debt Instrument, Interest Rate, Stated Percentage		5.66%	5.66%
Northwest Natural Gas Company [Member] | Note 5820 Series Due 2032 [Member]
Debt Instruments [Abstract]
Secured Debt		$ 30,000,000	$ 30,000,000
Short-term Debt, Other Disclosures [Abstract]
Debt Instrument, Interest Rate, Stated Percentage		5.82%	5.82%
Northwest Natural Gas Company [Member] | Note 7850 Series Due 2030 [Member]
Debt Instruments [Abstract]
Secured Debt		$ 10,000,000	$ 10,000,000
Short-term Debt, Other Disclosures [Abstract]
Debt Instrument, Interest Rate, Stated Percentage		7.85%	7.85%
Northwest Natural Gas Company [Member] | Note 7740 Series Due 2030 [Member]
Debt Instruments [Abstract]
Secured Debt		$ 20,000,000	$ 20,000,000
Short-term Debt, Other Disclosures [Abstract]
Debt Instrument, Interest Rate, Stated Percentage		7.74%	7.74%
Northwest Natural Gas Company [Member] | Note 3141 Series Due 2029 [Member]
Debt Instruments [Abstract]
Secured Debt		$ 50,000,000	$ 50,000,000
Short-term Debt, Other Disclosures [Abstract]
Debt Instrument, Interest Rate, Stated Percentage		3.141%	3.141%
Northwest Natural Gas Company [Member] | Note 6650 Series Due 2028 [Member]
Debt Instruments [Abstract]
Secured Debt		$ 10,000,000	$ 10,000,000
Short-term Debt, Other Disclosures [Abstract]
Debt Instrument, Interest Rate, Stated Percentage		6.65%	6.65%
Northwest Natural Gas Company [Member] | Note 6650 Series Due 2027 [Member]
Debt Instruments [Abstract]
Secured Debt		$ 19,700,000	$ 19,700,000
Short-term Debt, Other Disclosures [Abstract]
Debt Instrument, Interest Rate, Stated Percentage		6.65%	6.65%
Northwest Natural Gas Company [Member] | Note 2822 Series Due 2027 [Member]
Debt Instruments [Abstract]
Secured Debt		$ 25,000,000	$ 25,000,000
Short-term Debt, Other Disclosures [Abstract]
Debt Instrument, Interest Rate, Stated Percentage		2.822%	2.822%
Northwest Natural Gas Company [Member] | Note 7000 Series Due 2027 [Member]
Debt Instruments [Abstract]
Secured Debt		$ 20,000,000	$ 20,000,000
Short-term Debt, Other Disclosures [Abstract]
Debt Instrument, Interest Rate, Stated Percentage		7%	7%
Northwest Natural Gas Company [Member] | Note 3211 Series Due 2026 [Member]
Debt Instruments [Abstract]
Secured Debt		$ 35,000,000	$ 35,000,000
Short-term Debt, Other Disclosures [Abstract]
Debt Instrument, Interest Rate, Stated Percentage		3.211%	3.211%
Northwest Natural Gas Company [Member] | Note 7050 Series Due 2026 [Member]
Debt Instruments [Abstract]
Secured Debt		$ 20,000,000	$ 20,000,000
Short-term Debt, Other Disclosures [Abstract]
Debt Instrument, Interest Rate, Stated Percentage		7.05%	7.05%
Northwest Natural Gas Company [Member] | Note 6520 Series Due 2025 [Member]
Debt Instruments [Abstract]
Secured Debt		$ 10,000,000	$ 10,000,000
Short-term Debt, Other Disclosures [Abstract]
Debt Instrument, Interest Rate, Stated Percentage		6.52%	6.52%
Northwest Natural Gas Company [Member] | Note 7720 Series Due 2025 [Member]
Debt Instruments [Abstract]
Secured Debt		$ 20,000,000	$ 20,000,000
Short-term Debt, Other Disclosures [Abstract]
Debt Instrument, Interest Rate, Stated Percentage		7.72%	7.72%
Northwest Natural Gas Company [Member] | Note 5620 Series Due 2023 [Member]
Debt Instruments [Abstract]
Secured Debt		$ 40,000,000	$ 40,000,000
Short-term Debt, Other Disclosures [Abstract]
Debt Instrument, Interest Rate, Stated Percentage		5.62%	5.62%
Northwest Natural Gas Company [Member] | Note 3542 Series Due 2023 [Member]
Debt Instruments [Abstract]
Secured Debt		$ 50,000,000	$ 50,000,000
Short-term Debt, Other Disclosures [Abstract]
Debt Instrument, Interest Rate, Stated Percentage		3.542%	3.542%
Northwest Natural Gas Company [Member] | Note 4780 Series due 2052
Debt Instruments [Abstract]
Secured Debt		$ 140,000,000	$ 0
Short-term Debt, Other Disclosures [Abstract]
Debt Instrument, Interest Rate, Stated Percentage		4.78%	4.78%
Northwest Natural Gas Company [Member] | Note 3078 Series due 2051
Debt Instruments [Abstract]
Secured Debt		$ 130,000,000	$ 130,000,000
Short-term Debt, Other Disclosures [Abstract]
Debt Instrument, Interest Rate, Stated Percentage		3.078%	3.078%
Northwest Natural Gas Company [Member] | First Mortgage Bonds 4.8 Percent Series Due 2052
Debt Outstanding
Proceeds from Issuance of Debt		$ 140,000,000
Repayments of Long-term Debt [Abstract]
Debt Instrument, Redemption Price, Percentage of Principal Amount Redeemed		100%
Short-term Debt, Other Disclosures [Abstract]
Debt Instrument, Interest Rate, Stated Percentage		4.78%
NWN Water | NWN Water Term Loan Due 2026
Liabilities, Fair Value Disclosure [Abstract]
Long-term Debt		$ 55,000,000
Short-term Debt, Other Disclosures [Abstract]
Long-Term Debt, Weighted Average Interest Rate, at Point in Time		2.50%	0.80%
Security Overnight Financing Rate Basis		1 month
NWN Water | 18 Month Credit Agreement Due March 15, 2024
Credit Agreements [Abstract]
Debt Instrument Covenant Consolidated Indebtedness To Capitalization Ratio	7,000%	7,000%
Debt Outstanding
Proceeds from Issuance of Debt		$ 50,000,000	$ 0
Short-term Debt, Other Disclosures [Abstract]
Long-term Debt, Term	18 months
Long-Term Debt, Weighted Average Interest Rate, at Point in Time		4.20%	0%
Northwest Holdings [Member] | 18 Month Credit Agreement Due March 15, 2024
Debt Outstanding
Proceeds from Issuance of Debt		$ 100,000,000
Northwest Holdings Other [Member] | Corporate, Non-Segment [Member] | NWN Water Term Loan Due 2026
Liabilities, Fair Value Disclosure [Abstract]
Long-term Debt		$ 55,000,000
Short-term Debt, Other Disclosures [Abstract]
Long-term Debt, Term		5 years
Line of Credit [Member]
Credit Agreements [Abstract]
Line of Credit Facility, Maximum Borrowing Capacity		$ 200,000,000
Line of Credit Facility, Amount Outstanding		88,000,000	$ 144,000,000
Line of Credit Facility Contingent Increase To Maximum Borrowing Capacity		$ 300,000,000
Debt Instrument Covenant Consolidated Indebtedness To Capitalization Ratio		70%
Line of Credit [Member] | First Available Extension Period
Short-term Debt, Other Disclosures [Abstract]
Line of Credit Facility, Expiration Period		1 year
Line of Credit [Member] | Second Available Extension Period
Short-term Debt, Other Disclosures [Abstract]
Line of Credit Facility, Expiration Period		1 year
Line of Credit [Member] | Northwest Natural Gas Company [Member]
Credit Agreements [Abstract]
Line of Credit Facility, Maximum Borrowing Capacity		$ 400,000,000
Line of Credit Facility, Amount Outstanding		0	0
Line of Credit Facility Contingent Increase To Maximum Borrowing Capacity		$ 600,000,000
Line of Credit [Member] | Northwest Natural Gas Company [Member] | First Available Extension Period
Short-term Debt, Other Disclosures [Abstract]
Line of Credit Facility, Expiration Period		1 year
Line of Credit [Member] | Northwest Natural Gas Company [Member] | Second Available Extension Period
Short-term Debt, Other Disclosures [Abstract]
Line of Credit Facility, Expiration Period		1 year
Letter of Credit [Member]
Credit Agreements [Abstract]
Line of Credit Facility, Maximum Borrowing Capacity		$ 40,000,000
Letters of Credit Outstanding, Amount		0
Letter of Credit [Member] | Northwest Natural Gas Company [Member]
Credit Agreements [Abstract]
Line of Credit Facility, Maximum Borrowing Capacity		60,000,000
Letters of Credit Outstanding, Amount		$ 0	$ 0
Letter of Credit [Member] | Northwest Natural Gas Company [Member] | Subsequent Event [Member]
Credit Agreements [Abstract]
Letters of Credit Outstanding, Amount				$ 14,000,000

