Significant Accounting Policies - Regulatory Liability Disclosure - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022	Jun. 30, 2022
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	$ 61,546	$ 248,582	$ 97,277
Regulatory Liability, Noncurrent	672,215	689,578	658,925
Other [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	50	29	0
Regulatory Liability, Noncurrent	952	979	982
Northwest Natural Gas Company [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	61,496	248,553	97,277
Regulatory Liability, Noncurrent	671,263	688,599	657,943
Northwest Natural Gas Company [Member] | Gas costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	5,603	4,121	1,898
Regulatory Liability, Noncurrent	731	12,644	353
Northwest Natural Gas Company [Member] | Deferred Derivative Gain (Loss) [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	11,691	194,236	60,652
Regulatory Liability, Noncurrent	1,551	5,045	9,121
Northwest Natural Gas Company [Member] | Decoupling [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	8,715	14,026	14,242
Regulatory Liability, Noncurrent	1,358	3,814	2,557
Northwest Natural Gas Company [Member] | Income taxes [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	5,158	7,166	7,318
Regulatory Liability, Noncurrent	170,318	174,212	176,358
Northwest Natural Gas Company [Member] | Other [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	7,002	2,636	3,406
Regulatory Liability, Noncurrent	15,454	16,741	13,760
Northwest Natural Gas Company [Member] | Accrued asset removal costs [Member]
Regulatory Liabilities [Line Items]
Regulatory Liability, Noncurrent	481,851	467,742	455,794
Northwest Natural Gas Company [Member] | Asset Optimization Revenue Sharing
Regulatory Liabilities [Line Items]
Regulatory Liability, Current	23,327	26,368	9,761
Regulatory Liability, Noncurrent	$ 0	$ 8,401	$ 0