Income Tax - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Income taxes at statutory rates (federal and state)	$ 18,514	$ 20,332
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount	7,577	8,149
Differences required to be flowed-through by regulatory commissions	(1,579)	(2,909)
Other, net	(173)	(425)
Total provision for income taxes on continuing operations	$ 24,339	$ 25,147
Effective tax rate for continuing operations	27.60%	26.00%
Northwest Natural Gas Company [Member]
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Income taxes at statutory rates (federal and state)	$ 19,579	$ 21,412
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount	7,849	8,406
Differences required to be flowed-through by regulatory commissions	(1,580)	(2,909)
Other, net	(175)	(487)
Total provision for income taxes on continuing operations	$ 25,673	$ 26,422
Effective tax rate for continuing operations	27.50%	25.90%