Pension and Other Postretirem_3

Pension and Other Postretirement Benefits Costs - Changes in Benefit Obligations and Fair Value of Plan Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Pension Plan [Member]
Reconciliation of change in plan assets:
Fair value of plan assets at January 1	$ 399,217
Fair value of plan assets at December 31	280,306	$ 399,217
Qualified Pension Plans, Defined Benefit [Member]
Reconciliation of change in plan assets:
Defined Benefit Plan, Accumulated Benefit Obligation	353,400	464,400
Northwest Natural Gas Company [Member] | Other Postretirement Benefits Plan [Member]
Reconciliation of change in benefit obligation:
Obligation at January 1	27,223	29,039
Service cost	193	238
Interest cost	724	684
Net actuarial gain	(6,234)	(688)
Benefits paid	(2,026)	(2,050)	$ (1,837)
Obligation at December 31	19,880	27,223	29,039
Reconciliation of change in plan assets:
Fair value of plan assets at January 1	0	0
Actual return on plan assets	0	0
Employer contributions	2,026	2,050
Benefits paid	(2,026)	(2,050)	(1,837)
Fair value of plan assets at December 31	0	0	0
Northwest Natural Gas Company [Member] | Pension Plan [Member]
Reconciliation of change in benefit obligation:
Obligation at January 1	542,618	566,147
Service cost	5,933	6,982
Interest cost	14,593	13,447
Net actuarial gain	(122,168)	(18,587)
Benefits paid	(27,563)	(25,371)	(25,073)
Obligation at December 31	413,413	542,618	566,147
Reconciliation of change in plan assets:
Fair value of plan assets at January 1	399,217	373,932
Actual return on plan assets	(93,703)	38,712
Employer contributions	2,353	11,944
Benefits paid	(27,563)	(25,371)	(25,073)
Fair value of plan assets at December 31	280,304	399,217	$ 373,932
Defined Benefit Plan, Benefit Obligation, Period Increase (Decrease)	122,300
Defined Benefit Plan, Plan Assets, Period Increase (Decrease)	(118,900)
Northwest Natural Gas Company [Member] | Non-qualified Benefit Plans
Reconciliation of change in plan assets:
Defined Benefit Plan, Benefit Obligation, Period Increase (Decrease)	6,900
Northwest Natural Gas Company [Member] | Qualified Pension Plans, Defined Benefit [Member]
Reconciliation of change in benefit obligation:
Obligation at January 1	503,900
Obligation at December 31	381,600	503,900
Reconciliation of change in plan assets:
Fair value of plan assets at January 1	399,200
Fair value of plan assets at December 31	280,300	399,200
Defined Benefit Plan, Funded (Unfunded) Status of Plan	(101,300)
Northwest Holdings and Northwest Natural [Member] | Other Postretirement Benefits Plan [Member]
Reconciliation of change in plan assets:
Defined Benefit Plan, Funded (Unfunded) Status of Plan	(19,880)	(27,223)
Defined Benefit Plan, Benefit Obligation, Period Increase (Decrease)	7,300
Northwest Holdings and Northwest Natural [Member] | Pension Plan [Member]
Reconciliation of change in plan assets:
Defined Benefit Plan, Funded (Unfunded) Status of Plan	(133,109)	$ (143,401)
Defined Benefit Plan, Increase in Net Liability	$ 3,300

Pension and Other Postretirem_4

Pension and Other Postretirement Benefits Costs - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Ultimate Health Care Cost Trend Rate	4%
Defined Benefit Plan, Year Health Care Cost Trend Rate Reaches Ultimate Trend Rate	2029
Pension Plan Withdrawal Liability, Payments	20 years
Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Plan Assets, Amount	$ 280,306	$ 399,217
Other Postretirement Benefits Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Next Fiscal Year	7%
Non-Qualified Pension Plans, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Plan Assets, Amount	$ 0
Defined Benefit Plan, Benefit Obligation	31,800	38,700
Qualified Pension Plans, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Accumulated Benefit Obligation	$ 353,400	$ 464,400

Pension and Other Postretirem_5

Pension and Other Postretirement Benefits Costs - Schedule of Amounts Realized in Other Comprehensive Loss (Income) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Regulatory Asset, Net actuarial loss (gain)	$ 2,833	$ (32,258)	$ 16,170
Regulatory Asset, Prior service cost	0	0	0
Regulatory Asset, Actuarial loss	(11,531)	(21,250)	(18,627)
Regulatory Asset, Total	(8,698)	(53,508)	(2,457)
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Regulatory Asset, Net actuarial loss (gain)	(6,234)	(688)	145
Regulatory Asset, Prior service cost	333	468	468
Regulatory Asset, Actuarial loss	(426)	(645)	(607)
Regulatory Asset, Total	(6,327)	(865)	6
Qualified Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Amounts reclassified to AOCL	(5,706)	(812)	3,873
Other Comprehensive Loss (Income), Prior service cost	0	0	0
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, before Tax	(1,081)	(1,225)	(923)
Total reclassifications before tax	$ (6,787)	$ (2,037)	$ 2,950

Pension and Other Postretirem_6

Pension and Other Postretirement Benefits Costs - Schedule of Amount Recognized in AOCL (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Qualified Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
AOCL, Prior Service Costs (Credit)	$ 0	$ 0
AOCL, Net Actuarial Loss	8,717	15,399
AOCL, Total	8,717	15,399
Pension Costs [Member]
Defined Benefit Plan Disclosure [Line Items]
Regulatory Assets, Prior Service Cost (Credit)	0	0
Regulatory Assets, Net Actuarial Loss	102,240	112,182
Regulatory Assets	102,240	112,182
Postretirement Benefit Costs [Member]
Defined Benefit Plan Disclosure [Line Items]
Regulatory Assets, Prior Service Cost (Credit)	0	(333)
Regulatory Assets, Net Actuarial Loss	826	5,834
Regulatory Assets	$ 826	$ 5,501

