Debt Fair Value of Long Term Debt - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022	Sep. 30, 2022
Debt Instrument [Line Items]
Gross long-term debt	$ 1,625,545	$ 1,345,851	$ 1,345,968
Unamortized debt issuance costs	(10,245)	(8,987)	(8,348)
Long-term Debt	1,615,300	1,336,864	1,337,620
Estimated fair value	1,385,144	1,148,395	1,133,087
Northwest Natural Gas Company [Member]
Debt Instrument [Line Items]
Gross long-term debt	1,414,700	1,134,700	1,134,700
Unamortized debt issuance costs	(10,147)	(8,823)	(8,229)
Long-term Debt	1,404,553	1,125,877	1,126,471
Estimated fair value	$ 1,176,212	$ 944,383	$ 927,372