Significant Accounting Policies - Regulatory Asset Disclosure - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2022
Regulatory Assets [Line Items]
Regulatory Assets, Current	$ 126,546	$ 117,491	$ 64,481
Regulatory Assets, Noncurrent	$ 311,419	340,432	297,546
Inactive Account, Period Outstanding Prior to Write-Off	120 days
General Payment Term of NGD Receivables	15 days
Age of Closed or Inactive Accounts	120 days
Other [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Noncurrent	$ 25	25	64
Northwest Natural Gas Company [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Current	126,546	117,491	64,481
Regulatory Assets, Noncurrent	311,394	340,407	297,482
Northwest Natural Gas Company [Member] | Deferred Derivative Gain (Loss) [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Current	44,370	28,728	3,855
Regulatory Assets, Noncurrent	15,382	20,838	592
Northwest Natural Gas Company [Member] | Gas costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Current	51,296	61,223	33,215
Regulatory Assets, Noncurrent	6,546	22,355	10,054
Northwest Natural Gas Company [Member] | Environmental costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Current	6,947	7,392	7,082
Regulatory Assets, Noncurrent	99,541	104,253	87,566
Northwest Natural Gas Company [Member] | Decoupling [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Current	0	0	469
Northwest Natural Gas Company [Member] | Pension balancing [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Current	7,131	7,131	7,131
Regulatory Assets, Noncurrent	30,613	32,997	35,974
Northwest Natural Gas Company [Member] | Income taxes [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Current	2,208	2,208	2,299
Regulatory Assets, Noncurrent	10,540	10,943	11,129
Northwest Natural Gas Company [Member] | Pension and other postretirement benefit liabilities [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Noncurrent	101,413	101,413	113,494
Northwest Natural Gas Company [Member] | Other [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Current	14,594	10,809	10,430
Regulatory Assets, Noncurrent	$ 47,359	$ 47,608	$ 38,673