Pension and Other Postretirem_7

Pension and Other Postretirement Benefits Costs - Schedule of AOCL and Changes in AOCL, Non-Qualified Employee Plans (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 11,404
Ending balance	6,285	$ 11,404
Northwest Holdings and Northwest Natural [Member] | Non-Qualified Pension Plans, Defined Benefit [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	11,404	12,902
Amounts reclassified to AOCL	5,706	812
Amortization of actuarial losses	1,081	1,225
Total reclassifications before tax	6,787	2,037
Tax benefit	(1,797)	(539)
Total reclassifications for the period	4,990	1,498
Ending balance	(6,414)	11,404
Northwest Natural Gas Company [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	11,404
Ending balance	$ 6,414	$ 11,404

Pension and Other Postretirem_8

Pension and Other Postretirement Benefits Costs - Schedule of Pension Plan Target Allocations (Details) - Northwest Natural Gas Company [Member]	Dec. 31, 2022
Long government/credit [Member]
Defined Benefit Plan Disclosure [Line Items]
Target allocation, percentage	20%
U.S. large cap equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Target allocation, percentage	18%
Non-U.S. equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Target allocation, percentage	18%
Absolute Return Strategy Investment Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target allocation, percentage	12%
U.S. small/mid cap equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Target allocation, percentage	10%
Real estate funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Target allocation, percentage	7%
High yield bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Target allocation, percentage	5%
Emerging markets equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Target allocation, percentage	5%
Emerging market debt [Member]
Defined Benefit Plan Disclosure [Line Items]
Target allocation, percentage	5%

Pension and Other Postretirem_9

Pension and Other Postretirement Benefits Costs - Schedule of Components of Net Periodic Benefit Cost for NW Natural (Details) - Northwest Natural Gas Company Consolidated [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 193	$ 238	$ 258
Interest cost	724	684	905
Expected return on plan assets	0	0	0
Amortization of prior service credit	(333)	(468)	(468)
Amortization of net actuarial loss	(426)	(645)	(607)
Net periodic benefit cost	1,010	1,099	1,302
Amount allocated to construction	76	93	98
Net periodic benefit cost charged to expense	934	1,006	1,204
Amortization of Regulatory Balancing Account	0	0	0
Defined Benefit Plan Net Amount Charged To Expense	934	1,006	1,204
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	5,933	6,981	6,614
Interest cost	14,593	13,448	16,161
Expected return on plan assets	25,698	24,232	21,865
Amortization of prior service credit	0	0	0
Amortization of net actuarial loss	(12,612)	(22,475)	(19,550)
Net periodic benefit cost	7,440	18,672	20,460
Amount allocated to construction	2,621	3,015	2,798
Net periodic benefit cost charged to expense	4,819	15,657	17,662
Amortization of Regulatory Balancing Account	7,131	7,131	7,131
Defined Benefit Plan Net Amount Charged To Expense	11,950	$ 22,788	$ 24,793
Operating Expense [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Regulatory Pension Disallowance	2,600
Other Nonoperating Income (Expense) [Member] | Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Regulatory Pension Disallowance	$ 4,500

Pension and Other Postretire_10

Pension and Other Postretirement Benefits Costs - Schedule of Assumptions Used (Details)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2024	Dec. 31, 2023
Forecast [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Thereafter				4%
Other Postretirement Benefits Plan [Member]
Assumptions for net periodic benefit cost:
Weighted-average discount rate	2.72%	2.34%	3.11%
Assumptions for year-end funded status:
Weighted-average discount rate	5.19%	2.72%	2.34%
Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Next Fiscal Year	7%
Pension Plan [Member]
Assumptions for net periodic benefit cost:
Weighted-average discount rate	2.71%	2.40%	3.18%
Expected long-term rate of return	7%	7.25%	7.25%
Assumptions for year-end funded status:
Weighted-average discount rate	5.18%	2.71%	2.36%
Expected long-term rate of return	7.50%	7%	7.25%
Minimum [Member] | Forecast [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Thereafter				4%	4.50%
Minimum [Member] | Pension Plan [Member]
Assumptions for net periodic benefit cost:
Rate of Compensation Increase	3.50%
Assumptions for year-end funded status:
Rate of Compensation Increase	4%	3.50%	3.50%
Maximum [Member] | Forecast [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Thereafter				6%	5%
Maximum [Member] | Pension Plan [Member]
Assumptions for net periodic benefit cost:
Rate of Compensation Increase	3.50%	3.50%	3.50%
Assumptions for year-end funded status:
Rate of Compensation Increase	6%	3.50%	6.50%

Pension and Other Postretire_11

Pension and Other Postretirement Benefits Costs - Schedule of Future Employer Contributions and Benefit Payments (Details) - Northwest Natural Gas Company [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 22, 2013
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
Defined Contribution Plan, Cost	$ 9,600	$ 8,800	$ 8,300
Western States Office and Professional Employees Union Pension Fund [Member]
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
Multiemployer Plan, Employer Contribution, Cost	600	$ 400	$ 700
Multiemployer Plan, Pension, Insignificant, Plan Contribution	600
Multiemployer Plans, Withdrawal Obligation	5,400			$ 8,300
Western States Office and Professional Employees Union Pension Fund [Member] | Maximum [Member]
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
Multiemployer Plan, Pension, Insignificant, Employer Contribution under Collective-Bargaining Arrangement to All Participating Employer Contributions, Percentage		5%	5%
Western States Office and Professional Employees Union Pension Fund [Member] | Minimum [Member]
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
Multiemployer Plan, Pension, Insignificant, Employer Contribution under Collective-Bargaining Arrangement to All Participating Employer Contributions, Percentage		3%	3%
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Payment for Pension and Other Postretirement Benefits	2,353	$ 11,944
Expected future employer contributions	2,333
Benefits paid	27,563	25,371	$ 25,073
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
Year 1	26,499
Year 2	27,029
Year 3	27,541
Year 4	27,981
Year 6	36,485
Thereafter	145,486
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Payment for Pension and Other Postretirement Benefits	2,026	2,050
Expected future employer contributions	1,586
Benefits paid	2,026	$ 2,050	$ 1,837
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
Year 1	1,586
Year 2	1,591
Year 3	1,586
Year 4	1,560
Year 6	1,552
Thereafter	$ 7,345

Income Tax (Details)

