Northwest Natural Holding (NWN) 10-Q 5 Nov 21 2021 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2021	Oct. 27, 2021
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Transition Report	false
Document Period End Date	Sep. 30, 2021
Entity Registrant Name	NORTHWEST NATURAL HOLDING COMPANY
Entity File Number	1-38681
Entity Incorporation, State or Country Code	OR
Entity Tax Identification Number	82-4710680
Entity Address, Address Line One	250 SW Taylor Street
Entity Address, City or Town	Portland
Entity Address, State or Province	OR
Entity Address, Postal Zip Code	97204
City Area Code	(503)
Local Phone Number	226-4211
Title of 12(b) Security	Common Stock
Trading Symbol	NWN
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		30,730,274
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Central Index Key	0001733998
Northwest Natural Gas Company [Member]
Document Information [Line Items]
Document Type	10-Q
Document Period End Date	Sep. 30, 2021
Entity Registrant Name	NORTHWEST NATURAL GAS COMPANY
Entity File Number	1-15973
Entity Incorporation, State or Country Code	OR
Entity Tax Identification Number	93-0256722
Entity Address, Address Line One	250 SW Taylor Street
Entity Address, City or Town	Portland
Entity Address, State or Province	OR
Entity Address, Postal Zip Code	97204
City Area Code	(503)
Local Phone Number	226-4211
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Central Index Key	0000073020

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Operating revenues [Abstract]
Operating revenues	$ 101,447	$ 93,284	$ 566,310	$ 513,406
Operating expenses:
Cost of gas	25,266	23,741	178,669	173,489
Operations and maintenance	47,329	41,352	149,567	134,256
Environmental remediation	806	867	6,092	6,494
General taxes	9,061	8,656	29,344	26,924
Revenue taxes	3,891	3,555	22,226	19,752
Depreciation and amortization	28,438	25,934	84,679	76,445
Other operating expenses	1,047	767	2,794	2,246
Total operating expenses	115,838	104,872	473,371	439,606
Income from operations	(14,391)	(11,588)	92,939	73,800
Other income (expense), net	(2,216)	(3,287)	(8,355)	(9,902)
Interest expense, net	11,175	9,165	33,329	32,339
Income (loss) before income taxes	(27,782)	(24,040)	51,255	31,559
Income tax expense (benefit)	(7,127)	(5,363)	13,117	7,092
Net income (loss) from continuing operations	(20,655)	(18,677)	38,138	24,467
Income from discontinued operations, net of tax	0	765	0	267
Net income (loss)	(20,655)	(17,912)	38,138	24,734
Other comprehensive income:
Amortization of non-qualified employee benefit plan liability, net of taxes	234	186	676	506
Comprehensive income (loss)	(20,421)	(17,726)	38,814	25,240
Supplemental Income Statement Elements [Abstract]
Amortization of non-qualified employee benefit plan liability, tax	$ 80	$ 66	$ 240	$ 182
Average common shares outstanding:
Basic (in shares)	30,696	30,555	30,659	30,528
Diluted (in shares)	30,696	30,555	30,708	30,575
Earnings from continuing operations per share of common stock:
Basic (in dollars per share)	$ (0.67)	$ (0.61)	$ 1.24	$ 0.80
Diluted (in dollars per share)	(0.67)	(0.61)	1.24	0.80
Loss from discontinued operations per share of common stock:
Basic (in dollars per share)	0	0.02	0	0.01
Diluted (in dollars per share)	0	0.02	0	0.01
Earnings (loss) per share of common stock:
Basic (in dollars per share)	(0.67)	(0.59)	1.24	0.81
Diluted (in dollars per share)	$ (0.67)	$ (0.59)	$ 1.24	$ 0.81
Northwest Natural Gas Company [Member]
Operating revenues [Abstract]
Operating revenues	$ 96,036	$ 88,367	$ 552,965	$ 502,053
Operating expenses:
Cost of gas	25,322	23,797	178,837	173,657
Operations and maintenance	43,768	38,657	137,894	126,111
Environmental remediation	806	867	6,092	6,494
General taxes	8,999	8,554	29,041	26,564
Revenue taxes	3,838	3,555	22,143	19,752
Depreciation and amortization	27,719	25,681	82,418	74,857
Other operating expenses	669	725	2,368	2,167
Total operating expenses	111,121	101,836	458,793	429,602
Income from operations	(15,085)	(13,469)	94,172	72,451
Other income (expense), net	(2,295)	(4,002)	(8,526)	(10,744)
Interest expense, net	10,850	8,806	32,336	30,518
Income (loss) before income taxes	(28,230)	(26,277)	53,310	31,189
Income tax expense (benefit)	(7,212)	(6,057)	13,628	6,942
Net income (loss)	(21,018)	(20,220)	39,682	24,247
Other comprehensive income:
Amortization of non-qualified employee benefit plan liability, net of taxes	234	186	676	506
Comprehensive income (loss)	(20,784)	(20,034)	40,358	24,753
Supplemental Income Statement Elements [Abstract]
Amortization of non-qualified employee benefit plan liability, tax	$ 80	$ 66	$ 240	$ 182

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020
Current assets:
Cash and cash equivalents	$ 19,502	$ 30,168	$ 35,926
Accounts receivable	39,209	88,083	40,278
Accrued unbilled revenue	16,809	57,949	14,787
Allowance for uncollectible accounts	(2,702)	(3,219)	(1,786)
Regulatory assets	80,638	31,745	29,740
Derivative instruments	105,175	13,678	24,094
Inventories	59,997	42,691	45,082
Gas reserves	6,266	11,409	12,265
Income Taxes Receivable, Current	0	6,000	0
Other current assets	33,285	44,741	25,534
Discontinued operations current assets	0	0	16,928
Total current assets	358,179	323,245	242,848
Non-current assets:
Property, plant, and equipment	3,919,096	3,734,039	3,680,872
Less: Accumulated depreciation	1,112,734	1,079,269	1,073,623
Property, Plant and Equipment, Net	2,806,362	2,654,770	2,607,249
Gas reserves	28,021	34,484	37,696
Regulatory assets	325,071	348,927	324,176
Derivative instruments	24,555	6,135	12,921
Other investments	48,006	49,259	48,963
Operating lease right of use asset, net	75,634	77,446	78,036
Assets under sales-type leases	140,189	143,759	144,971
Goodwill	69,789	69,225	70,292
Other non-current assets	53,419	49,129	50,945
Total non-current assets	3,571,046	3,433,134	3,375,249
Total assets	3,929,225	3,756,379	3,618,097
Current liabilities:
Short-term debt	399,500	304,525	223,000
Current maturities of long-term debt	278	95,344	95,173
Accounts payable	94,897	97,966	83,813
Taxes accrued	16,558	13,812	13,772
Interest accrued	9,315	7,441	9,645
Regulatory liabilities	164,168	50,362	59,236
Derivative instruments	9,818	4,198	1,784
Operating lease liabilities	1,213	1,105	1,081
Other current liabilities	39,218	52,330	49,870
Discontinued operations current liabilities	0	0	13,922
Total current liabilities	734,965	627,083	551,296
Long-term debt	916,026	860,081	860,235
Deferred credits and other non-current liabilities:
Deferred tax liabilities	323,925	319,292	296,516
Regulatory liabilities	665,390	639,663	649,521
Pension and other postretirement benefit liabilities	202,287	217,287	202,938
Derivative instruments	268	2,852	921
Operating lease liabilities	79,789	80,621	80,854
Other non-current liabilities	115,114	120,767	123,041
Total deferred credits and other non-current liabilities	1,386,773	1,380,482	1,353,791
Commitments and contingencies (Note 16)
Equity:
Common stock	$ 573,578	$ 565,112	$ 563,852
Shares Authorized (in shares)	100,000,000	100,000,000	100,000,000
Shares outstanding (in shares)	30,730,000	30,589,000	30,565,000
Shares issued (in shares)	30,730,000	30,589,000	30,565,000
Par Value (in dollars per share)	$ 0	$ 0	$ 0
Retained earnings	$ 330,109	$ 336,523	$ 299,150
Accumulated other comprehensive loss	(12,226)	(12,902)	(10,227)
Total equity	891,461	888,733	852,775
Total liabilities and equity	3,929,225	3,756,379	3,618,097
Northwest Natural Gas Company [Member]
Current assets:
Cash and cash equivalents	9,697	10,453	27,133
Accounts receivable	37,328	80,035	31,659
Accrued unbilled revenue	16,702	57,890	14,709
Receivables from affiliates	628	660	641
Allowance for uncollectible accounts	(2,658)	(3,107)	(1,784)
Regulatory assets	80,638	31,745	29,740
Derivative instruments	105,175	13,678	24,094
Inventories	59,641	42,325	44,709
Gas reserves	6,266	11,409	12,265
Other current assets	22,809	37,909	20,236
Total current assets	336,226	282,997	203,402
Non-current assets:
Property, plant, and equipment	3,857,652	3,683,776	3,633,570
Less: Accumulated depreciation	1,106,901	1,075,446	1,070,405
Property, Plant and Equipment, Net	2,750,751	2,608,330	2,563,165
Gas reserves	28,021	34,484	37,696
Regulatory assets	325,031	348,887	324,136
Derivative instruments	24,555	6,135	12,921
Other investments	47,970	49,242	48,929
Operating lease right of use asset, net	75,565	77,328	77,949
Assets under sales-type leases	140,189	143,759	144,972
Other non-current assets	52,653	48,174	50,197
Total non-current assets	3,444,735	3,316,339	3,259,965
Total assets	3,780,961	3,599,336	3,463,367
Current liabilities:
Short-term debt	370,500	231,525	150,000
Current maturities of long-term debt	0	59,955	59,940
Accounts payable	91,947	95,170	82,582
Payables to affiliates	2,568	13,820	11,134
Taxes accrued	16,472	13,724	13,604
Interest accrued	9,258	7,338	9,552
Regulatory liabilities	164,168	50,362	59,236
Derivative instruments	9,818	4,198	1,784
Operating lease liabilities	1,184	1,054	1,020
Other current liabilities	38,642	51,907	48,555
Total current liabilities	704,557	529,053	437,407
Long-term debt	857,760	857,265	857,174
Deferred credits and other non-current liabilities:
Deferred tax liabilities	321,636	318,034	307,257
Regulatory liabilities	664,521	638,793	648,651
Pension and other postretirement benefit liabilities	202,287	217,287	202,938
Derivative instruments	268	2,852	921
Operating lease liabilities	79,752	80,559	80,830
Other non-current liabilities	114,438	120,309	122,684
Total deferred credits and other non-current liabilities	1,382,902	1,377,834	1,363,281
Equity:
Common stock	321,641	319,506	319,557
Retained earnings	526,327	528,580	496,175
Accumulated other comprehensive loss	(12,226)	(12,902)	(10,227)
Total equity	835,742	835,184	805,505
Total liabilities and equity	$ 3,780,961	$ 3,599,336	$ 3,463,367

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	$ 319,557	$ 513,372	$ (10,733)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	24,734		24,734		24,247		24,247
Dividends on common stock			(44,034)				(41,444)
Other comprehensive income	25,240			506	24,753			506
Stock-based compensation		4,085
Shares issued pursuant to equity based plans		1,485
Issuances of common stock, net of issuance costs		0
Adjustments to Additional Paid in Capital, Other						0
Ending Balance at Sep. 30, 2020	$ 852,775	563,852	299,150	(10,227)	805,505	319,557	496,175	(10,227)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends per share of common stock	$ 1.4325
Beginning 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]
Net income	(17,912)		(17,912)		(20,220)		(20,220)
Dividends on common stock			(14,586)				(13,830)
Other comprehensive income	(17,726)			186	(20,034)			186
Stock-based compensation		459
Shares issued pursuant to equity based plans		627
Issuances of common stock, net of issuance costs		0
Adjustments to Additional Paid in Capital, Other						0
Ending Balance at Sep. 30, 2020	$ 852,775	563,852	299,150	(10,227)	805,505	319,557	496,175	(10,227)
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	319,506	528,580	(12,902)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	38,138		38,138		39,682		39,682
Dividends on common stock			(44,552)				(41,935)
Other comprehensive income	38,814			676	40,358			676
Stock-based compensation		2,973
Shares issued pursuant to equity based plans		3,386
Issuances of common stock, net of issuance costs		2,107
Adjustments to Additional Paid in Capital, Other						2,135
Ending Balance at Sep. 30, 2021	$ 891,461	573,578	330,109	(12,226)	835,742	321,641	526,327	(12,226)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends per share of common stock	$ 1.4400
Beginning 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]
Net income	(20,655)		(20,655)		(21,018)		(21,018)
Dividends on common stock			(14,737)				(14,000)
Other comprehensive income	(20,421)			234	(20,784)			234
Stock-based compensation		527
Shares issued pursuant to equity based plans		1,159
Issuances of common stock, net of issuance costs		2,107
Adjustments to Additional Paid in Capital, Other						2,135
Ending Balance at Sep. 30, 2021	$ 891,461	$ 573,578	$ 330,109	$ (12,226)	$ 835,742	$ 321,641	$ 526,327	$ (12,226)
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	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Operating activities:
Net income	$ 38,138	$ 24,734
Adjustments to reconcile net income to cash provided by operations:
Depreciation and amortization	84,679	76,445
Regulatory amortization of gas reserves	11,606	13,711
Deferred income taxes	2,748	(390)
Qualified defined benefit pension plan expense	12,075	13,800
Contributions to qualified defined benefit pension plans	(9,590)	(23,670)
Deferred environmental expenditures, net	(14,952)	(16,469)
Amortization of environmental remediation	6,092	6,494
Other	5,815	(4,483)
Changes in assets and liabilities:
Receivables, net	83,826	77,236
Inventories	(17,307)	(1,126)
Income and other taxes	19,620	12,038
Accounts payable	(18,057)	(20,311)
Deferred gas costs	(33,379)	(2,472)
Asset optimization revenue sharing	41,407	(9,695)
Decoupling mechanism	(9,172)	4,175
Other, net	(21,825)	74
Discontinued operations	0	706
Cash provided by operating activities	181,724	150,797
Investing activities:
Capital expenditures	(212,376)	(193,336)
Acquisitions, net of cash acquired	(375)	(38,078)
Leasehold improvement expenditures	(570)	(7,827)
Proceeds from the sale of assets	2,712	8,003
Proceeds from Sale of Equity Method Investments	7,000	7,000
Other	88	(240)
Discontinued operations	0	(2,287)
Cash used in investing activities	(203,521)	(226,765)
Financing activities:
Proceeds from common stock issued, net	2,107	68
Long-term debt issued	55,000	150,000
Long-term debt retired	(95,000)	(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
Change in other short-term debt, net	190,000	(76,100)
Cash dividend payments on common stock	(41,827)	(41,508)
Other	(1,240)	(2,957)
Net Cash Provided by (Used in) Financing Activities	14,015	104,503
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	27,672	41,171
Increase in cash and cash equivalents	(7,782)	28,535
Supplemental disclosure of cash flow information:
Interest paid, net of capitalization	30,910	29,829
Income taxes paid, net of refunds	6,980	9,344
Northwest Natural Gas Company [Member]
Operating activities:
Net income	39,682	24,247
Adjustments to reconcile net income to cash provided by operations:
Depreciation and amortization	82,418	74,857
Regulatory amortization of gas reserves	11,606	13,711
Deferred income taxes	1,687	(2,407)
Qualified defined benefit pension plan expense	12,075	13,800
Contributions to qualified defined benefit pension plans	(9,590)	(23,670)
Deferred environmental expenditures, net	(14,952)	(16,469)
Amortization of environmental remediation	6,092	6,494
Other	4,675	(4,410)
Changes in assets and liabilities:
Receivables, net	84,726	78,217
Inventories	(17,317)	(842)
Income and other taxes	5,175	22,104
Accounts payable	(22,929)	(22,703)
Deferred gas costs	(33,379)	(2,472)
Asset optimization revenue sharing	41,407	(9,695)
Decoupling mechanism	(9,172)	4,175
Other, net	(20,376)	2,033
Cash provided by operating activities	161,828	156,970
Investing activities:
Capital expenditures	(199,399)	(188,553)
Leasehold improvement expenditures	(570)	(7,827)
Proceeds from the sale of assets	2,712	8,003
Other	88	(234)
Cash used in investing activities	(197,169)	(188,611)
Financing activities:
Proceeds from Contributions from Parent	2,135	0
Long-term debt issued	0	150,000
Long-term debt retired	(60,000)	(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
Change in other short-term debt, net	234,000	(125,100)
Cash dividend payments on common stock	(41,935)	(41,444)
Other	(1,706)	(3,344)
Net Cash Provided by (Used in) Financing Activities	37,469	55,112
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	17,867	32,378
Increase in cash and cash equivalents	2,128	23,471
Supplemental disclosure of cash flow information:
Interest paid, net of capitalization	29,920	28,139
Income taxes paid, net of refunds	$ 23,035	$ 950

Organization and Principles of

Organization and Principles of Consolidation	9 Months Ended
	Sep. 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 14 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 were classified as discontinued operations assets and liabilities on the NW Holdings consolidated balance sheet. The sale closed on December 4, 2020. See Note 18 for additional information.

