Related Parties and Parties-In-Interest Transactions (Details) - EBP 008 - NW Natural Holding Company unitized stock - USD ($)	12 Months Ended
Dec. 31, 2025	Dec. 31, 2024
EBP, Related Party and Party-in-Interest Transactions [Line Items]
Investment, purchased, number of shares (in shares)	29,437	30,917
Cost of asset	$ 1,238,762	$ 1,178,947
Investment sold, number of shares (in shares)	29,534	35,048
Selling price	$ 1,262,108	$ 1,357,687

Cost of investment, excluding plan interest in master trust, acquired by employee stock purchase, saving, or similar plan (employee benefit plan (EBP)).

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- Definition

Number of shares or units of investment purchased by employee stock purchase, saving, or similar plan (employee benefit plan (EBP)).

+ References

+ Details

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- Definition

Number of shares or units of investment sold by employee stock purchase, saving, or similar plan (employee benefit plan (EBP)).

+ References

+ Details

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- Definition

Amount of selling price for investment, excluding plan interest in master trust, sold by employee stock purchase, saving, or similar plan (employee benefit plan (EBP)).

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name Employee Retirement Income Security Act of 1974
-Number 2520
-Section 103
-Subsection 10
-Paragraph b
-Subparagraph (3)
-Publisher DOL-EBSA

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 962
-SubTopic 205
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6A-04(2)(b))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477804/962-205-S99-1

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Name Employee Retirement Income Security Act of 1974
-Number 2520
-Section 103
-Subsection 6
-Paragraph d
-Subparagraph (1)(iii)
-Publisher DOL-EBSA

Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
-Name Employee Retirement Income Security Act of 1974
-Number 2520
-Section 103
-Subsection 6
-Paragraph d
-Subparagraph (2)(iv)
-Publisher DOL-EBSA

Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef
-Name Employee Retirement Income Security Act of 1974
-Number 2520
-Section 103
-Subsection 10
-Paragraph b
-Subparagraph (2)(i)(D)
-Publisher DOL-EBSA

+ Details

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- 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/2009/role/commonPracticeRef
-Topic 962
-SubTopic 205
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6A-02)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477804/962-205-S99-1

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 962
-SubTopic 235
-Name Accounting Standards Codification
-Section S50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479143/962-235-S50-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483326/850-10-50-1

+ Details

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- Details

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- Details

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