Northwest Natural Holding (NWN) 10-Q 5 Aug 21 2021 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2021	Jul. 23, 2021
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Transition Report	false
Document Period End Date	Jun. 30, 2021
Entity File Number	1-38681
Entity Registrant Name	NORTHWEST NATURAL HOLDING COMPANY
Entity Incorporation, State or Country Code	OR
Entity Tax Identification Number	82-4710680
Entity Address, Address Line One	250 SW Taylor Street
Entity Address, City or Town	Portland
Entity Address, State or Province	OR
Entity Address, Postal Zip Code	97204
City Area Code	(503)
Local Phone Number	226-4211
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Title of 12(b) Security	Common Stock
Trading Symbol	NWN
Security Exchange Name	NYSE
Entity Common Stock, Shares Outstanding		30,672,722
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q2
Amendment Flag	false
Entity Central Index Key	0001733998
Northwest Natural Gas Company [Member]
Document Information [Line Items]
Document Type	10-Q
Document Period End Date	Jun. 30, 2021
Entity File Number	1-15973
Entity Registrant Name	NORTHWEST NATURAL GAS COMPANY
Entity Incorporation, State or Country Code	OR
Entity Tax Identification Number	93-0256722
Entity Address, Address Line One	250 SW Taylor Street
Entity Address, City or Town	Portland
Entity Address, State or Province	OR
Entity Address, Postal Zip Code	97204
City Area Code	(503)
Local Phone Number	226-4211
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q2
Amendment Flag	false
Entity Central Index Key	0000073020

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Operating revenues [Abstract]
Operating revenues	$ 148,917	$ 134,971	$ 464,863	$ 420,122
Operating expenses:
Cost of gas	41,193	41,210	153,403	149,748
Operations and maintenance	50,047	43,983	102,238	92,904
Environmental remediation	1,509	1,622	5,286	5,627
General taxes	8,914	8,373	20,283	18,268
Revenue taxes	5,671	4,454	18,335	16,197
Depreciation and amortization	28,144	25,836	56,241	50,511
Other operating expenses	815	551	1,747	1,479
Total operating expenses	136,293	126,029	357,533	334,734
Income from operations	12,624	8,942	107,330	85,388
Other income (expense), net	(2,597)	(3,040)	(6,139)	(6,615)
Interest expense, net	11,028	12,706	22,154	23,174
Income (loss) before income taxes	(1,001)	(6,804)	79,037	55,599
Income tax expense (benefit)	(277)	(1,672)	20,244	12,455
Net income (loss) from continuing operations	(724)	(5,132)	58,793	43,144
Income (loss) from discontinued operations, net of tax	0	280	0	(498)
Net income (loss)	(724)	(4,852)	58,793	42,646
Other comprehensive income:
Amortization of non-qualified employee benefit plan liability, net of taxes	221	160	442	320
Comprehensive income (loss)	(503)	(4,692)	59,235	42,966
Supplemental Income Statement Elements [Abstract]
Amortization of non-qualified employee benefit plan liability, tax	$ 80	$ 58	$ 160	$ 116
Average common shares outstanding:
Basic (in shares)	30,664	30,537	30,639	30,514
Diluted (in shares)	30,664	30,537	30,671	30,559
Earnings from continuing operations per share of common stock:
Basic (in dollars per share)	$ (0.02)	$ (0.17)	$ 1.92	$ 1.41
Diluted (in dollars per share)	(0.02)	(0.17)	1.92	1.41
Loss from discontinued operations per share of common stock:
Basic (in dollars per share)	0	0.01	0	(0.01)
Diluted (in dollars per share)	0	0.01	0	(0.01)
Earnings (loss) per share of common stock:
Basic (in dollars per share)	(0.02)	(0.16)	1.92	1.40
Diluted (in dollars per share)	$ (0.02)	$ (0.16)	$ 1.92	$ 1.40
Northwest Natural Gas Company [Member]
Operating revenues [Abstract]
Operating revenues	$ 144,579	$ 131,157	$ 456,929	$ 413,686
Operating expenses:
Cost of gas	41,249	41,265	153,515	149,860
Operations and maintenance	44,939	41,198	94,126	87,454
Environmental remediation	1,509	1,622	5,286	5,627
General taxes	8,783	8,211	20,042	18,010
Revenue taxes	5,650	4,454	18,305	16,197
Depreciation and amortization	27,530	24,986	54,699	49,176
Other operating expenses	780	522	1,699	1,442
Total operating expenses	130,440	122,258	347,672	327,766
Income from operations	14,139	8,899	109,257	85,920
Other income (expense), net	(2,566)	(3,179)	(6,231)	(6,742)
Interest expense, net	10,696	11,851	21,486	21,712
Income (loss) before income taxes	877	(6,131)	81,540	57,466
Income tax expense (benefit)	288	(1,419)	20,840	12,999
Net income (loss)	589	(4,712)	60,700	44,467
Other comprehensive income:
Amortization of non-qualified employee benefit plan liability, net of taxes	221	160	442	320
Comprehensive income (loss)	810	(4,552)	61,142	44,787
Supplemental Income Statement Elements [Abstract]
Amortization of non-qualified employee benefit plan liability, tax	$ 80	$ 58	$ 160	$ 116

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020
Current assets:
Cash and cash equivalents	$ 20,084	$ 30,168	$ 137,057
Accounts receivable	60,713	88,083	35,196
Accrued unbilled revenue	13,592	57,949	15,393
Allowance for uncollectible accounts	(3,283)	(3,219)	(1,592)
Regulatory assets	60,672	31,745	30,021
Derivative instruments	46,168	13,678	5,996
Inventories	39,024	42,691	44,009
Gas reserves	8,444	11,409	13,646
Income Taxes Receivable, Current	6,000	6,000	0
Other current assets	22,427	44,741	20,318
Discontinued operations current assets	0	0	16,392
Total current assets	273,841	323,245	316,436
Non-current assets:
Property, plant, and equipment	3,849,792	3,734,039	3,608,902
Less: Accumulated depreciation	1,093,863	1,079,269	1,062,299
Property, Plant and Equipment, Net	2,755,929	2,654,770	2,546,603
Gas reserves	29,852	34,484	41,459
Regulatory assets	330,710	348,927	324,358
Derivative instruments	7,912	6,135	3,958
Other investments	47,725	49,259	62,130
Operating lease right of use asset, net	76,294	77,446	78,566
Assets under sales-type leases	141,408	143,759	146,208
Goodwill	69,313	69,225	70,183
Other non-current assets	50,516	49,129	51,446
Total non-current assets	3,509,659	3,433,134	3,324,911
Total assets	3,783,500	3,756,379	3,641,347
Current liabilities:
Short-term debt	240,000	304,525	233,000
Current maturities of long-term debt	60,274	95,344	35,209
Accounts payable	97,854	97,966	79,903
Taxes accrued	15,143	13,812	18,535
Interest accrued	7,425	7,441	7,234
Regulatory liabilities	103,210	50,362	41,126
Derivative instruments	3,393	4,198	3,067
Operating lease liabilities	1,228	1,105	931
Other current liabilities	43,946	52,330	54,323
Discontinued operations current liabilities	0	0	13,574
Total current liabilities	572,473	627,083	486,902
Long-term debt	915,501	860,081	918,887
Deferred credits and other non-current liabilities:
Deferred tax liabilities	325,600	319,292	297,995
Regulatory liabilities	645,046	639,663	632,400
Pension and other postretirement benefit liabilities	203,854	217,287	218,493
Derivative instruments	453	2,852	1,658
Operating lease liabilities	80,088	80,621	80,159
Other non-current liabilities	117,659	120,767	120,852
Total deferred credits and other non-current liabilities	1,372,700	1,380,482	1,351,557
Commitments and contingencies (Note 16)
Equity:
Common stock	$ 569,785	$ 565,112	$ 562,766
Shares Authorized (in shares)	100,000,000	100,000,000	100,000,000
Shares outstanding (in shares)	30,672,000	30,589,000	30,546,000
Shares issued (in shares)	30,672,000	30,589,000	30,546,000
Par Value (in dollars per share)	$ 0	$ 0	$ 0
Retained earnings	$ 365,501	$ 336,523	$ 331,648
Accumulated other comprehensive loss	(12,460)	(12,902)	(10,413)
Total equity	922,826	888,733	884,001
Total liabilities and equity	3,783,500	3,756,379	3,641,347
Northwest Natural Gas Company [Member]
Current assets:
Cash and cash equivalents	11,488	10,453	120,284
Accounts receivable	51,849	80,035	33,985
Accrued unbilled revenue	13,474	57,890	15,236
Receivables from affiliates	301	660	563
Allowance for uncollectible accounts	(3,239)	(3,107)	(1,591)
Regulatory assets	60,672	31,745	30,021
Derivative instruments	46,168	13,678	5,996
Inventories	38,549	42,325	43,619
Gas reserves	8,444	11,409	13,646
Other current assets	22,186	37,909	20,287
Total current assets	249,892	282,997	282,046
Non-current assets:
Property, plant, and equipment	3,794,870	3,683,776	3,564,707
Less: Accumulated depreciation	1,088,743	1,075,446	1,059,760
Property, Plant and Equipment, Net	2,706,127	2,608,330	2,504,947
Gas reserves	29,852	34,484	41,459
Regulatory assets	330,670	348,887	324,320
Derivative instruments	7,912	6,135	3,958
Other investments	47,695	49,242	48,673
Operating lease right of use asset, net	76,211	77,328	78,464
Assets under sales-type leases	141,408	143,759	146,208
Other non-current assets	49,665	48,174	50,629
Total non-current assets	3,389,540	3,316,339	3,198,658
Total assets	3,639,432	3,599,336	3,480,704
Current liabilities:
Short-term debt	198,000	231,525	153,000
Current maturities of long-term debt	59,987	59,955	0
Accounts payable	95,109	95,170	77,993
Payables to affiliates	22,869	13,820	18,450
Taxes accrued	10,072	13,724	7,376
Interest accrued	7,373	7,338	7,156
Regulatory liabilities	103,210	50,362	41,126
Derivative instruments	3,393	4,198	3,067
Operating lease liabilities	1,193	1,054	868
Other current liabilities	43,389	51,907	52,939
Total current liabilities	544,595	529,053	361,975
Long-term debt	857,422	857,265	917,012
Deferred credits and other non-current liabilities:
Deferred tax liabilities	323,522	318,034	309,977
Regulatory liabilities	644,177	638,793	631,531
Pension and other postretirement benefit liabilities	203,854	217,287	218,493
Derivative instruments	453	2,852	1,658
Operating lease liabilities	80,043	80,559	80,120
Other non-current liabilities	116,975	120,309	120,569
Total deferred credits and other non-current liabilities	1,369,024	1,377,834	1,362,348
Equity:
Common stock	319,506	319,506	319,557
Retained earnings	561,345	528,580	530,225
Accumulated other comprehensive loss	(12,460)	(12,902)	(10,413)
Total equity	868,391	835,184	839,369
Total liabilities and equity	$ 3,639,432	$ 3,599,336	$ 3,480,704

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]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		$ 513,372	$ (10,733)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	42,646		42,646		44,467		44,467
Dividends on common stock			(29,448)				(27,614)
Other comprehensive income	42,966			320	44,787			320
Stock-based compensation		3,626
Shares issued pursuant to equity based plans		858
Ending Balance at Jun. 30, 2020	$ 884,001	562,766	331,648	(10,413)	839,369	$ 319,557	530,225	(10,413)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends per share of common stock	$ 0.9550
Beginning Balance at Mar. 31, 2020	$ 901,741	561,264	351,050	(10,573)	857,739		548,755	(10,573)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	(4,852)		(4,852)		(4,712)		(4,712)
Dividends on common stock			(14,550)				(13,818)
Other comprehensive income	(4,692)			160	(4,552)			160
Stock-based compensation		254
Shares issued pursuant to equity based plans		1,248
Ending Balance at Jun. 30, 2020	$ 884,001	562,766	331,648	(10,413)	839,369	319,557	530,225	(10,413)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends per share of common stock	$ 0.4775
Beginning Balance at Dec. 31, 2020	$ 888,733	565,112	336,523	(12,902)	835,184		528,580	(12,902)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	58,793		58,793		60,700		60,700
Dividends on common stock			(29,815)				(27,935)
Other comprehensive income	59,235			442	61,142			442
Stock-based compensation		2,446
Shares issued pursuant to equity based plans		2,227
Ending Balance at Jun. 30, 2021	$ 922,826	569,785	365,501	(12,460)	868,391	319,506	561,345	(12,460)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends per share of common stock	$ 0.9600
Beginning Balance at Mar. 31, 2021	$ 936,324	568,066	380,939	(12,681)	881,565		574,740	(12,681)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	(724)		(724)		589		589
Dividends on common stock			(14,714)				(13,984)
Other comprehensive income	(503)			221	810			221
Stock-based compensation		416
Shares issued pursuant to equity based plans		1,303
Ending Balance at Jun. 30, 2021	$ 922,826	$ 569,785	$ 365,501	$ (12,460)	$ 868,391	$ 319,506	$ 561,345	$ (12,460)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends per share of common stock	$ 0.4800

Consolidated Statement of Cash

Consolidated Statement of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Operating activities:
Net income	$ 58,793	$ 42,646
Adjustments to reconcile net income to cash provided by operations:
Depreciation and amortization	56,241	50,511
Regulatory amortization of gas reserves	7,597	8,567
Deferred income taxes	1,048	(2,004)
Qualified defined benefit pension plan expense	7,874	8,892
Contributions to qualified defined benefit pension plans	(9,590)	(8,470)
Deferred environmental expenditures, net	(9,625)	(9,897)
Amortization of environmental remediation	5,286	5,627
Other	1,610	(5,931)
Changes in assets and liabilities:
Receivables, net	73,133	73,954
Inventories	3,666	(52)
Income and other taxes	21,467	20,966
Accounts payable	(17,239)	(18,919)
Deferred gas costs	(26,962)	115
Asset optimization revenue sharing	36,872	(11,657)
Decoupling mechanism	(6,860)	4,281
Other, net	(9,030)	3,967
Discontinued operations	0	(547)
Cash provided by operating activities	194,281	162,049
Investing activities:
Capital expenditures	(130,108)	(122,282)
Acquisitions, net of cash acquired	(55)	(37,940)
Leasehold improvement expenditures	(163)	(7,519)
Proceeds from the sale of assets	2,234	7,905
Other	209	263
Discontinued operations	0	(846)
Cash used in investing activities	(127,883)	(160,419)
Financing activities:
Proceeds from common stock issued	0	68
Long-term debt issued	55,000	150,000
Long-term debt retired	(35,000)	(75,000)
Proceeds from term loan due within one year	100,000	150,000
Repayments of commercial paper, maturities greater than 90 days	(195,025)	0
Proceeds from (Repayments of) Short-term Debt	30,500	(66,100)
Cash dividend payments on common stock	(27,842)	(27,679)
Other	(1,175)	(3,007)
Net Cash Provided by (Used in) Financing Activities	(73,542)	128,282
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	28,310	142,548
Increase in cash and cash equivalents	(7,144)	129,912
Supplemental disclosure of cash flow information:
Interest paid, net of capitalization	21,971	23,156
Income taxes paid, net of refunds	7,405	544
Northwest Natural Gas Company [Member]
Operating activities:
Net income	60,700	44,467
Adjustments to reconcile net income to cash provided by operations:
Depreciation and amortization	54,699	49,176
Regulatory amortization of gas reserves	7,597	8,567
Deferred income taxes	201	(2,766)
Qualified defined benefit pension plan expense	7,874	8,892
Contributions to qualified defined benefit pension plans	(9,590)	(8,470)
Deferred environmental expenditures, net	(9,625)	(9,897)
Amortization of environmental remediation	5,286	5,627
Other	481	(6,746)
Changes in assets and liabilities:
Receivables, net	74,354	74,625
Inventories	3,775	249
Income and other taxes	19,440	22,038
Accounts payable	(19,936)	(22,186)
Deferred gas costs	(26,962)	115
Asset optimization revenue sharing	36,872	(11,657)
Decoupling mechanism	(6,860)	4,281
Other, net	(8,361)	5,979
Cash provided by operating activities	189,945	162,294
Investing activities:
Capital expenditures	(125,167)	(118,227)
Leasehold improvement expenditures	(163)	(7,519)
Proceeds from the sale of assets	2,234	7,905
Other	209	269
Cash used in investing activities	(122,887)	(117,572)
Financing activities:
Long-term debt issued	0	150,000
Long-term debt retired	0	(75,000)
Proceeds from term loan due within one year	100,000	150,000
Repayments of commercial paper, maturities greater than 90 days	(195,025)	0
Proceeds from (Repayments of) Short-term Debt	61,500	(122,100)
Cash dividend payments on common stock	(27,935)	(27,614)
Other	(1,623)	(3,140)
Net Cash Provided by (Used in) Financing Activities	(63,083)	72,146
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	19,714	125,775
Increase in cash and cash equivalents	3,975	116,868
Supplemental disclosure of cash flow information:
Interest paid, net of capitalization	21,285	21,794
Income taxes paid, net of refunds	$ 10,910	$ 950

Organization and Principles of

Organization and Principles of Consolidation	6 Months Ended
	Jun. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Principles of Consolidation	ORGANIZATION AND PRINCIPLES OF CONSOLIDATION The accompanying consolidated financial statements represent the respective, consolidated financial results of 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 businesses, and other investments are aggregated and reported as other at their respective registrant. 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, which is accounted for under the equity method, and NWN Energy's investment in Trail West Holdings, LLC (TWH), which was accounted for under the equity method through August 6, 2020. See Note 13 for activity related to TWH. NW Holdings and its direct and indirect subsidiaries are collectively referred to herein as NW Holdings, and NW Natural and its direct and indirect subsidiaries are collectively referred to herein as NW Natural. The consolidated financial statements of NW Holdings and NW Natural are presented after elimination of all intercompany balances and transactions. Information presented in these interim consolidated financial statements is unaudited, but includes all material adjustments management considers necessary for a fair statement of the results for each period reported including normal recurring accruals. These consolidated financial statements should be read in conjunction with the audited consolidated financial statements and related notes included in NW Holdings' and NW Natural's combined 2020 Annual Report on Form 10-K (2020 Form 10-K). A significant part of NW Holdings' and NW Natural's business is of a seasonal nature; therefore, NW Holdings and NW Natural results of operations for interim periods are not necessarily indicative of full year results. Seasonality affects the comparability of the results of other operations across quarters but not across years. 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 provides for the sale of all of the membership interests in its wholly-owned subsidiary, 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 have been classified as discontinued operations assets and liabilities on the NW Holdings consolidated balance sheet. The sale closed on December 4, 2020. See Note 17 for additional information.

