TargetHedgeAchieved

No definition available.

Name:	nwn_TargetHedgeAchieved
Namespace Prefix:	nwn_
Data Type:	dtr-types1:percentItemType
Balance Type:	na
Period Type:	instant

- 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

+ Details

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

- Definition

Nominal number of units used to calculate payment on derivative.

+ 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

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1I
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1I

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-18

Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480434/815-10-50-1B

Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1A
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480434/815-10-50-1A

+ Details

Name:	us-gaap_DerivativeNonmonetaryNotionalAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

- Definition

Nominal or face amount used to calculate payment on derivative.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480434/815-10-50-1B

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1A
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480434/815-10-50-1A

+ Details

Name:	us-gaap_DerivativeNotionalAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

- Details

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

- Details

Name:	nwn_GasYearAxis=nwn_GasYear20232024Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementGeographicalAxis=stpr_OR
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementGeographicalAxis=stpr_WA
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

Name:	us-gaap_UnderlyingAssetClassAxis=nwn_NaturalGasThermsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

Derivative Instruments Notional Amounts - Northwest Natural Gas Company [Member] therm in Thousands, $ in Thousands	Jun. 30, 2024 USD ($) therm	Dec. 31, 2023 USD ($) therm	Jun. 30, 2023 USD ($) therm
Gas Year 2023 - 2024
Derivative [Line Items]
TargetHedgeAchieved	82.00%
Gas Year 2023 - 2024 \| Oregon [Member]
Derivative [Line Items]
TargetHedgeAchieved	85.00%
Gas Year 2023 - 2024 \| WASHINGTON
Derivative [Line Items]
TargetHedgeAchieved	55.00%
Financial [Member] \| Gas Year 2023 - 2024
Derivative [Line Items]
TargetHedgeAchieved	66.00%
Financial [Member] \| Gas Year 2023 - 2024 \| Oregon [Member]
Derivative [Line Items]
TargetHedgeAchieved	69.00%
Financial [Member] \| Gas Year 2023 - 2024 \| WASHINGTON
Derivative [Line Items]
TargetHedgeAchieved	42.00%
Physical [Member] \| Gas Year 2023 - 2024
Derivative [Line Items]
TargetHedgeAchieved	16.00%
Physical [Member] \| Gas Year 2023 - 2024 \| Oregon [Member]
Derivative [Line Items]
TargetHedgeAchieved	16.00%
Physical [Member] \| Gas Year 2023 - 2024 \| WASHINGTON
Derivative [Line Items]
TargetHedgeAchieved	13.00%
Natural Gas Therms [Member] \| Financial [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	776,400	948,425	801,020
Natural Gas Therms [Member] \| Physical [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	615,300	571,610	538,794
Foreign Exchange Contract [Member]
Derivative [Line Items]
Derivative, Notional Amount \| $	$ 10,406	$ 11,926	$ 10,438