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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.

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- Definition

Amount of allowance for credit loss on accounts receivable.

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- Definition

Amount of increase (decrease) in allowance for credit loss on accounts receivable.

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Amount of increase in allowance for credit loss on accounts receivable, from recovery.

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- Definition

Carrying amount as of the balance sheet date of capitalized costs of regulated entities that are not expected to be recovered through revenue sources within one year or the normal operating cycle if longer.

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- Definition

Amount of allowance for credit loss on net investment in sales-type lease.

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Significant Accounting Policies - Credit Losses - ASU 2016-13 $ in Thousands	3 Months Ended
	Mar. 31, 2024 USD ($) numberOfLeases	Dec. 31, 2023 USD ($)	Mar. 31, 2023 USD ($)
Accounts Receivable, Noncurrent, Credit Quality Indicator [Line Items]
Number of Net Investments in Sales-Type Leases \| numberOfLeases	2
Sales-type Lease, Net Investment in Lease, Allowance for Credit Loss	$ 0
Regulatory Assets, Noncurrent	309,173	$ 333,443	$ 311,419
Other Northwest Holdings [Member]
Accounts Receivable, Noncurrent, Credit Quality Indicator [Line Items]
Accounts Receivable, Allowance for Credit Loss	235	227
Accounts Receivable, Allowance for Credit Loss, Period Increase (Decrease)	8
Accounts Receivable, Allowance for Credit Loss, Recovery	0
Northwest Holdings [Member]
Accounts Receivable, Noncurrent, Credit Quality Indicator [Line Items]
Accounts Receivable, Allowance for Credit Loss	4,181	3,455
Accounts Receivable, Allowance for Credit Loss, Period Increase (Decrease)	996
Accounts Receivable, Allowance for Credit Loss, Recovery	(270)
Northwest Natural Gas Company [Member]
Accounts Receivable, Noncurrent, Credit Quality Indicator [Line Items]
Accounts Receivable, Allowance for Credit Loss	3,946	3,228
Accounts Receivable, Allowance for Credit Loss, Period Increase (Decrease)	988
Accounts Receivable, Allowance for Credit Loss, Recovery	(270)
Regulatory Assets, Noncurrent	309,067	333,418	$ 311,394
Residential [Member] \| Northwest Natural Gas Company [Member]
Accounts Receivable, Noncurrent, Credit Quality Indicator [Line Items]
Accounts Receivable, Allowance for Credit Loss	3,140	2,397
Accounts Receivable, Allowance for Credit Loss, Period Increase (Decrease)	935
Accounts Receivable, Allowance for Credit Loss, Recovery	(192)
Commercial [Member] \| Northwest Natural Gas Company [Member]
Accounts Receivable, Noncurrent, Credit Quality Indicator [Line Items]
Accounts Receivable, Allowance for Credit Loss	531	501
Accounts Receivable, Allowance for Credit Loss, Period Increase (Decrease)	93
Accounts Receivable, Allowance for Credit Loss, Recovery	(63)
Industrial [Member] \| Northwest Natural Gas Company [Member]
Accounts Receivable, Noncurrent, Credit Quality Indicator [Line Items]
Accounts Receivable, Allowance for Credit Loss	56	65
Accounts Receivable, Allowance for Credit Loss, Period Increase (Decrease)	(9)
Accounts Receivable, Allowance for Credit Loss, Recovery	0
Accrued unbilled and other [Member] \| Northwest Natural Gas Company [Member]
Accounts Receivable, Noncurrent, Credit Quality Indicator [Line Items]
Accounts Receivable, Allowance for Credit Loss	219	$ 265
Accounts Receivable, Allowance for Credit Loss, Period Increase (Decrease)	(31)
Accounts Receivable, Allowance for Credit Loss, Recovery	$ (15)