Derivative Instruments Credit Rating - USD ($)	Sep. 30, 2023	Dec. 31, 2022	Sep. 30, 2022
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	10,100,000	$ 153,300,000	40,800,000
Derivative liability	$ 48,100,000	$ 3,600,000	$ 8,500,000

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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