Significant Accounting Policies

Significant Accounting Policies	6 Months Ended
	Jun. 30, 2021
Accounting Policies [Abstract]
Significant Accounting Policies	SIGNIFICANT ACCOUNTING POLICIES Significant accounting policies are described in Note 2 of the 2020 Form 10-K. There were no material changes to those accounting policies during the six months ended June 30, 2021 other than those set forth in this Note 2. The following are current updates to certain critical accounting policy estimates and new accounting standards. Industry Regulation 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 Oregon Public Utilities Commission (OPUC), Washington Utilities and Transportation Commission (WUTC), Idaho Public Utilities Commission (IPUC) or Public Utility Commission of Texas (PUCT), which provide for the recovery of revenues or expenses from, or refunds to, utility customers in future periods, including a return or a carrying charge in certain cases. Amounts deferred as regulatory assets and liabilities for NW Holdings and NW Natural were as follows: Regulatory Assets June 30, December 31, In thousands 2021 2020 2020 NW Natural: Current: Unrealized loss on derivatives (1) $ 3,393 $ 2,956 $ 4,198 Gas costs 29,486 6,046 1,979 Environmental costs (2) 5,688 4,176 4,992 Decoupling (3) 1,011 85 361 Pension balancing (4) 7,131 7,131 7,131 Income taxes 2,345 2,208 3,484 Other (5) 11,618 7,419 9,600 Total current $ 60,672 $ 30,021 $ 31,745 Non-current: Unrealized loss on derivatives (1) $ 453 $ 1,658 $ 2,852 Pension balancing (4) 40,342 45,315 43,383 Income taxes 13,903 17,608 15,368 Pension and other postretirement benefit liabilities 160,385 164,091 170,812 Environmental costs (2) 85,423 81,757 90,623 Gas costs 5,742 94 3,925 Decoupling (3) 198 — 1,031 Other (5) 24,224 13,797 20,893 Total non-current $ 330,670 $ 324,320 $ 348,887 Other (NW Holdings) 40 38 40 Total non-current - NW Holdings $ 330,710 $ 324,358 $ 348,927 Regulatory Liabilities June 30, December 31, In thousands 2021 2020 2020 NW Natural: Current: Gas costs $ 1,519 $ 3,767 $ 1,118 Unrealized gain on derivatives (1) 46,168 5,950 13,674 Decoupling (3) 5,821 11,498 11,793 Income taxes 8,217 7,098 8,217 Asset optimization revenue sharing 39,348 7,116 10,298 Other (5) 2,137 5,697 5,262 Total current $ 103,210 $ 41,126 $ 50,362 Non-current: Gas costs $ 101 $ 538 $ 314 Unrealized gain on derivatives (1) 7,912 3,958 6,135 Decoupling (3) 652 2,108 1,723 Income taxes (6) 182,977 193,414 189,587 Accrued asset removal costs (7) 439,685 414,719 427,960 Other (5) 12,850 16,794 13,074 Total non-current - NW Natural $ 644,177 $ 631,531 $ 638,793 Other (NW Holdings) 869 869 870 Total non-current - NW Holdings $ 645,046 $ 632,400 $ 639,663 (1) Unrealized gains or losses on derivatives are non-cash items and therefore do not earn a rate of return or a carrying charge. These amounts are recoverable through NGD rates as part of the annual Purchased Gas Adjustment (PGA) mechanism when realized at settlement. (2) Refer to footnote (3) of the Deferred Regulatory Asset table in Note 16 for a description of environmental costs. (3) This deferral represents the margin adjustment resulting from differences between actual and expected volumes. (4) Balance represents deferred net periodic benefit costs as approved by the OPUC. (5) Balances consist of deferrals and amortizations under approved regulatory mechanisms and typically earn a rate of return or carrying charge. (6) Balance represents excess deferred income tax benefits subject to regulatory flow-through. (7) Estimated costs of removal on certain regulated properties are collected through rates. We believe all costs incurred and deferred at June 30, 2021 are prudent. All regulatory assets and liabilities are reviewed annually for recoverability, or more often if circumstances warrant. If we should determine that all or a portion of these regulatory assets or liabilities no longer meet the criteria for continued application of regulatory accounting, then NW Holdings and NW Natural would be required to write-off the net unrecoverable balances in the period such determination is made. Supplemental Cash Flow Information Restricted cash is primarily comprised of funds from public purpose charges for programs that assist low-income customers with bill payments or energy efficiency. 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 June 30, 2021 and 2020 and December 31, 2020: June 30, December 31, In thousands 2021 2020 2020 Cash and cash equivalents $ 20,084 $ 137,057 $ 30,168 Restricted cash included in other current assets 8,226 5,491 5,286 Cash, cash equivalents and restricted cash $ 28,310 $ 142,548 $ 35,454 The following table provides a reconciliation of the cash, cash equivalents and restricted cash balances at NW Natural as of June 30, 2021 and 2020 and December 31, 2020: June 30, December 31, In thousands 2021 2020 2020 Cash and cash equivalents $ 11,488 $ 120,284 $ 10,453 Restricted cash included in other current assets 8,226 5,491 5,286 Cash, cash equivalents and restricted cash $ 19,714 $ 125,775 $ 15,739 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 Accounts receivable consist primarily of amounts due for natural gas sales and transportation services to NGD customers and amounts due for gas storage services. The payment term of these 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 enhance our review and analysis. After considering the significant exposure to quarantine-related job losses in Oregon and Washington state, NW Holdings and NW Natural expanded our standard review procedures for our allowance for uncollectible accounts calculation, including analyzing the significant indications of unemployment rate and comparing to historic economic data during the 2007-2009 time period when the country experienced an economic recession. We then considered other qualitative information including recent customer interactions related to payment plans and credit issues, statistics from our website related to credit inquiries, and economic stimulus provided by the federal government which could have a beneficial impact on residential and commercial customers' abilities to ultimately make payment on their accounts. Our provision calculation for residential accounts is estimated based on the factors noted above including a review of percentage of accounts with no payment received for 90 or more days. In addition, for the residential allowance calculation we also consider the funds applied or granted to customers through the special COVID arrearage forgiveness programs in Oregon and Washington. For commercial accounts, we have resumed normal collection processes and our provision is based on historical write-off trends and current information on delinquent accounts. For industrial accounts, we continue to analyze those accounts on an account-by-account basis with specific reserves taken as necessary. 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 As of December 31, 2020 Six Months Ended June 30, 2021 June 30, 2021 In thousands Beginning Balance Provision recorded, net of adjustments Write-offs recognized, net of recoveries Ending Balance (1) Allowance for uncollectible accounts: Residential $ 2,153 $ 1,294 $ (637) $ 2,810 Commercial 704 (233) (265) 206 Industrial 142 (68) 5 79 Accrued unbilled and other 220 22 (54) 188 Total $ 3,219 $ 1,015 $ (951) $ 3,283 (1) Includes $2.9 million that was deferred to a regulatory asset for costs associated with COVID-19 that are recoverable in future rates. 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 6 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 uncollectability 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. 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 other COVID-19 related costs, net of offsetting direct expense reductions associated with COVID-19. As of June 30, 2021, we deferred to a regulatory asset approximately $5.8 million for incurred costs associated with COVID-19 that we believe are recoverable. New Accounting Standards We 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 NW Holdings' or NW Natural's consolidated financial position or results of operations. Recently Adopted Accounting Pronouncements INCOME TAXES. On December 18, 2019, the FASB issued ASU 2019-12, "Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes." The purpose of the amendment is to reduce cost and complexity related to accounting for income taxes by removing certain exceptions to the general principles and improving consistent application for other areas in Topic 740. The amendments in this ASU were effective beginning January 1, 2021. The amended presentation and disclosure guidance was applied retrospectively. The adoption did not materially affect the financial statements and disclosures of NW Holdings or NW Natural. REFERENCE RATE REFORM. On March 12, 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 LIBOR or another reference rate expected to be discontinued because of reference rate reform.

Earnings Per Share

Earnings Per Share	6 Months Ended
	Jun. 30, 2021
Earnings Per Share [Abstract]
Earnings Per Share	EARNINGS PER SHARE Basic earnings per share are computed using NW Holdings' net income 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 per common share. NW Holdings' diluted earnings or loss per share are calculated as follows: Three Months Ended June 30, Six Months Ended June 30, In thousands, except per share data 2021 2020 2021 2020 Net income (loss) from continuing operations $ (724) $ (5,132) $ 58,793 $ 43,144 Income (loss) from discontinued operations, net of tax — 280 — (498) Net income (loss) $ (724) $ (4,852) $ 58,793 $ 42,646 Average common shares outstanding - basic 30,664 30,537 30,639 30,514 Additional shares for stock-based compensation plans (See Note 7) — — 32 45 Average common shares outstanding - diluted 30,664 30,537 30,671 30,559 Earnings (loss) from continuing operations per share of common stock: Basic $ (0.02) $ (0.17) $ 1.92 $ 1.41 Diluted $ (0.02) $ (0.17) $ 1.92 $ 1.41 Earnings (loss) from discontinued operations per share of common stock: Basic $ — $ 0.01 $ — $ (0.01) Diluted $ — $ 0.01 $ — $ (0.01) Earnings (loss) per share of common stock: Basic $ (0.02) $ (0.16) $ 1.92 $ 1.40 Diluted $ (0.02) $ (0.16) $ 1.92 $ 1.40 Additional information: Anti-dilutive shares 48 41 7 —

Segment Information

Segment Information	6 Months Ended
	Jun. 30, 2021
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 s egment. NW Natural and NW Holdings also have investments and b usiness activities not specifically related to the NGD, which are aggregated and reported as other and described below for each entity. Natural Gas Distribution NW Natural's local gas distribution segment is a regulated utility principally engaged in the purchase, sale, and delivery of natural gas and related services to customers in Oregon and southwest Washington. In addition to NW Natural's local gas distribution business, the NGD segment also includes the portion of the Mist underground storage facility used to serve NGD customers, the North Mist gas storage expansion, 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 renewable natural gas. NW Natural NW Natural's activities in Other include Interstate Storage Services and third-party asset management service for NW Natural’s contracted interstate pipeline and storage capacity, appliance retail center operations, and corporate operating and non-operating revenues and expenses that cannot be allocated to NGD operations. Earnings from third party asset management include earnings from the management of upstream interstate pipeline and storage 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 in a deferred regulatory account for prospective NGD customer billing credits. 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 sector through itself and wholly-owned subsidiaries; NWN Gas Storage, a wholly-owned subsidiary of NWN Energ y; NWN Energy's equity investment in TWH through August 6, 2020; and other pipeline assets in NNG Financial. For more information on the sale of TWH, see Note 13. Other a lso includes corporate revenues and expenses that cannot be allocated to other operations, including certain business development activities . Segment Information Summary Inter-segment transactions were immaterial for the periods presented. The following table presents summary financial information concerning the reportable segment and other of continuing operations. See Note 17 for information regarding discontinued operations for NW Holdings. Three Months Ended June 30, In thousands NGD Other NW Natural Other NW Holdings 2021 Operating revenues $ 139,614 $ 4,965 $ 144,579 $ 4,338 $ 148,917 Depreciation and amortization 27,273 257 27,530 614 28,144 Income (loss) from operations 11,331 2,808 14,139 (1,515) 12,624 Net income (loss) from continuing operations (1,381) 1,970 589 (1,313) (724) Capital expenditures 60,376 693 61,069 3,337 64,406 2020 Operating revenues $ 126,992 $ 4,165 $ 131,157 $ 3,814 $ 134,971 Depreciation and amortization 24,738 248 24,986 850 25,836 Income (loss) from operations 6,434 2,465 8,899 43 8,942 Net income (loss) from continuing operations (6,347) 1,635 (4,712) (420) (5,132) Capital expenditures 61,472 521 61,993 2,843 64,836 Six Months Ended June 30, In thousands NGD Other NW Natural Other NW Holdings 2021 Operating revenues $ 440,952 $ 15,977 $ 456,929 $ 7,934 $ 464,863 Depreciation and amortization 54,186 513 54,699 1,542 56,241 Income (loss) from operations 97,818 11,439 109,257 (1,927) 107,330 Net income (loss) from continuing operations 52,544 8,156 60,700 (1,907) 58,793 Capital expenditures 124,368 799 125,167 4,941 130,108 Total assets at June 30, 2021 3,587,966 51,466 3,639,432 144,068 3,783,500 2020 Operating revenues $ 405,479 $ 8,207 $ 413,686 $ 6,436 $ 420,122 Depreciation and amortization 48,684 492 49,176 1,335 50,511 Income (loss) from operations 81,692 4,228 85,920 (532) 85,388 Net income (loss) from continuing operations 41,596 2,871 44,467 (1,323) 43,144 Capital expenditures 117,629 598 118,227 4,055 122,282 Total assets at June 30, 2020 (1) 3,470,306 10,398 3,480,704 144,251 3,624,955 Total assets at December 31, 2020 3,549,868 49,468 3,599,336 157,043 3,756,379 (1) Total assets for NW Holdings exclude assets related to discontinued operations of $16.4 million as of June 30, 2020. Natural Gas Distribution Margin NGD margin is a financial measure used by the Chief Operating Decision Maker (CODM) , consisting of NGD operating revenues, reduced by the associated cost of gas, environmental remediation expense, and revenue taxes. The cost of gas purchased for NGD customers is generally a pass-through cost in the amount of revenues billed to regulated NGD customers. Environmental remediation expense represents collections received from customers through the environmental recovery mechanism in Oregon as well as adjustments for the environmental earnings test when applicable. This is offset by environmental remediation expense presented in operating expenses. Revenue taxes are collected from NGD customers and remitted to taxing authorities. The collections from customers are offset by the expense recognition of the obligation to the taxing authority. By subtracting cost of gas, environmental remediation expense, and revenue taxes from NGD operating revenues, NGD margin provides a key metric used by the CODM in assessing the performance of the NGD segment. The following table presents additional segment information concerning NGD margin: Three Months Ended June 30, Six Months Ended June 30, In thousands 2021 2020 2021 2020 NGD margin calculation: NGD distribution revenues $ 134,849 $ 122,071 $ 431,402 $ 395,632 Other regulated services 4,765 4,921 9,550 9,847 Total NGD operating revenues 139,614 126,992 440,952 405,479 Less: NGD cost of gas 41,249 41,265 153,515 149,860 Environmental remediation 1,509 1,622 5,286 5,627 Revenue taxes 5,650 4,454 18,305 16,197 NGD margin $ 91,206 $ 79,651 $ 263,846 $ 233,795

Revenue

Revenue	6 Months Ended
	Jun. 30, 2021
Revenue from Contract with Customer [Abstract]
Revenue from Contract with Customer	REVENUE The following tables present disaggregated revenue from continuing operations: Three Months Ended June 30, In thousands NGD Other NW Natural Other NW Holdings 2021 Natural gas sales $ 123,739 $ — $ 123,739 $ — $ 123,739 Gas storage revenue, net — 2,805 2,805 — 2,805 Asset management revenue, net — 817 817 — 817 Appliance retail center revenue — 1,343 1,343 — 1,343 Other revenue 399 — 399 4,338 4,737 Revenue from contracts with customers 124,138 4,965 129,103 4,338 133,441 Alternative revenue 11,083 — 11,083 — 11,083 Leasing revenue 4,393 — 4,393 — 4,393 Total operating revenues $ 139,614 $ 4,965 $ 144,579 $ 4,338 $ 148,917 2020 Natural gas sales $ 116,682 $ — $ 116,682 $ — $ 116,682 Gas storage revenue, net — 2,449 2,449 — 2,449 Asset management revenue, net — 910 910 — 910 Appliance retail center revenue — 806 806 — 806 Other revenue 332 — 332 3,814 4,146 Revenue from contracts with customers 117,014 4,165 121,179 3,814 124,993 Alternative revenue 5,365 — 5,365 — 5,365 Leasing revenue 4,613 — 4,613 — 4,613 Total operating revenues $ 126,992 $ 4,165 $ 131,157 $ 3,814 $ 134,971 Six Months Ended June 30, In thousands NGD Other NW Natural Other NW Holdings 2021 Natural gas sales $ 419,822 $ — $ 419,822 $ — $ 419,822 Gas storage revenue, net — 5,300 5,300 — 5,300 Asset management revenue, net — 7,745 7,745 — 7,745 Appliance retail center revenue — 2,932 2,932 — 2,932 Other revenue 814 — 814 7,934 8,748 Revenue from contracts with customers 420,636 15,977 436,613 7,934 444,547 Alternative revenue 11,536 — 11,536 — 11,536 Leasing revenue 8,780 — 8,780 — 8,780 Total operating revenues $ 440,952 $ 15,977 $ 456,929 $ 7,934 $ 464,863 2020 Natural gas sales $ 390,686 $ — $ 390,686 $ — $ 390,686 Gas storage revenue, net — 4,785 4,785 — 4,785 Asset management revenue, net — 1,060 1,060 — 1,060 Appliance retail center revenue — 2,362 2,362 — 2,362 Other revenue 669 — 669 6,436 7,105 Revenue from contracts with customers 391,355 8,207 399,562 6,436 405,998 Alternative revenue 4,893 — 4,893 — 4,893 Leasing revenue 9,231 — 9,231 — 9,231 Total operating revenues $ 405,479 $ 8,207 $ 413,686 $ 6,436 $ 420,122 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 offsetting expense recognized in operating expense in the consolidated statements of comprehensive income. Revenue-based taxes are primarily franchise taxes, which are collected from 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 6 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 third-party 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 June 30, 2021, u nrecognized revenue for the fixed component of the transaction price related to gas storage and asset management revenue was approximately $79.2 million. Of this amount, approximately $9.6 million will be recognized during the remainder of 2021, $19.4 million in 2022, $17.8 million in 2023, $14.0 million in 2024, $11.1 million in 2025 and $7.3 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. We applied the significant financing practical expedient and have not adjusted the consideration we expect to receive from water distribution customers for the effects of a significant financing component as all payment arrangements are settled annually. Due to the election of the right to invoice practical expedient, we do not disclose the value of unsatisfied performance obligations.

Leases

Leases	6 Months Ended
	Jun. 30, 2021
Leases [Abstract]
Leases of Lessee Disclosure	LEASES Lease Revenue Leasing revenue primarily consists of NW Natural's North Mist natural gas storage agreement with Portland General Electric (PGE), which is billed under an OPUC-approved rate schedule and includes an initial 30-year term 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: Three Months Ended June 30, Six Months Ended June 30, In thousands 2021 2020 2021 2020 Lease revenue Operating leases $ 25 $ 25 $ 43 $ 53 Sales-type leases 4,368 4,588 8,737 9,178 Total lease revenue $ 4,393 $ 4,613 $ 8,780 $ 9,231 Total future minimum lease payments to be received under non-cancellable leases at June 30, 2021 are as follows: In thousands Operating Sales-Type Total NW Natural: Remainder of 2021 $ 36 $ 8,701 $ 8,737 2022 72 17,026 17,098 2023 64 16,557 16,621 2024 65 15,867 15,932 2025 60 15,306 15,366 Thereafter 229 251,721 251,950 Total lease revenue $ 526 $ 325,178 $ 325,704 Less: imputed interest 183,237 Total leases receivable $ 141,941 Other (NW Holdings): Remainder of 2021 $ 25 $ — $ 25 2022 50 — 50 2023 51 — 51 2024 52 — 52 2025 53 — 53 Thereafter 970 — 970 Total lease revenue $ 1,201 $ — $ 1,201 NW Holdings: Remainder of 2021 $ 61 $ 8,701 $ 8,762 2022 122 17,026 17,148 2023 115 16,557 16,672 2024 117 15,867 15,984 2025 113 15,306 15,419 Thereafter 1,199 251,721 252,920 Total lease revenue $ 1,727 $ 325,178 $ 326,905 Less: imputed interest 183,237 Total leases receivable $ 141,941 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 $4.5 million, $4.1 million and $4.3 million at June 30, 2021 and 2020 and December 31, 2020, 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 corporate operations center. Our leases have remaining lease terms of two months to 19 years. Many of our lease agreements include options to extend the lease, which we do not include in our minimum lease terms unless they are reasonably certain to be exercised. Short-term leases with a term of 12 months or less are not recorded on the balance sheet. As most of our leases do not provide an implicit rate and are entered into by NW Natural, we use an estimated discount rate representing the rate we would have incurred to finance the funds necessary to purchase the leased asset and is based on information available at the lease commencement date in determining the present value of lease payments. The components of lease expense, a portion of which is capitalized, were as follows: Three Months Ended June 30, Six Months Ended June 30, In thousands 2021 2020 2021 2020 NW Natural: Operating lease expense $ 1,710 $ 914 $ 3,388 $ 2,116 Short-term lease expense $ 349 $ 285 $ 569 $ 483 Other (NW Holdings): Operating lease expense $ 18 $ 40 $ 36 $ 92 NW Holdings: Operating lease expense $ 1,728 $ 954 $ 3,424 $ 2,208 Short-term lease expense $ 349 $ 285 $ 569 $ 483 Supplemental balance sheet information related to operating leases as of June 30, 2021 is as follows: In thousands June 30, December 31, 2021 2020 2020 NW Natural: Operating lease right of use asset $ 76,211 $ 78,464 $ 77,328 Operating lease liabilities - current liabilities $ 1,193 $ 868 $ 1,054 Operating lease liabilities - non-current liabilities 80,043 80,120 80,559 Total operating lease liabilities $ 81,236 $ 80,988 $ 81,613 Other (NW Holdings): Operating lease right of use asset $ 83 $ 102 $ 118 Operating lease liabilities - current liabilities $ 35 $ 63 $ 51 Operating lease liabilities - non-current liabilities 45 39 62 Total operating lease liabilities $ 80 $ 102 $ 113 NW Holdings: Operating lease right of use asset $ 76,294 $ 78,566 $ 77,446 Operating lease liabilities - current liabilities $ 1,228 $ 931 $ 1,105 Operating lease liabilities - non-current liabilities 80,088 80,159 80,621 Total operating lease liabilities $ 81,316 $ 81,090 $ 81,726 The weighted-average remaining lease terms and weighted-average discount rates for the operating leases at NW Natural were as follows: In thousands June 30, December 31, 2021 2020 2020 Weighted-average remaining lease term (years) 18.7 19.7 19.2 Weighted-average discount rate 7.2 % 7.2 % 7.2 % Commencement of Significant Lease NW Natural commenced a 20-year operating lease agreement in March 2020 for a new corporate operations center in Portland, Oregon. Total estimated base rent payments over the life of the lease are $159.4 million. There is an option to extend the term of the lease for two additional periods of seven years. There is a material timing difference between the minimum lease payments and expense recognition as calculated under operating lease accounting rules. OPUC issued an order allowing us to align our expense recognition with cash payments for ratemaking purposes. We recorded the difference between the minimum lease payments and the aggregate of the imputed interest on the finance lease obligation and amortization of the right-of-use asset as a deferred regulatory asset on our balance sheet. The balance of the regulatory asset was $5.0 million, $2.4 million and $4.2 million as of June 30, 2021 and 2020 and December 31, 2020, respectively. Maturities of operating lease liabilities at June 30, 2021 were as follows: In thousands NW Natural Other NW Holdings Remainder of 2021 $ 3,445 $ 25 $ 3,470 2022 6,933 24 6,957 2023 6,986 6 6,992 2024 7,150 6 7,156 2025 7,185 6 7,191 Thereafter 123,784 24 123,808 Total lease payments 155,483 91 155,574 Less: imputed interest 74,247 11 74,258 Total lease obligations 81,236 80 81,316 Less: current obligations 1,193 35 1,228 Long-term lease obligations $ 80,043 $ 45 $ 80,088 As of June 30, 2021, finance lease liabilities with maturities of less than one year were $0.2 million at NW Natural. Supplemental cash flow information related to leases was as follows: Three Months Ended June 30, Six Months Ended June 30, In thousands 2021 2020 2021 2020 NW Natural: Cash paid for amounts included in the measurement of lease liabilities Operating cash flows from operating leases $ 1,717 $ 931 $ 3,386 $ 2,127 Finance cash flows from finance leases $ 134 $ 302 $ 678 $ 457 Right of use assets obtained in exchange for lease obligations Operating leases $ — $ 445 $ 154 $ 78,433 Finance leases $ 20 $ 477 $ 94 $ 710 Other (NW Holdings): Cash paid for amounts included in the measurement of lease liabilities Operating cash flows from operating leases $ 17 $ 39 $ 33 $ 91 NW Holdings: Cash paid for amounts included in the measurement of lease liabilities Operating cash flows from operating leases $ 1,734 $ 970 $ 3,419 $ 2,218 Finance cash flows from finance leases $ 134 $ 302 $ 678 $ 457 Right of use assets obtained in exchange for lease obligations Operating leases $ — $ 445 $ 154 $ 78,433 Finance leases $ 20 $ 477 $ 94 $ 710 Finance Leases