Significant Accounting Policies

Significant Accounting Policies	9 Months Ended
	Sep. 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 nine months ended September 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), as applicable, which provide for the recovery of revenues or expenses from, or refunds to, utility customers in future periods, including a return or a carrying charge in certain cases. Amounts deferred as regulatory assets and liabilities for NW Holdings and NW Natural were as follows: Regulatory Assets September 30, December 31, In thousands 2021 2020 2020 NW Natural: Current: Unrealized loss on derivatives (1) $ 9,818 $ 1,459 $ 4,198 Gas costs 39,622 5,207 1,979 Environmental costs (2) 7,068 4,440 4,992 Decoupling (3) 1,628 155 361 Pension balancing (4) 7,131 7,131 7,131 Income taxes 2,939 2,208 3,484 Other (5) 12,432 9,140 9,600 Total current $ 80,638 $ 29,740 $ 31,745 Non-current: Unrealized loss on derivatives (1) $ 268 $ 921 $ 2,852 Pension balancing (4) 40,176 45,203 43,383 Income taxes 13,912 16,792 15,368 Pension and other postretirement benefit liabilities 155,077 159,207 170,812 Environmental costs (2) 83,969 84,567 90,623 Gas costs 2,858 110 3,925 Decoupling (3) 118 6 1,031 Other (5) 28,653 17,330 20,893 Total non-current $ 325,031 $ 324,136 $ 348,887 Other (NW Holdings) 40 40 40 Total non-current - NW Holdings $ 325,071 $ 324,176 $ 348,927 Regulatory Liabilities September 30, December 31, In thousands 2021 2020 2020 NW Natural: Current: Gas costs $ 847 $ 1,625 $ 1,118 Unrealized gain on derivatives (1) 105,175 23,738 13,674 Decoupling (3) 4,484 12,702 11,793 Income taxes 8,217 6,900 8,217 Asset optimization revenue sharing 43,883 9,020 10,298 Other (5) 1,562 5,251 5,262 Total current $ 164,168 $ 59,236 $ 50,362 Non-current: Gas costs $ — $ 69 $ 314 Unrealized gain on derivatives (1) 24,555 12,921 6,135 Decoupling (3) 214 874 1,723 Income taxes (6) 186,429 196,558 189,587 Accrued asset removal costs (7) 440,410 421,353 427,960 Asset optimization revenue sharing — 58 1,231 Other (5) 12,913 16,818 11,843 Total non-current - NW Natural $ 664,521 $ 648,651 $ 638,793 Other (NW Holdings) 869 870 870 Total non-current - NW Holdings $ 665,390 $ 649,521 $ 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 17 for a description of environmental costs. (3) This deferral represents the margin adjustment resulting from differences between actual and expected volumes. (4) Balance represents deferred net periodic benefit costs as approved by the OPUC. (5) Balances consist of deferrals and amortizations under approved regulatory mechanisms and typically earn a rate of return or carrying charge. (6) Balance represents excess deferred income tax benefits subject to regulatory flow-through. (7) Estimated costs of removal on certain regulated properties are collected through rates. We believe all costs incurred and deferred at September 30, 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 September 30, 2021 and 2020 and December 31, 2020: September 30, December 31, In thousands 2021 2020 2020 Cash and cash equivalents $ 19,502 $ 35,926 $ 30,168 Restricted cash included in other current assets 8,170 5,245 5,286 Cash, cash equivalents and restricted cash $ 27,672 $ 41,171 $ 35,454 The following table provides a reconciliation of the cash, cash equivalents and restricted cash balances at NW Natural as of September 30, 2021 and 2020 and December 31, 2020: September 30, December 31, In thousands 2021 2020 2020 Cash and cash equivalents $ 9,697 $ 27,133 $ 10,453 Restricted cash included in other current assets 8,170 5,245 5,286 Cash, cash equivalents and restricted cash $ 17,867 $ 32,378 $ 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 COVID-19 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 unemployment rate and comparing it to historic economic data during the 2007-2009 time period when the country experienced an economic recession. We are also considering other qualitative information including recent customer interactions related to payment plans and credit issues, statistics from our website related to credit inquiries, and bill assistance programs including the arrearage management program. Our provision calculation for residential accounts is estimated based on the factors noted above including a review of percentage of delinquent accounts. For the residential allowance calculation, we consider the funds applied or granted to customers through a variety of assistance programs including the COVID arrearage management programs in Oregon and Washington. During the third quarter of 2021, the normal collection process for residential accounts resumed and the percentage of accounts disconnected for non-payment was also considered in the provision. 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 Nine Months Ended September 30, 2021 September 30, 2021 In thousands Beginning Balance Provision recorded, net of adjustments Write-offs recognized, net of recoveries Ending Balance Allowance for uncollectible accounts: Residential $ 2,153 $ 1,322 $ (1,111) $ 2,364 Commercial 704 (337) (303) 64 Industrial 142 (106) 5 41 Accrued unbilled and other 220 96 (83) 233 Total $ 3,219 $ 975 $ (1,492) $ 2,702 Allowance for Net Investments in Sales-Type Leases NW Natural currently holds two net investments in sales-type leases, with substantially all of the net investment balance related to the North Mist natural gas storage agreement with Portland General Electric (PGE) which is billed under an OPUC-approved rate schedule. See Note 7 for more information on the North Mist lease. Due to the nature of this service, PGE may recover the costs of the lease through general rate cases. Therefore, we expect the risk of loss due to the credit of this lessee to be remote. As such, no allowance for 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 September 30, 2021, we deferred to a regulatory asset approximately $7.4 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 London Inter-Bank Offered Rate (LIBOR) or another reference rate expected to be discontinued because of reference rate reform.

Earnings Per Share

Earnings Per Share	9 Months Ended
	Sep. 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 September 30, Nine Months Ended September 30, In thousands, except per share data 2021 2020 2021 2020 Net income (loss) from continuing operations $ (20,655) $ (18,677) $ 38,138 $ 24,467 Income from discontinued operations, net of tax — 765 — 267 Net income (loss) $ (20,655) $ (17,912) $ 38,138 $ 24,734 Average common shares outstanding - basic 30,696 30,555 30,659 30,528 Additional shares for stock-based compensation plans (See Note 8) — — 49 47 Average common shares outstanding - diluted 30,696 30,555 30,708 30,575 Earnings (loss) from continuing operations per share of common stock: Basic $ (0.67) $ (0.61) $ 1.24 $ 0.80 Diluted $ (0.67) $ (0.61) $ 1.24 $ 0.80 Earnings from discontinued operations per share of common stock: Basic $ — $ 0.02 $ — $ 0.01 Diluted $ — $ 0.02 $ — $ 0.01 Earnings (loss) per share of common stock: Basic $ (0.67) $ (0.59) $ 1.24 $ 0.81 Diluted $ (0.67) $ (0.59) $ 1.24 $ 0.81 Additional information: Anti-dilutive shares 51 47 6 1

Segment Information

Segment Information	9 Months Ended
	Sep. 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 14. 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 18 for information regarding discontinued operations for NW Holdings. Three Months Ended September 30, In thousands NGD Other NW Natural Other NW Holdings 2021 Operating revenues $ 91,042 $ 4,994 $ 96,036 $ 5,411 $ 101,447 Depreciation and amortization 27,462 257 27,719 719 28,438 Income (loss) from operations (18,288) 3,203 (15,085) 694 (14,391) Net income (loss) from continuing operations (23,297) 2,279 (21,018) 363 (20,655) Capital expenditures 72,822 1,410 74,232 8,036 82,268 2020 Operating revenues $ 83,761 $ 4,606 $ 88,367 $ 4,917 $ 93,284 Depreciation and amortization 25,433 248 25,681 253 25,934 Income (loss) from operations (16,196) 2,727 (13,469) 1,881 (11,588) Net income (loss) from continuing operations (22,120) 1,900 (20,220) 1,543 (18,677) Capital expenditures 69,213 1,113 70,326 728 71,054 Nine Months Ended September 30, In thousands NGD Other NW Natural Other NW Holdings 2021 Operating revenues $ 531,994 $ 20,971 $ 552,965 $ 13,345 $ 566,310 Depreciation and amortization 81,648 770 82,418 2,261 84,679 Income (loss) from operations 79,530 14,642 94,172 (1,233) 92,939 Net income (loss) from continuing operations 29,247 10,435 39,682 (1,544) 38,138 Capital expenditures 197,190 2,209 199,399 12,977 212,376 Total assets at September 30, 2021 3,730,595 50,366 3,780,961 148,264 3,929,225 2020 Operating revenues $ 489,240 $ 12,813 $ 502,053 $ 11,353 $ 513,406 Depreciation and amortization 74,117 740 74,857 1,588 76,445 Income (loss) from operations 65,496 6,955 72,451 1,349 73,800 Net income (loss) from continuing operations 19,476 4,771 24,247 220 24,467 Capital expenditures 186,842 1,711 188,553 4,783 193,336 Total assets at September 30, 2020 (1) 3,451,771 11,596 3,463,367 137,802 3,601,169 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 $16.9 million as of September 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 September 30, Nine Months Ended September 30, In thousands 2021 2020 2021 2020 NGD margin calculation: NGD distribution revenues $ 86,271 $ 79,357 $ 517,673 $ 474,989 Other regulated services 4,771 4,404 14,321 14,251 Total NGD operating revenues 91,042 83,761 531,994 489,240 Less: NGD cost of gas 25,322 23,797 178,837 173,657 Environmental remediation 806 867 6,092 6,494 Revenue taxes 3,838 3,555 22,143 19,752 NGD margin $ 61,076 $ 55,542 $ 324,922 $ 289,337

Equity

Equity	9 Months Ended
	Sep. 30, 2021
Equity [Abstract]
Stockholders' Equity Note Disclosure	COMMON STOCKIn August 2021, NW Holdings initiated an at-the-market (ATM) equity program by entering into an equity distribution agreement under which NW Holdings may issue and sell from time to time shares of common stock, no par value, having an aggregate gross sales price of up to $200 million. NW Holdings is under no obligation to offer and sell common stock under the ATM equity program, which expires in August 2024. Any shares of common stock offered under the ATM equity program are registered on NW Holdings’ universal shelf registration statement filed with the SEC. During the quarter ended September 30, 2021, NW Holdings issued and sold 41,421 shares of common stock pursuant to the ATM equity program resulting in cash proceeds of $2.1 million, net of fees and commissions paid to agents of $22 thousand. As of September 30, 2021, NW Holdings had issued and sold 41,421 shares of common stock pursuant to the ATM equity program resulting in cash proceeds of $2.1 million, net of fees and commissions paid to agents of $22 thousand. The ATM equity program was initiated to raise funds for general corporate purposes, including for NW Holdings’ subsidiaries, that are reflected as equity transfers on occurrence. Contributions received by NW Natural may also be used, in part, to repay short-term indebtedness.

