Income Tax - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Income taxes at statutory rates (federal and state)	$ (6,716)	$ (5,533)	$ 13,928	$ 10,710
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount	(2,742)	(2,376)	5,618	4,298
Differences required to be flowed-through by regulatory commissions	1,015	1,232	(2,055)	(2,003)
Other, net	151	(81)	(393)	(370)
Total provision for income taxes on continuing operations	$ (8,292)	$ (6,758)	$ 17,098	$ 12,635
Effective tax rate for continuing operations	25.90%	25.70%	25.80%	24.80%
Northwest Natural Gas Company [Member]
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Income taxes at statutory rates (federal and state)	$ (6,131)	$ (5,305)	$ 15,723	$ 11,554
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount	(2,633)	(2,306)	5,990	4,497
Differences required to be flowed-through by regulatory commissions	1,018	1,232	(2,051)	(2,003)
Other, net	39	(76)	(625)	(370)
Total provision for income taxes on continuing operations	$ (7,707)	$ (6,455)	$ 19,037	$ 13,678
Effective tax rate for continuing operations	26.40%	25.60%	25.40%	24.90%