Pension and Other Postretirement Benefits Costs - Schedule of AOCL and Changes in AOCL, Non-Qualified Employee Plans (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 11,404
Ending balance	6,285	$ 11,404
Northwest Holdings and Northwest Natural [Member] | Non-Qualified Pension Plans, Defined Benefit [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	11,404	12,902
Amounts reclassified to AOCL	5,706	812
Amortization of actuarial losses	1,081	1,225
Total reclassifications before tax	6,787	2,037
Tax benefit	(1,797)	(539)
Total reclassifications for the period	4,990	1,498
Ending balance	(6,414)	11,404
Northwest Natural Gas Company [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	11,404
Ending balance	$ 6,414	$ 11,404