Environmental Matters - Regulatory Deferred Assets - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2022	Dec. 31, 2021	Sep. 30, 2021
Site Contingency [Line Items]
Regulatory Assets, Current	$ 104,830	$ 72,391	$ 80,638
Regulatory Assets, Noncurrent	$ 301,660	$ 314,579	$ 325,071
Remediation Non-recovery Percentage	3.30%	3.30%	3.30%
Annual tariff rider collection	$ 5,000
Annual insurance proceeds to apply against remediation costs	5,000
Total annual remediation expense and interest	$ 10,000
Oregon [Member]
Site Contingency [Line Items]
Remediation Recovery Percentage	96.70%
Front Street [Member] | Environmental costs [Member]
Site Contingency [Line Items]
Accrued site liabilities	$ 34	$ 62	$ 62
Northwest Natural Gas Company [Member]
Site Contingency [Line Items]
Regulatory Assets, Current	104,830	72,391	80,638
Regulatory Assets, Noncurrent	301,596	314,539	325,031
Northwest Natural Gas Company [Member] | Environmental costs [Member]
Site Contingency [Line Items]
Deferred costs and interest	47,011	45,122	45,019
Accrued site liabilities	99,795	115,773	105,607
Insurance proceeds and interest	(54,678)	(59,564)	(59,589)
Regulatory Assets	92,128	101,331	91,037
Regulatory Assets, Current	9,461	6,694	7,068
Regulatory Assets, Noncurrent	$ 82,667	$ 94,636	$ 83,969