Income Tax (Details) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Regulatory Assets [Line Items]
Unrecognized Tax Benefits	$ 0	$ 0	$ 0
Deferred Tax Liabilities, Property, Plant and Equipment	326,326,000	310,471,000
Deferred Tax Liabilities, Leasing Arrangements	36,873,000	38,123,000
Deferred Tax Liabilities, Lease Right of Use Assets	21,272,000	21,362,000
Deferred Tax Liabilities Non Regulated Liabilities	17,050,000	7,793,000
Deferred Tax Liabilities, Net	366,022,000	340,231,000
Deferred Tax Assets, Lease Liabilities	21,306,000	21,376,000
Deferred Tax Assets, Tax Credit Carryforwards, Alternative Minimum Tax	56,000
Deferred Tax Assets, Tax Credit Carryforwards, Other	101,000	126,000
Deferred Tax Assets, Net of Valuation Allowance	71,624,000	75,433,000
Regulatory Liability, Noncurrent	689,578,000	658,332,000
Deferred Tax Assets, Goodwill and Intangible Assets	1,947,000	3,484,000
Deferred Tax Liabilities, Gross	437,646,000	415,664,000
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Income Tax Reconciliation, Income Tax Expense (Benefit), at Federal Statutory Income Tax Rate	24,241,000	22,275,000	19,185,000
Income Tax Reconciliation, State and Local Income Taxes, net of federal tax benefit	10,139,000	9,962,000	6,389,000
Income Tax Reconciliation, Differences Regulatory Commission	(4,748,000)	(4,655,000)	(3,960,000)
Income Tax Reconciliation, Other Adjustments	(502,000)	(176,000)	(532,000)
Income Tax Expense (Benefit)	$ 29,130,000	$ 27,406,000	$ 21,082,000
Effective Income Tax Rate	25.20%	25.80%	23.10%
Tax Provision Current And Deferred [Abstract]
Current Federal Tax Expense (Benefit)	$ 5,172,000	$ 6,508,000	$ 10,106,000
Current State and Local Tax Expense (Benefit)	6,551,000	6,281,000	5,971,000
Current Income Tax Expense (Benefit)	11,723,000	12,789,000	16,077,000
Deferred Federal Income Tax Expense (Benefit)	11,124,000	8,289,000	2,888,000
Deferred State and Local Income Tax Expense (Benefit)	6,283,000	6,328,000	2,117,000
Deferred Income Tax Expense (Benefit)	17,407,000	14,617,000	5,005,000
Income Tax Expense (Benefit)	29,130,000	27,406,000	21,082,000
Tax Provision Regulated And Nonutility [Abstract]
Income Tax Expense (Benefit)	29,130,000	27,406,000	21,082,000
Pension Plan [Member]
Regulatory Assets [Line Items]
Deferred Tax Liabilities, Regulatory Assets	22,973,000	23,097,000
Income taxes [Member]
Regulatory Assets [Line Items]
Deferred Tax Liabilities, Regulatory Assets	13,152,000	14,818,000
Deferred Tax Assets, Regulatory Assets and Liabilities	48,270,000	50,447,000
Tax Provision Regulated And Nonutility [Abstract]
Deferred Tax Assets, Regulatory Assets and Liabilities	48,270,000	50,447,000
Northwest Natural Gas Company [Member]
Regulatory Assets [Line Items]
Deferred Tax Liabilities, Property, Plant and Equipment	320,121,000	303,928,000
Deferred Tax Liabilities, Leasing Arrangements	36,873,000	38,123,000
Deferred Tax Liabilities, Lease Right of Use Assets	21,084,000	21,350,000
Deferred Tax Liabilities Non Regulated Liabilities	17,314,000	8,003,000
Deferred Tax Liabilities, Net	362,353,000	337,717,000
Deferred Tax Assets, Lease Liabilities	21,102,000	21,365,000
Deferred Tax Assets, Tax Credit Carryforwards, Other	44,000	44,000
Deferred Tax Assets, Net of Valuation Allowance	69,164,000	71,602,000
Regulatory Liability, Noncurrent	688,599,000	657,350,000
Deferred Tax Assets, Goodwill and Intangible Assets	0	0
Deferred Tax Liabilities, Gross	431,517,000	409,319,000
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Income Tax Reconciliation, Income Tax Expense (Benefit), at Federal Statutory Income Tax Rate	25,746,000	22,996,000	19,248,000
Income Tax Reconciliation, State and Local Income Taxes, net of federal tax benefit	10,504,000	10,150,000	6,385,000
Income Tax Reconciliation, Differences Regulatory Commission	(4,746,000)	(4,738,000)	(3,960,000)
Income Tax Reconciliation, Other Adjustments	(468,000)	(75,000)	(578,000)
Income Tax Expense (Benefit)	$ 31,036,000	$ 28,333,000	$ 21,095,000
Effective Income Tax Rate	25.30%	25.90%	23%
Tax Provision Current And Deferred [Abstract]
Current Federal Tax Expense (Benefit)	$ 7,442,000	$ 7,570,000	$ 11,092,000
Current State and Local Tax Expense (Benefit)	7,307,000	7,540,000	5,357,000
Current Income Tax Expense (Benefit)	14,749,000	15,110,000	16,449,000
Deferred Federal Income Tax Expense (Benefit)	10,298,000	7,915,000	1,921,000
Deferred State and Local Income Tax Expense (Benefit)	5,989,000	5,308,000	2,725,000
Deferred Income Tax Expense (Benefit)	16,287,000	13,223,000	4,646,000
Income Tax Expense (Benefit)	31,036,000	28,333,000	21,095,000
Tax Provision Regulated And Nonutility [Abstract]
Income Tax Expense (Benefit)	31,036,000	28,333,000	$ 21,095,000
Northwest Natural Gas Company [Member] | Income taxes [Member] | Equity Portion, AFUDC
Regulatory Assets [Line Items]
Regulatory Assets	2,900,000	2,400,000
Northwest Natural Gas Company [Member] | Income taxes [Member] | Oregon Corporate Activity Tax
Regulatory Assets [Line Items]
Regulatory Assets		400,000
Northwest Natural Gas Company [Member] | Pension Plan [Member]
Regulatory Assets [Line Items]
Deferred Tax Liabilities, Regulatory Assets	22,973,000	23,097,000
Northwest Natural Gas Company [Member] | Income taxes [Member]
Regulatory Assets [Line Items]
Deferred Tax Liabilities, Regulatory Assets	13,152,000	14,818,000
Deferred Tax Assets, Regulatory Assets and Liabilities	48,018,000	50,193,000
Regulatory Liabilities	181,400,000	189,600,000
Regulatory Liability, Noncurrent	174,212,000	181,404,000
Tax Provision Regulated And Nonutility [Abstract]
Deferred Tax Assets, Regulatory Assets and Liabilities	48,018,000	50,193,000
Excluding AFUDC [Member] | Northwest Natural Gas Company [Member] | Income taxes [Member]
Regulatory Assets [Line Items]
Regulatory Assets	10,200,000	$ 12,400,000
Domestic Tax Authority [Member]
Regulatory Assets [Line Items]
Operating Loss Carryforwards	100,000
State and Local Jurisdiction [Member]
Regulatory Assets [Line Items]
Operating Loss Carryforwards	$ 100,000