Stock-Based Compensation

Stock-Based Compensation	6 Months Ended
	Jun. 30, 2021
Share-based Payment Arrangement [Abstract]
Stock-Based Compensation	STOCK-BASED COMPENSATION Stock-based compensation plans are designed to promote stock ownership in NW Holdings by employees and officers. These compensation plans include a Long Term Incentive Plan (LTIP), an Employee Stock Purchase Plan (ESPP), and a Restated Stock Option Plan. For additional information on stock-based compensation plans, see Note 8 in the 2020 Form 10-K and the updates provided below. Long Term Incentive Plan Performance Shares LTIP performance shares incorporate a combination of market, performance, and service-based factors. During the six months ended June 30, 2021, the final performance factor under the 2019 LTIP was approved and 28,866 performance-based shares were granted under the 2019 LTIP for accounting purposes. As such, NW Natural and other subsidiaries began recognizing compensation expense. In February 2020 and 2021, LTIP shares were awarded to participants; however, the agreements allow for one of the performance factors to remain variable until the first quarter of the third year of the award period. As the performance factor will not be approved until the first quarters of 2022 and 2023, respectively, there is not a mutual understanding of the awards' key terms and conditions between NW Holdings and the participants as of June 30, 2021, and therefore, no expense was recognized for the 2020 and 2021 awards. NW Holdings will calculate the grant date fair value and NW Natural will recognize expense over the remaining service period for each award once the final performance factor has been approved. For the 2020 and 2021 LTIP awards, share payouts range from a threshold of 0% to a maximum of 200% based on achievement of pre-established goals. The performance criteria for the 2020 and 2021 performance shares consists of a three-year Return on Invested Capital (ROIC) threshold that must be satisfied and a cumulative EPS factor, which can be modified by a total shareholder return factor (TSR modifier) relative to the performance of peer group companies over the performance period of three years for each respective award. If the targets were achieved for the 2020 and 2021 awards, NW Holdings would grant for accounting purposes 31,830 and 56,335 shares in the first quarters of 2022 and 2023, respectively. As of June 30, 2021, there was $0.2 million of unrecognized compensation cost associated with the 2019 LTIP grants, which is expected to be recognized through 2021. Restricted Stock Units During the six months ended June 30, 2021, 37,756 RSUs were granted under the LTIP with a weighted-average grant date fair value of $49.16 per share. Generally, the RSUs awarded are forfeitable and include a performance-based threshold as well as a vesting period of four years from the grant date. The majority of our RSU grants obligate NW Holdings, upon vesting, to issue the RSU holder one share of common stock. The grant may also include a cash payment equal to the total amount of dividends paid per share between the grant date and vesting date of that portion of the RSU depending on the structure of the award agreement. The fair value of an RSU is equal to the closing market price of common stock on the grant date. As of June 30, 2021, there was $4.2 million of unrecognized compensation cost from grants of RSUs, which is expected to be recognized by NW Natural and other subsidiaries over a period extending through 2025. Restated Stock Option Plan The Restated Stock Option Plan (Restated SOP) was terminated with respect to new grants in 2012; however, options granted before the Restated SOP was terminated remained outstanding until the earlier of their expiration, forfeiture, or exercise. Options were exercisable for shares of NW Holdings common stock. As of June 30, 2021 there were no options exercisable or outstanding.

Debt

Debt	6 Months Ended
	Jun. 30, 2021
Debt Disclosure [Abstract]
Debt	DEBT Short-Term Debt In June 2021, NW Natural entered into a $100.0 million 364-Day Term Loan Credit Agreement (Term Loan) and borrowed the full amount. All principal and unpaid interest under the Term Loan is due and payable in June 2022. The Term Loan 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 June 30, 2021, with a consolidated indebtedness to total capitalization ratio of 56.2%. At June 30, 2021, NW Holdings and NW Natural had short-term debt outstanding of $240.0 million and $198.0 million, respectively. NW Holdings' short-term debt consisted of $42.0 million in revolving credit agreement loans at NW Holdings, $98.0 million of commercial paper outstanding at NW Natural, and the aforementioned $100.0 million Term Loan. T he weighted average interest rate on the revolving credit agreement at June 30, 2021 was 1.1% at NW Holdings. The weighted average interest rate of commercial paper and the Term Loan outstanding at June 30, 2021 was 0.2% and 0.6%, respectively, at NW Natural. At June 30, 2021, NW Natural's commercial paper had a maximum remaining maturity of 29 days and an average remaining maturity of 15 days. Long-Term Debt At June 30, 2021, NW Holdings and NW Natural had long-term debt outstanding of $975.8 million and $917.4 million, respectively, which included $7.4 million and $7.3 million of unamortized debt issuance costs at NW Holdings and NW Natural, respectively. NW Natural's long-term debt consists of first mortgage bonds (FMBs) with maturity dates ranging from 2021 through 2050, interest rates ranging from 2.8% to 9.1%, and a weighted average interest rate of 4.6%. In June 2019, NW Natural Water, a wholly-owned subsidiary of NW Holdings, entered into a two-year term loan agreement for $35.0 million. The loan was repaid in June 2021 upon its maturity date. In June 2021, NW Natural Water entered into a five-year term loan credit agreement for $55.0 million and borrowed the full amount. The loan carried an interest rate of 0.9% at June 30, 2021, which is based upon the one-month LIBOR ra te plus a spread. Th e loan is guaranteed by NW Holdings and 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 June 30, 2021, with a consolidated indebtedness to total capitalization ratio of 56.8%. Fair Value of Long-Term Debt NW Holdings' and NW Natural's outstanding debt does not trade in active markets. The fair value of long-term 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 in the 2020 Form 10-K for a description of the fair value hierarchy. The following table provides an estimate of the fair value of NW Holdings' long-term debt, including current maturities of long-term debt, using market prices in effect on the valuation date: NW Holdings June 30, December 31, In thousands 2021 2020 2020 Gross long-term debt $ 983,221 $ 961,784 $ 962,905 Unamortized debt issuance costs (7,446) (7,688) (7,480) Carrying amount $ 975,775 $ 954,096 $ 955,425 Estimated fair value (1) $ 1,104,230 $ 1,135,349 $ 1,136,311 (1) Estimated fair value does not include unamortized debt issuance costs. The following table provides an estimate of the fair value of NW Natural's long-term debt, including current maturities of long-term debt, using market prices in effect on the valuation date: NW Natural June 30, December 31, In thousands 2021 2020 2020 Gross long-term debt $ 924,700 $ 924,700 $ 924,700 Unamortized debt issuance costs (7,291) (7,688) (7,480) Carrying amount $ 917,409 $ 917,012 $ 917,220 Estimated fair value (1) $ 1,043,696 $ 1,097,188 $ 1,097,348 (1) Estimated fair value does not include unamortized debt issuance costs.

Pension and Other Postretiremen

Pension and Other Postretirement Benefit Costs	6 Months Ended
	Jun. 30, 2021
Pension and Other Postretirement Benefits Cost (Reversal of Cost) [Abstract]
Pension and Other Postretirement Benefit Costs	PENSION AND OTHER POSTRETIREMENT BENEFIT COSTS NW Natural maintains a qualified non-contributory defined benefit pension plan (Pension Plan), non-qualified supplemental pension plans for eligible executive officers and other key employees, and other postretirement employee benefit plans. NW Natural also has a qualified defined contribution plan (Retirement K Savings Plan) for all eligible employees. The Pension Plan and Retirement K Savings Plan have plan assets, which are held in qualified trusts to fund retirement benefits. The service cost component of net periodic benefit cost for NW Natural pension and other postretirement benefit plans is recognized in operations and maintenance expense in the consolidated statements of comprehensive income. The other non-service cost components are recognized in other income (expense), net in the consolidated statements of comprehensive income. The following table provides the components of net periodic benefit cost for the pension and other postretirement benefit plans: Three Months Ended June 30, Six Months Ended June 30, Pension Benefits Other Postretirement Pension Benefits Other In thousands 2021 2020 2021 2020 2021 2020 2021 2020 Service cost $ 1,714 $ 1,658 $ 56 $ 64 $ 3,428 $ 3,315 $ 111 $ 128 Interest cost 3,342 4,011 165 223 6,685 8,022 330 446 Expected return on plan assets (6,099) (5,496) — — (12,198) (10,992) — — Amortization of prior service credit — — (117) (117) — — (234) (234) Amortization of net actuarial loss 5,500 4,778 131 142 11,001 9,556 262 285 Net periodic benefit cost 4,457 4,951 235 312 8,916 9,901 469 625 Amount allocated to construction (743) (680) (22) (23) (1,469) (1,348) (43) (46) Net periodic benefit cost charged to expense 3,714 4,271 213 289 7,447 8,553 426 579 Amortization of regulatory balancing account 1,281 1,281 — — 4,082 4,082 — — Net amount charged to expense $ 4,995 $ 5,552 $ 213 $ 289 $ 11,529 $ 12,635 $ 426 $ 579 Net periodic benefit costs are reduced by amounts capitalized to NGD plant. In addition, net periodic benefit costs were recorded to a regulatory balancing account as approved by the OPUC and amortized accordingly. The following table presents amounts recognized in accumulated other comprehensive loss (AOCL) and the changes in AOCL related to non-qualified employee benefit plans: Three Months Ended June 30, Six Months Ended June 30, In thousands 2021 2020 2021 2020 Beginning balance $ (12,681) $ (10,573) $ (12,902) $ (10,733) Amounts reclassified from AOCL: Amortization of actuarial losses 301 218 602 436 Total reclassifications before tax 301 218 602 436 Tax benefit (80) (58) (160) (116) Total reclassifications for the period 221 160 442 320 Ending balance $ (12,460) $ (10,413) $ (12,460) $ (10,413) Employer Contributions to Company-Sponsored Defined Benefit Pension Plans For the six months ended June 30, 2021, NW Natural made cash contributions totaling $9.6 million to qualified defined benefit pension plans. The American Rescue Plan, which was signed into law on March 11, 2021, includes a provision for pension relief that extends the amortization period for required contributions from 7 to 15 years and provides for the stabilization of interest rates used to calculate future required contributions. As a result, NW Natural does not expect to make any further plan contributions during the remainder of 2021. Defined Contribution Plan The Retirement K Savings Plan is a qualified defined contribution plan under Internal Revenue Code Sections 401(a) and 401(k). Employer contributions totaled $4.7 million and $4.4 million for the six months ended June 30, 2021 and 2020, respectively. See Note 10 in the 2020 Form 10-K for more information concerning these retirement and other postretirement benefit plans.

Income Tax

Income Tax	6 Months Ended
	Jun. 30, 2021
Income Tax Disclosure [Abstract]
Income Tax	INCOME TAX An estimate of annual income tax expense is made each interim period using estimates for annual pre-tax income, regulatory flow-through adjustments, tax credits, and other items. The estimated annual effective tax rate is applied to year-to-date, pre-tax income to determine income tax expense for the interim period consistent with the annual estimate. Discrete events are recorded in the interim period in which they occur or become known. The effective income tax rate varied from the federal statutory rate due to the following: Three Months Ended June 30, NW Holdings NW Natural In thousands 2021 2020 2021 2020 Income tax at statutory rate (federal) $ (210) $ (1,429) $ 184 $ (1,287) State income tax (48) (333) 41 (281) Increase (decrease): Differences required to be flowed-through by regulatory commissions 21 173 21 173 Other, net (40) (83) 42 (24) Total provision for income taxes on continuing operations $ (277) $ (1,672) $ 288 $ (1,419) Effective income tax rate for continuing operations 27.7 % 24.6 % 32.8 % 23.1 % Six Months Ended June 30, NW Holdings NW Natural In thousands 2021 2020 2021 2020 Income tax at statutory rate (federal) $ 16,598 $ 11,676 $ 17,123 $ 12,068 State income tax 7,260 3,344 7,366 3,456 Increase (decrease): Differences required to be flowed-through by regulatory commissions (3,584) (2,352) (3,584) (2,352) Other, net (30) (213) (65) (173) Total provision for income taxes on continuing operations $ 20,244 $ 12,455 $ 20,840 $ 12,999 Effective income tax rate for continuing operations 25.6 % 22.4 % 25.6 % 22.6 % The NW Holdings and NW Natural effective income tax rates for the six months ended June 30, 2021 compared to the same period in 2020 changed primarily as a result of changes in pre-tax income, the Oregon Corporate Activity Tax (CAT), and regulatory amortization of deferred Tax Cuts and Jobs Act (TCJA) benefits. See Note 11 in the 2020 Form 10-K for more detail on income taxes and effective tax rates. The IRS Compliance Assurance Process (CAP) examination of the 2019 tax year was completed during the first quarter of 2021. There were no material changes to the return as filed. The 2020 and 2021 tax years are subject to examination under CAP.

Property, Plant and Equipment

Property, Plant and Equipment	6 Months Ended
	Jun. 30, 2021
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment Disclosure [Text Block]	PROPERTY, PLANT, AND EQUIPMENT The following table sets forth the major classifications of property, plant, and equipment and accumulated depreciation of continuing operations: June 30, December 31, In thousands 2021 2020 2020 NW Natural: NGD plant in service $ 3,623,092 $ 3,404,145 $ 3,548,543 NGD work in progress 99,646 90,903 63,901 Less: Accumulated depreciation 1,068,603 1,040,616 1,055,809 NGD plant, net 2,654,135 2,454,432 2,556,635 Other plant in service 66,315 64,317 66,300 Other construction work in progress 5,817 5,342 5,032 Less: Accumulated depreciation 20,140 19,144 19,637 Other plant, net 51,992 50,515 51,695 Total property, plant, and equipment, net $ 2,706,127 $ 2,504,947 $ 2,608,330 Other (NW Holdings): Other plant in service $ 54,922 $ 44,195 $ 50,263 Less: Accumulated depreciation 5,120 2,539 3,823 Other plant, net $ 49,802 $ 41,656 $ 46,440 NW Holdings: Total property, plant, and equipment, net $ 2,755,929 $ 2,546,603 $ 2,654,770 NW Natural: Capital expenditures in accrued liabilities $ 37,968 $ 31,847 $ 25,129 NW Holdings: Capital expenditures in accrued liabilities $ 38,395 $ 31,847 $ 25,129 NW Holdings Other plant balances include long-lived assets associated with water and wastewater utility operations and non-regulated activities not held by NW Natural or its subsidiaries. NW Natural Other plant balances primarily include non-utility gas storage assets at the Mist facility and other long-lived assets not related to NGD.

Gas Reserves

Gas Reserves	6 Months Ended
	Jun. 30, 2021
Gas Reserves [Abstract]
Gas Reserves	GAS RESERVES NW Natural has invested $188 million through the gas reserves program in the Jonah Field located in Wyoming as of June 30, 2021. Gas reserves are stated at cost, net of regulatory amortization, with the associated deferred tax benefits recorded as liabilities in the consolidated balance sheets. The investment in gas reserves provides long-term price protection for NGD customers through the original agreement with Encana Oil & Gas (USA) Inc. under which NW Natural invested $178 million and the amended agreement with Jonah Energy LLC under which an additional $10 million was invested. The cost of gas, including a carrying cost for the rate base investment, is included in the annual Oregon PGA filing, which allows NW Natural to recover these costs through customer rates. The investment under the original agreement, less accumulated amortization and deferred taxes, earns a rate of return. See Note 13 in the 2020 Form 10-K. Gas produced from the additional wells is included in the Oregon PGA at a fixed rate of $0.4725 per therm, which approximates the 10-year hedge rate plus financing costs at the inception of the investment. The following table outlines NW Natural's net gas reserves investment: June 30, December 31, In thousands 2021 2020 2020 Gas reserves, current $ 8,444 $ 13,646 $ 11,409 Gas reserves, non-current 178,863 173,661 175,898 Less: Accumulated amortization 149,011 132,202 141,414 Total gas reserves (1) 38,296 55,105 45,893 Less: Deferred taxes on gas reserves 8,760 13,324 10,572 Net investment in gas reserves $ 29,536 $ 41,781 $ 35,321 (1) The net investment in additional wells included in total gas reserves was $2.7 million, $3.4 million and $3.0 million at June 30, 2021 and 2020 and December 31, 2020, respectively. NW Natural's investment is included in NW Holdings' and NW Natural's consolidated balance sheets under gas reserves with the maximum loss exposure limited to the investment balance.

Investments

Investments	6 Months Ended
	Jun. 30, 2021
Investments [Abstract]
Investments	INVESTMENTS Investment in Life Insurance Policies Other investments include financial investments in life insurance policies, which are accounted for at cash surrender value, net of policy loans. See Note 14 in the 2020 Form 10-K. Investments in Gas Pipeline On August 6, 2020, NWN Energy completed the sale of 100% of its interest in Trail West Holdings, LLC (TWH) to an unrelated third party for a purchase price of $14.0 million, $7.0 million of which was paid upon closing the transaction, and $7.0 million is to be paid upon the one-year anniversary of the close date. The completion of the sale resulted in an after-tax gain of approximately $0.5 million. TWH was a variable interest entity reported under equity method accounting through its sale. The investment in TWH did not meet the criteria to be classified as held for sale or discontinued operations. The investment balance in TWH was $13.4 million at June 30, 2020. See Note 14 in the 2020 Form 10-K.