Revenue

Revenue	9 Months Ended
	Sep. 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 September 30, In thousands NGD Other NW Natural Other NW Holdings 2021 Natural gas sales $ 83,947 $ — $ 83,947 $ — $ 83,947 Gas storage revenue, net — 2,794 2,794 — 2,794 Asset management revenue, net — 1,012 1,012 — 1,012 Appliance retail center revenue — 1,188 1,188 — 1,188 Other revenue 403 — 403 5,411 5,814 Revenue from contracts with customers 84,350 4,994 89,344 5,411 94,755 Alternative revenue 2,307 — 2,307 — 2,307 Leasing revenue 4,385 — 4,385 — 4,385 Total operating revenues $ 91,042 $ 4,994 $ 96,036 $ 5,411 $ 101,447 2020 Natural gas sales $ 78,427 $ — $ 78,427 $ — $ 78,427 Gas storage revenue, net — 2,482 2,482 — 2,482 Asset management revenue, net — 939 939 — 939 Appliance retail center revenue — 1,185 1,185 — 1,185 Other revenue 333 — 333 4,917 5,250 Revenue from contracts with customers 78,760 4,606 83,366 4,917 88,283 Alternative revenue 395 — 395 — 395 Leasing revenue 4,606 — 4,606 — 4,606 Total operating revenues $ 83,761 $ 4,606 $ 88,367 $ 4,917 $ 93,284 Nine Months Ended September 30, In thousands NGD Other NW Natural Other NW Holdings 2021 Natural gas sales $ 503,769 $ — $ 503,769 $ — $ 503,769 Gas storage revenue, net — 8,094 8,094 — 8,094 Asset management revenue, net — 8,757 8,757 — 8,757 Appliance retail center revenue — 4,120 4,120 — 4,120 Other revenue 1,217 — 1,217 13,345 14,562 Revenue from contracts with customers 504,986 20,971 525,957 13,345 539,302 Alternative revenue 13,843 — 13,843 — 13,843 Leasing revenue 13,165 — 13,165 — 13,165 Total operating revenues $ 531,994 $ 20,971 $ 552,965 $ 13,345 $ 566,310 2020 Natural gas sales $ 469,113 $ — $ 469,113 $ — $ 469,113 Gas storage revenue, net — 7,267 7,267 — 7,267 Asset management revenue, net — 1,999 1,999 — 1,999 Appliance retail center revenue — 3,547 3,547 — 3,547 Other revenue 1,002 — 1,002 11,353 12,355 Revenue from contracts with customers 470,115 12,813 482,928 11,353 494,281 Alternative revenue 5,288 — 5,288 — 5,288 Leasing revenue 13,837 — 13,837 — 13,837 Total operating revenues $ 489,240 $ 12,813 $ 502,053 $ 11,353 $ 513,406 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 7 for additional information. NW Natural Other Gas Storage Revenue NW Natural's other revenue includes gas storage activity, which includes Interstate Storage Services used to store natural gas for customers. Gas storage revenue is generally recognized over time as the gas storage service is provided to the customer and the amount of consideration received and recognized as revenue is dependent on set rates defined per the storage agreements. Noncash consideration in the form of dekatherms of natural gas is received as consideration for providing gas injection services to gas storage customers. This noncash consideration is measured at fair value using the average spot rate. Customer accounts are generally paid in full each month, and there is no right of return or warranty for services provided. Revenues include firm and interruptible storage services, net of the profit sharing amount refunded to NGD customers. Asset Management Revenue Revenues include the optimization of 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 September 30, 2021, u nrecognized revenue for the fixed component of the transaction price related to gas storage and asset management revenue was approximately $103.3 million. Of this amount, approximately $4.9 million will be recognized during the remainder of 2021, $19.7 million in 2022, $18.1 million in 2023, $15.7 million in 2024, $13.5 million in 2025 and $31.4 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	9 Months Ended
	Sep. 30, 2021
Leases [Abstract]
Lessee, Operating Leases	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 and NW Holdings to third parties. These transactions are accounted for as operating leases and the revenue is recognized over the term of the lease agreement. The components of lease revenue at NW Natural were as follows: Three Months Ended September 30, Nine Months Ended September 30, In thousands 2021 2020 2021 2020 Lease revenue Operating leases $ 18 $ 18 $ 61 $ 71 Sales-type leases 4,367 4,588 13,104 13,766 Total lease revenue $ 4,385 $ 4,606 $ 13,165 $ 13,837 Additionally, lease revenue of $0.1 million was recognized for the three months ended September 30, 2021 and 2020 and lease revenue of $0.4 million was recognized for the nine months ended September 30, 2021 and 2020 related to operating leases associated with non-utility property rentals. Lease revenue related to these leases was presented in other income (expense), net on the consolidated statements of comprehensive income as it is non-operating income. Total future minimum lease payments to be received under non-cancellable leases at September 30, 2021 are as follows: In thousands Operating Sales-Type Total NW Natural: Remainder of 2021 $ 138 $ 4,338 $ 4,476 2022 551 17,026 17,577 2023 74 16,557 16,631 2024 74 15,867 15,941 2025 66 15,306 15,372 Thereafter 58 251,721 251,779 Total minimum lease payments $ 961 $ 320,815 $ 321,776 Less: imputed interest 180,198 Total leases receivable $ 140,617 Other (NW Holdings): Remainder of 2021 $ 12 $ — $ 12 2022 50 — 50 2023 51 — 51 2024 52 — 52 2025 53 — 53 Thereafter 970 — 970 Total minimum lease payments $ 1,188 $ — $ 1,188 NW Holdings: Remainder of 2021 $ 150 $ 4,338 $ 4,488 2022 601 17,026 17,627 2023 125 16,557 16,682 2024 126 15,867 15,993 2025 119 15,306 15,425 Thereafter 1,028 251,721 252,749 Total minimum lease payments $ 2,149 $ 320,815 $ 322,964 Less: imputed interest 180,198 Total leases receivable $ 140,617 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 $4.6 million, $4.2 million and $4.3 million at September 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 three 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 September 30, Nine Months Ended September 30, In thousands 2021 2020 2021 2020 NW Natural: Operating lease expense $ 1,735 $ 746 $ 5,123 $ 2,862 Short-term lease expense $ 499 $ 300 $ 1,068 $ 783 Other (NW Holdings): Operating lease expense $ 14 $ 17 $ 50 $ 109 NW Holdings: Operating lease expense $ 1,749 $ 763 $ 5,173 $ 2,971 Short-term lease expense $ 499 $ 300 $ 1,068 $ 783 Supplemental balance sheet information related to operating leases as of September 30, 2021 is as follows: In thousands September 30, December 31, 2021 2020 2020 NW Natural: Operating lease right of use asset $ 75,565 $ 77,949 $ 77,328 Operating lease liabilities - current liabilities $ 1,184 $ 1,020 $ 1,054 Operating lease liabilities - non-current liabilities 79,752 80,830 80,559 Total operating lease liabilities $ 80,936 $ 81,850 $ 81,613 Other (NW Holdings): Operating lease right of use asset $ 69 $ 87 $ 118 Operating lease liabilities - current liabilities $ 29 $ 61 $ 51 Operating lease liabilities - non-current liabilities 37 24 62 Total operating lease liabilities $ 66 $ 85 $ 113 NW Holdings: Operating lease right of use asset $ 75,634 $ 78,036 $ 77,446 Operating lease liabilities - current liabilities $ 1,213 $ 1,081 $ 1,105 Operating lease liabilities - non-current liabilities 79,789 80,854 80,621 Total operating lease liabilities $ 81,002 $ 81,935 $ 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 September 30, December 31, 2021 2020 2020 Weighted-average remaining lease term (years) 18.4 19.4 19.2 Weighted-average discount rate 7.2 % 7.2 % 7.2 % Corporate Operations Center 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 $5.3 million, $3.7 million and $4.2 million as of September 30, 2021 and 2020 and December 31, 2020, respectively. Maturities of operating lease liabilities at September 30, 2021 were as follows: In thousands NW Natural Other NW Holdings Remainder of 2021 $ 1,727 $ 6 $ 1,733 2022 6,968 24 6,992 2023 7,013 6 7,019 2024 7,150 6 7,156 2025 7,185 6 7,191 Thereafter 123,784 24 123,808 Total lease payments 153,827 72 153,899 Less: imputed interest 72,891 6 72,897 Total lease obligations 80,936 66 81,002 Less: current obligations 1,184 29 1,213 Long-term lease obligations $ 79,752 $ 37 $ 79,789 As of September 30, 2021, finance lease liabilities with maturities of less than one year were $0.1 million at NW Natural. Supplemental cash flow information related to leases was as follows: Three Months Ended September 30, Nine Months Ended September 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 $ 1,727 $ 673 $ 5,113 $ 2,800 Finance cash flows from finance leases $ 123 $ 215 $ 801 $ 672 Right of use assets obtained in exchange for lease obligations Operating leases $ — $ 106 $ 154 $ 78,539 Finance leases $ 75 $ 676 $ 169 $ 1,386 Other (NW Holdings): Cash paid for amounts included in the measurement of lease liabilities Operating cash flows from operating leases $ 18 $ 18 $ 51 $ 109 NW Holdings: Cash paid for amounts included in the measurement of lease liabilities Operating cash flows from operating leases $ 1,745 $ 691 $ 5,164 $ 2,909 Finance cash flows from finance leases $ 123 $ 215 $ 801 $ 672 Right of use assets obtained in exchange for lease obligations Operating leases $ — $ 106 $ 154 $ 78,539 Finance leases $ 75 $ 676 $ 169 $ 1,386 Finance Leases

Stock-Based Compensation

Stock-Based Compensation	9 Months Ended
	Sep. 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 nine months ended September 30, 2021, the final performance factor under the 2019 LTIP was approved and 29,492 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 September 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 September 30, 2021, there was $0.1 million of unrecognized compensation cost associated with the 2019 LTIP grants, which is expected to be recognized through 2021. Restricted Stock Units During the nine months ended September 30, 2021, 37,576 RSUs were granted under the LTIP with a weighted-average grant date fair value of $49.16 per share. Generally, the RSUs 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 September 30, 2021, there was $3.8 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 September 30, 2021 there were no options exercisable or outstanding.

Debt

Debt	9 Months Ended
	Sep. 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 September 30, 2021, with a consolidated indebtedness to total capitalization ratio of 59.5%. At September 30, 2021, NW Holdings and NW Natural had short-term debt outstanding of $399.5 million and $370.5 million, respectively. NW Holdings' short-term debt consisted of $29.0 million in revolving credit agreement loans at NW Holdings, $270.5 million of commercial paper outstanding at NW Natural, and the aforementioned $100.0 million Term Loan. The weighted average interest rate on the revolving credit agreement at September 30, 2021 was 1.1% at NW Holdings. The weighted average interest rate of commercial paper and the Term Loan outstanding at September 30, 2021 was 0.2% and 0.7%, respectively, at NW Natural. At September 30, 2021, NW Natural's commercial paper had a maximum remaining maturity of 63 days and an average remaining maturity of 34 days. Long-Term Debt At September 30, 2021, NW Holdings and NW Natural had long-term debt outstanding of $916.3 million and $857.8 million, respectively, which included $7.1 million and $6.9 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 2023 through 2050, interest rates ranging from 2.8% to 7.9%, and a weighted average interest rate of 4.5%. In August 2021, NW Natural retired $10.0 million of FMBs with an interest rate of 9.1%. In September 2021, NW Natural retired $50.0 million of FMBs with an interest rate of 3.2%. No other long-term debt is scheduled to mature over the next twelve months following September 30, 2021 . 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 September 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 September 30, 2021, with a consolidated indebtedness to total capitalization ratio of 59.6%. 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 long-term debt, including current maturities of long-term debt, using market prices in effect on the valuation date: September 30, December 31, In thousands 2021 2020 2020 NW Natural: Gross long-term debt $ 864,700 $ 924,700 $ 924,700 Unamortized debt issuance costs (6,940) (7,586) (7,480) Carrying amount $ 857,760 $ 917,114 $ 917,220 Estimated fair value (1) $ 978,613 $ 1,080,663 $ 1,097,348 NW Holdings: Gross long-term debt $ 923,355 $ 962,994 $ 962,905 Unamortized debt issuance costs (7,051) (7,586) (7,480) Carrying amount $ 916,304 $ 955,408 $ 955,425 Estimated fair value (1) $ 1,042,705 $ 1,118,565 $ 1,136,311 (1) Estimated fair value does not include unamortized debt issuance costs.

Pension and Other Postretiremen

Pension and Other Postretirement Benefit Costs	9 Months Ended
	Sep. 30, 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 September 30, Nine Months Ended September 30, Pension Benefits Other Postretirement Pension Benefits Other In thousands 2021 2020 2021 2020 2021 2020 2021 2020 Service cost $ 1,717 $ 1,673 $ 69 $ 67 $ 5,145 $ 4,988 $ 180 $ 195 Interest cost 3,316 4,071 180 229 10,001 12,093 510 675 Expected return on plan assets (5,802) (5,358) — — (18,000) (16,350) — — Amortization of prior service credit — — (119) (119) — — (353) (353) Amortization of net actuarial loss 5,515 5,082 226 173 16,516 14,638 488 458 Net periodic benefit cost 4,746 5,468 356 350 13,662 15,369 825 975 Amount allocated to construction (759) (695) (27) (25) (2,228) (2,043) (70) (71) Net periodic benefit cost charged to expense 3,987 4,773 329 325 11,434 13,326 755 904 Amortization of regulatory balancing account 675 675 — — 4,757 4,757 — — Net amount charged to expense $ 4,662 $ 5,448 $ 329 $ 325 $ 16,191 $ 18,083 $ 755 $ 904 Net periodic benefit costs are reduced by amounts capitalized to NGD plant. In addition, net periodic benefit costs were recorded to a regulatory balancing account as approved by the OPUC and amortized accordingly. The following table presents amounts recognized in accumulated other comprehensive loss (AOCL) and the changes in AOCL related to non-qualified employee benefit plans: Three Months Ended September 30, Nine Months Ended September 30, In thousands 2021 2020 2021 2020 Beginning balance $ (12,460) $ (10,413) $ (12,902) $ (10,733) Amounts reclassified from AOCL: Amortization of actuarial losses 314 252 916 688 Total reclassifications before tax 314 252 916 688 Tax benefit (80) (66) (240) (182) Total reclassifications for the period 234 186 676 506 Ending balance $ (12,226) $ (10,227) $ (12,226) $ (10,227) Employer Contributions to Company-Sponsored Defined Benefit Pension Plans For the nine months ended September 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 $6.7 million and $6.2 million for the nine months ended September 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	9 Months Ended
	Sep. 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 September 30, NW Holdings NW Natural In thousands 2021 2020 2021 2020 Income tax at statutory rate (federal) $ (5,834) $ (5,048) $ (5,928) $ (5,518) State income tax (2,599) (1,452) (2,618) (1,595) Increase (decrease): Differences required to be flowed-through by regulatory commissions 1,318 1,051 1,318 1,051 Other, net (12) 86 16 5 Total benefit for income taxes on continuing operations $ (7,127) $ (5,363) $ (7,212) $ (6,057) Effective income tax rate for continuing operations 25.7 % 22.3 % 25.5 % 23.1 % Nine Months Ended September 30, NW Holdings NW Natural In thousands 2021 2020 2021 2020 Income tax at statutory rate (federal) $ 10,764 $ 6,628 $ 11,195 $ 6,550 State income tax 4,660 1,892 4,748 1,861 Increase (decrease): Differences required to be flowed-through by regulatory commissions (2,266) (1,301) (2,266) (1,301) Other, net (41) (127) (49) (168) Total provision for income taxes on continuing operations $ 13,117 $ 7,092 $ 13,628 $ 6,942 Effective income tax rate for continuing operations 25.6 % 22.5 % 25.6 % 22.3 % The NW Holdings and NW Natural effective income tax rates for the nine months ended September 30, 2021 compared to the same period in 2020 changed primarily as a result of changes in pre-tax income, Oregon's 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	9 Months Ended
	Sep. 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: September 30, December 31, In thousands 2021 2020 2020 NW Natural: NGD plant in service $ 3,663,699 $ 3,441,301 $ 3,548,543 NGD work in progress 120,412 120,722 63,901 Less: Accumulated depreciation 1,086,510 1,051,018 1,055,809 NGD plant, net 2,697,601 2,511,005 2,556,635 Other plant in service 66,314 65,103 66,300 Other construction work in progress 7,228 6,444 5,032 Less: Accumulated depreciation 20,392 19,387 19,637 Other plant, net 53,150 52,160 51,695 Total property, plant, and equipment, net $ 2,750,751 $ 2,563,165 $ 2,608,330 Other (NW Holdings): Other plant in service $ 61,443 $ 47,302 $ 50,263 Less: Accumulated depreciation 5,832 3,218 3,823 Other plant, net $ 55,611 $ 44,084 $ 46,440 NW Holdings: Total property, plant, and equipment, net $ 2,806,362 $ 2,607,249 $ 2,654,770 NW Natural: Capital expenditures in accrued liabilities $ 33,968 $ 37,236 $ 25,129 NW Holdings: Capital expenditures in accrued liabilities $ 35,955 $ 37,236 $ 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	9 Months Ended
	Sep. 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 September 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: September 30, December 31, In thousands 2021 2020 2020 Gas reserves, current $ 6,266 $ 12,265 $ 11,409 Gas reserves, non-current 181,041 175,042 175,898 Less: Accumulated amortization 153,020 137,346 141,414 Total gas reserves (1) 34,287 49,961 45,893 Less: Deferred taxes on gas reserves 7,768 11,972 10,572 Net investment in gas reserves $ 26,519 $ 37,989 $ 35,321 (1) The net investment in additional wells included in total gas reserves was $2.5 million, $3.2 million and $3.0 million at September 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	9 Months Ended
	Sep. 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 which was 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 for the year ended December 31, 2020. 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. See Note 14 in the 2020 Form 10-K.