Property, Plant and Equipment_2

Property, Plant and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment, Net, by Type [Abstract]
Property, Plant and Equipment, Gross	$ 4,261,566	$ 3,997,243
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	1,147,166	1,125,873
Total property, plant, and equipment, net	3,114,400	2,871,370
Property, Plant, Equipment non-cash	25,318	38,333
Regulatory Liability, Noncurrent	689,578	658,332
Natural Gas Distribution [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Property, Plant and Equipment, Gross	3,992,676	3,721,939
Public Utilities, Property, Plant and Equipment, Construction Work in Progress	78,897	135,398
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	1,115,690	1,098,715
Total property, plant, and equipment, net	2,955,883	2,758,622
Other Northwest Natural [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Property, Plant and Equipment, Gross	70,368	69,332
Public Utilities, Property, Plant and Equipment, Construction Work in Progress	6,606	4,971
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	21,541	20,646
Total property, plant, and equipment, net	55,433	53,657
Northwest Natural Gas Company [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Total property, plant, and equipment, net	3,011,316	2,812,279
Property, Plant, Equipment non-cash	24,584	37,537
Northwest Holdings Other [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Property, Plant and Equipment, Gross	92,979	57,184
Public Utilities, Property, Plant and Equipment, Construction Work in Progress	20,040	8,419
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	9,935	6,512
Total property, plant, and equipment, net	$ 103,084	$ 59,091
Natural Gas Distribution [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Public Utilities, Property, Plant and Equipment, Disclosure of Composite Depreciation Rate for Plants in Service	3%	3%	3%
Other Northwest Natural [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Weighted Average Depreciation Rates	1.80%	1.80%	1.80%
Northwest Natural Gas Company [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Property, Plant and Equipment, Gross	$ 4,148,547	$ 3,931,640
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	1,137,231	1,119,361
Total property, plant, and equipment, net	3,011,316	2,812,279
Regulatory Liability, Noncurrent	688,599	657,350
Northwest Natural Gas Company [Member] | Asset Removal Costs [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Regulatory Liability, Noncurrent	$ 467,742	$ 445,952

Investments (Details)

Investments (Details) $ in Thousands	6 Months Ended	12 Months Ended
	Dec. 31, 2022 USD ($) numberOfCustomerConnections projects numberOfEmployees	Dec. 31, 2022 USD ($) numberOfCustomerConnections projects numberOfEmployees	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Jul. 31, 2022 USD ($)
Schedule of Investments [Line Items]
Total Cumulative Gas Reserves Investment	$ 188,000	$ 188,000
Other Investments [Abstract]
Life Insurance, Corporate or Bank Owned, Amount	49,358	49,358	$ 48,178
Equity Method Investments	22,970	22,970	26,608
Equity Method Investment, Aggregate Cost	23,376	23,376	14,492
Total Other investments	95,704	95,704	89,278
Investments in Unconsolidated Affiliates [Abstract]
Equity Method Investment, Underlying Equity in Net Assets	$ 23,400	23,400	14,500
Proceeds from Sale of Equity Method Investments		0	7,000	$ 7,000
Proceeds from sale of discontinued operations		$ 0	0	12,500
Discontinued Operations, Held-for-sale [Member] | Gill Ranch [Member]
Investments in Unconsolidated Affiliates [Abstract]
Proceeds from sale of discontinued operations				$ 13,500	$ 1,000
DiscontinuedOperationGainLossOnDisposalStatementOfIncomeOrComprehensiveIncomeExtensibleEnumerationNotDisclosedFlag			$ 5,900
Avion Water
Investments in Unconsolidated Affiliates [Abstract]
Ownership percentage	37.30%	37.30%
Equity Method Investment, Underlying Equity in Net Assets	$ 14,500	$ 14,500
Equity Method Investment, Number of Customer Connections | numberOfCustomerConnections	15,000	15,000
Equity Method Investment, Number of Employees | numberOfEmployees	35	35
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity	$ 9,400	$ 9,400
Trail West Holdings [Member]
Investments in Unconsolidated Affiliates [Abstract]
Percentage of Equity Method Investment Sold			10,000%
Equity Method Investment, Realized Gain (Loss) on Disposal			$ 500
BioCarbN Partnership | Maximum [Member]
Investments in Unconsolidated Affiliates [Abstract]
RNG Development Projects | projects	4	4
Northwest Holdings Other [Member] | Avion Water
Investments in Unconsolidated Affiliates [Abstract]
Ownership percentage	40.30%	40.30%
Equity Method Investment, Additional Underlying Equity in Net Assets						$ 1,000
Northwest Holdings Other [Member] | Trail West Holdings [Member]
Investments in Unconsolidated Affiliates [Abstract]
Proceeds from Sale of Equity Method Investments		$ 14,000
Northwest Natural Gas Company [Member]
Other Investments [Abstract]
Total Other investments	$ 80,110	80,110	74,786
Investments in Unconsolidated Affiliates [Abstract]
Deferred Taxes Related To Gas Reserves	5,200	$ 5,200	$ 6,900
Gas Reserves Percent Gas Supplies YTD		3%	4%
Deferred Gas Cost	3,400	$ 3,400	$ 5,400
Cash and Cash Equivalents [Member] | Trail West Holdings [Member]
Investments in Unconsolidated Affiliates [Abstract]
Proceeds from Sale of Equity Method Investments			7,000
Notes Receivable [Member] | Trail West Holdings [Member]
Investments in Unconsolidated Affiliates [Abstract]
Proceeds from Sale of Equity Method Investments		7,000
Northwest Natural Gas Company [Member]
Other Investments [Abstract]
Life Insurance, Corporate or Bank Owned, Amount	49,358	49,358	48,178
Equity Method Investments	22,970	22,970	26,608
Equity Method Investment, Aggregate Cost	7,782	7,782	0
Total Other investments	80,110	$ 80,110	$ 74,786
Northwest Natural Gas Company [Member] | Lexington
Investments in Unconsolidated Affiliates [Abstract]
Deconsolidation, Gain (Loss), Amount	$ 0

Business Combinations (Details)

Business Combinations (Details)	12 Months Ended
	Dec. 31, 2022 USD ($) connections multiplier	Dec. 31, 2021 USD ($) numberOfConnections	Dec. 31, 2020 USD ($)	Oct. 05, 2022 USD ($)
Business Acquisition [Line Items]
Goodwill	$ 149,283,000	$ 70,570,000
Goodwill, Impairment Loss	0
Operating revenues	$ 1,037,353,000	$ 860,400,000	$ 773,679,000
Average Annual System Operating Revenue Multiplier, Contingent Consideration | multiplier	4
Suncadia & T&W Water
Business Acquisition [Line Items]
Business Combination, Consideration Transferred			$ 38,100,000
Number of Businesses Acquired			2
Other insignificant acquisitions [Member]
Business Acquisition [Line Items]
Business Combination, Consideration Transferred	$ 8,700,000		$ 1,500,000
Number of Businesses Acquired	6	4	3
Far West Water & Sewer, Inc.
Business Acquisition [Line Items]
Business Combination, Consideration Transferred	$ 97,000,000
Goodwill	70,842,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Assets	684,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities	(1,136,000)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities	(9,011,000)
Business Acquisition, Goodwill, Expected Tax Deductible Amount	61,800,000
Cash Acquired from Acquisition	88,404,000
Business Combination, Contingent Consideration, Liability	8,100,000
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High	12,000,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets	1,281,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment	25,744,000
Payments to Acquire Businesses, Gross	$ 88,400,000
Business Combination, Connections of Business Acquired | connections	25,000
Average Annual System Operating Revenue Threshold, Contingent Consideration	$ 13,000,000
Business Combination, Pro Forma Information, Revenue of Acquiree since Acquisition Date, Actual	$ 2,900,000
Far West Water & Sewer, Inc. | Fair Value of Contingent Consideration
Business Acquisition [Line Items]
Business Combination, Contingent Consideration, Liability				$ 8,100,000
Far West Water & Sewer, Inc. | Deferred Contingent Consideration
Business Acquisition [Line Items]
Business Combination, Contingent Consideration, Liability				$ 500,000

