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

The amount for the individual regulatory liability as itemized in a table of regulatory liabilities as of the end of the period.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 980
-SubTopic 405
-Name Accounting Standards Codification
-Section 25
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481854/980-405-25-1

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The amount for the individual regulatory noncurrent liability as itemized in a table of regulatory noncurrent liabilities as of the end of the period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.24)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1

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