Business Combinations Business

Business Combinations Business Combinations	9 Months Ended
	Sep. 30, 2021
Business Combinations [Abstract]
Business Combination Disclosure	BUSINESS COMBINATIONS 2021 Business Combinations During the nine months ended September 30, 2021, NWN Water completed three acquisitions qualifying as business combinations. The aggregate fair value of the preliminary consideration transferred for these acquisitions were not material and are 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 $69.8 million, $70.3 million and $69.2 million as of September 30, 2021, September 30, 2020 and December 31, 2020, respectively. The decrease in the goodwill balance from the third 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	9 Months Ended
	Sep. 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: September 30, December 31, In thousands 2021 2020 2020 Natural gas (in therms): Financial 749,595 860,400 784,400 Physical 613,524 706,592 457,593 Foreign exchange $ 6,299 $ 6,754 $ 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 2021-22 and 2020-21 gas years with forecasted sales volumes hedged at 53% and 51% in financial swap and option contracts, and 17% and 17% in physical gas supplies, respectively. Hedge contracts entered into prior to the PGA filing in September 2021 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 September 30, 2021 2020 In thousands Natural gas commodity Foreign exchange Natural gas commodity Foreign exchange Benefit (expense) to cost of gas $ 69,239 $ (106) $ 28,122 $ 136 Operating revenues (expense) — — 658 — Amounts deferred to regulatory accounts on balance sheet (69,239) 106 (28,684) (136) Total gain (loss) in pre-tax earnings $ — $ — $ 96 $ — Nine Months Ended September 30, 2021 2020 In thousands Natural gas commodity Foreign exchange Natural gas commodity Foreign exchange Benefit (expense) to cost of gas $ 106,044 $ (74) $ 28,271 $ 129 Operating revenues (expense) (26) — (1,021) — Amounts deferred to regulatory accounts on balance sheet (106,022) 74 (27,398) (129) Total gain (loss) in pre-tax earnings $ (4) $ — $ (148) $ — 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 $6.1 million and $15.4 million for the three and nine months ended September 30, 2021 from the settlement of natural gas financial derivative contracts, whereas, net losses of $3.2 million were realized for the nine months ended September 30, 2020. There were no net gains or losses realized for the three months ended September 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 September 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 September 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 $132.2 million and $34.1 million at September 30, 2021 and 2020, respectively. If netted by counterparty, NW Natural's physical and financial derivative position would result in an asset of $124.5 million and a liability of $4.9 million as of September 30, 2021, an asset of $35.6 million and a liability of $1.3 million as of September 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	9 Months Ended
	Sep. 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 ongoing nature of several site investigations and studies, in some cases, NW Natural may not be able to reasonably estimate the high end of the range of possible loss. In those cases, the nature of the possible loss has been disclosed, as has the fact that the high end of the range cannot be reasonably estimated where a range of potential loss is available. Unless there is an estimate within the range of possible losses that is more likely than other cost estimates within that range, NW Natural records the liability at the low end of this range. It is likely changes in these estimates and ranges will occur throughout the remediation process for each of these sites due to the continued evaluation and clarification concerning responsibility, the complexity of environmental laws and regulations and the determination by regulators of remediation alternatives. In addition to remediation costs, NW Natural could also be subject to Natural Resource Damages (NRD) claims. NW Natural will assess the likelihood and probability of each claim and recognize a liability if deemed appropriate. Refer to " Other Portland Harbor " below. Environmental Sites The following table summarizes information regarding liabilities related to environmental sites, which are recorded in other current liabilities and other noncurrent liabilities in NW Natural's balance sheet: Current Liabilities Non-Current Liabilities September 30, December 31, September 30, December 31, In thousands 2021 2020 2020 2021 2020 2020 Portland Harbor site: Gasco/Siltronic Sediments $ 6,925 $ 8,338 $ 7,596 $ 40,929 $ 43,509 $ 43,725 Other Portland Harbor 2,392 2,760 1,942 6,222 5,882 7,020 Gasco/Siltronic Upland site 9,720 8,775 14,887 37,408 41,515 40,250 Front Street site 1,002 10,610 3,816 893 1,044 1,107 Oregon Steel Mills — — — 179 179 179 Total $ 20,039 $ 30,483 $ 28,241 $ 85,631 $ 92,129 $ 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 for the Gasco sediments site. These preliminary design discussions did not include a cost estimate for remedial actions. None of the alternatives in the EE/CA 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 $47.9 million to $350 million. NW Natural has recorded a liability of $47.9 million for the Gasco sediment clean-up, which reflects the low end of the range. At this time, we believe sediments at the Gasco sediments site represent the largest portion of NW Natural's liability related to the Portland Harbor site discussed above. OTHER PORTLAND HARBOR. While we believe liabilities associated with the Gasco/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 portion. 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 $1.9 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: September 30, December 31, In thousands 2021 2020 2020 Deferred costs and interest (1) $ 45,019 $ 35,919 $ 44,516 Accrued site liabilities (2) 105,607 122,226 120,352 Insurance proceeds and interest (59,589) (69,138) (69,253) Total regulatory asset deferral (1) $ 91,037 $ 89,007 $ 95,615 Current regulatory assets (3) 7,068 4,440 4,992 Long-term regulatory assets (3) 83,969 84,567 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 September 30, 2021, $0.4 million at September 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 relating to the Oregon Steel Mills site 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 their 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	9 Months Ended
	Sep. 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 September 30, 2021 or December 31, 2020 and there was no activity in the consolidated statement of comprehensive income for the three and nine months ended September 30, 2021. The assets and liabilities of the discontinued operations classified as held for sale in the consolidated balance sheet at September 30, 2020 include the following: NW Holdings In thousands September 30, 2020 Assets: Accounts receivable $ 1,106 Inventories 730 Other current assets 64 Property, plant, and equipment, net 14,663 Operating lease right of use asset 118 Other non-current assets 247 Total discontinued operations assets - current assets (1) $ 16,928 Liabilities: Accounts payable $ 1,747 Other current liabilities 796 Operating lease liabilities 113 Other non-current liabilities 11,266 Total discontinued operations liabilities - current liabilities (1) $ 13,922 (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 September 30, Nine Months Ended September 30, In thousands, except per share data 2020 2020 Revenues $ 3,584 $ 7,866 Expenses: Operations and maintenance 2,148 6,332 General taxes 61 161 Depreciation and amortization 105 317 Other expenses and interest 229 688 Total expenses 2,543 7,498 Income from discontinued operations before income taxes 1,041 368 Income tax expense 276 101 Income from discontinued operations, net of tax $ 765 $ 267 Earnings from discontinued operations per share of common stock: Basic $ 0.02 $ 0.01 Diluted $ 0.02 $ 0.01

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2021
Subsequent Events [Abstract]
Subsequent Events	SUBSEQUENT EVENTS Credit Agreements On November 3, 2021, NW Holdings entered into an amended and restated $200 million credit agreement with a maturity date of November 3, 2026 and an available extension of commitments for two additional one-year periods, subject to lender approval (Amended NW Holdings Credit Agreement). The prior NW Holdings credit agreement was terminated upon closing of this new agreement. The Amended NW Holdings Credit Agreement permits the issuance of letters of credit in an aggregate amount of up to $40 million. On November 3, 2021, NW Natural entered into a $400 million credit agreement with a maturity date of November 3, 2026 and an available extension of commitments for two additional one-year periods, subject to lender approval (Amended NW Natural Credit Agreement). The prior NW Natural credit agreement was terminated upon closing of this new agreement. The Amended NW Natural Credit Agreement permits the issuance of letters of credit in an aggregate amount of up to $60 million.

Significant Accounting Polici_2

Significant Accounting Policies	9 Months Ended
	Sep. 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), as applicable, 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 London Inter-Bank Offered Rate (LIBOR) or another reference rate expected to be discontinued because of reference rate reform.

Significant Accounting Polici_3

Significant Accounting Policies	9 Months Ended
	Sep. 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 September 30, December 31, In thousands 2021 2020 2020 NW Natural: Current: Unrealized loss on derivatives (1) $ 9,818 $ 1,459 $ 4,198 Gas costs 39,622 5,207 1,979 Environmental costs (2) 7,068 4,440 4,992 Decoupling (3) 1,628 155 361 Pension balancing (4) 7,131 7,131 7,131 Income taxes 2,939 2,208 3,484 Other (5) 12,432 9,140 9,600 Total current $ 80,638 $ 29,740 $ 31,745 Non-current: Unrealized loss on derivatives (1) $ 268 $ 921 $ 2,852 Pension balancing (4) 40,176 45,203 43,383 Income taxes 13,912 16,792 15,368 Pension and other postretirement benefit liabilities 155,077 159,207 170,812 Environmental costs (2) 83,969 84,567 90,623 Gas costs 2,858 110 3,925 Decoupling (3) 118 6 1,031 Other (5) 28,653 17,330 20,893 Total non-current $ 325,031 $ 324,136 $ 348,887 Other (NW Holdings) 40 40 40 Total non-current - NW Holdings $ 325,071 $ 324,176 $ 348,927
Schedule of Regulatory Liabilities	Regulatory Liabilities September 30, December 31, In thousands 2021 2020 2020 NW Natural: Current: Gas costs $ 847 $ 1,625 $ 1,118 Unrealized gain on derivatives (1) 105,175 23,738 13,674 Decoupling (3) 4,484 12,702 11,793 Income taxes 8,217 6,900 8,217 Asset optimization revenue sharing 43,883 9,020 10,298 Other (5) 1,562 5,251 5,262 Total current $ 164,168 $ 59,236 $ 50,362 Non-current: Gas costs $ — $ 69 $ 314 Unrealized gain on derivatives (1) 24,555 12,921 6,135 Decoupling (3) 214 874 1,723 Income taxes (6) 186,429 196,558 189,587 Accrued asset removal costs (7) 440,410 421,353 427,960 Asset optimization revenue sharing — 58 1,231 Other (5) 12,913 16,818 11,843 Total non-current - NW Natural $ 664,521 $ 648,651 $ 638,793 Other (NW Holdings) 869 870 870 Total non-current - NW Holdings $ 665,390 $ 649,521 $ 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 17 for a description of environmental costs. (3) This deferral represents the margin adjustment resulting from differences between actual and expected volumes. (4) Balance represents deferred net periodic benefit costs as approved by the OPUC. (5) 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 Nine Months Ended September 30, 2021 September 30, 2021 In thousands Beginning Balance Provision recorded, net of adjustments Write-offs recognized, net of recoveries Ending Balance Allowance for uncollectible accounts: Residential $ 2,153 $ 1,322 $ (1,111) $ 2,364 Commercial 704 (337) (303) 64 Industrial 142 (106) 5 41 Accrued unbilled and other 220 96 (83) 233 Total $ 3,219 $ 975 $ (1,492) $ 2,702
Schedule of Cash Flow, Supplemental Disclosures	The following table provides a reconciliation of the cash, cash equivalents and restricted cash balances at NW Holdings as of September 30, 2021 and 2020 and December 31, 2020: September 30, December 31, In thousands 2021 2020 2020 Cash and cash equivalents $ 19,502 $ 35,926 $ 30,168 Restricted cash included in other current assets 8,170 5,245 5,286 Cash, cash equivalents and restricted cash $ 27,672 $ 41,171 $ 35,454 The following table provides a reconciliation of the cash, cash equivalents and restricted cash balances at NW Natural as of September 30, 2021 and 2020 and December 31, 2020: September 30, December 31, In thousands 2021 2020 2020 Cash and cash equivalents $ 9,697 $ 27,133 $ 10,453 Restricted cash included in other current assets 8,170 5,245 5,286 Cash, cash equivalents and restricted cash $ 17,867 $ 32,378 $ 15,739

Earnings Per Share_2

Earnings Per Share	9 Months Ended
	Sep. 30, 2021
Earnings Per Share [Abstract]
EPS Calculation	NW Holdings' diluted earnings or loss per share are calculated as follows: Three Months Ended September 30, Nine Months Ended September 30, In thousands, except per share data 2021 2020 2021 2020 Net income (loss) from continuing operations $ (20,655) $ (18,677) $ 38,138 $ 24,467 Income from discontinued operations, net of tax — 765 — 267 Net income (loss) $ (20,655) $ (17,912) $ 38,138 $ 24,734 Average common shares outstanding - basic 30,696 30,555 30,659 30,528 Additional shares for stock-based compensation plans (See Note 8) — — 49 47 Average common shares outstanding - diluted 30,696 30,555 30,708 30,575 Earnings (loss) from continuing operations per share of common stock: Basic $ (0.67) $ (0.61) $ 1.24 $ 0.80 Diluted $ (0.67) $ (0.61) $ 1.24 $ 0.80 Earnings from discontinued operations per share of common stock: Basic $ — $ 0.02 $ — $ 0.01 Diluted $ — $ 0.02 $ — $ 0.01 Earnings (loss) per share of common stock: Basic $ (0.67) $ (0.59) $ 1.24 $ 0.81 Diluted $ (0.67) $ (0.59) $ 1.24 $ 0.81 Additional information: Anti-dilutive shares 51 47 6 1

Segment Information_2

Segment Information	9 Months Ended
	Sep. 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 18 for information regarding discontinued operations for NW Holdings. Three Months Ended September 30, In thousands NGD Other NW Natural Other NW Holdings 2021 Operating revenues $ 91,042 $ 4,994 $ 96,036 $ 5,411 $ 101,447 Depreciation and amortization 27,462 257 27,719 719 28,438 Income (loss) from operations (18,288) 3,203 (15,085) 694 (14,391) Net income (loss) from continuing operations (23,297) 2,279 (21,018) 363 (20,655) Capital expenditures 72,822 1,410 74,232 8,036 82,268 2020 Operating revenues $ 83,761 $ 4,606 $ 88,367 $ 4,917 $ 93,284 Depreciation and amortization 25,433 248 25,681 253 25,934 Income (loss) from operations (16,196) 2,727 (13,469) 1,881 (11,588) Net income (loss) from continuing operations (22,120) 1,900 (20,220) 1,543 (18,677) Capital expenditures 69,213 1,113 70,326 728 71,054 Nine Months Ended September 30, In thousands NGD Other NW Natural Other NW Holdings 2021 Operating revenues $ 531,994 $ 20,971 $ 552,965 $ 13,345 $ 566,310 Depreciation and amortization 81,648 770 82,418 2,261 84,679 Income (loss) from operations 79,530 14,642 94,172 (1,233) 92,939 Net income (loss) from continuing operations 29,247 10,435 39,682 (1,544) 38,138 Capital expenditures 197,190 2,209 199,399 12,977 212,376 Total assets at September 30, 2021 3,730,595 50,366 3,780,961 148,264 3,929,225 2020 Operating revenues $ 489,240 $ 12,813 $ 502,053 $ 11,353 $ 513,406 Depreciation and amortization 74,117 740 74,857 1,588 76,445 Income (loss) from operations 65,496 6,955 72,451 1,349 73,800 Net income (loss) from continuing operations 19,476 4,771 24,247 220 24,467 Capital expenditures 186,842 1,711 188,553 4,783 193,336 Total assets at September 30, 2020 (1) 3,451,771 11,596 3,463,367 137,802 3,601,169 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 September 30, Nine Months Ended September 30, In thousands 2021 2020 2021 2020 NGD margin calculation: NGD distribution revenues $ 86,271 $ 79,357 $ 517,673 $ 474,989 Other regulated services 4,771 4,404 14,321 14,251 Total NGD operating revenues 91,042 83,761 531,994 489,240 Less: NGD cost of gas 25,322 23,797 178,837 173,657 Environmental remediation 806 867 6,092 6,494 Revenue taxes 3,838 3,555 22,143 19,752 NGD margin $ 61,076 $ 55,542 $ 324,922 $ 289,337

