Derivative Instruments Credit Rating - USD ($)	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023
Collateral Posted with NW Natural Counterparties [Member]
Derivative [Line Items]
Additional Collateral, Aggregate Fair Value	$ 0		$ 0
Northwest Natural Gas Company [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	4,100,000	$ 9,000,000	1,600,000
Derivative liability	$ 61,400,000	$ 124,200,000	$ 51,500,000

The aggregate fair value of assets that are already posted, at the end of the reporting period, as collateral for derivative instruments with credit-risk-related contingent features.

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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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