Business Combinations Business

Business Combinations Business Combinations	6 Months Ended
	Jun. 30, 2021
Business Combinations [Abstract]
Business Combination Disclosure	BUSINESS COMBINATIONS 2021 Business Combinations During the six months ended June 30, 2021, NWN Water completed one acquisition of a water system that qualified as a business combination. The aggregate fair value of the preliminary consideration transferred for this acquisition was not material and is not significant to NW Holdings' results of operations. 2020 Business Combinations During 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. As each of these acquisitions met the criteria of a business combination, a preliminary allocation of the consideration to the acquired net assets based on their estimated fair value as of the acquisition date was performed. 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 Suncadia Water Company, LLC and T&W Water Service Company. Final goodwill of $18.2 million was recognized from the acquisitions described above. No intangible assets aside from goodwill were acquired. The goodwill recognized is attributable to the regulated water utility service territories, experienced workforces, and the strategic benefits from both the water and wastewater utilities expected from growth in their service territories. The total amount of goodwill that is expected to be deductible for income tax purposes is approximately $16.5 million. The acquisition costs associated with each business combination were expensed as incurred. The results of these business combinations were not material to the consolidated financial results of NW Holdings. Other Business Combinations During 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 preliminary 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 $69.3 million, $70.2 million and $69.2 million as of June 30, 2021, June 30, 2020 and December 31, 2020, respectively. The decrease in the goodwill balance from the second quarter of 2020 is primarily due to a measurement period adjustment that occurred in the fourth quarter of 2020, partially offset by acquisitions in the water sector. The increase in the goodwill balance from the fourth quarter of 2020 is primarily due to additions associated with our acquisitions in the water 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	6 Months Ended
	Jun. 30, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments	DERIVATIVE INSTRUMENTS 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 exchange contracts. NW Natural enters into these financial derivatives, up to prescribed limits, primarily to hedge price variability related to 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 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: June 30, December 31, In thousands 2021 2020 2020 Natural gas (in therms): Financial 680,335 654,145 784,400 Physical 419,148 570,600 457,593 Foreign exchange $ 6,477 $ 7,176 $ 5,896 Purchased Gas Adjustment (PGA) 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. 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 2020-21 and 2019-20 gas years with forecasted sales volumes hedged at 53% and 52% 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 2020 were included in the PGA for the 2020-21 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, which also represents all derivative instruments at NW Holdings: Three Months Ended June 30, 2021 2020 In thousands Natural gas commodity Foreign exchange Natural gas commodity Foreign exchange Benefit (expense) to cost of gas $ 16,323 $ (45) $ 5,492 $ 459 Operating revenues (expense) — — 754 — Amounts deferred to regulatory accounts on balance sheet (16,323) 45 (6,119) (459) Total gain (loss) in pre-tax earnings $ — $ — $ 127 $ — Six Months Ended June 30, 2021 2020 In thousands Natural gas commodity Foreign exchange Natural gas commodity Foreign exchange Benefit (expense) to cost of gas $ 36,805 $ 32 $ 149 $ (7) Operating revenues (expense) (27) — (1,679) — Amounts deferred to regulatory accounts on balance sheet (36,782) (32) 1,286 7 Total gain (loss) in pre-tax earnings $ (4) $ — $ (244) $ — 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 $4.2 million and $9.3 million for the three and six months ended June 30, 2021 from the settlement of natural gas financial derivative contracts, whereas, net losses of $1.1 million and $3.2 million were realized for the three and six months ended June 30, 2020. Realized gains and losses offset the higher or lower cost of gas purchased, resulting in no incremental amounts to collect or refund to customers. Credit Risk Management of Financial Derivatives Instruments No collateral was posted with or by NW Natural counterparties as of June 30, 2021 or 2020. NW Natural attempts to minimize the potential exposure to collateral calls by diversifying counterparties to manage liquidity risk. Counterparties generally allow a certain credit limit threshold before requiring NW Natural to post collateral against loss positions. Given NW Natural's counterparty credit limits and portfolio diversification, it was not subject to collateral calls in 2021 or 2020. 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 in the event of a material adverse change. If credit-risk related contingent features within these contracts were triggered as of June 30, 2021, assuming current gas prices and a credit rating downgrade to a speculative level, we would not be required to post collateral calls, including estimates for adequate assurance. 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. NW Natural’s current commodity financial swap and option contracts outstanding reflect unrealized gains of $54.3 million and $5.3 million at June 30, 2021 and June 30, 2020, respectively. If netted by counterparty, NW Natural's physical and financial derivative position would result in an asset of $51.8 million and a liability of $1.6 million as of June 30, 2021, an asset of $6.7 million and a liability of $1.5 million as of June 30, 2020, and an asset of $14.1 million and a liability of $1.3 million as of December 31, 2020. 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. In certain cases, NW Natural requires guarantees or letters of credit from counterparties to meet its minimum credit requirement standards. See Note 16 in the 2020 Form 10-K for additional information. Fair Value

Environmental Matters

Environmental Matters	6 Months Ended
	Jun. 30, 2021
Environmental Remediation Obligations [Abstract]
Environmental Matters	ENVIRONMENTAL MATTERS NW Natural owns, or previously owned, properties that may require environmental remediation or action. The range of loss for environmental liabilities is estimated based on current remediation technology, enacted laws and regulations, industry experience gained at similar sites, and an assessment of the probable level of involvement and financial condition of other potentially responsible parties (PRPs). When amounts are prudently expended related to site remediation of those sites described herein, NW Natural has recovery mechanisms in place to collect 96.7% of remediation costs allocable to Oregon customers and 3.3% of costs allocable to Washington customers. These sites are subject to the remediation process prescribed by the Environmental Protection Agency (EPA) and the Oregon Department of Environmental Quality (ODEQ). The process begins with a remedial investigation (RI) to determine the nature and extent of contamination and then a risk assessment (RA) to establish whether the contamination at the site poses unacceptable risks to humans and the environment. Next, a feasibility study (FS) or an engineering evaluation/cost analysis (EE/CA) evaluates various remedial alternatives. It is at this point in the process when NW Natural is able to estimate a range of remediation costs and record a reasonable potential remediation liability, or make an adjustment to the existing liability. From this study, the regulatory agency selects a remedy and issues a Record of Decision (ROD). After a ROD is issued, NW Natural would seek to negotiate a consent decree or consent judgment for designing and implementing the remedy. NW Natural would have the ability to further refine estimates of remediation liabilities at that time. Remediation may include treatment of contaminated media such as sediment, soil and groundwater, removal and disposal of media, institutional controls such as legal restrictions on future property use, or natural recovery. Following construction of the remedy, the EPA and ODEQ also have requirements for ongoing maintenance, monitoring and other post-remediation care that may continue for many years. Where appropriate and reasonably known, NW Natural will provide for these costs in the remediation liabilities described below. Due to the numerous uncertainties surrounding the course of environmental remediation and the preliminary nature of several site investigations, in some cases, NW Natural may not be able to reasonably estimate the high end of the range of possible loss. In those cases, the nature of the possible loss has been disclosed, as has the fact that the high end of the range cannot be reasonably estimated where a range of potential loss is available. Unless there is an estimate within the range of possible losses that is more likely than other cost estimates within that range, NW Natural records the liability at the low end of this range. It is likely changes in these estimates and ranges will occur throughout the remediation process for each of these sites due to the continued evaluation and clarification concerning responsibility, the complexity of environmental laws and regulations and the determination by regulators of remediation alternatives. In addition to remediation costs, NW Natural could also be subject to Natural Resource Damages (NRD) claims. NW Natural will assess the likelihood and probability of each claim and recognize a liability if deemed appropriate. Refer to " Other Portland Harbor " below. Environmental Sites The following table summarizes information regarding liabilities related to environmental sites, which are recorded in other current liabilities and other noncurrent liabilities in NW Natural's balance sheet: Current Liabilities Non-Current Liabilities June 30, December 31, June 30, December 31, In thousands 2021 2020 2020 2021 2020 2020 Portland Harbor site: Gasco/Siltronic Sediments $ 6,658 $ 10,431 $ 7,596 $ 41,652 $ 41,945 $ 43,725 Other Portland Harbor 2,195 2,434 1,942 6,588 6,228 7,020 Gasco/Siltronic Upland site 12,442 10,979 14,887 38,401 41,878 40,250 Front Street site 1,219 10,222 3,816 975 1,059 1,107 Oregon Steel Mills — — — 179 179 179 Total $ 22,514 $ 34,066 $ 28,241 $ 87,795 $ 91,289 $ 92,281 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 the 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/Siltronic Sediments and Other Portland Harbor projects. GASCO/SILTRONIC 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. These preliminary design discussions did not include a cost estimate for alternatives, none of the alternatives are more likely than others 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 $48.3 million to $350 million. NW Natural has recorded a liability of $48.3 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/Siltronic 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 Remedial 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 to incorporate a portion of the Siltronic property adjacent to the Gasco site formerly owned by Portland Gas & Coke between 1939 and 1960 into the Gasco RA and FS, excluding the uplands for Siltronic. 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 Gasco sediment exposure. 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 early July 2020 and was completed in October 2020. NW Natural has recognized an additional liability of $2.2 million for long term monitoring, 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 . See Note 18 in the 2020 Form 10-K for a description of SRRM and ECRM collection processes. The following table presents information regarding the total regulatory asset deferred: June 30, December 31, In thousands 2021 2020 2020 Deferred costs and interest (1) $ 50,604 $ 42,098 $ 44,516 Accrued site liabilities (2) 110,237 124,981 120,352 Insurance proceeds and interest (69,730) (81,146) (69,253) Total regulatory asset deferral (1) $ 91,111 $ 85,933 $ 95,615 Current regulatory assets (3) 5,688 4,176 4,992 Long-term regulatory assets (3) 85,423 81,757 90,623 (1) Includes pre-review and post-review deferred costs, amounts currently in amortization, and interest, net of amounts collected from customers. (2) Exclude s 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 $0.1 million at June 30, 2021, $0.4 million at June 30, 2020, and $0.2 million at December 31, 2020, (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. Environmental Earnings Test To the extent NW Natural earns at or below its authorized Return on Equity (ROE) as defined by the SRRM, remediation expenses and interest in excess of the $5.0 million tariff rider and $5.0 million insurance proceeds are recoverable through the SRRM. To the extent NW Natural earns more than its authorized ROE in a year, it is required to cover environmental expenses and interest on expenses greater than the $10.0 million with those earnings that exceed its authorized ROE. Legal Proceedings NW Holdings is not currently party to any direct claims or litigation, though in the future it may be subject to claims and litigation arising in the ordinary course of business. NW Natural is subject to claims and litigation arising in the ordinary course of business including the matters discussed above and ordinary course claims and litigation noted below. Although the final outcome of any of these legal proceedings cannot be predicted with certainty, including the matter described below, NW Natural and NW Holdings do not expect that the ultimate disposition of any of these matters will have a material effect on financial condition, results of operations or cash flows. See also Part II, Item 1, “ Legal Proceedings" . Oregon Steel Mills Site See Note 18 in the 2020 Form 10-K. For additional information regarding other commitments and contingencies, see Note 17 in the 2020 Form 10-K.

Discontinued Operations

Discontinued Operations	6 Months Ended
	Jun. 30, 2019
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 . As a result of the disposition of the membership interests in Gill Ranch, there were no assets or liabilities classified as held for sale at June 30, 2021 or December 31, 2020 and there was no activity in the consolidated statement of comprehensive income for the three and six months ended June 30, 2021. The assets and liabilities of the discontinued operations classified as held for sale in the consolidated balance sheet at June 30, 2020 include the following: NW Holdings In thousands June 30, 2020 Assets: Accounts receivable $ 1,621 Inventories 821 Other current assets 250 Property, plant, and equipment, net 13,328 Operating lease right of use asset 118 Other non-current assets 254 Total discontinued operations assets - current assets (1) $ 16,392 Liabilities: Accounts payable $ 999 Other current liabilities 1,119 Operating lease liabilities 112 Other non-current liabilities 11,344 Total discontinued operations liabilities - current liabilities (1) $ 13,574 (1) The total assets and liabilities of Gill Ranch were classified as current because it was probable that the sale would be completed within one year. The following table presents the operating results of Gill Ranch and is presented net of tax on the consolidated statements of comprehensive income: NW Holdings Three Months Ended June 30, Six Months Ended June 30, In thousands, except per share data 2020 2020 Revenues $ 3,374 $ 4,282 Expenses: Operations and maintenance 2,604 4,184 General taxes 53 100 Depreciation and amortization 106 212 Other expenses and interest 228 459 Total expenses 2,991 4,955 Income (loss) from discontinued operations before income taxes 383 (673) Income tax expense (benefit) 103 (175) Income (loss) from discontinued operations, net of tax $ 280 $ (498) Earnings (loss) from discontinued operations per share of common stock: Basic $ 0.01 $ (0.01) Diluted $ 0.01 $ (0.01)

Significant Accounting Polici_2

Significant Accounting Policies	6 Months Ended
	Jun. 30, 2021
Accounting Policies [Abstract]
Industry Regulation	Industry Regulation 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 Oregon Public Utilities Commission (OPUC), Washington Utilities and Transportation Commission (WUTC), Idaho Public Utilities Commission (IPUC) or Public Utility Commission of Texas (PUCT), which provide for the recovery of revenues or expenses from, or refunds to, utility customers in future periods, including a return or a carrying charge in certain cases.
New Accounting Standards	New Accounting Standards We 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 NW Holdings' or NW Natural's consolidated financial position or results of operations. Recently Adopted Accounting Pronouncements INCOME TAXES. On December 18, 2019, the FASB issued ASU 2019-12, "Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes." The purpose of the amendment is to reduce cost and complexity related to accounting for income taxes by removing certain exceptions to the general principles and improving consistent application for other areas in Topic 740. The amendments in this ASU were effective beginning January 1, 2021. The amended presentation and disclosure guidance was applied retrospectively. The adoption did not materially affect the financial statements and disclosures of NW Holdings or NW Natural. REFERENCE RATE REFORM. On March 12, 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 LIBOR or another reference rate expected to be discontinued because of reference rate reform.

Significant Accounting Polici_3

Significant Accounting Policies	6 Months Ended
	Jun. 30, 2021
Accounting Policies [Abstract]
Schedule of Regulatory Assets	Amounts deferred as regulatory assets and liabilities for NW Holdings and NW Natural were as follows: Regulatory Assets June 30, December 31, In thousands 2021 2020 2020 NW Natural: Current: Unrealized loss on derivatives (1) $ 3,393 $ 2,956 $ 4,198 Gas costs 29,486 6,046 1,979 Environmental costs (2) 5,688 4,176 4,992 Decoupling (3) 1,011 85 361 Pension balancing (4) 7,131 7,131 7,131 Income taxes 2,345 2,208 3,484 Other (5) 11,618 7,419 9,600 Total current $ 60,672 $ 30,021 $ 31,745 Non-current: Unrealized loss on derivatives (1) $ 453 $ 1,658 $ 2,852 Pension balancing (4) 40,342 45,315 43,383 Income taxes 13,903 17,608 15,368 Pension and other postretirement benefit liabilities 160,385 164,091 170,812 Environmental costs (2) 85,423 81,757 90,623 Gas costs 5,742 94 3,925 Decoupling (3) 198 — 1,031 Other (5) 24,224 13,797 20,893 Total non-current $ 330,670 $ 324,320 $ 348,887 Other (NW Holdings) 40 38 40 Total non-current - NW Holdings $ 330,710 $ 324,358 $ 348,927
Schedule of Regulatory Liabilities	Regulatory Liabilities June 30, December 31, In thousands 2021 2020 2020 NW Natural: Current: Gas costs $ 1,519 $ 3,767 $ 1,118 Unrealized gain on derivatives (1) 46,168 5,950 13,674 Decoupling (3) 5,821 11,498 11,793 Income taxes 8,217 7,098 8,217 Asset optimization revenue sharing 39,348 7,116 10,298 Other (5) 2,137 5,697 5,262 Total current $ 103,210 $ 41,126 $ 50,362 Non-current: Gas costs $ 101 $ 538 $ 314 Unrealized gain on derivatives (1) 7,912 3,958 6,135 Decoupling (3) 652 2,108 1,723 Income taxes (6) 182,977 193,414 189,587 Accrued asset removal costs (7) 439,685 414,719 427,960 Other (5) 12,850 16,794 13,074 Total non-current - NW Natural $ 644,177 $ 631,531 $ 638,793 Other (NW Holdings) 869 869 870 Total non-current - NW Holdings $ 645,046 $ 632,400 $ 639,663 (1) Unrealized gains or losses on derivatives are non-cash items and therefore do not earn a rate of return or a carrying charge. These amounts are recoverable through NGD rates as part of the annual Purchased Gas Adjustment (PGA) mechanism when realized at settlement. (2) Refer to footnote (3) of the Deferred Regulatory Asset table in Note 16 for a description of environmental costs. (3) This deferral represents the margin adjustment resulting from differences between actual and expected volumes. (4) Balance represents deferred net periodic benefit costs as approved by the OPUC. (5) Balances consist of deferrals and amortizations under approved regulatory mechanisms and typically earn a rate of return or carrying charge. (6) Balance represents excess deferred income tax benefits subject to regulatory flow-through.
Accounts Receivable, Allowance for Credit Loss [Table Text Block]	The following table presents the activity related to the NW Holdings provision for uncollectible accounts by pool, substantially all of which is related to NW Natural's accounts receivable: As of As of December 31, 2020 Six Months Ended June 30, 2021 June 30, 2021 In thousands Beginning Balance Provision recorded, net of adjustments Write-offs recognized, net of recoveries Ending Balance (1) Allowance for uncollectible accounts: Residential $ 2,153 $ 1,294 $ (637) $ 2,810 Commercial 704 (233) (265) 206 Industrial 142 (68) 5 79 Accrued unbilled and other 220 22 (54) 188 Total $ 3,219 $ 1,015 $ (951) $ 3,283 (1) Includes $2.9 million that was deferred to a regulatory asset for costs associated with COVID-19 that are recoverable in future rates.
Schedule of Cash Flow, Supplemental Disclosures	The following table provides a reconciliation of the cash, cash equivalents and restricted cash balances at NW Holdings as of June 30, 2021 and 2020 and December 31, 2020: June 30, December 31, In thousands 2021 2020 2020 Cash and cash equivalents $ 20,084 $ 137,057 $ 30,168 Restricted cash included in other current assets 8,226 5,491 5,286 Cash, cash equivalents and restricted cash $ 28,310 $ 142,548 $ 35,454 The following table provides a reconciliation of the cash, cash equivalents and restricted cash balances at NW Natural as of June 30, 2021 and 2020 and December 31, 2020: June 30, December 31, In thousands 2021 2020 2020 Cash and cash equivalents $ 11,488 $ 120,284 $ 10,453 Restricted cash included in other current assets 8,226 5,491 5,286 Cash, cash equivalents and restricted cash $ 19,714 $ 125,775 $ 15,739

Earnings Per Share_2

Earnings Per Share	6 Months Ended
	Jun. 30, 2021
Earnings Per Share [Abstract]
EPS Calculation	NW Holdings' diluted earnings or loss per share are calculated as follows: Three Months Ended June 30, Six Months Ended June 30, In thousands, except per share data 2021 2020 2021 2020 Net income (loss) from continuing operations $ (724) $ (5,132) $ 58,793 $ 43,144 Income (loss) from discontinued operations, net of tax — 280 — (498) Net income (loss) $ (724) $ (4,852) $ 58,793 $ 42,646 Average common shares outstanding - basic 30,664 30,537 30,639 30,514 Additional shares for stock-based compensation plans (See Note 7) — — 32 45 Average common shares outstanding - diluted 30,664 30,537 30,671 30,559 Earnings (loss) from continuing operations per share of common stock: Basic $ (0.02) $ (0.17) $ 1.92 $ 1.41 Diluted $ (0.02) $ (0.17) $ 1.92 $ 1.41 Earnings (loss) from discontinued operations per share of common stock: Basic $ — $ 0.01 $ — $ (0.01) Diluted $ — $ 0.01 $ — $ (0.01) Earnings (loss) per share of common stock: Basic $ (0.02) $ (0.16) $ 1.92 $ 1.40 Diluted $ (0.02) $ (0.16) $ 1.92 $ 1.40 Additional information: Anti-dilutive shares 48 41 7 —

