Incremental Cost or Benefit to Collect or Refund to Customers

No definition available.

Name:	nwn_IncrementalCostOrBenefitToCollectOrRefundToCustomers
Namespace Prefix:	nwn_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-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

+ Details

Name:	us-gaap_DerivativeGainLossOnDerivativeNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of increase in the fair value of derivatives recognized in the income statement.

+ 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

+ Details

Name:	us-gaap_DerivativeGainOnDerivative
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

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
-URI https://asc.fasb.org//1943274/2147480237/815-40-50-5

+ Details

Name:	us-gaap_DerivativeLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of decrease in the fair value of derivatives recognized in the income statement.

+ References

+ Details

Name:	us-gaap_DerivativeLossOnDerivative
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Aggregate net gain (loss) on all derivative instruments recognized in earnings during the period, before tax effects.

+ References

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

+ Details

Name:	us-gaap_GainLossOnDerivativeInstrumentsNetPretax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=nwn_FinancialMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=nwn_NorthwestHoldingsandNorthwestNaturalMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_CommodityContractMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_ForeignExchangeContractMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeStatementLocationAxis=us-gaap_CostOfSalesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeStatementLocationAxis=us-gaap_SalesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=nwn_NorthwestNaturalGasCompanyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RegulatoryAssetAxis=us-gaap_DeferredDerivativeGainLossMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Unrealized and Realized Gain/Loss - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
Unrealized and Realized Gain/Loss - USD ($) $ in Thousands	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Derivative [Line Items]
Derivative, Gain (Loss) on Derivative, Net	$ 58	$ 1,236	$ 404	$ 825
Financial [Member]
Derivative [Line Items]
Incremental Cost or Benefit to Collect or Refund to Customers			0
Northwest Holdings and Northwest Natural [Member] \| Natural gas commodity
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	0	0	0	0
Northwest Holdings and Northwest Natural [Member] \| Foreign exchange
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	0	0	0	0
Northwest Holdings and Northwest Natural [Member] \| Benefit (expense) to cost of gas \| Natural gas commodity
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	493	11,936	38,457	73,257
Northwest Holdings and Northwest Natural [Member] \| Benefit (expense) to cost of gas \| Foreign exchange
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	17	168	(162)	181
Northwest Holdings and Northwest Natural [Member] \| Sales [Member] \| Natural gas commodity
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	0	0	0	0
Northwest Holdings and Northwest Natural [Member] \| Sales [Member] \| Foreign exchange
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	0	0	0	0
Northwest Natural Gas Company [Member]
Derivative [Line Items]
Derivative, Gain on Derivative				153,200
Derivative, Loss on Derivative	18,700	19,200	69,200
Deferred Derivative Gain (Loss) [Member] \| Northwest Holdings and Northwest Natural [Member] \| Natural gas commodity
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	(493)	11,936	(38,457)	73,257
Deferred Derivative Gain (Loss) [Member] \| Northwest Holdings and Northwest Natural [Member] \| Foreign exchange
Derivative [Line Items]
Gain (Loss) on Derivative Instruments, Net, Pretax	$ (17)	$ (168)	$ 162	$ (181)