Significant Accounting Policies - Regulatory Liability Disclosure - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2022
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	$ 57,523	$ 248,582	$ 111,791
Regulatory Liability, Noncurrent	669,328	689,578	652,977
Other [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	29	29	0
Regulatory Liability, Noncurrent	980	979	982
Northwest Natural Gas Company [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	57,494	248,553	111,791
Regulatory Liability, Noncurrent	668,348	688,599	651,995
Northwest Natural Gas Company [Member] | Gas costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	5,670	4,121	1,922
Regulatory Liability, Noncurrent	2,024	12,644	532
Northwest Natural Gas Company [Member] | Deferred Derivative Gain (Loss) [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	8,890	194,236	84,438
Regulatory Liability, Noncurrent	1,432	5,045	6,955
Northwest Natural Gas Company [Member] | Decoupling [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	12,606	14,026	8,236
Regulatory Liability, Noncurrent	3,931	3,814	3,585
Northwest Natural Gas Company [Member] | Income taxes [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	5,143	7,166	7,318
Regulatory Liability, Noncurrent	170,289	174,212	176,138
Northwest Natural Gas Company [Member] | Other [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	6,145	2,636	4,691
Regulatory Liability, Noncurrent	15,908	16,741	13,812
Northwest Natural Gas Company [Member] | Accrued asset removal costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Noncurrent	474,764	467,742	450,973
Northwest Natural Gas Company [Member] | Asset Optimization Revenue Sharing
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	19,040	26,368	5,186
Regulatory Liability, Noncurrent	$ 0	$ 8,401	$ 0