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Fixed interest rate related to the interest rate derivative.

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No definition available.

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Amount, after deduction of unamortized premium (discount) and debt issuance cost, of long-term debt. Excludes lease obligation.

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Amount, after deduction of unamortized premium (discount) and debt issuance cost, of long-term debt classified as current. Excludes lease obligation.

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Amount, after deduction of unamortized premium (discount) and debt issuance cost, of long-term debt classified as noncurrent. Excludes lease obligation.

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Weighted average interest rate of long-term debt outstanding calculated at point in time.

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Amount of long-term debt classified as other.

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The cash inflow during the period from additional borrowings in aggregate debt. Includes proceeds from short-term and long-term debt.

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Amount of cash outflow for short-term and long-term debt. Excludes payment of lease obligation.

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The remaining balance of debt issuance expenses that were capitalized and are being amortized against income over the lives of the respective bond issues. This does not include the amounts capitalized as part of the cost of the utility plant or asset.

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No definition available.

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Long-Term Debt - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
Long-Term Debt - USD ($) $ in Thousands	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Mar. 15, 2024
Debt Instrument [Line Items]
Long-term Debt	$ 1,575,604	$ 1,535,302	$ 1,576,300
Other Long-Term Debt	6,500	6,000	6,600
Unamortized debt issuance costs	10,585	10,428	10,044
Long-term Debt, Gross	1,586,189	1,545,730	1,586,344
Long-term debt, Current Maturities, Gross	900	240,700	150,900
Long-term debt	1,574,735	1,294,590	1,425,435
Current maturities of long-term debt	869	240,712	150,865
Northwest Natural Gas Company [Member]
Debt Instrument [Line Items]
Long-term Debt	1,364,899	1,324,422	1,364,732
Unamortized debt issuance costs	$ 9,801	$ 10,278	$ 9,968
Weighted average interest rate	4.60%	4.60%	4.70%
Long-term Debt, Gross	$ 1,374,700	$ 1,334,700	$ 1,374,700
Long-term debt	1,364,899	1,234,460	1,364,732
Current maturities of long-term debt	$ 0	89,962	0
Northwest Natural Gas Company [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Stated interest rate	2.82%
Northwest Natural Gas Company [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Stated interest rate	7.85%
Northwest Holdings and Northwest Natural [Member]
Debt Instrument [Line Items]
Unamortized debt issuance costs	$ 10,600	$ 10,400	$ 10,000
18 Month Credit Agreement Due March 15, 2024
Debt Instrument [Line Items]
Weighted average interest rate	0.00%	5.40%	5.50%
Proceeds from Issuance of Debt	$ 0	$ 100,000	$ 100,000
Long-term Debt, Gross				$ 100,000
Derivative, Fixed Interest Rate	4.70%
18 Month Credit Agreement Due March 15, 2024 \| Northwest Natural Gas Company [Member]
Debt Instrument [Line Items]
Repayments of Debt	$ 100,000
18 Month Credit Agreement Due March 15, 2024 \| NWN Water
Debt Instrument [Line Items]
Weighted average interest rate	0.00%	5.30%	5.80%
Proceeds from Issuance of Debt	$ 0	$ 50,000	$ 50,000
Repayments of Debt	$ 50,000
NWN Water Term Loan Due 2026
Debt Instrument [Line Items]
Derivative, Fixed Interest Rate	3.80%
NWN Water Term Loan Due 2026 \| Corporate, Non-Segment [Member] \| Other Northwest Holdings [Member]
Debt Instrument [Line Items]
Long-term Debt	$ 55,000
NWN Water Term Loan Due 2026 \| NWN Water
Debt Instrument [Line Items]
Long-term Debt	$ 55,000	$ 55,000	$ 55,000
Weighted average interest rate	4.70%	4.90%	4.70%
Note 5780 Series due 2028
Debt Instrument [Line Items]
Stated interest rate	5.78%
Proceeds from Issuance of Debt	$ 100,000
Note 5840 Series due 2029
Debt Instrument [Line Items]
Stated interest rate	5.84%
Proceeds from Issuance of Debt	$ 50,000
NW Holdings Unsecured Senior Bonds
Debt Instrument [Line Items]
Weighted average interest rate	5.80%	0.00%	0.00%
Proceeds from Issuance of Debt	$ 150,000	$ 0	$ 0