Segment Information_2

Segment Information	6 Months Ended
	Jun. 30, 2021
Segment Reporting [Abstract]
Schedule of Segment Reporting Information, by Segment	The following table presents summary financial information concerning the reportable segment and other of continuing operations. See Note 17 for information regarding discontinued operations for NW Holdings. Three Months Ended June 30, In thousands NGD Other NW Natural Other NW Holdings 2021 Operating revenues $ 139,614 $ 4,965 $ 144,579 $ 4,338 $ 148,917 Depreciation and amortization 27,273 257 27,530 614 28,144 Income (loss) from operations 11,331 2,808 14,139 (1,515) 12,624 Net income (loss) from continuing operations (1,381) 1,970 589 (1,313) (724) Capital expenditures 60,376 693 61,069 3,337 64,406 2020 Operating revenues $ 126,992 $ 4,165 $ 131,157 $ 3,814 $ 134,971 Depreciation and amortization 24,738 248 24,986 850 25,836 Income (loss) from operations 6,434 2,465 8,899 43 8,942 Net income (loss) from continuing operations (6,347) 1,635 (4,712) (420) (5,132) Capital expenditures 61,472 521 61,993 2,843 64,836 Six Months Ended June 30, In thousands NGD Other NW Natural Other NW Holdings 2021 Operating revenues $ 440,952 $ 15,977 $ 456,929 $ 7,934 $ 464,863 Depreciation and amortization 54,186 513 54,699 1,542 56,241 Income (loss) from operations 97,818 11,439 109,257 (1,927) 107,330 Net income (loss) from continuing operations 52,544 8,156 60,700 (1,907) 58,793 Capital expenditures 124,368 799 125,167 4,941 130,108 Total assets at June 30, 2021 3,587,966 51,466 3,639,432 144,068 3,783,500 2020 Operating revenues $ 405,479 $ 8,207 $ 413,686 $ 6,436 $ 420,122 Depreciation and amortization 48,684 492 49,176 1,335 50,511 Income (loss) from operations 81,692 4,228 85,920 (532) 85,388 Net income (loss) from continuing operations 41,596 2,871 44,467 (1,323) 43,144 Capital expenditures 117,629 598 118,227 4,055 122,282 Total assets at June 30, 2020 (1) 3,470,306 10,398 3,480,704 144,251 3,624,955 Total assets at December 31, 2020 3,549,868 49,468 3,599,336 157,043 3,756,379
NGD Margin	The following table presents additional segment information concerning NGD margin: Three Months Ended June 30, Six Months Ended June 30, In thousands 2021 2020 2021 2020 NGD margin calculation: NGD distribution revenues $ 134,849 $ 122,071 $ 431,402 $ 395,632 Other regulated services 4,765 4,921 9,550 9,847 Total NGD operating revenues 139,614 126,992 440,952 405,479 Less: NGD cost of gas 41,249 41,265 153,515 149,860 Environmental remediation 1,509 1,622 5,286 5,627 Revenue taxes 5,650 4,454 18,305 16,197 NGD margin $ 91,206 $ 79,651 $ 263,846 $ 233,795

Revenue_2

Revenue	3 Months Ended
	Jun. 30, 2021
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenue	The following tables present disaggregated revenue from continuing operations: Three Months Ended June 30, In thousands NGD Other NW Natural Other NW Holdings 2021 Natural gas sales $ 123,739 $ — $ 123,739 $ — $ 123,739 Gas storage revenue, net — 2,805 2,805 — 2,805 Asset management revenue, net — 817 817 — 817 Appliance retail center revenue — 1,343 1,343 — 1,343 Other revenue 399 — 399 4,338 4,737 Revenue from contracts with customers 124,138 4,965 129,103 4,338 133,441 Alternative revenue 11,083 — 11,083 — 11,083 Leasing revenue 4,393 — 4,393 — 4,393 Total operating revenues $ 139,614 $ 4,965 $ 144,579 $ 4,338 $ 148,917 2020 Natural gas sales $ 116,682 $ — $ 116,682 $ — $ 116,682 Gas storage revenue, net — 2,449 2,449 — 2,449 Asset management revenue, net — 910 910 — 910 Appliance retail center revenue — 806 806 — 806 Other revenue 332 — 332 3,814 4,146 Revenue from contracts with customers 117,014 4,165 121,179 3,814 124,993 Alternative revenue 5,365 — 5,365 — 5,365 Leasing revenue 4,613 — 4,613 — 4,613 Total operating revenues $ 126,992 $ 4,165 $ 131,157 $ 3,814 $ 134,971 Six Months Ended June 30, In thousands NGD Other NW Natural Other NW Holdings 2021 Natural gas sales $ 419,822 $ — $ 419,822 $ — $ 419,822 Gas storage revenue, net — 5,300 5,300 — 5,300 Asset management revenue, net — 7,745 7,745 — 7,745 Appliance retail center revenue — 2,932 2,932 — 2,932 Other revenue 814 — 814 7,934 8,748 Revenue from contracts with customers 420,636 15,977 436,613 7,934 444,547 Alternative revenue 11,536 — 11,536 — 11,536 Leasing revenue 8,780 — 8,780 — 8,780 Total operating revenues $ 440,952 $ 15,977 $ 456,929 $ 7,934 $ 464,863 2020 Natural gas sales $ 390,686 $ — $ 390,686 $ — $ 390,686 Gas storage revenue, net — 4,785 4,785 — 4,785 Asset management revenue, net — 1,060 1,060 — 1,060 Appliance retail center revenue — 2,362 2,362 — 2,362 Other revenue 669 — 669 6,436 7,105 Revenue from contracts with customers 391,355 8,207 399,562 6,436 405,998 Alternative revenue 4,893 — 4,893 — 4,893 Leasing revenue 9,231 — 9,231 — 9,231 Total operating revenues $ 405,479 $ 8,207 $ 413,686 $ 6,436 $ 420,122

Leases_2

Leases	6 Months Ended	12 Months Ended
	Jun. 30, 2021	Dec. 31, 2019
Leases [Abstract]
Lease Revenue	The components of lease revenue at NW Natural were as follows: Three Months Ended June 30, Six Months Ended June 30, In thousands 2021 2020 2021 2020 Lease revenue Operating leases $ 25 $ 25 $ 43 $ 53 Sales-type leases 4,368 4,588 8,737 9,178 Total lease revenue $ 4,393 $ 4,613 $ 8,780 $ 9,231
Lessor, Operating Lease, Payments to be Received, Maturity	Total future minimum lease payments to be received under non-cancellable leases at June 30, 2021 are as follows: In thousands Operating Sales-Type Total NW Natural: Remainder of 2021 $ 36 $ 8,701 $ 8,737 2022 72 17,026 17,098 2023 64 16,557 16,621 2024 65 15,867 15,932 2025 60 15,306 15,366 Thereafter 229 251,721 251,950 Total lease revenue $ 526 $ 325,178 $ 325,704 Less: imputed interest 183,237 Total leases receivable $ 141,941 Other (NW Holdings): Remainder of 2021 $ 25 $ — $ 25 2022 50 — 50 2023 51 — 51 2024 52 — 52 2025 53 — 53 Thereafter 970 — 970 Total lease revenue $ 1,201 $ — $ 1,201 NW Holdings: Remainder of 2021 $ 61 $ 8,701 $ 8,762 2022 122 17,026 17,148 2023 115 16,557 16,672 2024 117 15,867 15,984 2025 113 15,306 15,419 Thereafter 1,199 251,721 252,920 Total lease revenue $ 1,727 $ 325,178 $ 326,905 Less: imputed interest 183,237 Total leases receivable $ 141,941
Lease Expense	The components of lease expense, a portion of which is capitalized, were as follows: Three Months Ended June 30, Six Months Ended June 30, In thousands 2021 2020 2021 2020 NW Natural: Operating lease expense $ 1,710 $ 914 $ 3,388 $ 2,116 Short-term lease expense $ 349 $ 285 $ 569 $ 483 Other (NW Holdings): Operating lease expense $ 18 $ 40 $ 36 $ 92 NW Holdings: Operating lease expense $ 1,728 $ 954 $ 3,424 $ 2,208 Short-term lease expense $ 349 $ 285 $ 569 $ 483
Operating Lease, Lease Asset and Liabilities	Supplemental balance sheet information related to operating leases as of June 30, 2021 is as follows: In thousands June 30, December 31, 2021 2020 2020 NW Natural: Operating lease right of use asset $ 76,211 $ 78,464 $ 77,328 Operating lease liabilities - current liabilities $ 1,193 $ 868 $ 1,054 Operating lease liabilities - non-current liabilities 80,043 80,120 80,559 Total operating lease liabilities $ 81,236 $ 80,988 $ 81,613 Other (NW Holdings): Operating lease right of use asset $ 83 $ 102 $ 118 Operating lease liabilities - current liabilities $ 35 $ 63 $ 51 Operating lease liabilities - non-current liabilities 45 39 62 Total operating lease liabilities $ 80 $ 102 $ 113 NW Holdings: Operating lease right of use asset $ 76,294 $ 78,566 $ 77,446 Operating lease liabilities - current liabilities $ 1,228 $ 931 $ 1,105 Operating lease liabilities - non-current liabilities 80,088 80,159 80,621 Total operating lease liabilities $ 81,316 $ 81,090 $ 81,726
Operating Lease, Weighted Average Remaining Term and Discount Rates [Table Text Block]	The weighted-average remaining lease terms and weighted-average discount rates for the operating leases at NW Natural were as follows: In thousands June 30, December 31, 2021 2020 2020 Weighted-average remaining lease term (years) 18.7 19.7 19.2 Weighted-average discount rate 7.2 % 7.2 % 7.2 %
Lessee, Operating Lease, Liability, Maturity		Maturities of operating lease liabilities at June 30, 2021 were as follows: In thousands NW Natural Other NW Holdings Remainder of 2021 $ 3,445 $ 25 $ 3,470 2022 6,933 24 6,957 2023 6,986 6 6,992 2024 7,150 6 7,156 2025 7,185 6 7,191 Thereafter 123,784 24 123,808 Total lease payments 155,483 91 155,574 Less: imputed interest 74,247 11 74,258 Total lease obligations 81,236 80 81,316 Less: current obligations 1,193 35 1,228 Long-term lease obligations $ 80,043 $ 45 $ 80,088
Lessee, Leases, Supplemental Cash Flow Information	Supplemental cash flow information related to leases was as follows: Three Months Ended June 30, Six Months Ended June 30, In thousands 2021 2020 2021 2020 NW Natural: Cash paid for amounts included in the measurement of lease liabilities Operating cash flows from operating leases $ 1,717 $ 931 $ 3,386 $ 2,127 Finance cash flows from finance leases $ 134 $ 302 $ 678 $ 457 Right of use assets obtained in exchange for lease obligations Operating leases $ — $ 445 $ 154 $ 78,433 Finance leases $ 20 $ 477 $ 94 $ 710 Other (NW Holdings): Cash paid for amounts included in the measurement of lease liabilities Operating cash flows from operating leases $ 17 $ 39 $ 33 $ 91 NW Holdings: Cash paid for amounts included in the measurement of lease liabilities Operating cash flows from operating leases $ 1,734 $ 970 $ 3,419 $ 2,218 Finance cash flows from finance leases $ 134 $ 302 $ 678 $ 457 Right of use assets obtained in exchange for lease obligations Operating leases $ — $ 445 $ 154 $ 78,433 Finance leases $ 20 $ 477 $ 94 $ 710

Debt_2

Debt	6 Months Ended
	Jun. 30, 2021
Debt Disclosure [Abstract]
Schedule of Carrying Values and Estimated Fair Values of Debt Instruments	The following table provides an estimate of the fair value of NW Holdings' long-term debt, including current maturities of long-term debt, using market prices in effect on the valuation date: NW Holdings June 30, December 31, In thousands 2021 2020 2020 Gross long-term debt $ 983,221 $ 961,784 $ 962,905 Unamortized debt issuance costs (7,446) (7,688) (7,480) Carrying amount $ 975,775 $ 954,096 $ 955,425 Estimated fair value (1) $ 1,104,230 $ 1,135,349 $ 1,136,311 (1) Estimated fair value does not include unamortized debt issuance costs. The following table provides an estimate of the fair value of NW Natural's long-term debt, including current maturities of long-term debt, using market prices in effect on the valuation date: NW Natural June 30, December 31, In thousands 2021 2020 2020 Gross long-term debt $ 924,700 $ 924,700 $ 924,700 Unamortized debt issuance costs (7,291) (7,688) (7,480) Carrying amount $ 917,409 $ 917,012 $ 917,220 Estimated fair value (1) $ 1,043,696 $ 1,097,188 $ 1,097,348 (1) Estimated fair value does not include unamortized debt issuance costs.

Pension and Other Postretirem_2

Pension and Other Postretirement Benefit Costs	6 Months Ended
	Jun. 30, 2021
Pension and Other Postretirement Benefits Cost (Reversal of Cost) [Abstract]
Schedule of Net Benefit Costs	The following table provides the components of net periodic benefit cost for the pension and other postretirement benefit plans: Three Months Ended June 30, Six Months Ended June 30, Pension Benefits Other Postretirement Pension Benefits Other In thousands 2021 2020 2021 2020 2021 2020 2021 2020 Service cost $ 1,714 $ 1,658 $ 56 $ 64 $ 3,428 $ 3,315 $ 111 $ 128 Interest cost 3,342 4,011 165 223 6,685 8,022 330 446 Expected return on plan assets (6,099) (5,496) — — (12,198) (10,992) — — Amortization of prior service credit — — (117) (117) — — (234) (234) Amortization of net actuarial loss 5,500 4,778 131 142 11,001 9,556 262 285 Net periodic benefit cost 4,457 4,951 235 312 8,916 9,901 469 625 Amount allocated to construction (743) (680) (22) (23) (1,469) (1,348) (43) (46) Net periodic benefit cost charged to expense 3,714 4,271 213 289 7,447 8,553 426 579 Amortization of regulatory balancing account 1,281 1,281 — — 4,082 4,082 — — Net amount charged to expense $ 4,995 $ 5,552 $ 213 $ 289 $ 11,529 $ 12,635 $ 426 $ 579
Schedule of Amounts Recognized in Other Comprehensive Income (Loss)	The following table presents amounts recognized in accumulated other comprehensive loss (AOCL) and the changes in AOCL related to non-qualified employee benefit plans: Three Months Ended June 30, Six Months Ended June 30, In thousands 2021 2020 2021 2020 Beginning balance $ (12,681) $ (10,573) $ (12,902) $ (10,733) Amounts reclassified from AOCL: Amortization of actuarial losses 301 218 602 436 Total reclassifications before tax 301 218 602 436 Tax benefit (80) (58) (160) (116) Total reclassifications for the period 221 160 442 320 Ending balance $ (12,460) $ (10,413) $ (12,460) $ (10,413)

Income Tax_2

Income Tax	6 Months Ended
	Jun. 30, 2021
Income Tax Disclosure [Abstract]
Schedule of Effective Income Tax Rate Reconciliation	The effective income tax rate varied from the federal statutory rate due to the following: Three Months Ended June 30, NW Holdings NW Natural In thousands 2021 2020 2021 2020 Income tax at statutory rate (federal) $ (210) $ (1,429) $ 184 $ (1,287) State income tax (48) (333) 41 (281) Increase (decrease): Differences required to be flowed-through by regulatory commissions 21 173 21 173 Other, net (40) (83) 42 (24) Total provision for income taxes on continuing operations $ (277) $ (1,672) $ 288 $ (1,419) Effective income tax rate for continuing operations 27.7 % 24.6 % 32.8 % 23.1 % Six Months Ended June 30, NW Holdings NW Natural In thousands 2021 2020 2021 2020 Income tax at statutory rate (federal) $ 16,598 $ 11,676 $ 17,123 $ 12,068 State income tax 7,260 3,344 7,366 3,456 Increase (decrease): Differences required to be flowed-through by regulatory commissions (3,584) (2,352) (3,584) (2,352) Other, net (30) (213) (65) (173) Total provision for income taxes on continuing operations $ 20,244 $ 12,455 $ 20,840 $ 12,999 Effective income tax rate for continuing operations 25.6 % 22.4 % 25.6 % 22.6 %

Property, Plant and Equipment_2

Property, Plant and Equipment	6 Months Ended
	Jun. 30, 2021
Property, Plant and Equipment [Abstract]
Public Utility Property, Plant, and Equipment [Table Text Block]	The following table sets forth the major classifications of property, plant, and equipment and accumulated depreciation of continuing operations: June 30, December 31, In thousands 2021 2020 2020 NW Natural: NGD plant in service $ 3,623,092 $ 3,404,145 $ 3,548,543 NGD work in progress 99,646 90,903 63,901 Less: Accumulated depreciation 1,068,603 1,040,616 1,055,809 NGD plant, net 2,654,135 2,454,432 2,556,635 Other plant in service 66,315 64,317 66,300 Other construction work in progress 5,817 5,342 5,032 Less: Accumulated depreciation 20,140 19,144 19,637 Other plant, net 51,992 50,515 51,695 Total property, plant, and equipment, net $ 2,706,127 $ 2,504,947 $ 2,608,330 Other (NW Holdings): Other plant in service $ 54,922 $ 44,195 $ 50,263 Less: Accumulated depreciation 5,120 2,539 3,823 Other plant, net $ 49,802 $ 41,656 $ 46,440 NW Holdings: Total property, plant, and equipment, net $ 2,755,929 $ 2,546,603 $ 2,654,770 NW Natural: Capital expenditures in accrued liabilities $ 37,968 $ 31,847 $ 25,129 NW Holdings: Capital expenditures in accrued liabilities $ 38,395 $ 31,847 $ 25,129

Gas Reserves_2

Gas Reserves	6 Months Ended
	Jun. 30, 2021
Gas Reserves [Abstract]
Gas Reserves	The following table outlines NW Natural's net gas reserves investment: June 30, December 31, In thousands 2021 2020 2020 Gas reserves, current $ 8,444 $ 13,646 $ 11,409 Gas reserves, non-current 178,863 173,661 175,898 Less: Accumulated amortization 149,011 132,202 141,414 Total gas reserves (1) 38,296 55,105 45,893 Less: Deferred taxes on gas reserves 8,760 13,324 10,572 Net investment in gas reserves $ 29,536 $ 41,781 $ 35,321

Derivative Instruments_2

Derivative Instruments	6 Months Ended
	Jun. 30, 2021
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: June 30, December 31, In thousands 2021 2020 2020 Natural gas (in therms): Financial 680,335 654,145 784,400 Physical 419,148 570,600 457,593 Foreign exchange $ 6,477 $ 7,176 $ 5,896
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, which also represents all derivative instruments at NW Holdings: Three Months Ended June 30, 2021 2020 In thousands Natural gas commodity Foreign exchange Natural gas commodity Foreign exchange Benefit (expense) to cost of gas $ 16,323 $ (45) $ 5,492 $ 459 Operating revenues (expense) — — 754 — Amounts deferred to regulatory accounts on balance sheet (16,323) 45 (6,119) (459) Total gain (loss) in pre-tax earnings $ — $ — $ 127 $ — Six Months Ended June 30, 2021 2020 In thousands Natural gas commodity Foreign exchange Natural gas commodity Foreign exchange Benefit (expense) to cost of gas $ 36,805 $ 32 $ 149 $ (7) Operating revenues (expense) (27) — (1,679) — Amounts deferred to regulatory accounts on balance sheet (36,782) (32) 1,286 7 Total gain (loss) in pre-tax earnings $ (4) $ — $ (244) $ —

Environmental Matters_2

Environmental Matters	6 Months Ended
	Jun. 30, 2021
Environmental Remediation Obligations [Abstract]
Schedule of Environmental Loss Contingencies by Site	The following table summarizes information regarding liabilities related to environmental sites, which are recorded in other current liabilities and other noncurrent liabilities in NW Natural's balance sheet: Current Liabilities Non-Current Liabilities June 30, December 31, June 30, December 31, In thousands 2021 2020 2020 2021 2020 2020 Portland Harbor site: Gasco/Siltronic Sediments $ 6,658 $ 10,431 $ 7,596 $ 41,652 $ 41,945 $ 43,725 Other Portland Harbor 2,195 2,434 1,942 6,588 6,228 7,020 Gasco/Siltronic Upland site 12,442 10,979 14,887 38,401 41,878 40,250 Front Street site 1,219 10,222 3,816 975 1,059 1,107 Oregon Steel Mills — — — 179 179 179 Total $ 22,514 $ 34,066 $ 28,241 $ 87,795 $ 91,289 $ 92,281
Environmental Regulatory Table	The following table presents information regarding the total regulatory asset deferred: June 30, December 31, In thousands 2021 2020 2020 Deferred costs and interest (1) $ 50,604 $ 42,098 $ 44,516 Accrued site liabilities (2) 110,237 124,981 120,352 Insurance proceeds and interest (69,730) (81,146) (69,253) Total regulatory asset deferral (1) $ 91,111 $ 85,933 $ 95,615 Current regulatory assets (3) 5,688 4,176 4,992 Long-term regulatory assets (3) 85,423 81,757 90,623 (1) Includes pre-review and post-review deferred costs, amounts currently in amortization, and interest, net of amounts collected from customers. (2) Exclude s 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 $0.1 million at June 30, 2021, $0.4 million at June 30, 2020, and $0.2 million at December 31, 2020, (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.

