Debt Fair Value of Long Term Debt - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021	Sep. 30, 2021
Debt Instrument [Line Items]
Gross long-term debt	$ 1,345,968	$ 1,053,241	$ 923,355
Unamortized debt issuance costs	(8,348)	(8,309)	(7,051)
Carrying amount	1,337,620	1,044,932	916,304
Estimated fair value	1,133,087	1,174,500	1,042,705
Northwest Natural Gas Company [Member]
Debt Instrument [Line Items]
Gross long-term debt	1,134,700	994,700	864,700
Unamortized debt issuance costs	(8,229)	(8,205)	(6,940)
Carrying amount	1,126,471	986,495	857,760
Estimated fair value	$ 927,372	$ 1,110,741	$ 978,613