Revenue_2

Revenue	3 Months Ended
	Sep. 30, 2021
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenue	The following tables present disaggregated revenue from continuing operations: Three Months Ended September 30, In thousands NGD Other NW Natural Other NW Holdings 2021 Natural gas sales $ 83,947 $ — $ 83,947 $ — $ 83,947 Gas storage revenue, net — 2,794 2,794 — 2,794 Asset management revenue, net — 1,012 1,012 — 1,012 Appliance retail center revenue — 1,188 1,188 — 1,188 Other revenue 403 — 403 5,411 5,814 Revenue from contracts with customers 84,350 4,994 89,344 5,411 94,755 Alternative revenue 2,307 — 2,307 — 2,307 Leasing revenue 4,385 — 4,385 — 4,385 Total operating revenues $ 91,042 $ 4,994 $ 96,036 $ 5,411 $ 101,447 2020 Natural gas sales $ 78,427 $ — $ 78,427 $ — $ 78,427 Gas storage revenue, net — 2,482 2,482 — 2,482 Asset management revenue, net — 939 939 — 939 Appliance retail center revenue — 1,185 1,185 — 1,185 Other revenue 333 — 333 4,917 5,250 Revenue from contracts with customers 78,760 4,606 83,366 4,917 88,283 Alternative revenue 395 — 395 — 395 Leasing revenue 4,606 — 4,606 — 4,606 Total operating revenues $ 83,761 $ 4,606 $ 88,367 $ 4,917 $ 93,284 Nine Months Ended September 30, In thousands NGD Other NW Natural Other NW Holdings 2021 Natural gas sales $ 503,769 $ — $ 503,769 $ — $ 503,769 Gas storage revenue, net — 8,094 8,094 — 8,094 Asset management revenue, net — 8,757 8,757 — 8,757 Appliance retail center revenue — 4,120 4,120 — 4,120 Other revenue 1,217 — 1,217 13,345 14,562 Revenue from contracts with customers 504,986 20,971 525,957 13,345 539,302 Alternative revenue 13,843 — 13,843 — 13,843 Leasing revenue 13,165 — 13,165 — 13,165 Total operating revenues $ 531,994 $ 20,971 $ 552,965 $ 13,345 $ 566,310 2020 Natural gas sales $ 469,113 $ — $ 469,113 $ — $ 469,113 Gas storage revenue, net — 7,267 7,267 — 7,267 Asset management revenue, net — 1,999 1,999 — 1,999 Appliance retail center revenue — 3,547 3,547 — 3,547 Other revenue 1,002 — 1,002 11,353 12,355 Revenue from contracts with customers 470,115 12,813 482,928 11,353 494,281 Alternative revenue 5,288 — 5,288 — 5,288 Leasing revenue 13,837 — 13,837 — 13,837 Total operating revenues $ 489,240 $ 12,813 $ 502,053 $ 11,353 $ 513,406

Leases_2

Leases	3 Months Ended	9 Months Ended
	Mar. 31, 2020	Sep. 30, 2021
Leases [Abstract]
Lease Revenue		The components of lease revenue at NW Natural were as follows: Three Months Ended September 30, Nine Months Ended September 30, In thousands 2021 2020 2021 2020 Lease revenue Operating leases $ 18 $ 18 $ 61 $ 71 Sales-type leases 4,367 4,588 13,104 13,766 Total lease revenue $ 4,385 $ 4,606 $ 13,165 $ 13,837
Lessor, Operating Lease, Payments to be Received, Maturity		Total future minimum lease payments to be received under non-cancellable leases at September 30, 2021 are as follows: In thousands Operating Sales-Type Total NW Natural: Remainder of 2021 $ 138 $ 4,338 $ 4,476 2022 551 17,026 17,577 2023 74 16,557 16,631 2024 74 15,867 15,941 2025 66 15,306 15,372 Thereafter 58 251,721 251,779 Total minimum lease payments $ 961 $ 320,815 $ 321,776 Less: imputed interest 180,198 Total leases receivable $ 140,617 Other (NW Holdings): Remainder of 2021 $ 12 $ — $ 12 2022 50 — 50 2023 51 — 51 2024 52 — 52 2025 53 — 53 Thereafter 970 — 970 Total minimum lease payments $ 1,188 $ — $ 1,188 NW Holdings: Remainder of 2021 $ 150 $ 4,338 $ 4,488 2022 601 17,026 17,627 2023 125 16,557 16,682 2024 126 15,867 15,993 2025 119 15,306 15,425 Thereafter 1,028 251,721 252,749 Total minimum lease payments $ 2,149 $ 320,815 $ 322,964 Less: imputed interest 180,198 Total leases receivable $ 140,617
Lease Expense		The components of lease expense, a portion of which is capitalized, were as follows: Three Months Ended September 30, Nine Months Ended September 30, In thousands 2021 2020 2021 2020 NW Natural: Operating lease expense $ 1,735 $ 746 $ 5,123 $ 2,862 Short-term lease expense $ 499 $ 300 $ 1,068 $ 783 Other (NW Holdings): Operating lease expense $ 14 $ 17 $ 50 $ 109 NW Holdings: Operating lease expense $ 1,749 $ 763 $ 5,173 $ 2,971 Short-term lease expense $ 499 $ 300 $ 1,068 $ 783
Operating Lease, Lease Asset and Liabilities		Supplemental balance sheet information related to operating leases as of September 30, 2021 is as follows: In thousands September 30, December 31, 2021 2020 2020 NW Natural: Operating lease right of use asset $ 75,565 $ 77,949 $ 77,328 Operating lease liabilities - current liabilities $ 1,184 $ 1,020 $ 1,054 Operating lease liabilities - non-current liabilities 79,752 80,830 80,559 Total operating lease liabilities $ 80,936 $ 81,850 $ 81,613 Other (NW Holdings): Operating lease right of use asset $ 69 $ 87 $ 118 Operating lease liabilities - current liabilities $ 29 $ 61 $ 51 Operating lease liabilities - non-current liabilities 37 24 62 Total operating lease liabilities $ 66 $ 85 $ 113 NW Holdings: Operating lease right of use asset $ 75,634 $ 78,036 $ 77,446 Operating lease liabilities - current liabilities $ 1,213 $ 1,081 $ 1,105 Operating lease liabilities - non-current liabilities 79,789 80,854 80,621 Total operating lease liabilities $ 81,002 $ 81,935 $ 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 September 30, December 31, 2021 2020 2020 Weighted-average remaining lease term (years) 18.4 19.4 19.2 Weighted-average discount rate 7.2 % 7.2 % 7.2 %
Lessee, Operating Lease, Liability, Maturity	Maturities of operating lease liabilities at September 30, 2021 were as follows: In thousands NW Natural Other NW Holdings Remainder of 2021 $ 1,727 $ 6 $ 1,733 2022 6,968 24 6,992 2023 7,013 6 7,019 2024 7,150 6 7,156 2025 7,185 6 7,191 Thereafter 123,784 24 123,808 Total lease payments 153,827 72 153,899 Less: imputed interest 72,891 6 72,897 Total lease obligations 80,936 66 81,002 Less: current obligations 1,184 29 1,213 Long-term lease obligations $ 79,752 $ 37 $ 79,789
Lessee, Leases, Supplemental Cash Flow Information		Supplemental cash flow information related to leases was as follows: Three Months Ended September 30, Nine Months Ended September 30, In thousands 2021 2020 2021 2020 NW Natural: Cash paid for amounts included in the measurement of lease liabilities Operating cash flows from operating leases $ 1,727 $ 673 $ 5,113 $ 2,800 Finance cash flows from finance leases $ 123 $ 215 $ 801 $ 672 Right of use assets obtained in exchange for lease obligations Operating leases $ — $ 106 $ 154 $ 78,539 Finance leases $ 75 $ 676 $ 169 $ 1,386 Other (NW Holdings): Cash paid for amounts included in the measurement of lease liabilities Operating cash flows from operating leases $ 18 $ 18 $ 51 $ 109 NW Holdings: Cash paid for amounts included in the measurement of lease liabilities Operating cash flows from operating leases $ 1,745 $ 691 $ 5,164 $ 2,909 Finance cash flows from finance leases $ 123 $ 215 $ 801 $ 672 Right of use assets obtained in exchange for lease obligations Operating leases $ — $ 106 $ 154 $ 78,539 Finance leases $ 75 $ 676 $ 169 $ 1,386

Debt_2

Debt	9 Months Ended
	Sep. 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 long-term debt, including current maturities of long-term debt, using market prices in effect on the valuation date: September 30, December 31, In thousands 2021 2020 2020 NW Natural: Gross long-term debt $ 864,700 $ 924,700 $ 924,700 Unamortized debt issuance costs (6,940) (7,586) (7,480) Carrying amount $ 857,760 $ 917,114 $ 917,220 Estimated fair value (1) $ 978,613 $ 1,080,663 $ 1,097,348 NW Holdings: Gross long-term debt $ 923,355 $ 962,994 $ 962,905 Unamortized debt issuance costs (7,051) (7,586) (7,480) Carrying amount $ 916,304 $ 955,408 $ 955,425 Estimated fair value (1) $ 1,042,705 $ 1,118,565 $ 1,136,311 (1) Estimated fair value does not include unamortized debt issuance costs.

Pension and Other Postretirem_2

Pension and Other Postretirement Benefit Costs	9 Months Ended
	Sep. 30, 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 September 30, Nine Months Ended September 30, Pension Benefits Other Postretirement Pension Benefits Other In thousands 2021 2020 2021 2020 2021 2020 2021 2020 Service cost $ 1,717 $ 1,673 $ 69 $ 67 $ 5,145 $ 4,988 $ 180 $ 195 Interest cost 3,316 4,071 180 229 10,001 12,093 510 675 Expected return on plan assets (5,802) (5,358) — — (18,000) (16,350) — — Amortization of prior service credit — — (119) (119) — — (353) (353) Amortization of net actuarial loss 5,515 5,082 226 173 16,516 14,638 488 458 Net periodic benefit cost 4,746 5,468 356 350 13,662 15,369 825 975 Amount allocated to construction (759) (695) (27) (25) (2,228) (2,043) (70) (71) Net periodic benefit cost charged to expense 3,987 4,773 329 325 11,434 13,326 755 904 Amortization of regulatory balancing account 675 675 — — 4,757 4,757 — — Net amount charged to expense $ 4,662 $ 5,448 $ 329 $ 325 $ 16,191 $ 18,083 $ 755 $ 904
Schedule of Amounts Recognized in Other Comprehensive Income (Loss)	The following table presents amounts recognized in accumulated other comprehensive loss (AOCL) and the changes in AOCL related to non-qualified employee benefit plans: Three Months Ended September 30, Nine Months Ended September 30, In thousands 2021 2020 2021 2020 Beginning balance $ (12,460) $ (10,413) $ (12,902) $ (10,733) Amounts reclassified from AOCL: Amortization of actuarial losses 314 252 916 688 Total reclassifications before tax 314 252 916 688 Tax benefit (80) (66) (240) (182) Total reclassifications for the period 234 186 676 506 Ending balance $ (12,226) $ (10,227) $ (12,226) $ (10,227)

Income Tax_2

Income Tax	9 Months Ended
	Sep. 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 September 30, NW Holdings NW Natural In thousands 2021 2020 2021 2020 Income tax at statutory rate (federal) $ (5,834) $ (5,048) $ (5,928) $ (5,518) State income tax (2,599) (1,452) (2,618) (1,595) Increase (decrease): Differences required to be flowed-through by regulatory commissions 1,318 1,051 1,318 1,051 Other, net (12) 86 16 5 Total benefit for income taxes on continuing operations $ (7,127) $ (5,363) $ (7,212) $ (6,057) Effective income tax rate for continuing operations 25.7 % 22.3 % 25.5 % 23.1 % Nine Months Ended September 30, NW Holdings NW Natural In thousands 2021 2020 2021 2020 Income tax at statutory rate (federal) $ 10,764 $ 6,628 $ 11,195 $ 6,550 State income tax 4,660 1,892 4,748 1,861 Increase (decrease): Differences required to be flowed-through by regulatory commissions (2,266) (1,301) (2,266) (1,301) Other, net (41) (127) (49) (168) Total provision for income taxes on continuing operations $ 13,117 $ 7,092 $ 13,628 $ 6,942 Effective income tax rate for continuing operations 25.6 % 22.5 % 25.6 % 22.3 %

Property, Plant and Equipment_2

Property, Plant and Equipment	9 Months Ended
	Sep. 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: September 30, December 31, In thousands 2021 2020 2020 NW Natural: NGD plant in service $ 3,663,699 $ 3,441,301 $ 3,548,543 NGD work in progress 120,412 120,722 63,901 Less: Accumulated depreciation 1,086,510 1,051,018 1,055,809 NGD plant, net 2,697,601 2,511,005 2,556,635 Other plant in service 66,314 65,103 66,300 Other construction work in progress 7,228 6,444 5,032 Less: Accumulated depreciation 20,392 19,387 19,637 Other plant, net 53,150 52,160 51,695 Total property, plant, and equipment, net $ 2,750,751 $ 2,563,165 $ 2,608,330 Other (NW Holdings): Other plant in service $ 61,443 $ 47,302 $ 50,263 Less: Accumulated depreciation 5,832 3,218 3,823 Other plant, net $ 55,611 $ 44,084 $ 46,440 NW Holdings: Total property, plant, and equipment, net $ 2,806,362 $ 2,607,249 $ 2,654,770 NW Natural: Capital expenditures in accrued liabilities $ 33,968 $ 37,236 $ 25,129 NW Holdings: Capital expenditures in accrued liabilities $ 35,955 $ 37,236 $ 25,129

Gas Reserves_2

Gas Reserves	9 Months Ended
	Sep. 30, 2021
Gas Reserves [Abstract]
Gas Reserves	The following table outlines NW Natural's net gas reserves investment: September 30, December 31, In thousands 2021 2020 2020 Gas reserves, current $ 6,266 $ 12,265 $ 11,409 Gas reserves, non-current 181,041 175,042 175,898 Less: Accumulated amortization 153,020 137,346 141,414 Total gas reserves (1) 34,287 49,961 45,893 Less: Deferred taxes on gas reserves 7,768 11,972 10,572 Net investment in gas reserves $ 26,519 $ 37,989 $ 35,321

Derivative Instruments_2

Derivative Instruments	9 Months Ended
	Sep. 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: September 30, December 31, In thousands 2021 2020 2020 Natural gas (in therms): Financial 749,595 860,400 784,400 Physical 613,524 706,592 457,593 Foreign exchange $ 6,299 $ 6,754 $ 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 September 30, 2021 2020 In thousands Natural gas commodity Foreign exchange Natural gas commodity Foreign exchange Benefit (expense) to cost of gas $ 69,239 $ (106) $ 28,122 $ 136 Operating revenues (expense) — — 658 — Amounts deferred to regulatory accounts on balance sheet (69,239) 106 (28,684) (136) Total gain (loss) in pre-tax earnings $ — $ — $ 96 $ — Nine Months Ended September 30, 2021 2020 In thousands Natural gas commodity Foreign exchange Natural gas commodity Foreign exchange Benefit (expense) to cost of gas $ 106,044 $ (74) $ 28,271 $ 129 Operating revenues (expense) (26) — (1,021) — Amounts deferred to regulatory accounts on balance sheet (106,022) 74 (27,398) (129) Total gain (loss) in pre-tax earnings $ (4) $ — $ (148) $ —