Discontinued Operations_2

Discontinued Operations	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2019
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
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 . As a result of the disposition of the membership interests in Gill Ranch, there were no assets or liabilities classified as held for sale at June 30, 2021 or December 31, 2020 and there was no activity in the consolidated statement of comprehensive income for the three and six months ended June 30, 2021. The assets and liabilities of the discontinued operations classified as held for sale in the consolidated balance sheet at June 30, 2020 include the following: NW Holdings In thousands June 30, 2020 Assets: Accounts receivable $ 1,621 Inventories 821 Other current assets 250 Property, plant, and equipment, net 13,328 Operating lease right of use asset 118 Other non-current assets 254 Total discontinued operations assets - current assets (1) $ 16,392 Liabilities: Accounts payable $ 999 Other current liabilities 1,119 Operating lease liabilities 112 Other non-current liabilities 11,344 Total discontinued operations liabilities - current liabilities (1) $ 13,574 (1) The total assets and liabilities of Gill Ranch were classified as current because it was probable that the sale would be completed within one year. The following table presents the operating results of Gill Ranch and is presented net of tax on the consolidated statements of comprehensive income: NW Holdings Three Months Ended June 30, Six Months Ended June 30, In thousands, except per share data 2020 2020 Revenues $ 3,374 $ 4,282 Expenses: Operations and maintenance 2,604 4,184 General taxes 53 100 Depreciation and amortization 106 212 Other expenses and interest 228 459 Total expenses 2,991 4,955 Income (loss) from discontinued operations before income taxes 383 (673) Income tax expense (benefit) 103 (175) Income (loss) from discontinued operations, net of tax $ 280 $ (498) Earnings (loss) from discontinued operations per share of common stock: Basic $ 0.01 $ (0.01) Diluted $ 0.01 $ (0.01)
Northwest Holdings [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Groups, Including Discontinued Operations	The following table presents the operating results of Gill Ranch and is presented net of tax on the consolidated statements of comprehensive income: NW Holdings Three Months Ended June 30, Six Months Ended June 30, In thousands, except per share data 2020 2020 Revenues $ 3,374 $ 4,282 Expenses: Operations and maintenance 2,604 4,184 General taxes 53 100 Depreciation and amortization 106 212 Other expenses and interest 228 459 Total expenses 2,991 4,955 Income (loss) from discontinued operations before income taxes 383 (673) Income tax expense (benefit) 103 (175) Income (loss) from discontinued operations, net of tax $ 280 $ (498) Earnings (loss) from discontinued operations per share of common stock: Basic $ 0.01 $ (0.01) Diluted $ 0.01 $ (0.01)
Northwest Holdings [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Groups, Including Discontinued Operations	NW Holdings In thousands June 30, 2020 Assets: Accounts receivable $ 1,621 Inventories 821 Other current assets 250 Property, plant, and equipment, net 13,328 Operating lease right of use asset 118 Other non-current assets 254 Total discontinued operations assets - current assets (1) $ 16,392 Liabilities: Accounts payable $ 999 Other current liabilities 1,119 Operating lease liabilities 112 Other non-current liabilities 11,344 Total discontinued operations liabilities - current liabilities (1) $ 13,574 (1) The total assets and liabilities of Gill Ranch were classified as current because it was probable that the sale would be completed within one year.

Significant Accounting Polici_4

Significant Accounting Policies - Regulatory Asset Disclosure - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020
Regulatory Assets [Line Items]
Regulatory Assets, Current	$ 60,672	$ 31,745	$ 30,021
Regulatory Assets, Noncurrent	330,710	348,927	324,358
Other [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Noncurrent	40	40	38
Northwest Natural Gas Company [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Current	60,672	31,745	30,021
Regulatory Assets, Noncurrent	330,670	348,887	324,320
Northwest Natural Gas Company [Member] | Deferred Derivative Gain (Loss) [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Current	3,393	4,198	2,956
Regulatory Assets, Noncurrent	453	2,852	1,658
Northwest Natural Gas Company [Member] | Gas costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Current	29,486	1,979	6,046
Regulatory Assets, Noncurrent	5,742	3,925	94
Northwest Natural Gas Company [Member] | Environmental costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Current	5,688	4,992	4,176
Regulatory Assets, Noncurrent	85,423	90,623	81,757
Northwest Natural Gas Company [Member] | Decoupling [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Current	1,011	361	85
Regulatory Assets, Noncurrent	198	1,031	0
Northwest Natural Gas Company [Member] | Pension balancing [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Current	7,131	7,131	7,131
Regulatory Assets, Noncurrent	40,342	43,383	45,315
Northwest Natural Gas Company [Member] | Income taxes [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Current	2,345	3,484	2,208
Regulatory Assets, Noncurrent	13,903	15,368	17,608
Northwest Natural Gas Company [Member] | Pension and other postretirement benefit liabilities [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Noncurrent	160,385	170,812	164,091
Northwest Natural Gas Company [Member] | Other [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Current	11,618	9,600	7,419
Regulatory Assets, Noncurrent	$ 24,224	$ 20,893	$ 13,797

Significant Accounting Polici_5

Significant Accounting Policies - Regulatory Liability Disclosure - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	$ 103,210	$ 50,362	$ 41,126
Regulatory Liability, Noncurrent	645,046	639,663	632,400
Other [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Noncurrent	869	870	869
Northwest Natural Gas Company [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	103,210	50,362	41,126
Regulatory Liability, Noncurrent	644,177	638,793	631,531
Northwest Natural Gas Company [Member] | Gas costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	1,519	1,118	3,767
Regulatory Liability, Noncurrent	101	314	538
Northwest Natural Gas Company [Member] | Deferred Derivative Gain (Loss) [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	46,168	13,674	5,950
Regulatory Liability, Noncurrent	7,912	6,135	3,958
Northwest Natural Gas Company [Member] | Decoupling [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	5,821	11,793	11,498
Regulatory Liability, Noncurrent	652	1,723	2,108
Northwest Natural Gas Company [Member] | Income taxes [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	8,217	8,217	7,098
Regulatory Liability, Noncurrent	182,977	189,587	193,414
Northwest Natural Gas Company [Member] | Other [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	2,137	5,262	5,697
Regulatory Liability, Noncurrent	12,850	13,074	16,794
Northwest Natural Gas Company [Member] | Accrued asset removal costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Noncurrent	439,685	427,960	414,719
Northwest Natural Gas Company [Member] | Asset Optimization Revenue Sharing
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	$ 39,348	$ 10,298	$ 7,116

Significant Accounting Polici_6

Significant Accounting Policies - Credit Losses - ASU 2016-13 $ in Thousands	6 Months Ended
	Jun. 30, 2021USD ($)numberOfLeases	Dec. 31, 2020USD ($)	Jun. 30, 2020USD ($)
Accounts Receivable, Noncurrent, Credit Quality Indicator [Line Items]
Accounts Receivable, Allowance for Credit Loss	$ 3,283	$ 3,219
Accounts Receivable, Allowance for Credit Loss, Period Increase (Decrease)	1,015
Accounts Receivable, Allowance for Credit Loss, Recovery	(951)
Regulatory Assets, Noncurrent	$ 330,710	348,927	$ 324,358
Number of Net Investments in Sales-Type Leases | numberOfLeases	2
COVID-19 Related Costs
Accounts Receivable, Noncurrent, Credit Quality Indicator [Line Items]
Regulatory Assets, Noncurrent	$ 5,800
COVID-19 Related Costs | Accounts Receivable
Accounts Receivable, Noncurrent, Credit Quality Indicator [Line Items]
Regulatory Assets, Noncurrent	2,900
Residential [Member]
Accounts Receivable, Noncurrent, Credit Quality Indicator [Line Items]
Accounts Receivable, Allowance for Credit Loss	2,810	2,153
Accounts Receivable, Allowance for Credit Loss, Period Increase (Decrease)	1,294
Accounts Receivable, Allowance for Credit Loss, Recovery	(637)
Commercial [Member]
Accounts Receivable, Noncurrent, Credit Quality Indicator [Line Items]
Accounts Receivable, Allowance for Credit Loss	206	704
Accounts Receivable, Allowance for Credit Loss, Period Increase (Decrease)	(233)
Accounts Receivable, Allowance for Credit Loss, Recovery	(265)
Industrial [Member]
Accounts Receivable, Noncurrent, Credit Quality Indicator [Line Items]
Accounts Receivable, Allowance for Credit Loss	79	142
Accounts Receivable, Allowance for Credit Loss, Period Increase (Decrease)	(68)
Accounts Receivable, Allowance for Credit Loss, Writeoff	5
Accrued unbilled and other [Member]
Accounts Receivable, Noncurrent, Credit Quality Indicator [Line Items]
Accounts Receivable, Allowance for Credit Loss	188	$ 220
Accounts Receivable, Allowance for Credit Loss, Period Increase (Decrease)	22
Accounts Receivable, Allowance for Credit Loss, Recovery	$ (54)

Supplemental Cash Flow

Supplemental Cash Flow - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020	Dec. 31, 2019
Restricted Cash and Cash Equivalents Items [Line Items]
Cash and cash equivalents	$ 20,084	$ 30,168	$ 137,057
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	28,310	35,454	142,548	$ 12,636
Northwest Natural Gas Company [Member]
Restricted Cash and Cash Equivalents Items [Line Items]
Cash and cash equivalents	11,488	10,453	120,284
Restricted Cash	8,226	5,286	5,491
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	19,714	15,739	125,775	$ 8,907
Other Current Assets
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted Cash	$ 8,226	$ 5,286	$ 5,491

Earnings Per Share_2_3

Earnings Per Share - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Income Statement [Line Items]
Net income from continuing operations	$ (724)	$ (5,132)	$ 58,793	$ 43,144
Loss from discontinued operations, net of tax	0	280	0	(498)
Net income	$ (724)	$ (4,852)	$ 58,793	$ 42,646
Average common shares outstanding:
Average common shares outstanding - basic (in shares)	30,664	30,537	30,639	30,514
Additional shares for stock-based compensation plans	0	0	32	45
Average common shares outstanding - diluted (in shares)	30,664	30,537	30,671	30,559
Earnings from continuing operations per share of common stock:
Basic (in dollars per share)	$ (0.02)	$ (0.17)	$ 1.92	$ 1.41
Diluted (in dollars per share)	(0.02)	(0.17)	1.92	1.41
Loss from discontinued operations per share of common stock:
Basic (in dollars per share)	0	0.01	0	(0.01)
Diluted (in dollars per share)	0	0.01	0	(0.01)
Earnings (loss) per share of common stock
Basic (in dollars per share)	(0.02)	(0.16)	1.92	1.40
Diluted (in dollars per share)	$ (0.02)	$ (0.16)	$ 1.92	$ 1.40
Antidilutive shares	48	41	7	0
Discontinued Operations, Held-for-sale [Member] | Gill Ranch [Member]
Income Statement [Line Items]
Loss from discontinued operations, net of tax		$ 280		$ (498)
Loss from discontinued operations per share of common stock:
Basic (in dollars per share)	$ 0	$ 0.01	$ 0	$ (0.01)
Diluted (in dollars per share)	$ 0	$ 0.01	$ 0	$ (0.01)

Segment Information - Narrative

Segment Information - Narrative	6 Months Ended
	Jun. 30, 2021
Operating Segments [Member]
Segment Reporting Information [Line Items]
Number of Reportable Segments	1
Oregon [Member] | Northwest Holdings and Northwest Natural [Member] | Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Percent Of Pre Tax Income From Gas Storage Retained When The Costs Of The Capacity Are Not In Utility Rates	80.00%
Percent Of Pre Tax Income From Gas Storage Retained When The Costs Of The Capacity Are In Utility Rates	10.00%
Percent Of Pre Tax Income From Gas Storage Credited To Deferred Regulatory Account	20.00%
Percent Of Pre Tax Income From Gas Storage Credited To Deferred Regulatory Account When In Rates	90.00%

Segment Information - Schedule

Segment Information - Schedule of Summarized Financial Information by Segment - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Segment Reporting Information [Line Items]
Operating revenues	$ 148,917	$ 134,971	$ 464,863	$ 420,122
Depreciation and amortization	28,144	25,836	56,241	50,511
Income from operations	12,624	8,942	107,330	85,388
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	(724)	(5,132)	58,793	43,144
Total assets	3,783,500	3,641,347	3,783,500	3,641,347	$ 3,756,379
Discontinued operations - total assets		16,400		16,400
Natural Gas Distribution [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating revenues	139,614	126,992	440,952	405,479
Depreciation and amortization	27,273	24,738	54,186	48,684
Income from operations	11,331	6,434	97,818	81,692
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	(1,381)	(6,347)	52,544	41,596
Capital expenditures	60,376	61,472	124,368	117,629
Total assets	3,587,966	3,470,306	3,587,966	3,470,306	3,549,868
Other Northwest Natural [Member] | Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Operating revenues	4,965	4,165	15,977	8,207
Depreciation and amortization	257	248	513	492
Income from operations	2,808	2,465	11,439	4,228
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	1,970	1,635	8,156	2,871
Capital expenditures	693	521	799	598
Total assets	51,466	10,398	51,466	10,398	49,468
Northwest Natural Gas Company [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating revenues	144,579	131,157	456,929	413,686
Depreciation and amortization	27,530	24,986	54,699	49,176
Income from operations	14,139	8,899	109,257	85,920
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	589	(4,712)	60,700	44,467
Capital expenditures	61,069	61,993	125,167	118,227
Total assets	3,639,432	3,480,704	3,639,432	3,480,704	3,599,336
Other Northwest Holdings [Member] | Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Operating revenues	4,338	3,814	7,934	6,436
Depreciation and amortization	614	850	1,542	1,335
Income from operations	(1,515)	43	(1,927)	(532)
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	(1,313)	(420)	(1,907)	(1,323)
Capital expenditures	3,337	2,843	4,941	4,055
Total assets	144,068	144,251	144,068	144,251	157,043
Northwest Natural Gas Company [Member]
Segment Reporting Information [Line Items]
Operating revenues	144,579	131,157	456,929	413,686
Depreciation and amortization	27,530	24,986	54,699	49,176
Income from operations	14,139	8,899	109,257	85,920
Total assets	3,639,432	3,480,704	3,639,432	3,480,704	3,599,336
Northwest Natural Gas Company [Member] | Natural Gas Distribution [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating revenues	139,614	126,992	440,952	405,479
Northwest Natural Gas Company [Member] | Other Northwest Natural [Member] | Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Operating revenues	4,965	4,165	15,977	8,207
Northwest Natural Gas Company [Member] | Northwest Natural Gas Company [Member]
Segment Reporting Information [Line Items]
Operating revenues	144,579	131,157	456,929	413,686
Parent Company [Member]
Segment Reporting Information [Line Items]
Operating revenues	148,917	134,971	464,863	420,122
Depreciation and amortization	28,144	25,836	56,241	50,511
Income from operations	12,624	8,942	107,330	85,388
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	(724)	(5,132)	58,793	43,144
Capital expenditures	64,406	64,836	130,108	122,282
Total assets	$ 3,783,500	$ 3,624,955	$ 3,783,500	$ 3,624,955	$ 3,756,379

Segment Information - Additiona

Segment Information - Additional Segment Information - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Segment Reporting Information [Line Items]
Operating revenues	$ 148,917	$ 134,971	$ 464,863	$ 420,122
Cost of gas	41,193	41,210	153,403	149,748
Environmental remediation	1,509	1,622	5,286	5,627
Operating Segments [Member] | Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Natural Gas Distribution revenues	134,849	122,071	431,402	395,632
Other regulated services	4,765	4,921	9,550	9,847
Operating revenues	139,614	126,992	440,952	405,479
Cost of gas	41,249	41,265	153,515	149,860
Environmental remediation	1,509	1,622	5,286	5,627
Revenue taxes	5,650	4,454	18,305	16,197
NGD margin	$ 91,206	$ 79,651	$ 263,846	$ 233,795

Revenue - Disaggregation of Rev

Revenue - Disaggregation of Revenue - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	$ 133,441	$ 124,993	$ 444,547	$ 405,998
Revenues	148,917	134,971	464,863	420,122
Operating leases	25	25	43	53
Natural Gas Sales [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	123,739	116,682	419,822	390,686
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	2,805	2,449	5,300	4,785
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	817	910	7,745	1,060
Appliance Center Revenue [Member] | Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	1,343	806	2,932	2,362
Other revenue [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	4,737	4,146	8,748	7,105
Alternative revenue [Member]
Disaggregation of Revenue [Line Items]
Revenues	11,083	5,365	11,536	4,893
Leasing revenue [Member]
Disaggregation of Revenue [Line Items]
Operating leases	4,393	4,613	8,780	9,231
Northwest Natural Gas Company [Member]
Disaggregation of Revenue [Line Items]
Revenues	144,579	131,157	456,929	413,686
Northwest Natural Gas Company [Member] | Northwest Natural Gas Company [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	129,103	121,179	436,613	399,562
Revenues	144,579	131,157	456,929	413,686
Northwest Natural Gas Company [Member] | Northwest Natural Gas Company [Member] | Natural Gas Sales [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	123,739	116,682	419,822	390,686
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	2,805	2,449	5,300	4,785
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	817	910	7,745	1,060
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	1,343	806	2,932	2,362
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	399	332	814	669
Northwest Natural Gas Company [Member] | Northwest Natural Gas Company [Member] | Alternative revenue [Member]
Disaggregation of Revenue [Line Items]
Revenues	11,083	5,365	11,536	4,893
Northwest Natural Gas Company [Member] | Northwest Natural Gas Company [Member] | Leasing revenue [Member]
Disaggregation of Revenue [Line Items]
Operating leases	4,393	4,613	8,780	9,231
Operating Segments [Member] | Natural Gas Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenues	139,614	126,992	440,952	405,479
Operating Segments [Member] | Natural Gas Distribution [Member] | Northwest Natural Gas Company [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	124,138	117,014	420,636	391,355
Revenues	139,614	126,992	440,952	405,479
Operating Segments [Member] | Natural Gas Distribution [Member] | Northwest Natural Gas Company [Member] | Natural Gas Sales [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	123,739	116,682	419,822	390,686
Operating Segments [Member] | Natural Gas Distribution [Member] | Northwest Natural Gas Company [Member] | Gas Storage Revenue, Net of Regulatory Sharing [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Operating Segments [Member] | Natural Gas Distribution [Member] | Northwest Natural Gas Company [Member] | Asset Management Revenue, Net of Regulatory Sharing [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Operating Segments [Member] | Natural Gas Distribution [Member] | Northwest Natural Gas Company [Member] | Appliance Center Revenue [Member] | Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0	0	0
Operating Segments [Member] | Natural Gas Distribution [Member] | Northwest Natural Gas Company [Member] | Other revenue [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	399	332	814	669
Operating Segments [Member] | Natural Gas Distribution [Member] | Northwest Natural Gas Company [Member] | Alternative revenue [Member]
Disaggregation of Revenue [Line Items]
Revenues	11,083	5,365	11,536	4,893
Operating Segments [Member] | Natural Gas Distribution [Member] | Northwest Natural Gas Company [Member] | Leasing revenue [Member]
Disaggregation of Revenue [Line Items]
Operating leases	4,393	4,613	8,780	9,231
Operating Segments [Member] | Northwest Natural Gas Company [Member]
Disaggregation of Revenue [Line Items]
Revenues	144,579	131,157	456,929	413,686
Corporate, Non-Segment [Member] | Other Northwest Natural [Member]
Disaggregation of Revenue [Line Items]
Revenues	4,965	4,165	15,977	8,207
Corporate, Non-Segment [Member] | Other Northwest Natural [Member] | Northwest Natural Gas Company [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	4,965	4,165	15,977	8,207
Revenues	4,965	4,165	15,977	8,207
Corporate, Non-Segment [Member] | Other Northwest Natural [Member] | Northwest Natural Gas Company [Member] | Natural Gas Sales [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0	0
Corporate, Non-Segment [Member] | Other Northwest Natural [Member] | Northwest Natural Gas Company [Member] | Gas Storage Revenue, Net of Regulatory Sharing [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	2,805	2,449	5,300	4,785
Corporate, Non-Segment [Member] | Other Northwest Natural [Member] | Northwest Natural Gas Company [Member] | Asset Management Revenue, Net of Regulatory Sharing [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	817	910	7,745	1,060
Corporate, Non-Segment [Member] | Other Northwest Natural [Member] | Northwest Natural Gas Company [Member] | Appliance Center Revenue [Member] | Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	1,343	806	2,932	2,362
Corporate, Non-Segment [Member] | Other Northwest Natural [Member] | Northwest Natural Gas Company [Member] | Other revenue [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0	0
Corporate, Non-Segment [Member] | Other Northwest Natural [Member] | Northwest Natural Gas Company [Member] | Alternative revenue [Member]
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Corporate, Non-Segment [Member] | Other Northwest Natural [Member] | Northwest Natural Gas Company [Member] | Leasing revenue [Member]
Disaggregation of Revenue [Line Items]
Operating leases	0	0	0	0
Corporate, Non-Segment [Member] | Other Northwest Holdings [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	4,338	3,814	7,934	6,436
Revenues	4,338	3,814	7,934	6,436
Corporate, Non-Segment [Member] | Other Northwest Holdings [Member] | Natural Gas Sales [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0	0
Corporate, Non-Segment [Member] | Other Northwest Holdings [Member] | Gas Storage Revenue, Net of Regulatory Sharing [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0	0
Corporate, Non-Segment [Member] | Other Northwest Holdings [Member] | Asset Management Revenue, Net of Regulatory Sharing [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0	0
Corporate, Non-Segment [Member] | Other Northwest Holdings [Member] | Appliance Center Revenue [Member] | Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0	0	0	0
Corporate, Non-Segment [Member] | Other Northwest Holdings [Member] | Other revenue [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	4,338	3,814	7,934	6,436
Corporate, Non-Segment [Member] | Other Northwest Holdings [Member] | Alternative revenue [Member]
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Corporate, Non-Segment [Member] | Other Northwest Holdings [Member] | Leasing revenue [Member]
Disaggregation of Revenue [Line Items]
Operating leases	$ 0	$ 0	$ 0	$ 0

