Property, Plant and Equipment - USD ($)	Jun. 30, 2024	Dec. 31, 2023	Jun. 30, 2023
Property, Plant and Equipment [Line Items]
Property, plant, and equipment	$ 4,764,593,000	$ 4,556,609,000	$ 4,391,993,000
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	1,234,148,000	1,198,555,000	1,181,230,000
Total property, plant, and equipment, net	3,530,445,000	3,358,054,000	3,210,763,000
Natural Gas Distribution [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment	4,330,415,000	4,206,455,000	4,060,392,000
Public Utilities, Property, Plant and Equipment, Construction Work in Progress	170,625,000	105,166,000	123,163,000
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	1,190,789,000	1,159,367,000	1,146,202,000
Total property, plant, and equipment, net	3,310,251,000	3,152,254,000	3,037,353,000
Other Northwest Natural [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment	68,712,000	71,175,000	70,364,000
Public Utilities, Property, Plant and Equipment, Construction Work in Progress	11,251,000	10,963,000	7,181,000
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	22,380,000	22,595,000	22,068,000
Total property, plant, and equipment, net	57,583,000	59,543,000	55,477,000
Northwest Natural Gas Company [Member]
Property, Plant and Equipment [Line Items]
Total property, plant, and equipment, net	3,367,834,000	3,211,797,000	3,092,830,000
Property, Plant, Equipment non-cash	24,586,000	24,168,000	28,466,000
Other Northwest Holdings [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment	169,785,000	147,040,000	122,161,000
Public Utilities, Property, Plant and Equipment, Construction Work in Progress	13,805,000	15,810,000	8,732,000
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	20,979,000	16,593,000	12,960,000
Total property, plant, and equipment, net	162,611,000	146,257,000	117,933,000
Northwest Holdings [Member]
Property, Plant and Equipment [Line Items]
Property, Plant, Equipment non-cash	28,370,000	27,879,000	31,439,000
Northwest Natural Gas Company [Member]
Property, Plant and Equipment [Line Items]
Property, plant, and equipment	4,581,003,000	4,393,759,000	4,261,100,000
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	1,213,169,000	1,181,962,000	1,168,270,000
Total property, plant, and equipment, net	$ 3,367,834,000	$ 3,211,797,000	$ 3,092,830,000

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- Definition

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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Period end amount of construction work in progress in public utility.

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