Property, Plant and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment, Net, by Type [Abstract]
Property, Plant and Equipment, Gross	$ 3,997,243	$ 3,734,039
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	1,125,873	1,079,269
Total property, plant, and equipment, net	2,871,370	2,654,770
Property, Plant, Equipment non-cash	38,333	25,129
Regulatory Liability, Noncurrent	658,332	639,663
Natural Gas Distribution [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Property, Plant and Equipment, Gross	3,721,939	3,548,543
Public Utilities, Property, Plant and Equipment, Construction Work in Progress	135,398	63,901
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	1,098,715	1,055,809
Total property, plant, and equipment, net	2,758,622	2,556,635
Other Northwest Natural [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Property, Plant and Equipment, Gross	69,332	66,300
Public Utilities, Property, Plant and Equipment, Construction Work in Progress	4,971	5,032
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	20,646	19,637
Total property, plant, and equipment, net	53,657	51,695
Northwest Natural Gas Company [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Total property, plant, and equipment, net	2,812,279	2,608,330
Property, Plant, Equipment non-cash	37,537	25,129
Northwest Holdings Other [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Property, Plant and Equipment, Gross	65,603	50,263
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	6,512	3,823
Total property, plant, and equipment, net	$ 59,091	$ 46,440
Natural Gas Distribution [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Public Utilities, Property, Plant and Equipment, Disclosure of Composite Depreciation Rate for Plants in Service	3.00%	3.00%	2.90%
Other Northwest Natural [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Weighted Average Depreciation Rates	1.80%	1.80%	1.80%
Northwest Natural Gas Company [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Property, Plant and Equipment, Gross	$ 3,931,640	$ 3,683,776
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	1,119,361	1,075,446
Total property, plant, and equipment, net	2,812,279	2,608,330
Regulatory Liability, Noncurrent	657,350	638,793
Northwest Natural Gas Company [Member] | Asset Removal Costs [Member]
Property, Plant and Equipment, Net, by Type [Abstract]
Regulatory Liability, Noncurrent	$ 445,952	$ 427,960