Environmental Matters_2

Environmental Matters	9 Months Ended
	Sep. 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 September 30, December 31, September 30, December 31, In thousands 2021 2020 2020 2021 2020 2020 Portland Harbor site: Gasco/Siltronic Sediments $ 6,925 $ 8,338 $ 7,596 $ 40,929 $ 43,509 $ 43,725 Other Portland Harbor 2,392 2,760 1,942 6,222 5,882 7,020 Gasco/Siltronic Upland site 9,720 8,775 14,887 37,408 41,515 40,250 Front Street site 1,002 10,610 3,816 893 1,044 1,107 Oregon Steel Mills — — — 179 179 179 Total $ 20,039 $ 30,483 $ 28,241 $ 85,631 $ 92,129 $ 92,281
Environmental Regulatory Table	The following table presents information regarding the total regulatory asset deferred: September 30, December 31, In thousands 2021 2020 2020 Deferred costs and interest (1) $ 45,019 $ 35,919 $ 44,516 Accrued site liabilities (2) 105,607 122,226 120,352 Insurance proceeds and interest (59,589) (69,138) (69,253) Total regulatory asset deferral (1) $ 91,037 $ 89,007 $ 95,615 Current regulatory assets (3) 7,068 4,440 4,992 Long-term regulatory assets (3) 83,969 84,567 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 September 30, 2021, $0.4 million at September 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	9 Months Ended
	Sep. 30, 2021	Sep. 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 September 30, 2021 or December 31, 2020 and there was no activity in the consolidated statement of comprehensive income for the three and nine months ended September 30, 2021. The assets and liabilities of the discontinued operations classified as held for sale in the consolidated balance sheet at September 30, 2020 include the following: NW Holdings In thousands September 30, 2020 Assets: Accounts receivable $ 1,106 Inventories 730 Other current assets 64 Property, plant, and equipment, net 14,663 Operating lease right of use asset 118 Other non-current assets 247 Total discontinued operations assets - current assets (1) $ 16,928 Liabilities: Accounts payable $ 1,747 Other current liabilities 796 Operating lease liabilities 113 Other non-current liabilities 11,266 Total discontinued operations liabilities - current liabilities (1) $ 13,922 (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 September 30, Nine Months Ended September 30, In thousands, except per share data 2020 2020 Revenues $ 3,584 $ 7,866 Expenses: Operations and maintenance 2,148 6,332 General taxes 61 161 Depreciation and amortization 105 317 Other expenses and interest 229 688 Total expenses 2,543 7,498 Income from discontinued operations before income taxes 1,041 368 Income tax expense 276 101 Income from discontinued operations, net of tax $ 765 $ 267 Earnings from discontinued operations per share of common stock: Basic $ 0.02 $ 0.01 Diluted $ 0.02 $ 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 September 30, Nine Months Ended September 30, In thousands, except per share data 2020 2020 Revenues $ 3,584 $ 7,866 Expenses: Operations and maintenance 2,148 6,332 General taxes 61 161 Depreciation and amortization 105 317 Other expenses and interest 229 688 Total expenses 2,543 7,498 Income from discontinued operations before income taxes 1,041 368 Income tax expense 276 101 Income from discontinued operations, net of tax $ 765 $ 267 Earnings from discontinued operations per share of common stock: Basic $ 0.02 $ 0.01 Diluted $ 0.02 $ 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 September 30, 2020 Assets: Accounts receivable $ 1,106 Inventories 730 Other current assets 64 Property, plant, and equipment, net 14,663 Operating lease right of use asset 118 Other non-current assets 247 Total discontinued operations assets - current assets (1) $ 16,928 Liabilities: Accounts payable $ 1,747 Other current liabilities 796 Operating lease liabilities 113 Other non-current liabilities 11,266 Total discontinued operations liabilities - current liabilities (1) $ 13,922 (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	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020
Regulatory Assets [Line Items]
Regulatory Assets, Current	$ 80,638	$ 31,745	$ 29,740
Regulatory Assets, Noncurrent	325,071	348,927	324,176
Other [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Noncurrent	40	40	40
Northwest Natural Gas Company [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Current	80,638	31,745	29,740
Regulatory Assets, Noncurrent	325,031	348,887	324,136
Northwest Natural Gas Company [Member] | Deferred Derivative Gain (Loss) [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Current	9,818	4,198	1,459
Regulatory Assets, Noncurrent	268	2,852	921
Northwest Natural Gas Company [Member] | Gas costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Current	39,622	1,979	5,207
Regulatory Assets, Noncurrent	2,858	3,925	110
Northwest Natural Gas Company [Member] | Environmental costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Current	7,068	4,992	4,440
Regulatory Assets, Noncurrent	83,969	90,623	84,567
Northwest Natural Gas Company [Member] | Decoupling [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Current	1,628	361	155
Regulatory Assets, Noncurrent	118	1,031	6
Northwest Natural Gas Company [Member] | Pension balancing [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Current	7,131	7,131	7,131
Regulatory Assets, Noncurrent	40,176	43,383	45,203
Northwest Natural Gas Company [Member] | Income taxes [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Current	2,939	3,484	2,208
Regulatory Assets, Noncurrent	13,912	15,368	16,792
Northwest Natural Gas Company [Member] | Pension and other postretirement benefit liabilities [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Noncurrent	155,077	170,812	159,207
Northwest Natural Gas Company [Member] | Other [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Current	12,432	9,600	9,140
Regulatory Assets, Noncurrent	$ 28,653	$ 20,893	$ 17,330

Significant Accounting Polici_5

Significant Accounting Policies - Regulatory Liability Disclosure - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	$ 164,168	$ 50,362	$ 59,236
Regulatory Liability, Noncurrent	665,390	639,663	649,521
Other [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Noncurrent	869	870	870
Northwest Natural Gas Company [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	164,168	50,362	59,236
Regulatory Liability, Noncurrent	664,521	638,793	648,651
Northwest Natural Gas Company [Member] | Gas costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	847	1,118	1,625
Regulatory Liability, Noncurrent	0	314	69
Northwest Natural Gas Company [Member] | Deferred Derivative Gain (Loss) [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	105,175	13,674	23,738
Regulatory Liability, Noncurrent	24,555	6,135	12,921
Northwest Natural Gas Company [Member] | Decoupling [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	4,484	11,793	12,702
Regulatory Liability, Noncurrent	214	1,723	874
Northwest Natural Gas Company [Member] | Income taxes [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	8,217	8,217	6,900
Regulatory Liability, Noncurrent	186,429	189,587	196,558
Northwest Natural Gas Company [Member] | Other [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	1,562	5,262	5,251
Regulatory Liability, Noncurrent	12,913	11,843	16,818
Northwest Natural Gas Company [Member] | Accrued asset removal costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Noncurrent	440,410	427,960	421,353
Northwest Natural Gas Company [Member] | Asset Optimization Revenue Sharing
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	43,883	10,298	9,020
Regulatory Liability, Noncurrent	$ 0	$ 1,231	$ 58

Significant Accounting Polici_6

Significant Accounting Policies - Credit Losses - ASU 2016-13 $ in Thousands	9 Months Ended
	Sep. 30, 2021USD ($)numberOfLeases	Dec. 31, 2020USD ($)	Sep. 30, 2020USD ($)
Accounts Receivable, Noncurrent, Credit Quality Indicator [Line Items]
Accounts Receivable, Allowance for Credit Loss	$ 2,702	$ 3,219
Accounts Receivable, Allowance for Credit Loss, Period Increase (Decrease)	975
Accounts Receivable, Allowance for Credit Loss, Recovery	(1,492)
Regulatory Assets, Noncurrent	$ 325,071	348,927	$ 324,176
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	$ 7,400
Residential [Member]
Accounts Receivable, Noncurrent, Credit Quality Indicator [Line Items]
Accounts Receivable, Allowance for Credit Loss	2,364	2,153
Accounts Receivable, Allowance for Credit Loss, Period Increase (Decrease)	1,322
Accounts Receivable, Allowance for Credit Loss, Recovery	(1,111)
Commercial [Member]
Accounts Receivable, Noncurrent, Credit Quality Indicator [Line Items]
Accounts Receivable, Allowance for Credit Loss	64	704
Accounts Receivable, Allowance for Credit Loss, Period Increase (Decrease)	(337)
Accounts Receivable, Allowance for Credit Loss, Recovery	(303)
Industrial [Member]
Accounts Receivable, Noncurrent, Credit Quality Indicator [Line Items]
Accounts Receivable, Allowance for Credit Loss	41	142
Accounts Receivable, Allowance for Credit Loss, Period Increase (Decrease)	(106)
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	233	$ 220
Accounts Receivable, Allowance for Credit Loss, Period Increase (Decrease)	96
Accounts Receivable, Allowance for Credit Loss, Recovery	$ (83)

Supplemental Cash Flow

Supplemental Cash Flow - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020	Dec. 31, 2019
Restricted Cash and Cash Equivalents Items [Line Items]
Cash and cash equivalents	$ 19,502	$ 30,168	$ 35,926
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	27,672	35,454	41,171	$ 12,636
Northwest Natural Gas Company [Member]
Restricted Cash and Cash Equivalents Items [Line Items]
Cash and cash equivalents	9,697	10,453	27,133
Restricted Cash	8,170	5,286	5,245
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	17,867	15,739	32,378	$ 8,907
Other Current Assets
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted Cash	$ 8,170	$ 5,286	$ 5,245

Earnings Per Share_2_3

Earnings Per Share - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Income Statement [Line Items]
Net income from continuing operations	$ (20,655)	$ (18,677)	$ 38,138	$ 24,467
Loss from discontinued operations, net of tax	0	765	0	267
Net income	$ (20,655)	$ (17,912)	$ 38,138	$ 24,734
Average common shares outstanding:
Average common shares outstanding - basic (in shares)	30,696	30,555	30,659	30,528
Additional shares for stock-based compensation plans	0	0	49	47
Average common shares outstanding - diluted (in shares)	30,696	30,555	30,708	30,575
Earnings from continuing operations per share of common stock:
Basic (in dollars per share)	$ (0.67)	$ (0.61)	$ 1.24	$ 0.80
Diluted (in dollars per share)	(0.67)	(0.61)	1.24	0.80
Loss from discontinued operations per share of common stock:
Basic (in dollars per share)	0	0.02	0	0.01
Diluted (in dollars per share)	0	0.02	0	0.01
Earnings (loss) per share of common stock
Basic (in dollars per share)	(0.67)	(0.59)	1.24	0.81
Diluted (in dollars per share)	$ (0.67)	$ (0.59)	$ 1.24	$ 0.81
Antidilutive shares	51	47	6	1
Discontinued Operations, Held-for-sale [Member] | Gill Ranch [Member]
Income Statement [Line Items]
Loss from discontinued operations, net of tax		$ 765		$ 267
Loss from discontinued operations per share of common stock:
Basic (in dollars per share)	$ 0	$ 0.02	$ 0	$ 0.01
Diluted (in dollars per share)	$ 0	$ 0.02	$ 0	$ 0.01

Segment Information - Narrative

Segment Information - Narrative	9 Months Ended
	Sep. 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		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Segment Reporting Information [Line Items]
Operating revenues	$ 101,447	$ 93,284	$ 566,310	$ 513,406
Depreciation and amortization	28,438	25,934	84,679	76,445
Income from operations	(14,391)	(11,588)	92,939	73,800
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	(20,655)	(18,677)	38,138	24,467
Total assets	3,929,225	3,618,097	3,929,225	3,618,097	$ 3,756,379
Discontinued operations - total assets		16,900		16,900
Natural Gas Distribution [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating revenues	91,042	83,761	531,994	489,240
Depreciation and amortization	27,462	25,433	81,648	74,117
Income from operations	(18,288)	(16,196)	79,530	65,496
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	(23,297)	(22,120)	29,247	19,476
Capital expenditures	72,822	69,213	197,190	186,842
Total assets	3,730,595	3,451,771	3,730,595	3,451,771	3,549,868
Other Northwest Natural [Member] | Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Operating revenues	4,994	4,606	20,971	12,813
Depreciation and amortization	257	248	770	740
Income from operations	3,203	2,727	14,642	6,955
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	2,279	1,900	10,435	4,771
Capital expenditures	1,410	1,113	2,209	1,711
Total assets	50,366	11,596	50,366	11,596	49,468
Northwest Natural Gas Company [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating revenues	96,036	88,367	552,965	502,053
Depreciation and amortization	27,719	25,681	82,418	74,857
Income from operations	(15,085)	(13,469)	94,172	72,451
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	(21,018)	(20,220)	39,682	24,247
Capital expenditures	74,232	70,326	199,399	188,553
Total assets	3,780,961	3,463,367	3,780,961	3,463,367	3,599,336
Other Northwest Holdings [Member] | Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Operating revenues	5,411	4,917	13,345	11,353
Depreciation and amortization	719	253	2,261	1,588
Income from operations	694	1,881	(1,233)	1,349
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	363	1,543	(1,544)	220
Capital expenditures	8,036	728	12,977	4,783
Total assets	148,264	137,802	148,264	137,802	157,043
Northwest Natural Gas Company [Member]
Segment Reporting Information [Line Items]
Operating revenues	96,036	88,367	552,965	502,053
Depreciation and amortization	27,719	25,681	82,418	74,857
Income from operations	(15,085)	(13,469)	94,172	72,451
Total assets	3,780,961	3,463,367	3,780,961	3,463,367	3,599,336
Northwest Natural Gas Company [Member] | Natural Gas Distribution [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating revenues	91,042	83,761	531,994	489,240
Northwest Natural Gas Company [Member] | Other Northwest Natural [Member] | Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Operating revenues	4,994	4,606	20,971	12,813
Northwest Natural Gas Company [Member] | Northwest Natural Gas Company [Member]
Segment Reporting Information [Line Items]
Operating revenues	96,036	88,367	552,965	502,053
Parent Company [Member]
Segment Reporting Information [Line Items]
Operating revenues	101,447	93,284	566,310	513,406
Depreciation and amortization	28,438	25,934	84,679	76,445
Income from operations	(14,391)	(11,588)	92,939	73,800
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	(20,655)	(18,677)	38,138	24,467
Capital expenditures	82,268	71,054	212,376	193,336
Total assets	$ 3,929,225	$ 3,601,169	$ 3,929,225	$ 3,601,169	$ 3,756,379

Segment Information - Additiona

Segment Information - Additional Segment Information - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Segment Reporting Information [Line Items]
Operating revenues	$ 101,447	$ 93,284	$ 566,310	$ 513,406
Cost of gas	25,266	23,741	178,669	173,489
Environmental remediation	806	867	6,092	6,494
Operating Segments [Member] | Natural Gas Distribution [Member]
Segment Reporting Information [Line Items]
Natural Gas Distribution revenues	86,271	79,357	517,673	474,989
Other regulated services	4,771	4,404	14,321	14,251
Operating revenues	91,042	83,761	531,994	489,240
Cost of gas	25,322	23,797	178,837	173,657
Environmental remediation	806	867	6,092	6,494
Revenue taxes	3,838	3,555	22,143	19,752
NGD margin	$ 61,076	$ 55,542	$ 324,922	$ 289,337

Equity - Narrative

Equity - Narrative - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020
Class of Stock [Line Items]
Par Value (in dollars per share)	$ 0	$ 0	$ 0	$ 0
Shares issued (in shares)	30,730,000	30,730,000	30,589,000	30,565,000
ATM Equity Program
Class of Stock [Line Items]
Par Value (in dollars per share)	$ 0	$ 0
Cumulative Proceeds Received on All Transactions		$ 2,100
Shares issued (in shares)	41,421	41,421
Sale of Stock, Consideration Received on Transaction	$ 2,100
Sale of Stock, Commissions and Fees Paid	$ 22
Sale of stock, cumulative number of shares issued		41,421
Sale of Stock, Cumulative Commissions and Fees Paid		$ 22
Maximum [Member] | Scenario, Plan | ATM Equity Program
Class of Stock [Line Items]
Cumulative Proceeds Received on All Transactions		$ 200,000