Revenue - Revenue, Remaining Pe

Revenue - Revenue, Remaining Performance Obligation $ in Thousands	Jun. 30, 2021USD ($)
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	$ 79,200
Natural Gas Distribution [Member] | Northwest Natural Gas Company [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Contract with Customer, Refund Liability	0
Other Northwest Natural [Member] | Northwest Natural Gas Company [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Contract with Customer, Refund Liability	0
Other Northwest Holdings [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Contract with Customer, Refund Liability	$ 0
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-07-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Year	6 months
Revenue, Remaining Performance Obligation, Amount	$ 9,600
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Year	1 year
Revenue, Remaining Performance Obligation, Amount	$ 19,400
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, Expected Timing of Satisfaction, Year	1 year
Revenue, Remaining Performance Obligation, Amount	$ 17,800
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Year	1 year
Revenue, Remaining Performance Obligation, Amount	$ 14,000
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Year	1 year
Revenue, Remaining Performance Obligation, Amount	$ 11,100
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2026-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Year	0 years
Revenue, Remaining Performance Obligation, Amount	$ 7,300

Leases - Lease Revenue

Leases - Lease Revenue - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Lessor, Lease, Description [Line Items]
Lessor, Sales-type Lease, Renewal Term	50 years		50 years
Lessor, Sales-type Lease, Term of Contract	30 years		30 years
Residual Value of Leased Asset	$ 4,500	$ 4,100	$ 4,500	$ 4,100	$ 4,300
Lease Revenue [Abstract]
Operating leases	25	25	43	53
Sales-type leases	4,368	4,588	8,737	9,178
Total lease revenue	4,393	$ 4,613	8,780	$ 9,231
Operating Leases Payment to be Received [Abstract]
Operating Lease, Payments to be Received, Remainder of Fiscal Year	61		61
Operating Lease, Payments to be Received, Two Years	115		115
Operating Lease, Payments to be Received, Three Years	117		117
Operating Lease, Payments to be Received, Four Years	113		113
Operating Lease, Payments to be Received, Thereafter	1,199		1,199
Total lease revenue	1,727		1,727
Total Lease Payments to be Received [Abstract]
Lease Payments to be Received, Remainder of Fiscal Year	8,762		8,762
Lease Payments to be Received, Two Years	17,148		17,148
Lease Payments to be Received, Three Years	16,672		16,672
Lease Payments to be Received, Four Years	15,984		15,984
Lease Payments to be Received, Five Years	15,419		15,419
Lease Payments to be Received, Thereafter	252,920		252,920
Total lease revenue	326,905		326,905
Lessor, Operating Lease, Payment to be Received, Year One	122		122
Northwest Natural Gas Company [Member]
Operating Leases Payment to be Received [Abstract]
Operating Lease, Payments to be Received, Remainder of Fiscal Year	36		36
Operating Lease, Payments to be Received, Two Years	64		64
Operating Lease, Payments to be Received, Three Years	65		65
Operating Lease, Payments to be Received, Four Years	60		60
Operating Lease, Payments to be Received, Thereafter	229		229
Total lease revenue	526		526
Total Lease Payments to be Received [Abstract]
Lease Payments to be Received, Remainder of Fiscal Year	8,737		8,737
Lease Payments to be Received, Two Years	17,098		17,098
Lease Payments to be Received, Three Years	16,621		16,621
Lease Payments to be Received, Four Years	15,932		15,932
Lease Payments to be Received, Five Years	15,366		15,366
Lease Payments to be Received, Thereafter	251,950		251,950
Total lease revenue	325,704		325,704
Lessor, Operating Lease, Payment to be Received, Year One	72		72
Other Northwest Holdings [Member]
Operating Leases Payment to be Received [Abstract]
Operating Lease, Payments to be Received, Remainder of Fiscal Year	25		25
Operating Lease, Payments to be Received, Two Years	51		51
Operating Lease, Payments to be Received, Three Years	52		52
Operating Lease, Payments to be Received, Four Years	53		53
Operating Lease, Payments to be Received, Thereafter	970		970
Total lease revenue	1,201		1,201
Total Lease Payments to be Received [Abstract]
Lease Payments to be Received, Remainder of Fiscal Year	25		25
Lease Payments to be Received, Two Years	50		50
Lease Payments to be Received, Three Years	51		51
Lease Payments to be Received, Four Years	52		52
Lease Payments to be Received, Five Years	53		53
Lease Payments to be Received, Thereafter	970		970
Total lease revenue	1,201		1,201
Lessor, Operating Lease, Payment to be Received, Year One	$ 50		$ 50
Compressed Natural Gas Lease [Member]
Lessor, Lease, Description [Line Items]
Lessor, Sales-type Lease, Term of Contract	10 years		10 years
Residual Value of Leased Asset	$ 0		$ 0
Variable Lease, Payment			0
North Mist Lease [Member]
Lessor, Lease, Description [Line Items]
Residual Value of Leased Asset	0		0
Variable Lease, Payment			0
Sales-type Lease [Member]
Sales-type Leases Payments to be Received [Abstract]
Sales-type Lease, Payments to be Received, Remainder of Fiscal Year	8,701		8,701
Sales-type Lease, Payments to be Received, Two Years	16,557		16,557
Sales-type Lease, Payments to be Received, Three Years	15,867		15,867
Sales-type Lease, Payments to be Received, Four Years	15,306		15,306
Sales-type Lease, Payments to be Received, Thereafter	251,721		251,721
Total lease revenue	325,178		325,178
Less: imputed interest	183,237		183,237
Total leases receivable	141,941		141,941
Total Lease Payments to be Received [Abstract]
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year One	17,026		17,026
Sales-type Lease [Member] | Northwest Natural Gas Company [Member]
Sales-type Leases Payments to be Received [Abstract]
Sales-type Lease, Payments to be Received, Remainder of Fiscal Year	8,701		8,701
Sales-type Lease, Payments to be Received, Two Years	16,557		16,557
Sales-type Lease, Payments to be Received, Three Years	15,867		15,867
Sales-type Lease, Payments to be Received, Four Years	15,306		15,306
Sales-type Lease, Payments to be Received, Thereafter	251,721		251,721
Total lease revenue	325,178		325,178
Less: imputed interest	183,237		183,237
Total leases receivable	141,941		141,941
Total Lease Payments to be Received [Abstract]
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year One	17,026		17,026
Sales-type Lease [Member] | Other Northwest Holdings [Member]
Sales-type Leases Payments to be Received [Abstract]
Sales-type Lease, Payments to be Received, Remainder of Fiscal Year	0		0
Sales-type Lease, Payments to be Received, Two Years	0		0
Sales-type Lease, Payments to be Received, Three Years	0		0
Sales-type Lease, Payments to be Received, Four Years	0		0
Sales-type Lease, Payments to be Received, Thereafter	0		0
Total lease revenue	0		0
Total Lease Payments to be Received [Abstract]
Sales-Type and Direct Financing Leases, Lease Receivable, to be Received, Year One	$ 0		$ 0

Leases - Lease Expense

Leases - Lease Expense - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Lessee, Lease, Description [Line Items]
Residual Value of Leased Asset	$ 4,500	$ 4,100	$ 4,500	$ 4,100	$ 4,300
Lease Expense [Abstract]
Operating Lease, Expense	1,728	954	3,424	2,208
Short-term Lease, Cost	$ 349	285	$ 569	483
Minimum [Member]
Operating Lease Terms [Abstract]
Lessee, Operating Lease, Term of Contract	2 months		2 months
Maximum [Member]
Operating Lease Terms [Abstract]
Lessee, Operating Lease, Term of Contract	19 years		19 years
Northwest Natural Gas Company [Member]
Lease Expense [Abstract]
Operating Lease, Expense	$ 1,710	914	$ 3,388	2,116
Short-term Lease, Cost	349	285	569	483
Other Northwest Holdings [Member] | Corporate, Non-Segment [Member]
Lease Expense [Abstract]
Operating Lease, Expense	$ 18	$ 40	$ 36	$ 92

Leases - Lease Asset and Liabil

Leases - Lease Asset and Liabilities - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Operating Lease Asset and Liabilities [Abstract]
Operating lease right of use asset	$ 76,294	$ 78,566	$ 76,294	$ 78,566	$ 77,446
Operating lease liabilities current liabilities	1,228	931	1,228	931	1,105
Operating lease liabilities noncurrent liabilities	80,088	80,159	80,088	80,159	80,621
Total operating lease liabilities	$ 81,316	$ 81,090	$ 81,316	$ 81,090	$ 81,726
Operating Lease, Weighted Average Remaining Lease Term	18 years 8 months 12 days	19 years 8 months 12 days	18 years 8 months 12 days	19 years 8 months 12 days	19 years 2 months 12 days
Operating Lease, Weighted Average Discount Rate, Percent	7.20%	7.20%	7.20%	7.20%	7.20%
Commencement of Significant Lease [Abstract]
Lessee, Operating Lease, Liability, Payments, Due	$ 155,574		$ 155,574
Regulatory Assets, Noncurrent	330,710	$ 324,358	330,710	$ 324,358	$ 348,927
Maturity of Operating Lease Liabilities [Abstract]
Lessee, Operating Lease, Liability, Payments, Remainder of Fiscal Year	3,470		3,470
Lessee, Operating Lease, Liability, to be Paid, Year One	6,957		6,957
Lessee, Operating Lease, Liability, Payments, Due Year Two	6,992		6,992
Lessee, Operating Lease, Liability, Payments, Due Year Three	7,156		7,156
Lessee, Operating Lease, Liability, Payments, Due Year Four	7,191		7,191
Lessee, Operating Lease, Liability, Payments, Due after Year Five	123,808		123,808
Lessee, Operating Lease, Liability, Payments, Due	155,574		155,574
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	74,258		74,258
Total operating lease liabilities	81,316	81,090	81,316	81,090	81,726
Operating lease liabilities current liabilities	1,228	931	1,228	931	1,105
Operating lease liabilities noncurrent liabilities	80,088	80,159	80,088	80,159	80,621
Finance Lease, Liability, Payments, Due Next Twelve Months	200		200
Leases Cash Flow [Abstract]
Operating cash flows from operating leases	1,734	970	3,419	2,218
Finance Lease, Principal Payments	134	302	678	457
Operating leases	0	445	154	78,433
Right-of-Use Asset Obtained in Exchange for Finance Lease Liability	20	477	94	710
Finance Leases [Abstract]
Finance Lease, Right-of-Use Asset	1,900	1,100	1,900	1,100	1,800
Finance Lease, Liability	0		0
Other Northwest Holdings [Member] | Corporate, Non-Segment [Member]
Operating Lease Asset and Liabilities [Abstract]
Operating lease right of use asset	83	102	83	102	118
Operating lease liabilities current liabilities	35	63	35	63	51
Operating lease liabilities noncurrent liabilities	45	39	45	39	62
Total operating lease liabilities	80	102	80	102	113
Commencement of Significant Lease [Abstract]
Lessee, Operating Lease, Liability, Payments, Due	91		91
Maturity of Operating Lease Liabilities [Abstract]
Lessee, Operating Lease, Liability, Payments, Remainder of Fiscal Year	25		25
Lessee, Operating Lease, Liability, to be Paid, Year One	24		24
Lessee, Operating Lease, Liability, Payments, Due Year Two	6		6
Lessee, Operating Lease, Liability, Payments, Due Year Three	6		6
Lessee, Operating Lease, Liability, Payments, Due Year Four	6		6
Lessee, Operating Lease, Liability, Payments, Due after Year Five	24		24
Lessee, Operating Lease, Liability, Payments, Due	91		91
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	11		11
Total operating lease liabilities	80	102	80	102	113
Operating lease liabilities current liabilities	35	63	35	63	51
Operating lease liabilities noncurrent liabilities	45	39	45	39	62
Leases Cash Flow [Abstract]
Operating cash flows from operating leases	17	39	33	91
Northwest Natural Gas Company [Member]
Operating Lease Asset and Liabilities [Abstract]
Operating lease right of use asset	76,211	78,464	76,211	78,464	77,328
Operating lease liabilities current liabilities	1,193	868	1,193	868	1,054
Operating lease liabilities noncurrent liabilities	80,043	80,120	80,043	80,120	80,559
Total operating lease liabilities	81,236	80,988	81,236	80,988	81,613
Commencement of Significant Lease [Abstract]
Lessee, Operating Lease, Liability, Payments, Due	155,483		155,483
Regulatory Assets, Noncurrent	330,670	324,320	330,670	324,320	348,887
Maturity of Operating Lease Liabilities [Abstract]
Lessee, Operating Lease, Liability, Payments, Remainder of Fiscal Year	3,445		3,445
Lessee, Operating Lease, Liability, to be Paid, Year One	6,933		6,933
Lessee, Operating Lease, Liability, Payments, Due Year Two	6,986		6,986
Lessee, Operating Lease, Liability, Payments, Due Year Three	7,150		7,150
Lessee, Operating Lease, Liability, Payments, Due Year Four	7,185		7,185
Lessee, Operating Lease, Liability, Payments, Due after Year Five	123,784		123,784
Lessee, Operating Lease, Liability, Payments, Due	155,483		155,483
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	74,247		74,247
Total operating lease liabilities	81,236	80,988	81,236	80,988	81,613
Operating lease liabilities current liabilities	1,193	868	1,193	868	1,054
Operating lease liabilities noncurrent liabilities	80,043	80,120	80,043	80,120	80,559
Leases Cash Flow [Abstract]
Operating cash flows from operating leases	1,717	931	3,386	2,127
Finance Lease, Principal Payments	134	302	678	457
Operating leases	0	445	154	78,433
Right-of-Use Asset Obtained in Exchange for Finance Lease Liability	$ 20	477	$ 94	710
New Headquarters Lease [Member]
Commencement of Significant Lease [Abstract]
Lessee, Operating Lease, Term of Contract	20 years		20 years
Lessee, Operating Lease, Liability, Payments, Due	$ 159,400		$ 159,400
Regulatory Assets, Noncurrent	5,000	$ 2,400	5,000	$ 2,400	$ 4,200
Maturity of Operating Lease Liabilities [Abstract]
Lessee, Operating Lease, Liability, Payments, Due	$ 159,400		$ 159,400
New Headquarters Lease Renewal Term 2 of 2 [Member] | New Headquarters Lease [Member]
Commencement of Significant Lease [Abstract]
Lessee, Operating Lease, Renewal Term	7 years		7 years
New Headquarters Lease Renewal Term 1 of 2 [Member] | New Headquarters Lease [Member]
Commencement of Significant Lease [Abstract]
Lessee, Operating Lease, Renewal Term	7 years		7 years
Maximum [Member]
Commencement of Significant Lease [Abstract]
Lessee, Operating Lease, Term of Contract	19 years		19 years

Stock-Based Compensation_2

Stock-Based Compensation $ / shares in Units, $ in Thousands	6 Months Ended
	Jun. 30, 2021USD ($)$ / sharesshares
Long Term Incentive Plan | Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares granted (in shares)	28,866
Award vesting period	3 years
Unrecognized compensation costs | $	$ 200
Long Term Incentive Plan | Performance Shares | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Conversion ratio, percent of target	0.00%
Long Term Incentive Plan | Performance Shares | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Conversion ratio, percent of target	200.00%
Long Term Incentive Plan | Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	4 years
Number of RSUs granted in period (in shares)	37,756
Weighted-average grant date fair value (in dollars per share) | $ / shares	$ 49.16
Unrecognized compensation costs | $	$ 4,200
Restated Stock Option Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number	0
A 2020 and 2021 Award | Long Term Incentive Plan | Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Payment Arrangement, Expense | $	$ 0
Target Achieved [Member] | A 2020 Award [Member] | Long Term Incentive Plan | Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share Based Compensation Award Target Share	31,830
Target Achieved [Member] | A 2021 Award | Long Term Incentive Plan | Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share Based Compensation Award Target Share	56,335

Debt Short-term Debt

Debt Short-term Debt $ in Thousands	6 Months Ended
	Jun. 30, 2021USD ($)	Dec. 31, 2020USD ($)	Jun. 30, 2020USD ($)
Short-term Debt [Line Items]
Ratio of Indebtedness to Net Capital	0.568
Short-term debt	$ 240,000	$ 304,525	$ 233,000
Commercial Paper Maximum Maturity	29 days
Commercial Paper Average Maturity	15 days
Northwest Natural Gas Company [Member]
Short-term Debt [Line Items]
Ratio of Indebtedness to Net Capital	0.562
Short-term debt	$ 198,000	$ 231,525	$ 153,000
Line of Credit [Member]
Short-term Debt [Line Items]
Short-term debt	$ 42,000
Debt, Weighted Average Interest Rate	1.10%
Commercial Paper [Member] | Northwest Natural Gas Company [Member]
Short-term Debt [Line Items]
Short-term debt	$ 98,000
Debt, Weighted Average Interest Rate	0.20%
364-Day Term Loan, Due 2022 | Northwest Natural Gas Company [Member]
Short-term Debt [Line Items]
Proceeds from Issuance of Debt	$ 100,000
Debt, Weighted Average Interest Rate	0.60%

Long-Term Debt

Long-Term Debt $ in Thousands	6 Months Ended
	Jun. 30, 2021USD ($)	Jun. 30, 2020USD ($)	Dec. 31, 2020USD ($)
Debt Instrument [Line Items]
Long-term Debt	$ 975,775	$ 954,096	$ 955,425
Unamortized debt issuance costs	$ 7,446	7,688	7,480
Ratio of Indebtedness to Net Capital	0.568
Northwest Natural Gas Company [Member]
Debt Instrument [Line Items]
Long-term Debt	$ 917,409	917,012	917,220
Unamortized debt issuance costs	$ 7,291	7,688	$ 7,480
Weighted average interest rate	4.60%
Ratio of Indebtedness to Net Capital	0.562
Northwest Natural Gas Company [Member] | Minimum [Member]
Debt Instrument [Line Items]
Stated interest rate	2.80%
Northwest Natural Gas Company [Member] | Maximum [Member]
Debt Instrument [Line Items]
Stated interest rate	9.10%
Two-year Term Loan Due 2021 [Member]
Debt Instrument [Line Items]
Proceeds from Issuance of Debt		$ 35,000
Debt Instrument Covenant Consolidated Indebtedness to Capitalization Ratio	70.00%
364-Day Term Loan, Due 2022 | Northwest Natural Gas Company [Member]
Debt Instrument [Line Items]
Proceeds from Issuance of Debt	$ 100,000
Five-year Term Loan Due 2026
Debt Instrument [Line Items]
Stated interest rate	0.90%
Proceeds from Issuance of Debt	$ 55,000