Derivative Instruments - Narrat

Derivative Instruments - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Derivative [Line Items]
Derivative, Fair Value, Net	$ 149,700	$ 48,000
Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	129	0	$ 0
Northwest Natural Gas Company [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	153,300	51,800
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	$ 3,600	$ 3,800
Northwest Natural Gas Company [Member] | Gas Year 2020 - 2021 | Financial [Member]
Derivative [Line Items]
TargetHedgeAchieved	60%
Northwest Natural Gas Company [Member] | Gas Year 2020 - 2021 | Physical [Member]
Derivative [Line Items]
TargetHedgeAchieved	19%
Northwest Natural Gas Company [Member] | Gas Year 2021 - 2022 | Financial [Member]
Derivative [Line Items]
TargetHedgeAchieved	67%
Northwest Natural Gas Company [Member] | Gas Year 2021 - 2022 | Physical [Member]
Derivative [Line Items]
TargetHedgeAchieved	17%

Derivative Instruments - Schedu

Derivative Instruments - Schedule of Notional Amounts (Details) - Northwest Natural Gas Company [Member] therm in Thousands, $ in Thousands	Dec. 31, 2022 USD ($) therm	Dec. 31, 2021 USD ($) therm
Natural Gas Therms [Member] | Financial [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	852,435	618,815
Natural Gas Therms [Member] | Physical [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	463,254	431,628
Foreign Exchange Contract [Member]
Derivative [Line Items]
Derivative, Notional Amount | $	$ 7,617	$ 6,268

Derivative Instruments - Sche_2

Derivative Instruments - Schedule of Unrealized and Realized Gain/Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
General Discussion of Derivative Instruments and Hedging Activities [Abstract]
Derivative, Gain, Statement of Income or Comprehensive Income [Extensible Enumeration]	Operating revenues	Operating revenues
Northwest Holdings and Northwest Natural [Member] | Foreign Exchange Contract [Member]
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	$ 0	$ 0
Northwest Holdings and Northwest Natural [Member] | Foreign Exchange Contract [Member] | Cost of Sales [Member]
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	(165)	(26)
Northwest Holdings and Northwest Natural [Member] | Foreign Exchange Contract [Member] | Sales [Member]
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	0	0
Northwest Holdings and Northwest Natural [Member] | Natural Gas Commodity [Member]
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	0	(4)
Northwest Holdings and Northwest Natural [Member] | Natural Gas Commodity [Member] | Cost of Sales [Member]
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	119,935	(36,539)
Northwest Holdings and Northwest Natural [Member] | Natural Gas Commodity [Member] | Sales [Member]
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	0	(26)
Northwest Holdings and Northwest Natural [Member] | Deferred Derivative Gain (Loss) [Member] | Foreign Exchange Contract [Member]
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	165	26
Northwest Holdings and Northwest Natural [Member] | Deferred Derivative Gain (Loss) [Member] | Natural Gas Commodity [Member]
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	$ (119,935)	$ (36,517)

- Schedule of Credit Rating Dow

- Schedule of Credit Rating Downgrade Scenarios (Details) - USD ($)	Dec. 31, 2022	Dec. 31, 2021
Collateral Posted by NW Natural Counterparties [Member]
Derivative [Line Items]
Collateral Already Posted, Aggregate Fair Value	$ 0	$ 0
Collateral Posted with NW Natural Counterparties [Member]
Derivative [Line Items]
Collateral Already Posted, Aggregate Fair Value	$ 0	$ 0

Commitments and Contingencies -

Commitments and Contingencies - Narrative (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2022 USD ($) therms	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Leases [Abstract]
Property, Plant and Equipment, Gross	$ 4,261,566	$ 3,997,243
Other Liabilities, Noncurrent	$ 123,438	114,979
Archaea RNG Agreement
Leases [Abstract]
Fixed Fee Purchase Obligation, Period	21 years
Maximum [Member]
Leases [Abstract]
Lessee, Operating Lease, Term of Contract	17 years
Maximum [Member] | Archaea RNG Agreement
Leases [Abstract]
Fixed Fee Purchase Obligation, Therms | therms	10,000,000
Northwest Natural Gas Company [Member]
Leases [Abstract]
Unrecorded Unconditional Purchase Obligation, Purchases	$ 90,200	82,900	$ 81,800
Unrecorded Unconditional Purchase Obligation Offsetting Sales	8,300	7,700	$ 4,800
Property, Plant and Equipment, Gross	4,148,547	3,931,640
Other Liabilities, Noncurrent	$ 114,527	$ 113,934

Commitments and Contingencies_2

Commitments and Contingencies - Schedule of Gas Purchase and Pipeline Capacity Purchase and Release Commitments (Details) - Northwest Natural Gas Company [Member] $ in Thousands	Dec. 31, 2022 USD ($)
Gas Purchase Agreements [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
2018	$ 400,370
2019	6,376
2020	6,426
2021	12,003
2022	11,330
Thereafter	189,050
Total	625,555
Less: Amount representing interest	86,250
Total at present value	539,305
Pipeline Capacity Purchase Agreements [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
2018	81,691
2019	77,327
2020	78,493
2021	66,782
2022	66,906
Thereafter	432,464
Total	803,663
Less: Amount representing interest	200,243
Total at present value	603,420
Pipeline Capacity Release Agreements [Member]
Unrecorded Unconditional Purchase Obligation [Line Items]
2018	8,154
2019	7,474
2020	3,397
2021	0
2022	0
Thereafter	0
Total	19,025
Less: Amount representing interest	989
Total at present value	$ 18,036

Environmental Matters (Details)

