Income Tax - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Income taxes at statutory rates (federal and state)	$ 20,332	$ 15,783
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount	8,149	6,513
Differences required to be flowed-through by regulatory commissions	(2,909)	(3,173)
Other, net	(425)	(200)
Total provision for income taxes on continuing operations	$ 25,147	$ 18,923
Effective tax rate for continuing operations	26.00%	25.20%
Northwest Natural Gas Company [Member]
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Income taxes at statutory rates (federal and state)	$ 21,412	$ 16,115
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount	8,406	6,584
Differences required to be flowed-through by regulatory commissions	(2,909)	(3,173)
Other, net	(487)	(203)
Total provision for income taxes on continuing operations	$ 26,422	$ 19,323
Effective tax rate for continuing operations	25.90%	25.20%