Environmental Matters - Regulatory Deferred Assets - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2022
Site Contingency [Line Items]
Regulatory Assets, Current	$ 126,546	$ 117,491	$ 64,481
Regulatory Assets, Noncurrent	$ 311,419	$ 340,432	$ 297,546
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	$ 45	$ 43	$ 54
Northwest Natural Gas Company [Member]
Site Contingency [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] | Environmental costs [Member]
Site Contingency [Line Items]
Deferred costs and interest	47,651	47,666	45,482
Accrued site liabilities	114,253	118,763	109,061
Insurance proceeds and interest	(55,416)	(54,784)	(59,895)
Regulatory Assets	106,488	111,645	94,648
Regulatory Assets, Current	6,947	7,392	7,082
Regulatory Assets, Noncurrent	$ 99,541	$ 104,253	$ 87,566