Environmental Matters (Details)	12 Months Ended
	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Accrual for Environmental Loss Contingencies [Abstract]
Site Contingency, Number of Remediation Projects	2
Insurance Proceeds Applied To Prudently Incurred Remediation Costs	$ 3,900,000
Environmental Regulatory Table [Abstract]
Regulatory Assets, Current	117,491,000	$ 72,391,000
Regulatory Assets, Noncurrent	$ 340,432,000	314,579,000
Insurance Proceeds, Amortization Period	10 years 6 months
Cost Recovery Period	3 years
WASHINGTON
Environmental Activity [Line Items]
Remediation Recovery Percentage	3.30%
Northwest Natural Gas Company [Member]
Environmental Activity [Line Items]
Remediation Recovery Percentage	96.70%
Accrual for Environmental Loss Contingencies [Abstract]
EPA Record Of Decision, Clean-Up Costs, Portland Harbor	$ 1,050,000,000
Annual Tariff Rider Collection	5,000,000
Environmental Settlement Insurance Proceeds Received To Date	150,000,000
Annual insurance proceeds to appy against remediation costs	5,000,000
Insurance Proceeds Applied To Prudently Incurred Remediation Costs	95,000,000
Environmental Regulatory Table [Abstract]
Regulatory Assets, Current	117,491,000	72,391,000
Regulatory Assets, Noncurrent	340,407,000	$ 314,539,000
Annual Insurance Proceeds to Apply Against Remediation Costs	5,000,000
Total Annual Remediation Expense and Interest	$ 10,000,000
Environmental Loss Contingency, Noncurrent, Statement of Financial Position [Extensible Enumeration]	Other non-current liabilities	Other non-current liabilities
Environmental Loss Contingency, Current, Statement of Financial Position [Extensible Enumeration]	Other current liabilities	Other current liabilities
Northwest Natural Gas Company [Member] | Minimum [Member]
Accrual for Environmental Loss Contingencies [Abstract]
EPA Record Of Decision, Clean-Up Costs, Portland Harbor	$ (0.30)
Northwest Natural Gas Company [Member] | Maximum [Member]
Accrual for Environmental Loss Contingencies [Abstract]
EPA Record Of Decision, Clean-Up Costs, Portland Harbor	0.50
Northwest Natural Gas Company [Member] | Gasco Siltronic Sediments [Member]
Accrual for Environmental Loss Contingencies [Abstract]
Environmental Current Liabilities	9,744,000	$ 7,582,000
Environmental Noncurrent Liabilities	42,120,000	42,076,000
Northwest Natural Gas Company [Member] | Portland Harbor Other [Member]
Accrual for Environmental Loss Contingencies [Abstract]
Environmental Current Liabilities	2,634,000	2,592,000
Environmental Noncurrent Liabilities	11,270,000	9,570,000
Northwest Natural Gas Company [Member] | Gasco Upland [Member]
Accrual for Environmental Loss Contingencies [Abstract]
Environmental Current Liabilities	16,067,000	15,711,000
Environmental Noncurrent Liabilities	35,457,000	36,215,000
Northwest Natural Gas Company [Member] | Front Street [Member]
Accrual for Environmental Loss Contingencies [Abstract]
Environmental Current Liabilities	457,000	1,100,000
Environmental Noncurrent Liabilities	879,000	811,000
Northwest Natural Gas Company [Member] | Oregon Steel Mills [Member]
Accrual for Environmental Loss Contingencies [Abstract]
Environmental Current Liabilities	0	0
Environmental Noncurrent Liabilities	179,000	179,000
Northwest Natural Gas Company [Member] | Environmental Restoration Costs [Member]
Environmental Regulatory Table [Abstract]
Environmental Regulatory Deferred Cost and Interest	47,666,000	45,122,000
Environmental Regulatory Accrued Site Liabilities	118,763,000	115,773,000
Environmental Regulatory Insurance Proceeds and Interest	(54,784,000)	(59,564,000)
Regulatory Assets, Current	7,392,000	6,694,000
Regulatory Assets, Noncurrent	104,253,000	94,636,000
Regulatory Assets	111,645,000	101,331,000
Northwest Natural Gas Company [Member] | Environmental Restoration Costs [Member] | Front Street [Member]
Environmental Regulatory Table [Abstract]
Environmental Regulatory Accrued Site Liabilities	43,000	$ 62,000
Front Street [Member] | Northwest Natural Gas Company [Member]
Accrual for Environmental Loss Contingencies [Abstract]
Liability For Studies And Design Costs	$ 1,300,000
Portland Harbor [Member]
Accrual for Environmental Loss Contingencies [Abstract]
Number Of Potentially Responsible Parties	one hundred
Gasco Siltronic Sediments [Member] | Maximum [Member]
Accrual for Environmental Loss Contingencies [Abstract]
Environmental Exit Costs, Anticipated Cost	$ 350,000,000
Gasco Siltronic Sediments [Member] | Northwest Natural Gas Company [Member]
Accrual for Environmental Loss Contingencies [Abstract]
Environmental Project Liability	$ 51,900,000
Yakama Nation [Member] | Portland Harbor Other [Member]
Accrual for Environmental Loss Contingencies [Abstract]
Trustee Council Members - Number of Claimants	1
Site Contingency, Number of Other Third-Party Defendants	29
NRD Liability Claim Yakama Nation	$ 300,000
Number of Amended Complaints Filed	2

Discontinued Operations (Detail

Discontinued Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sale of discontinued operations		$ 0	$ 0	$ 12,500
Gain on sale of discontinued operations, net of tax		0	0	5,902
Income from discontinued operations, net of tax		$ 0	0	6,508
Maximum [Member] | Forecast [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sale of discontinued operations	$ 15,000
Gill Ranch [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Percent ownership		75%
Discontinued Operations, Held-for-sale [Member] | Gill Ranch [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
DiscontinuedOperationGainLossOnDisposalStatementOfIncomeOrComprehensiveIncomeExtensibleEnumerationNotDisclosedFlag			5,900
Proceeds from sale of discontinued operations				$ 13,500	$ 1,000
Disposal Group, Including Discontinued Operation, Revenue		$ 10,193
Disposal Group, Including Discontinued Operation, Operating Expense		7,931
Disposal Group, Including Discontinued Operation, General and Administrative Expense		198
Disposal Group, Including Discontinued Operation, Depreciation and Amortization		391
Disposal Group, Including Discontinued Operation, Other Expense		848
Total Expenses Discontinued Operations		9,368
Discontinued Operation, Income (Loss) from Discontinued Operation, before Income Tax, Total		825
Gain on sale of discontinued operations, net of tax		8,027
Discontinued Operation, Income (Loss) from Discontinued Operation, before Income Tax, including gain on sale		8,852
Income tax benefit		2,344
Income from discontinued operations, net of tax		6,508
Discontinued Operation, Tax Effect of Gain (Loss) from Disposal of Discontinued Operation			2,100
Discontinued Operations, Held-for-sale [Member] | Gill Ranch [Member] | Estimate of Fair Value Measurement
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sale of discontinued operations		$ 0
Discontinued Operations, Held-for-sale or Disposed of by Sale [Member] | Gill Ranch [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Including Discontinued Operation, Liabilities, Total			$ 0

Subsequent Events (Details)

Subsequent Events (Details) - Subsequent Event [Member] - Northwest Natural Gas Company [Member] - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Mar. 31, 2023	Sep. 30, 2023	Aug. 04, 2023	Jan. 06, 2023
Note 5430 Series due 2053
Subsequent Event [Line Items]
Debt Instrument, Interest Rate, Stated Percentage				5.43%
Proceeds from Issuance of First Mortgage Bond	$ 100,000
Debt Instrument, Redemption Price, Percentage	100%
Note 5180 Series due 2034
Subsequent Event [Line Items]
Debt Instrument, Interest Rate, Stated Percentage			5.18%
Proceeds from Issuance of First Mortgage Bond		$ 80,000
Note 5230 Series due 2038
Subsequent Event [Line Items]
Debt Instrument, Interest Rate, Stated Percentage			5.23%
Proceeds from Issuance of First Mortgage Bond		$ 50,000