Debt Fair Value of Long Term De

Debt Fair Value of Long Term Debt - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020
Debt Instrument [Line Items]
Gross long-term debt	$ 983,221	$ 962,905	$ 961,784
Unamortized debt issuance costs	(7,446)	(7,480)	(7,688)
Carrying amount	975,775	955,425	954,096
Estimated fair value	1,104,230	1,136,311	1,135,349
Northwest Natural Gas Company [Member]
Debt Instrument [Line Items]
Gross long-term debt	924,700	924,700	924,700
Unamortized debt issuance costs	(7,291)	(7,480)	(7,688)
Carrying amount	917,409	917,220	917,012
Estimated fair value	$ 1,043,696	$ 1,097,348	$ 1,097,188

Pension and Other Postretirem_3

Pension and Other Postretirement Benefit Costs - Net Periodic Benefit Cost - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Pension Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 1,714	$ 1,658	$ 3,428	$ 3,315
Interest cost	3,342	4,011	6,685	8,022
Expected return on plan assets	(6,099)	(5,496)	(12,198)	(10,992)
Amortization of net actuarial loss	0	0	0	0
Defined Benefit Plan, Amortization of Gain (Loss)	5,500	4,778	11,001	9,556
Net periodic benefit cost	4,457	4,951	8,916	9,901
Amount allocated to construction	(743)	(680)	(1,469)	(1,348)
Defined Benefit Plan Net Periodic Benefit Cost Charged To Expense	3,714	4,271	7,447	8,553
Amortization of Regulatory Balancing Account	1,281	1,281	4,082	4,082
Net amount charged to expense	4,995	5,552	11,529	12,635
Other Postretirement Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	56	64	111	128
Interest cost	165	223	330	446
Expected return on plan assets	0	0	0	0
Amortization of net actuarial loss	(117)	(117)	(234)	(234)
Defined Benefit Plan, Amortization of Gain (Loss)	131	142	262	285
Net periodic benefit cost	235	312	469	625
Amount allocated to construction	(22)	(23)	(43)	(46)
Defined Benefit Plan Net Periodic Benefit Cost Charged To Expense	213	289	426	579
Amortization of Regulatory Balancing Account	0	0	0	0
Net amount charged to expense	$ 213	$ 289	$ 426	$ 579

Pension and Other Postretirem_4

Pension and Other Postretirement Benefit Costs - Amounts Recognized in Accumulated Other Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]
Beginning balance	$ (12,681)	$ (10,573)	$ (12,902)	$ (10,733)
Amortization of actuarial losses	301	218	602	436
Total reclassifications before tax	301	218	602	436
Tax benefit	(80)	(58)	(160)	(116)
Total reclassifications for the period	221	160	442	320
Ending balance	$ (12,460)	$ (10,413)	$ (12,460)	$ (10,413)

Pension and Other Postretirem_5

Pension and Other Postretirement Benefit Costs - Narrative - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Pension and Other Postretirement Benefits Cost (Reversal of Cost) [Abstract]
Employer contributions	$ 4.7	$ 4.4
Defined benefit pension plan cash contributions	$ 9.6

Income Tax_2_3

Income Tax - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Income taxes at statutory rates (federal and state)	$ (210)	$ (1,429)	$ 16,598	$ 11,676
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount	(48)	(333)	7,260	3,344
Differences required to be flowed-through by regulatory commissions	21	173	(3,584)	(2,352)
Other, net	(40)	(83)	(30)	(213)
Total provision for income taxes on continuing operations	$ (277)	$ (1,672)	$ 20,244	$ 12,455
Effective tax rate for continuing operations	27.70%	24.60%	25.60%	22.40%
Northwest Natural Gas Company [Member]
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Income taxes at statutory rates (federal and state)	$ 184	$ (1,287)	$ 17,123	$ 12,068
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount	41	(281)	7,366	3,456
Differences required to be flowed-through by regulatory commissions	21	173	(3,584)	(2,352)
Other, net	42	(24)	(65)	(173)
Total provision for income taxes on continuing operations	$ 288	$ (1,419)	$ 20,840	$ 12,999
Effective tax rate for continuing operations	32.80%	23.10%	25.60%	22.60%

Property, Plant and Equipment_3

Property, Plant and Equipment - USD ($)	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020
Property, Plant and Equipment [Line Items]
Property, plant, and equipment	$ 3,849,792,000	$ 3,734,039,000	$ 3,608,902,000
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	1,093,863,000	1,079,269,000	1,062,299,000
Property, Plant and Equipment, Net	2,755,929,000	2,654,770,000	2,546,603,000
Natural Gas Distribution [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment	3,623,092,000	3,548,543,000	3,404,145,000
Public Utilities, Property, Plant and Equipment, Construction Work in Progress	99,646,000	63,901,000	90,903,000
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	1,068,603,000	1,055,809,000	1,040,616,000
Property, Plant and Equipment, Net	2,654,135,000	2,556,635,000	2,454,432,000
Other Northwest Natural [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment	66,315,000	66,300,000	64,317,000
Public Utilities, Property, Plant and Equipment, Construction Work in Progress	5,817,000	5,032,000	5,342,000
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	20,140,000	19,637,000	19,144,000
Property, Plant and Equipment, Net	51,992,000	51,695,000	50,515,000
Northwest Natural Gas Company [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Net	2,706,127,000	2,608,330,000	2,504,947,000
Property, Plant, Equipment non-cash	37,968,000	25,129,000	31,847,000
Other Northwest Holdings [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment	54,922,000	50,263,000	44,195,000
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	5,120,000	3,823,000	2,539,000
Property, Plant and Equipment, Net	49,802,000	46,440,000	41,656,000
Northwest Holdings [Member]
Property, Plant and Equipment [Line Items]
Property, Plant, Equipment non-cash	38,395	25,129	31,847
Northwest Natural Gas Company [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment	3,794,870,000	3,683,776,000	3,564,707,000
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	1,088,743,000	1,075,446,000	1,059,760,000
Property, Plant and Equipment, Net	$ 2,706,127,000	$ 2,608,330,000	$ 2,504,947,000

Gas Reserves_2_3

Gas Reserves	6 Months Ended
	Jun. 30, 2021USD ($)
Reserve Quantities [Line Items]
Total cumulative gas reserves investment	$ 188,000,000
Term of hedge rate	10 years
Encana Oil & Gas (USA) Inc.
Reserve Quantities [Line Items]
Gas reserves investment	$ 178,000,000
Jonah Energy LLC
Reserve Quantities [Line Items]
Gas reserves investment	10,000,000
Additional rate per therm	$ 0.4725

Gas Reserves - Investment

Gas Reserves - Investment - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020
Reserve Quantities [Line Items]
Gas reserves	$ 8,444	$ 11,409	$ 13,646
Gas reserves, non-current	178,863	175,898	173,661
Less: Accumulated amortization	149,011	141,414	132,202
Total gas reserves	38,296	45,893	55,105
Less: Deferred taxes on gas reserves	8,760	10,572	13,324
Net investment in gas reserves	29,536	35,321	41,781
Jonah Energy LLC
Reserve Quantities [Line Items]
Total Gas Reserves Investment	$ 2,700	$ 3,000	$ 3,400

Investments_2

Investments - USD ($) $ in Millions	3 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Jun. 30, 2020
Schedule of Equity Method Investments [Line Items]
Percentage of Equity Method Investment Sold		100.00%
Investment balance in TWH			$ 13.4
Equity Method Investment, Realized Gain (Loss) on Disposal		$ 0.5
Forecast [Member]
Schedule of Equity Method Investments [Line Items]
Proceeds from Sale of Equity Method Investments	$ 14
Cash and Cash Equivalents [Member]
Schedule of Equity Method Investments [Line Items]
Proceeds from Sale of Equity Method Investments		7
Notes Receivable [Member]
Schedule of Equity Method Investments [Line Items]
Proceeds from Sale of Equity Method Investments		$ 7

Business Combinations Busines_2

Business Combinations Business Combinations	6 Months Ended
	Jun. 30, 2021USD ($)numberOfConnections	Jun. 30, 2020USD ($)	Dec. 31, 2020USD ($)
Business Acquisition [Line Items]
Goodwill	$ 69,313,000	$ 70,183,000	$ 69,225,000
Goodwill, Impairment Loss	0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets [Abstract]
Goodwill	69,313,000	70,183,000	$ 69,225,000
Suncadia & T&W Water [Member]
Business Acquisition [Line Items]
Business Combination, Consideration Transferred		$ 38,100,000
Goodwill	18,200,000
Business Acquisition, Goodwill, Expected Tax Deductible Amount	16,500,000
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill	0
Number of Businesses Acquired		2
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets [Abstract]
Goodwill	$ 18,200,000
Other insignificant acquisitions [Member]
Business Acquisition [Line Items]
Business Combination, Consideration Transferred		$ 1,500,000
Number of Businesses Acquired	1	3

Derivative Instruments Notional

Derivative Instruments Notional Amounts therm in Thousands	Jun. 30, 2021USD ($)therm	Dec. 31, 2020USD ($)therm	Jun. 30, 2020USD ($)therm
Collateral Posted with NW Natural Counterparties [Member]
Derivative [Line Items]
Additional Collateral, Aggregate Fair Value | $	$ 0		$ 0
Northwest Natural Gas Company [Member] | Financial [Member] | Gas Year 2019 - 2020 [Member]
Derivative [Line Items]
TargetHedgeAchieved	52.00%
Northwest Natural Gas Company [Member] | Financial [Member] | Gas Year 2020 - 2021
Derivative [Line Items]
TargetHedgeAchieved	53.00%
Northwest Natural Gas Company [Member] | Physical [Member] | Gas Year 2019 - 2020 [Member]
Derivative [Line Items]
TargetHedgeAchieved	19.00%
Northwest Natural Gas Company [Member] | Physical [Member] | Gas Year 2020 - 2021
Derivative [Line Items]
TargetHedgeAchieved	17.00%
Northwest Natural Gas Company [Member] | Natural Gas Therms [Member] | Financial [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount | therm	680,335	784,400	654,145
Northwest Natural Gas Company [Member] | Natural Gas Therms [Member] | Physical [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount | therm	419,148	457,593	570,600
Northwest Natural Gas Company [Member] | Foreign Exchange Contract [Member]
Derivative [Line Items]
Derivative, Notional Amount | $	$ 6,477,000	$ 5,896,000	$ 7,176,000

Derivative Instruments Fair Val

Derivative Instruments Fair Value - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020
Derivative [Line Items]
Derivative, Fair Value, Net	$ 50.2	$ 12.8	$ 5.2

Unrealized and Realized Gain_Lo

Unrealized and Realized Gain/Loss - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Derivative [Line Items]
Derivative, Gain on Derivative	$ 4,200		$ 9,300
Financial [Member]
Derivative [Line Items]
Derivative, Loss on Derivative		$ (1,100)		$ (3,200)
Incremental Cost or Benefit to Collect or Refund to Customers			0
Northwest Holdings and Northwest Natural [Member] | Natural gas commodity
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	0	(127)	4	244
Northwest Holdings and Northwest Natural [Member] | Foreign exchange
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	0	0	0	0
Northwest Holdings and Northwest Natural [Member] | Benefit (expense) to cost of gas | Natural gas commodity
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	(16,323)	5,492	(36,805)	149
Northwest Holdings and Northwest Natural [Member] | Benefit (expense) to cost of gas | Foreign exchange
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	45	(459)	(32)	7
Northwest Holdings and Northwest Natural [Member] | Sales [Member] | Natural gas commodity
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	0	(754)	27	1,679
Northwest Holdings and Northwest Natural [Member] | Sales [Member] | Foreign exchange
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	0	0	0	0
Deferred Derivative Gain (Loss) [Member] | Northwest Holdings and Northwest Natural [Member] | Natural gas commodity
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	16,323	6,119	36,782	(1,286)
Deferred Derivative Gain (Loss) [Member] | Northwest Holdings and Northwest Natural [Member] | Foreign exchange
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	$ (45)	$ 459	$ 32	$ (7)

Derivative Instruments Credit R

Derivative Instruments Credit Rating - USD ($)	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Derivative [Line Items]
Unrealized losses on derivatives	$ (54,300,000)	$ (5,300,000)
Collateral Posted with NW Natural Counterparties [Member]
Derivative [Line Items]
Additional Collateral, Aggregate Fair Value	0	0
Northwest Natural Gas Company [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	51,800,000	6,700,000	$ 14,100,000
Derivative liability	$ 1,600,000	$ 1,500,000	$ 1,300,000

Environmental Matters_2_3

Environmental Matters	Jun. 30, 2021
Oregon [Member]
Site Contingency [Line Items]
Remediation Recovery Percentage	96.70%
WASHINGTON
Site Contingency [Line Items]
Remediation Recovery Percentage	3.30%

Environmental Matters - Environ

Environmental Matters - Environmental Sites $ in Thousands	1 Months Ended	6 Months Ended
	Jan. 31, 2017USD ($)	Jun. 30, 2021USD ($)partyproperty	Dec. 31, 2020USD ($)	Jun. 30, 2020USD ($)
Site Contingency [Line Items]
Current Liabilities		$ 22,514	$ 28,241	$ 34,066
Non-Current Liabilities		87,795	92,281	91,289
Gasco/Siltronic Sediments
Site Contingency [Line Items]
Current Liabilities		6,658	7,596	10,431
Non-Current Liabilities		41,652	43,725	41,945
Site Contingency, Environmental Remediation Costs Recognized		48,300
Gasco/Siltronic Sediments | Minimum [Member]
Site Contingency [Line Items]
Environmental Exit Costs, Anticipated Cost		48,300
Gasco/Siltronic Sediments | Maximum [Member]
Site Contingency [Line Items]
Environmental Exit Costs, Anticipated Cost		350,000
Portland Harbor Other [Member]
Site Contingency [Line Items]
Current Liabilities		2,195	1,942	2,434
Non-Current Liabilities		$ 6,588	7,020	6,228
Gasco Uplands [Member]
Site Contingency [Line Items]
Site contingency: number of management pieces		2
Gasco/Siltronic Upland [Member]
Site Contingency [Line Items]
Current Liabilities		$ 12,442	14,887	10,979
Non-Current Liabilities		38,401	40,250	41,878
Front Street [Member]
Site Contingency [Line Items]
Current Liabilities		1,219	3,816	10,222
Non-Current Liabilities		975	1,107	1,059
Additional studies and design costs		2,200
Oregon Steel Mills [Member]
Site Contingency [Line Items]
Current Liabilities		0	0	0
Non-Current Liabilities		$ 179	$ 179	$ 179
Portland Harbor [Member]
Site Contingency [Line Items]
Number of potentially responsible parties (more than) | party		100
EPA final feasibility study and proposed remediation plan, clean-up costs, portland harbor	$ 1,050,000
Number of remediation projects | property		2
Portland Harbor [Member] | Minimum [Member]
Site Contingency [Line Items]
Percentage of clean-up costs	(30.00%)
Portland Harbor [Member] | Maximum [Member]
Site Contingency [Line Items]
Percentage of clean-up costs	50.00%
Yakama Nation [Member] | Portland Harbor Other [Member]
Site Contingency [Line Items]
Trustee Council Members - Number of Claimants		1
Site Contingency, Number of Other Third-Party Defendants		29
NRD liability claim yakama nation		$ 300
Number of Amended Complaints Filed		2

Environmental Matters - Regulat

Environmental Matters - Regulatory Deferred Assets - USD ($)	6 Months Ended
	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020
Site Contingency [Line Items]
Regulatory Assets, Current	$ 60,672,000	$ 31,745,000	$ 30,021,000
Regulatory Assets, Noncurrent	$ 330,710,000	$ 348,927,000	$ 324,358,000
Remediation Non-recovery Percentage	3.30%	3.30%	3.30%
Annual tariff rider collection	$ 5,000,000
Annual insurance proceeds to apply against remediation costs	5,000,000
Total annual remediation expense and interest	$ 10,000,000
Oregon [Member]
Site Contingency [Line Items]
Remediation Recovery Percentage	96.70%
Front Street [Member] | Environmental costs [Member]
Site Contingency [Line Items]
Accrued site liabilities	$ 100,000	$ 0.2	$ 400,000
Northwest Natural Gas Company [Member]
Site Contingency [Line Items]
Regulatory Assets, Current	60,672,000	31,745,000	30,021,000
Regulatory Assets, Noncurrent	330,670,000	348,887,000	324,320,000
Northwest Natural Gas Company [Member] | Environmental costs [Member]
Site Contingency [Line Items]
Deferred costs and interest	50,604,000	44,516,000	42,098,000
Accrued site liabilities	110,237,000	120,352,000	124,981,000
Insurance proceeds and interest	(69,730,000)	(69,253,000)	(81,146,000)
Regulatory Assets	91,111,000	95,615,000	85,933,000
Regulatory Assets, Current	5,688,000	4,992,000	4,176,000
Regulatory Assets, Noncurrent	$ 85,423,000	$ 90,623,000	$ 81,757,000

Discontinued Operations_2_3

Discontinued Operations - USD ($)	3 Months Ended			6 Months Ended		9 Months Ended	12 Months Ended
	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Sep. 30, 2020	Mar. 31, 2022	Dec. 31, 2020
Disposal Group, Including Discontinued Operation, Classified Balance Sheet Disclosures [Abstract]
Discontinued operations - total assets			$ 16,400,000		$ 16,400,000
Discontinued Operation, Income Statement Disclosures [Abstract]
Loss from discontinued operations, net of tax	$ 0		$ 280,000	$ 0	$ (498,000)
Loss from discontinued operations per share of common stock
Basic (in dollars per share)	$ 0		$ 0.01	$ 0	$ (0.01)
Diluted (in dollars per share)	$ 0		$ 0.01	$ 0	$ (0.01)
Gill Ranch [Member] | Discontinued Operations, Held-for-sale or Disposed of by Sale [Member]
Disposal Group, Including Discontinued Operation, Classified Balance Sheet Disclosures [Abstract]
Accounts receivable			$ 1,621,000		$ 1,621,000
Inventories			821,000		821,000
Other current assets			250,000		250,000
Property, plant, and equipment			13,328,000		13,328,000
Operating lease right of use asset			118,000		118,000
Other non-current assets			254,000		254,000
Discontinued operations - total assets	$ 0		16,392,000	$ 0	16,392,000
Accounts payable			999,000		999,000
Other current liabilities			1,119,000		1,119,000
Operating lease liabilities			112,000		112,000
Other non-current liabilities			11,344,000		11,344,000
Total discontinued operations liabilities		$ 0	13,574,000		13,574,000			$ 0
Gill Ranch [Member] | Discontinued Operations, Held-for-sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from divestiture of businesses		$ 13,500,000				$ 1,000,000
Discontinued Operation, Income Statement Disclosures [Abstract]
Revenues			3,374,000		4,282,000
Operations and maintenance			2,604,000		4,184,000
General taxes			53,000		100,000
Depreciation and amortization			106,000		212,000
Other expenses and interest			228,000		459,000
Total expenses			2,991,000		4,955,000
Loss from discontinued operations before income tax			383,000		(673,000)
Income tax benefit			103,000		(175,000)
Loss from discontinued operations, net of tax			$ 280,000		$ (498,000)
Loss from discontinued operations per share of common stock
Basic (in dollars per share)	$ 0		$ 0.01	$ 0	$ (0.01)
Diluted (in dollars per share)	$ 0		$ 0.01	$ 0	$ (0.01)
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax								$ 5,900,000
Gill Ranch [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Percent ownership	75.00%			75.00%
Forecast [Member] | Maximum [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from divestiture of businesses							$ 15,000,000