Derivative Instruments - Schedule of Unrealized and Realized Gain/Loss (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2023	Dec. 31, 2022
General Discussion of Derivative Instruments and Hedging Activities [Abstract]
Derivative, Gain, Statement of Income or Comprehensive Income [Extensible Enumeration]	Operating revenues	Operating revenues
AOCI, Cash Flow Hedge, Cumulative Gain (Loss), after Tax	$ 200	$ 100
Derivative Instruments, Gain Reclassified from Accumulated OCI into Income, Effective Portion	0
Northwest Holdings and Northwest Natural [Member] \| Foreign Exchange Contract [Member]
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	0	0
Northwest Holdings and Northwest Natural [Member] \| Foreign Exchange Contract [Member] \| Cost of Sales [Member]
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	168	(165)
Northwest Holdings and Northwest Natural [Member] \| Foreign Exchange Contract [Member] \| Sales [Member]
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	0	0
Northwest Holdings and Northwest Natural [Member] \| Natural Gas Commodity [Member]
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	0	0
Northwest Holdings and Northwest Natural [Member] \| Natural Gas Commodity [Member] \| Cost of Sales [Member]
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	(131,833)	(119,935)
Northwest Holdings and Northwest Natural [Member] \| Natural Gas Commodity [Member] \| Sales [Member]
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	0	0
Northwest Holdings and Northwest Natural [Member] \| Deferred Derivative Gain (Loss) [Member] \| Foreign Exchange Contract [Member]
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	(168)	165
Northwest Holdings and Northwest Natural [Member] \| Deferred Derivative Gain (Loss) [Member] \| Natural Gas Commodity [Member]
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	$ 131,833	$ (119,935)

Amount, after tax, of accumulated gain (loss) on derivative instrument designated and qualifying as cash flow hedge included in assessment of hedge effectiveness.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 11
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482790/220-10-45-11

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Indicates line item in statement of income or comprehensive income that includes gain from derivative.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4A
-Subparagraph (b)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480434/815-10-50-4A

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The effective portion of gain reclassified from accumulated other comprehensive income into income on derivative instruments designated and qualifying as hedging instruments.

+ References

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-Subparagraph (c)
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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (f)
-Publisher FASB
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Aggregate net gain (loss) on all derivative instruments recognized in earnings during the period, before tax effects.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4A
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-Publisher FASB
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