Revenue - Disaggregation of Rev

Revenue - Disaggregation of Revenue - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	$ 94,755	$ 88,283	$ 539,302	$ 494,281
Revenues	101,447	93,284	566,310	513,406
Natural Gas Sales [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	83,947	78,427	503,769	469,113
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	2,794	2,482	8,094	7,267
Asset Management Revenue, Net of Regulatory Sharing [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	1,012	939	8,757	1,999
Appliance Center Revenue [Member] | Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	1,188	1,185	4,120	3,547
Other revenue [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	5,814	5,250	14,562	12,355
Alternative revenue [Member]
Disaggregation of Revenue [Line Items]
Revenues	2,307	395	13,843	5,288
Leasing revenue [Member]
Disaggregation of Revenue [Line Items]
Operating leases	4,385	4,606	13,165	13,837
Northwest Natural Gas Company [Member]
Disaggregation of Revenue [Line Items]
Revenues	96,036	88,367	552,965	502,053
Operating leases	18	18	61	71
Northwest Natural Gas Company [Member] | Northwest Natural Gas Company [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	89,344	83,366	525,957	482,928
Revenues	96,036	88,367	552,965	502,053
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	83,947	78,427	503,769	469,113
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	2,794	2,482	8,094	7,267
Northwest Natural Gas Company [Member] | Northwest Natural Gas Company [Member] | Asset Management Revenue, Net of Regulatory Sharing [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	1,012	939	8,757	1,999
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	1,188	1,185	4,120	3,547
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	403	333	1,217	1,002
Northwest Natural Gas Company [Member] | Northwest Natural Gas Company [Member] | Alternative revenue [Member]
Disaggregation of Revenue [Line Items]
Revenues	2,307	395	13,843	5,288
Northwest Natural Gas Company [Member] | Northwest Natural Gas Company [Member] | Leasing revenue [Member]
Disaggregation of Revenue [Line Items]
Operating leases	4,385	4,606	13,165	13,837
Operating Segments [Member] | Natural Gas Distribution [Member]
Disaggregation of Revenue [Line Items]
Revenues	91,042	83,761	531,994	489,240
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	84,350	78,760	504,986	470,115
Revenues	91,042	83,761	531,994	489,240
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	83,947	78,427	503,769	469,113
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	403	333	1,217	1,002
Operating Segments [Member] | Natural Gas Distribution [Member] | Northwest Natural Gas Company [Member] | Alternative revenue [Member]
Disaggregation of Revenue [Line Items]
Revenues	2,307	395	13,843	5,288
Operating Segments [Member] | Natural Gas Distribution [Member] | Northwest Natural Gas Company [Member] | Leasing revenue [Member]
Disaggregation of Revenue [Line Items]
Operating leases	4,385	4,606	13,165	13,837
Operating Segments [Member] | Northwest Natural Gas Company [Member]
Disaggregation of Revenue [Line Items]
Revenues	96,036	88,367	552,965	502,053
Corporate, Non-Segment [Member] | Other Northwest Natural [Member]
Disaggregation of Revenue [Line Items]
Revenues	4,994	4,606	20,971	12,813
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	4,994	4,606	20,971	12,813
Revenues	4,994	4,606	20,971	12,813
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	2,794	2,482	8,094	7,267
Corporate, Non-Segment [Member] | Other Northwest Natural [Member] | Northwest Natural Gas Company [Member] | Asset Management Revenue, Net of Regulatory Sharing [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	1,012	939	8,757	1,999
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	1,188	1,185	4,120	3,547
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	5,411	4,917	13,345	11,353
Revenues	5,411	4,917	13,345	11,353
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	5,411	4,917	13,345	11,353
Corporate, Non-Segment [Member] | Other Northwest Holdings [Member] | Alternative revenue [Member]
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Corporate, Non-Segment [Member] | Other Northwest Holdings [Member] | Leasing revenue [Member]
Disaggregation of Revenue [Line Items]
Operating leases	$ 0	$ 0	$ 0	$ 0

Revenue - Revenue, Remaining Pe

Revenue - Revenue, Remaining Performance Obligation $ in Thousands	Sep. 30, 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	$ 103,300
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]: 2021-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Year	3 months
Revenue, Remaining Performance Obligation, Amount	$ 4,900
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	$ 19,700
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	$ 18,100
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	$ 15,700
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	$ 13,500
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	$ 31,400

Leases - Lease Revenue

Leases - Lease Revenue - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 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	$ 4,600	$ 4,200	$ 4,600	$ 4,200	$ 4,300
Lease Revenue [Abstract]
Total lease revenue	100	100	400	400
Operating Leases Payment to be Received [Abstract]
Operating Lease, Payments to be Received, Remainder of Fiscal Year	150		150
Operating Lease, Payments to be Received, Two Years	125		125
Operating Lease, Payments to be Received, Three Years	126		126
Operating Lease, Payments to be Received, Four Years	119		119
Operating Lease, Payments to be Received, Thereafter	1,028		1,028
Total minimum lease payments	2,149		2,149
Total Lease Payments to be Received [Abstract]
Lease Payments to be Received, Remainder of Fiscal Year	4,488		4,488
Lease Payments to be Received, Two Years	17,627		17,627
Lease Payments to be Received, Three Years	16,682		16,682
Lease Payments to be Received, Four Years	15,993		15,993
Lease Payments to be Received, Five Years	15,425		15,425
Lease Payments to be Received, Thereafter	252,749		252,749
Total minimum lease payments	322,964		322,964
Lessor, Operating Lease, Payment to be Received, Year One	601		601
Northwest Natural Gas Company [Member]
Lease Revenue [Abstract]
Operating leases	18	18	61	71
Sales-type leases	4,367	4,588	13,104	13,766
Total lease revenue	4,385	$ 4,606	13,165	$ 13,837
Operating Leases Payment to be Received [Abstract]
Operating Lease, Payments to be Received, Remainder of Fiscal Year	138		138
Operating Lease, Payments to be Received, Two Years	74		74
Operating Lease, Payments to be Received, Three Years	74		74
Operating Lease, Payments to be Received, Four Years	66		66
Operating Lease, Payments to be Received, Thereafter	58		58
Total minimum lease payments	961		961
Total Lease Payments to be Received [Abstract]
Lease Payments to be Received, Remainder of Fiscal Year	4,476		4,476
Lease Payments to be Received, Two Years	17,577		17,577
Lease Payments to be Received, Three Years	16,631		16,631
Lease Payments to be Received, Four Years	15,941		15,941
Lease Payments to be Received, Five Years	15,372		15,372
Lease Payments to be Received, Thereafter	251,779		251,779
Total minimum lease payments	321,776		321,776
Lessor, Operating Lease, Payment to be Received, Year One	551		551
Other Northwest Holdings [Member]
Operating Leases Payment to be Received [Abstract]
Operating Lease, Payments to be Received, Remainder of Fiscal Year	12		12
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 minimum lease payments	1,188		1,188
Total Lease Payments to be Received [Abstract]
Lease Payments to be Received, Remainder of Fiscal Year	12		12
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 minimum lease payments	1,188		1,188
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	4,338		4,338
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 minimum lease payments	320,815		320,815
Less: imputed interest	180,198		180,198
Total leases receivable	140,617		140,617
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	4,338		4,338
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 minimum lease payments	320,815		320,815
Less: imputed interest	180,198		180,198
Total leases receivable	140,617		140,617
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 minimum lease payments	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		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Lessee, Lease, Description [Line Items]
Residual Value of Leased Asset	$ 4,600	$ 4,200	$ 4,600	$ 4,200	$ 4,300
Lease Expense [Abstract]
Operating Lease, Expense	1,749	763	5,173	2,971
Short-term Lease, Cost	$ 499	300	$ 1,068	783
Minimum [Member]
Operating Lease Terms [Abstract]
Lessee, Operating Lease, Term of Contract	3 months		3 months
Maximum [Member]
Operating Lease Terms [Abstract]
Lessee, Operating Lease, Term of Contract	19 years		19 years
Northwest Natural Gas Company [Member]
Lease Expense [Abstract]
Operating Lease, Expense	$ 1,735	746	$ 5,123	2,862
Short-term Lease, Cost	499	300	1,068	783
Other Northwest Holdings [Member] | Corporate, Non-Segment [Member]
Lease Expense [Abstract]
Operating Lease, Expense	$ 14	$ 17	$ 50	$ 109

Leases - Lease Asset and Liabil

Leases - Lease Asset and Liabilities - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Operating Lease Asset and Liabilities [Abstract]
Operating lease right of use asset	$ 75,634	$ 78,036	$ 75,634	$ 78,036	$ 77,446
Operating lease liabilities current liabilities	1,213	1,081	1,213	1,081	1,105
Operating lease liabilities noncurrent liabilities	79,789	80,854	79,789	80,854	80,621
Total operating lease liabilities	$ 81,002	$ 81,935	$ 81,002	$ 81,935	$ 81,726
Operating Lease, Weighted Average Remaining Lease Term	18 years 4 months 24 days	19 years 4 months 24 days	18 years 4 months 24 days	19 years 4 months 24 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	$ 153,899		$ 153,899
Regulatory Assets, Noncurrent	325,071	$ 324,176	325,071	$ 324,176	$ 348,927
Maturity of Operating Lease Liabilities [Abstract]
Lessee, Operating Lease, Liability, Payments, Remainder of Fiscal Year	1,733		1,733
Lessee, Operating Lease, Liability, to be Paid, Year One	6,992		6,992
Lessee, Operating Lease, Liability, Payments, Due Year Two	7,019		7,019
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	153,899		153,899
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	72,897		72,897
Total operating lease liabilities	81,002	81,935	81,002	81,935	81,726
Operating lease liabilities current liabilities	1,213	1,081	1,213	1,081	1,105
Operating lease liabilities noncurrent liabilities	79,789	80,854	79,789	80,854	80,621
Finance Lease, Liability, Payments, Due Next Twelve Months	100		100
Leases Cash Flow [Abstract]
Operating cash flows from operating leases	1,745	691	5,164	2,909
Finance Lease, Principal Payments	123	215	801	672
Operating leases	0	106	154	78,539
Right-of-Use Asset Obtained in Exchange for Finance Lease Liability	75	676	169	1,386
Finance Leases [Abstract]
Finance Lease, Right-of-Use Asset	1,900	1,800	1,900	1,800	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	69	87	69	87	118
Operating lease liabilities current liabilities	29	61	29	61	51
Operating lease liabilities noncurrent liabilities	37	24	37	24	62
Total operating lease liabilities	66	85	66	85	113
Commencement of Significant Lease [Abstract]
Lessee, Operating Lease, Liability, Payments, Due	72		72
Maturity of Operating Lease Liabilities [Abstract]
Lessee, Operating Lease, Liability, Payments, Remainder of Fiscal Year	6		6
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	72		72
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	6		6
Total operating lease liabilities	66	85	66	85	113
Operating lease liabilities current liabilities	29	61	29	61	51
Operating lease liabilities noncurrent liabilities	37	24	37	24	62
Leases Cash Flow [Abstract]
Operating cash flows from operating leases	18	18	51	109
Northwest Natural Gas Company [Member]
Operating Lease Asset and Liabilities [Abstract]
Operating lease right of use asset	75,565	77,949	75,565	77,949	77,328
Operating lease liabilities current liabilities	1,184	1,020	1,184	1,020	1,054
Operating lease liabilities noncurrent liabilities	79,752	80,830	79,752	80,830	80,559
Total operating lease liabilities	80,936	81,850	80,936	81,850	81,613
Commencement of Significant Lease [Abstract]
Lessee, Operating Lease, Liability, Payments, Due	153,827		153,827
Regulatory Assets, Noncurrent	325,031	324,136	325,031	324,136	348,887
Maturity of Operating Lease Liabilities [Abstract]
Lessee, Operating Lease, Liability, Payments, Remainder of Fiscal Year	1,727		1,727
Lessee, Operating Lease, Liability, to be Paid, Year One	6,968		6,968
Lessee, Operating Lease, Liability, Payments, Due Year Two	7,013		7,013
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	153,827		153,827
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	72,891		72,891
Total operating lease liabilities	80,936	81,850	80,936	81,850	81,613
Operating lease liabilities current liabilities	1,184	1,020	1,184	1,020	1,054
Operating lease liabilities noncurrent liabilities	79,752	80,830	79,752	80,830	80,559
Leases Cash Flow [Abstract]
Operating cash flows from operating leases	1,727	673	5,113	2,800
Finance Lease, Principal Payments	123	215	801	672
Operating leases	0	106	154	78,539
Right-of-Use Asset Obtained in Exchange for Finance Lease Liability	$ 75	676	$ 169	1,386
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	5,300	$ 3,700	5,300	$ 3,700	$ 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	9 Months Ended
	Sep. 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)	29,492
Award vesting period	3 years
Unrecognized compensation costs | $	$ 100
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)	37,576
Weighted-average grant date fair value (in dollars per share) | $ / shares	$ 49.16
Unrecognized compensation costs | $	$ 3,800
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	9 Months Ended
	Sep. 30, 2021USD ($)	Dec. 31, 2020USD ($)	Sep. 30, 2020USD ($)
Short-term Debt [Line Items]
Ratio of Indebtedness to Net Capital	0.596
Short-term debt	$ 399,500	$ 304,525	$ 223,000
Commercial Paper Maximum Maturity	63 days
Commercial Paper Average Maturity	34 days
Northwest Natural Gas Company [Member]
Short-term Debt [Line Items]
Ratio of Indebtedness to Net Capital	0.595
Short-term debt	$ 370,500	$ 231,525	$ 150,000
Line of Credit [Member]
Short-term Debt [Line Items]
Short-term debt	$ 29,000
Debt, Weighted Average Interest Rate	1.10%
Commercial Paper [Member] | Northwest Natural Gas Company [Member]
Short-term Debt [Line Items]
Short-term debt	$ 270,500
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 Instrument Covenant Consolidated Indebtedness to Capitalization Ratio	70.00%
Debt, Weighted Average Interest Rate	0.70%

Long-Term Debt

Long-Term Debt $ in Thousands	9 Months Ended
	Sep. 30, 2021USD ($)	Sep. 30, 2019USD ($)	Dec. 31, 2020USD ($)	Sep. 30, 2020USD ($)
Debt Instrument [Line Items]
Long-term Debt	$ 916,304		$ 955,425	$ 955,408
Unamortized debt issuance costs	$ 7,051		7,480	7,586
Ratio of Indebtedness to Net Capital	0.596
Northwest Natural Gas Company [Member]
Debt Instrument [Line Items]
Long-term Debt	$ 857,760		917,220	917,114
Unamortized debt issuance costs	$ 6,940		$ 7,480	$ 7,586
Weighted average interest rate	4.50%
Ratio of Indebtedness to Net Capital	0.595
Northwest Natural Gas Company [Member] | Minimum [Member]
Debt Instrument [Line Items]
Stated interest rate	2.80%
Northwest Natural Gas Company [Member] | Maximum [Member]
Debt Instrument [Line Items]
Stated interest rate	7.90%
Two-year Term Loan Due 2021 [Member]
Debt Instrument [Line Items]
Proceeds from Issuance of Debt		$ 35,000
Repayments of Debt	$ 35,000
364-Day Term Loan, Due 2022 | Northwest Natural Gas Company [Member]
Debt Instrument [Line Items]
Proceeds from Issuance of Debt	$ 100,000
Debt Instrument Covenant Consolidated Indebtedness to Capitalization Ratio	70.00%
Five-year Term Loan Due 2026
Debt Instrument [Line Items]
Stated interest rate	0.90%
Proceeds from Issuance of Debt	$ 55,000
Debt Instrument Covenant Consolidated Indebtedness to Capitalization Ratio	70.00%
Note 9.1 Series Due 2021 | Northwest Natural Gas Company [Member]
Debt Instrument [Line Items]
Stated interest rate	9.10%
Repayments of Debt	$ 10,000
Note 3.2 Series Due 2021 | Northwest Natural Gas Company [Member]
Debt Instrument [Line Items]
Stated interest rate	3.20%
Repayments of Debt	$ 50,000