Condensed Financials Standalo_3

Condensed Financials Standalone Holdco Condensed Financials Standalone Holdco (Details) - USD ($) $ in Thousands		12 Months Ended
	Apr. 01, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Statement [Abstract]
Operations and maintenance		$ 224,667	$ 204,227	$ 180,129
Total operating expenses		869,876	697,283	625,328
Income (loss) from operations		167,477	163,117	148,351
Other income (expense), net		1,203	(12,559)	(13,944)
Interest expense, net		53,247	44,486	43,052
Income before income taxes		115,433	106,072	91,355
Income Tax Expense (Benefit)		29,130	27,406	21,082
Net income		86,303	78,666	76,781
Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]		129	0	0
Balance Sheet Related Disclosures [Abstract]
Cash and cash equivalents		29,270	18,559
Other current assets		61,286	59,288
Total current assets		744,213	437,276
Other investments		95,704	89,278
Other non-current assets		91,518	56,757
Total non-current assets		4,004,113	3,627,328
Total assets		4,748,326	4,064,604
Short-term debt		258,200	389,500
Accounts payable		180,667	133,486
Taxes accrued		15,625	15,520
Other current liabilities		64,552	54,432
Interest accrued		10,169	7,503
Total current liabilities		898,734	724,765
Long-term Debt		1,336,864	1,044,932
Long-term debt		(1,246,167)	(1,044,587)
Total deferred credits and other non-current liabilities		1,427,984	1,360,106
Common stock - no par value		805,253	590,771
Retained earnings		376,473	355,779
Total equity		1,175,441	935,146
Total liabilities and equity		4,748,326	4,064,604
Statement of Cash Flows [Abstract]
Net income		86,303	78,666	76,781
Deferred income taxes		17,410	14,617	18,667
Other		(21,558)	(20,622)	(10,028)
Receivables, net		76,454	44,128	16,799
Income and other taxes		6,908	3,292	(10,710)
Accounts payable		24,508	12,118	(15,910)
Additional Cash Flow Elements and Supplemental Cash Flow Information [Abstract]
Other, net		(12,351)	(18,662)	1,340
Cash provided by operating activities		147,672	160,353	145,318
Cash used in investing activities		(435,460)	(300,123)	(294,277)
Proceeds from Issuance of Common Stock	$ 138,600	208,561	17,501	0
Changes in other short-term debt, net		(131,300)	280,000	(39,600)
Cash dividend payments on common stock		(62,771)	(55,919)	(55,420)
Other		(2,858)	(5,121)	(3,228)
Cash provided by (used in) financing activities		301,632	131,436	171,777
Increase (decrease) in cash and cash equivalents		13,844	(8,334)	22,818
Cash, cash equivalents and restricted cash, beginning of period		18,559
Cash, cash equivalents and restricted cash, end of period		29,270	18,559
Total Dividends Paid to Registrant, Consolidated Subsidiaries		62,700	82,100	74,400
Comprehensive income (loss)		91,422	80,164	74,612
Parent Company, Condensed Statement of Cash Flows [Member]
Income Statement [Abstract]
Equity in earnings of subsidiaries, net of tax		92,727	83,072	78,450
Net income		86,303	78,666	76,781
Balance Sheet Related Disclosures [Abstract]
Cash and cash equivalents		7,280	265	11,267
Long-term Debt		100,000	0	0
Statement of Cash Flows [Abstract]
Net income		86,303	78,666	76,781
Equity in earnings of subsidiaries, net of tax		92,727	83,072	78,450
SEC Schedule, 12-04, Cash Dividends Paid to Registrant, Consolidated Subsidiaries		62,710	56,057	55,387
Deferred income taxes		(141)	(212)	20
Other		142	119	65
Receivables, net		(7,787)	12,558	(12,788)
Income and other taxes		8,161	1,299	(7,451)
Accounts payable		(2,499)	3,342	8,809
Additional Cash Flow Elements and Supplemental Cash Flow Information [Abstract]
Increase (Decrease) in Interest Payable, Net		156	57	77
Other, net		211	313	364
Cash provided by operating activities		54,107	68,501	42,086
Contributions to subsidiaries		(241,497)	(142,405)	(47,194)
Proceeds from Equity Method Investment, Distribution, Return of Capital		0	26,000	19,000
Cash used in investing activities		(241,497)	(116,405)	(28,194)
Proceeds from Issuance of Common Stock		208,561	17,501	0
Changes in other short-term debt, net		(56,000)	71,000	49,000
Cash dividend payments on common stock		(62,771)	(55,919)	(55,420)
Other		4,615	4,320	3,676
Cash provided by (used in) financing activities		194,405	36,902	(2,744)
Increase (decrease) in cash and cash equivalents		7,015	(11,002)	11,148
Cash, cash equivalents and restricted cash, beginning of period		265	11,267	119
Cash, cash equivalents and restricted cash, end of period		7,280	265	11,267
Parent Company, Condensed Balance Sheet [Member]
Balance Sheet Related Disclosures [Abstract]
Cash and cash equivalents		7,280	265
Receivables from affiliates		9,967	2,180
Other current assets		2,895	11,348
Total current assets		20,142	13,793
Investments in subsidiaries		1,357,599	1,080,949
Other investments		14	42
Deferred Income Tax Assets, Net		520	383
Other non-current assets		486	613
Total non-current assets		1,358,619	1,081,987
Total assets		1,378,761	1,095,780
Short-term debt		88,000	144,000
Accounts payable		402	286
Payables to affiliates		14,665	16,105
Other current liabilities		295	243
Total current liabilities		103,362	160,634
Long-term Debt		99,958	0
Total equity		1,175,441	935,146
Total liabilities and equity		1,378,761	1,095,780
Additional Cash Flow Elements and Supplemental Cash Flow Information [Abstract]
Cash, cash equivalents and restricted cash, beginning of period		265
Cash, cash equivalents and restricted cash, end of period		7,280	265
Parent Company, Condensed Income Statement [Member]
Income Statement [Abstract]
Operations and maintenance		3,828	4,837	771
Total operating expenses		3,828	4,837	771
Income (loss) from operations		(3,828)	(4,837)	(771)
Equity in earnings of subsidiaries, net of tax		(92,727)	(83,072)	(78,450)
Other income (expense), net		60	(143)	57
Interest expense, net		4,967	982	1,557
Income before income taxes		83,992	77,110	76,179
Income Tax Expense (Benefit)		(2,311)	(1,556)	(602)
Net income		86,303	78,666	76,781
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent		5,108	1,498	(2,169)
Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]		11	0	0
Statement of Cash Flows [Abstract]
Net income		86,303	78,666	76,781
Equity in earnings of subsidiaries, net of tax		(92,727)	(83,072)	(78,450)
Additional Cash Flow Elements and Supplemental Cash Flow Information [Abstract]
Comprehensive income (loss)		$ 91,422	80,164	$ 74,612
Adjustment to Stockholders' Equity Attributable to Parent			$ (3,600)

Valuation Allowances and Rese_3

Valuation Allowances and Reserves (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Entity Information [Line Items]
Allowance for Doubtful Accounts Receivable, beginning of period	$ 2,018	$ 3,219	$ 673
Valuation Allowances and Reserves, Charged to Cost and Expense	1,081	724	890
Valuation Allowances and Reserves, Charged to Other Accounts	1,810	(219)	2,333
SEC Schedule, 12-09, Valuation Allowances and Reserves, Deduction	1,613	1,706	677
Allowance for Doubtful Accounts Receivable, end of period	3,296	2,018	3,219
Northwest Natural Gas Company [Member]
Entity Information [Line Items]
Allowance for Doubtful Accounts Receivable, beginning of period	1,962	3,107	672
Valuation Allowances and Reserves, Charged to Cost and Expense	920	780	779
Valuation Allowances and Reserves, Charged to Other Accounts	1,810	(219)	2,333
SEC Schedule, 12-09, Valuation Allowances and Reserves, Deduction	1,613	1,706	677
Allowance for Doubtful Accounts Receivable, end of period	$ 3,079	$ 1,962	$ 3,107