Significant Accounting Policies - Regulatory Asset Disclosure - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022	Jun. 30, 2022
Regulatory Assets [Line Items]
Regulatory Assets, Current	$ 111,819	$ 117,491	$ 92,803
Regulatory Assets, Noncurrent	$ 307,999	340,432	301,855
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	65
Northwest Natural Gas Company [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Current	111,819	117,491	92,803
Regulatory Assets, Noncurrent	307,974	340,407	301,790
Northwest Natural Gas Company [Member] | Deferred Derivative Gain (Loss) [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Current	42,135	28,728	15,918
Regulatory Assets, Noncurrent	25,212	20,838	9,475
Northwest Natural Gas Company [Member] | Pension balancing [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Current	7,131	7,131	7,131
Regulatory Assets, Noncurrent	29,731	32,997	35,150
Northwest Natural Gas Company [Member] | Income taxes [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Current	2,208	2,208	2,276
Regulatory Assets, Noncurrent	10,540	10,943	11,161
Northwest Natural Gas Company [Member] | Pension and other postretirement benefit liabilities [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Noncurrent	101,413	101,413	110,548
Northwest Natural Gas Company [Member] | Environmental costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Current	6,749	7,392	6,975
Regulatory Assets, Noncurrent	98,160	104,253	86,411
Northwest Natural Gas Company [Member] | Gas costs [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Current	24,782	61,223	48,218
Regulatory Assets, Noncurrent	1,122	22,355	7,975
Northwest Natural Gas Company [Member] | Decoupling [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Current	1,520	0	212
Regulatory Assets, Noncurrent	267	0	0
Northwest Natural Gas Company [Member] | Washington Climate Commitment Act compliance
Regulatory Assets [Line Items]
Regulatory Assets, Current	10,379	0	0
Regulatory Assets, Noncurrent	1,823	0	0
Northwest Natural Gas Company [Member] | Other [Member]
Regulatory Assets [Line Items]
Regulatory Assets, Current	16,915	10,809	12,073
Regulatory Assets, Noncurrent	$ 39,706	$ 47,608	$ 41,070