Debt Fair Value of Long Term De

Debt Fair Value of Long Term Debt - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020
Debt Instrument [Line Items]
Gross long-term debt	$ 923,355	$ 962,905	$ 962,994
Unamortized debt issuance costs	(7,051)	(7,480)	(7,586)
Carrying amount	916,304	955,425	955,408
Estimated fair value	1,042,705	1,136,311	1,118,565
Northwest Natural Gas Company [Member]
Debt Instrument [Line Items]
Gross long-term debt	864,700	924,700	924,700
Unamortized debt issuance costs	(6,940)	(7,480)	(7,586)
Carrying amount	857,760	917,220	917,114
Estimated fair value	$ 978,613	$ 1,097,348	$ 1,080,663

Pension and Other Postretirem_3

Pension and Other Postretirement Benefit Costs - Net Periodic Benefit Cost - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Pension Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 1,717	$ 1,673	$ 5,145	$ 4,988
Interest cost	3,316	4,071	10,001	12,093
Expected return on plan assets	(5,802)	(5,358)	(18,000)	(16,350)
Amortization of net actuarial loss	0	0	0	0
Defined Benefit Plan, Amortization of Gain (Loss)	5,515	5,082	16,516	14,638
Net periodic benefit cost	4,746	5,468	13,662	15,369
Amount allocated to construction	(759)	(695)	(2,228)	(2,043)
Defined Benefit Plan Net Periodic Benefit Cost Charged To Expense	3,987	4,773	11,434	13,326
Amortization of Regulatory Balancing Account	675	675	4,757	4,757
Net amount charged to expense	4,662	5,448	16,191	18,083
Other Postretirement Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	69	67	180	195
Interest cost	180	229	510	675
Expected return on plan assets	0	0	0	0
Amortization of net actuarial loss	(119)	(119)	(353)	(353)
Defined Benefit Plan, Amortization of Gain (Loss)	226	173	488	458
Net periodic benefit cost	356	350	825	975
Amount allocated to construction	(27)	(25)	(70)	(71)
Defined Benefit Plan Net Periodic Benefit Cost Charged To Expense	329	325	755	904
Amortization of Regulatory Balancing Account	0	0	0	0
Net amount charged to expense	$ 329	$ 325	$ 755	$ 904

Pension and Other Postretirem_4

Pension and Other Postretirement Benefit Costs - Amounts Recognized in Accumulated Other Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]
Beginning balance	$ (12,460)	$ (10,413)	$ (12,902)	$ (10,733)
Amortization of actuarial losses	314	252	916	688
Total reclassifications before tax	314	252	916	688
Tax benefit	(80)	(66)	(240)	(182)
Total reclassifications for the period	234	186	676	506
Ending balance	$ (12,226)	$ (10,227)	$ (12,226)	$ (10,227)

Pension and Other Postretirem_5

Pension and Other Postretirement Benefit Costs - Narrative - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Pension and Other Postretirement Benefits Cost (Reversal of Cost) [Abstract]
Employer contributions	$ 6.7	$ 6.2
Defined benefit pension plan cash contributions	$ 9.6

Income Tax_2_3

Income Tax - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Income taxes at statutory rates (federal and state)	$ (5,834)	$ (5,048)	$ 10,764	$ 6,628
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount	(2,599)	(1,452)	4,660	1,892
Differences required to be flowed-through by regulatory commissions	1,318	1,051	(2,266)	(1,301)
Other, net	(12)	86	(41)	(127)
Total provision for income taxes on continuing operations	$ (7,127)	$ (5,363)	$ 13,117	$ 7,092
Effective tax rate for continuing operations	25.70%	22.30%	25.60%	22.50%
Northwest Natural Gas Company [Member]
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Income taxes at statutory rates (federal and state)	$ (5,928)	$ (5,518)	$ 11,195	$ 6,550
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount	(2,618)	(1,595)	4,748	1,861
Differences required to be flowed-through by regulatory commissions	1,318	1,051	(2,266)	(1,301)
Other, net	16	5	(49)	(168)
Total provision for income taxes on continuing operations	$ (7,212)	$ (6,057)	$ 13,628	$ 6,942
Effective tax rate for continuing operations	25.50%	23.10%	25.60%	22.30%

Property, Plant and Equipment_3

Property, Plant and Equipment - USD ($)	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020
Property, Plant and Equipment [Line Items]
Property, plant, and equipment	$ 3,919,096,000	$ 3,734,039,000	$ 3,680,872,000
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	1,112,734,000	1,079,269,000	1,073,623,000
Property, Plant and Equipment, Net	2,806,362,000	2,654,770,000	2,607,249,000
Natural Gas Distribution [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment	3,663,699,000	3,548,543,000	3,441,301,000
Public Utilities, Property, Plant and Equipment, Construction Work in Progress	120,412,000	63,901,000	120,722,000
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	1,086,510,000	1,055,809,000	1,051,018,000
Property, Plant and Equipment, Net	2,697,601,000	2,556,635,000	2,511,005,000
Other Northwest Natural [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment	66,314,000	66,300,000	65,103,000
Public Utilities, Property, Plant and Equipment, Construction Work in Progress	7,228,000	5,032,000	6,444,000
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	20,392,000	19,637,000	19,387,000
Property, Plant and Equipment, Net	53,150,000	51,695,000	52,160,000
Northwest Natural Gas Company [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Net	2,750,751,000	2,608,330,000	2,563,165,000
Property, Plant, Equipment non-cash	33,968,000	25,129,000	37,236,000
Other Northwest Holdings [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment	61,443,000	50,263,000	47,302,000
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	5,832,000	3,823,000	3,218,000
Property, Plant and Equipment, Net	55,611,000	46,440,000	44,084,000
Northwest Holdings [Member]
Property, Plant and Equipment [Line Items]
Property, Plant, Equipment non-cash	35,955	25,129	37,236
Northwest Natural Gas Company [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment	3,857,652,000	3,683,776,000	3,633,570,000
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	1,106,901,000	1,075,446,000	1,070,405,000
Property, Plant and Equipment, Net	$ 2,750,751,000	$ 2,608,330,000	$ 2,563,165,000

Gas Reserves_2_3

Gas Reserves	9 Months Ended
	Sep. 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	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020
Reserve Quantities [Line Items]
Gas reserves	$ 6,266	$ 11,409	$ 12,265
Gas reserves, non-current	181,041	175,898	175,042
Less: Accumulated amortization	153,020	141,414	137,346
Total gas reserves	34,287	45,893	49,961
Less: Deferred taxes on gas reserves	7,768	10,572	11,972
Net investment in gas reserves	26,519	35,321	37,989
Jonah Energy LLC
Reserve Quantities [Line Items]
Total Gas Reserves Investment	$ 2,500	$ 3,000	$ 3,200

Investments_2

Investments - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Schedule of Equity Method Investments [Line Items]
Percentage of Equity Method Investment Sold		100.00%
Proceeds from Sale of Equity Method Investments			$ 7,000	$ 7,000
Equity Method Investment, Realized Gain (Loss) on Disposal					$ 500
Other Northwest Holdings [Member]
Schedule of Equity Method Investments [Line Items]
Proceeds from Sale of Equity Method Investments	$ 14,000
Cash and Cash Equivalents [Member]
Schedule of Equity Method Investments [Line Items]
Proceeds from Sale of Equity Method Investments		$ 7,000
Notes Receivable [Member]
Schedule of Equity Method Investments [Line Items]
Proceeds from Sale of Equity Method Investments		$ 7,000

Business Combinations Busines_2

Business Combinations Business Combinations	9 Months Ended
	Sep. 30, 2021USD ($)numberOfConnections	Sep. 30, 2020USD ($)	Dec. 31, 2020USD ($)
Business Acquisition [Line Items]
Goodwill	$ 69,789,000	$ 70,292,000	$ 69,225,000
Goodwill, Impairment Loss	0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets [Abstract]
Goodwill	69,789,000	70,292,000	$ 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	3	3

Derivative Instruments Notional

Derivative Instruments Notional Amounts therm in Thousands	Sep. 30, 2021USD ($)therm	Dec. 31, 2020USD ($)therm	Sep. 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 2020 - 2021
Derivative [Line Items]
TargetHedgeAchieved	51.00%
Northwest Natural Gas Company [Member] | Financial [Member] | Gas Year 2021-2022
Derivative [Line Items]
TargetHedgeAchieved	53.00%
Northwest Natural Gas Company [Member] | Physical [Member] | Gas Year 2020 - 2021
Derivative [Line Items]
TargetHedgeAchieved	17.00%
Northwest Natural Gas Company [Member] | Physical [Member] | Gas Year 2021-2022
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	749,595	784,400	860,400
Northwest Natural Gas Company [Member] | Natural Gas Therms [Member] | Physical [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount | therm	613,524	457,593	706,592
Northwest Natural Gas Company [Member] | Foreign Exchange Contract [Member]
Derivative [Line Items]
Derivative, Notional Amount | $	$ 6,299,000	$ 5,896,000	$ 6,754,000

Derivative Instruments Fair Val

Derivative Instruments Fair Value - USD ($) $ in Millions	3 Months Ended
	Sep. 30, 2020	Sep. 30, 2021	Dec. 31, 2020
Derivative [Line Items]
Derivative, Loss on Derivative	$ 0
Derivative, Fair Value, Net	$ 34.3	$ 119.6	$ 12.8

Unrealized and Realized Gain_Lo

Unrealized and Realized Gain/Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Derivative [Line Items]
Derivative, Gain on Derivative	$ 6,100	$ 0	$ 15,400
Derivative, Loss on Derivative		0
Financial [Member]
Derivative [Line Items]
Derivative, Loss on Derivative				$ (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	(96)	4	148
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	(69,239)	28,122	(106,044)	28,271
Northwest Holdings and Northwest Natural [Member] | Benefit (expense) to cost of gas | Foreign exchange
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	106	(136)	74	(129)
Northwest Holdings and Northwest Natural [Member] | Sales [Member] | Natural gas commodity
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	0	(658)	26	1,021
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	69,239	28,684	106,022	27,398
Deferred Derivative Gain (Loss) [Member] | Northwest Holdings and Northwest Natural [Member] | Foreign exchange
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	$ (106)	$ 136	$ (74)	$ 129

Derivative Instruments Credit R

Derivative Instruments Credit Rating - USD ($)	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Derivative [Line Items]
Unrealized losses on derivatives	$ (132,200,000)	$ (34,100,000)
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	124,500,000	35,600,000	$ 14,100,000
Derivative liability	$ 4,900,000	$ 1,300,000	$ 1,300,000

Environmental Matters_2_3

Environmental Matters	Sep. 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	9 Months Ended
	Jan. 31, 2017USD ($)	Sep. 30, 2021USD ($)propertyparty	Dec. 31, 2020USD ($)	Sep. 30, 2020USD ($)
Site Contingency [Line Items]
Current Liabilities		$ 20,039	$ 28,241	$ 30,483
Non-Current Liabilities		85,631	92,281	92,129
Gasco/Siltronic Sediments
Site Contingency [Line Items]
Current Liabilities		6,925	7,596	8,338
Non-Current Liabilities		40,929	43,725	43,509
Site Contingency, Environmental Remediation Costs Recognized		47,900
Gasco/Siltronic Sediments | Minimum [Member]
Site Contingency [Line Items]
Environmental Exit Costs, Anticipated Cost		47,900
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		2,392	1,942	2,760
Non-Current Liabilities		$ 6,222	7,020	5,882
Gasco Uplands [Member]
Site Contingency [Line Items]
Site contingency: number of management pieces		2
Gasco/Siltronic Upland [Member]
Site Contingency [Line Items]
Current Liabilities		$ 9,720	14,887	8,775
Non-Current Liabilities		37,408	40,250	41,515
Front Street [Member]
Site Contingency [Line Items]
Current Liabilities		1,002	3,816	10,610
Non-Current Liabilities		893	1,107	1,044
Additional studies and design costs		1,900
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 ($)	9 Months Ended
	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020
Site Contingency [Line Items]
Regulatory Assets, Current	$ 80,638,000	$ 31,745,000	$ 29,740,000
Regulatory Assets, Noncurrent	$ 325,071,000	$ 348,927,000	$ 324,176,000
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	80,638,000	31,745,000	29,740,000
Regulatory Assets, Noncurrent	325,031,000	348,887,000	324,136,000
Northwest Natural Gas Company [Member] | Environmental costs [Member]
Site Contingency [Line Items]
Deferred costs and interest	45,019,000	44,516,000	35,919,000
Accrued site liabilities	105,607,000	120,352,000	122,226,000
Insurance proceeds and interest	(59,589,000)	(69,253,000)	(69,138,000)
Regulatory Assets	91,037,000	95,615,000	89,007,000
Regulatory Assets, Current	7,068,000	4,992,000	4,440,000
Regulatory Assets, Noncurrent	$ 83,969,000	$ 90,623,000	$ 84,567,000

Discontinued Operations_2_3

Discontinued Operations - USD ($)	3 Months Ended			9 Months Ended		12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Mar. 31, 2022	Dec. 31, 2020
Disposal Group, Including Discontinued Operation, Classified Balance Sheet Disclosures [Abstract]
Discontinued operations - total assets			$ 16,900,000		$ 16,900,000
Discontinued Operation, Income Statement Disclosures [Abstract]
Loss from discontinued operations, net of tax	$ 0		$ 765,000	$ 0	$ 267,000
Loss from discontinued operations per share of common stock
Basic (in dollars per share)	$ 0		$ 0.02	$ 0	$ 0.01
Diluted (in dollars per share)	$ 0		$ 0.02	$ 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			$ 1,106,000		$ 1,106,000
Inventories			730,000		730,000
Other current assets			64,000		64,000
Property, plant, and equipment			14,663,000		14,663,000
Operating lease right of use asset			118,000		118,000
Other non-current assets			247,000		247,000
Discontinued operations - total assets	$ 0	$ 0	16,928,000	$ 0	16,928,000		$ 0
Accounts payable			1,747,000		1,747,000
Other current liabilities			796,000		796,000
Operating lease liabilities			113,000		113,000
Other non-current liabilities			11,266,000		11,266,000
Total discontinued operations liabilities	$ 0	0	13,922,000	$ 0	13,922,000		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			3,584,000		7,866,000
Operations and maintenance			2,148,000		6,332,000
General taxes			61,000		161,000
Depreciation and amortization			105,000		317,000
Other expenses and interest			229,000		688,000
Total expenses			2,543,000		7,498,000
Loss from discontinued operations before income tax			1,041,000		368,000
Income tax benefit			276,000		101,000
Loss from discontinued operations, net of tax			$ 765,000		$ 267,000
Loss from discontinued operations per share of common stock
Basic (in dollars per share)	$ 0		$ 0.02	$ 0	$ 0.01
Diluted (in dollars per share)	$ 0		$ 0.02	$ 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

Subsequent Events_2

Subsequent Events - Subsequent Event [Member] $ in Thousands	Nov. 03, 2021USD ($)
Line of Credit [Member]
Subsequent Event [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 200,000
Line of Credit [Member] | Northwest Natural Gas Company [Member]
Subsequent Event [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	400,000
Letter of Credit
Subsequent Event [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	40,000
Letter of Credit | Northwest Natural Gas Company [Member]
Subsequent Event [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 60,000