Name:	nwn_PercentOfPreTaxIncomeFromGasStorageCreditedToDeferredRegulatoryAccount
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The percenage of pre-tax income from gas storage credited to a deferred regulatory account for crediting back to core utility customers when the costs of the capacity have been included in utility rates.

No definition available.

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The percenage of pre-tax income from gas storage retained when the costs of the capacity have been included in utility rates.

No definition available.

Name:	nwn_PercentOfPreTaxIncomeFromGasStorageRetainedWhenCostsOfCapacityAreInUtilityRates
Namespace Prefix:	nwn_
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The percenage of pre-tax income from gas storage retained when the costs of the capacity have not been included in utility rates.

No definition available.

Name:	nwn_PercentOfPreTaxIncomeFromGasStorageRetainedWhenCostsOfCapacityAreNotInUtilityRates
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Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-18

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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.

No definition available.

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