Long-term debt, Current Maturities, Gross

No definition available.

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Data Type:	xbrli:monetaryItemType
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- Definition

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

+ References

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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

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- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

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- Definition

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

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+ Details

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- Definition

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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- Definition

The cash inflow from a debt initially having maturity due after one year or beyond the operating cycle, if longer.

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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

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- Definition

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.

+ References

No definition available.

+ Details

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DEBT - Narrative (Details) - USD ($)	6 Months Ended
DEBT - Narrative (Details) - USD ($)	Jun. 30, 2026	Jun. 30, 2025	Jun. 10, 2026	Dec. 31, 2025
Short-term Debt [Line Items]
Long-term debt	$ 2,502,400,000
Less: unamortized debt issuance costs	16,100,000	$ 14,100,000		$ 15,900,000
Current maturities of long-term debt	125,685,000	141,541,000		160,627,000
Balance Outstanding	2,518,500,000	2,242,300,000		2,448,700,000
Long-term debt issued	125,000,000	375,000,000
NW Natural
Short-term Debt [Line Items]
Long-term debt	1,535,300,000	1,365,700,000		1,534,900,000
Less: unamortized debt issuance costs	9,400,000	9,000,000.0		9,800,000
Current maturities of long-term debt	74,972,000	29,997,000		54,948,000
Long-term debt, current maturities	75,000,000.0
Balance Outstanding	1,544,700,000	1,374,700,000		1,544,700,000
NWN Water
Short-term Debt [Line Items]
Long-term debt, current maturities	700,000
NWN Water \| Line of Credit
Short-term Debt [Line Items]
Line of credit facility, maximum borrowing capacity			$ 55,000,000.0
Natural first mortgage bonds \| Mortgages \| NW Natural
Short-term Debt [Line Items]
Balance Outstanding	1,544,700,000	1,374,700,000		1,544,700,000
NW Holdings Unsecured Senior Bonds \| Unsecured Debt
Short-term Debt [Line Items]
Balance Outstanding	$ 335,000,000.0	285,000,000.0		285,000,000.0
Junior Subordinated Debt \| Junior Subordinated Debt
Short-term Debt [Line Items]
Stated interest rate (as percent)	7.00%
Term Loan \| Secured Debt
Short-term Debt [Line Items]
Balance Outstanding	$ 50,000,000.0	$ 50,000,000.0		$ 50,000,000.0
Series A Senior Notes
Short-term Debt [Line Items]
Stated interest rate (as percent)	5.15%
Long-term debt issued	$ 33,000,000.0
Series B Senior Notes
Short-term Debt [Line Items]
Stated interest rate (as percent)	5.58%
Long-term debt issued	$ 42,000,000.0
Series F Notes \| Secured Debt
Short-term Debt [Line Items]
Stated interest rate (as percent)	5.35%
Long-term debt issued	$ 10,000,000.0
Series G Notes \| Secured Debt
Short-term Debt [Line Items]
Stated interest rate (as percent)	5.83%
Long-term debt issued	$ 60,000,000.0
Minimum \| Natural first mortgage bonds \| Mortgages \| NW Natural
Short-term Debt [Line Items]
Stated interest rate (as percent)	2.82%
Minimum \| SiEnergy secured senior notes \| Secured Debt
Short-term Debt [Line Items]
Stated interest rate (as percent)	4.86%
Minimum \| SiEnergy secured senior notes \| Secured Debt \| NWN Water
Short-term Debt [Line Items]
Stated interest rate (as percent)	5.15%
Minimum \| NW Holdings Unsecured Senior Bonds \| Unsecured Debt
Short-term Debt [Line Items]
Stated interest rate (as percent)	5.35%
Maximum \| Natural first mortgage bonds \| Mortgages \| NW Natural
Short-term Debt [Line Items]
Stated interest rate (as percent)	7.85%
Maximum \| SiEnergy secured senior notes \| Secured Debt
Short-term Debt [Line Items]
Stated interest rate (as percent)	6.04%
Maximum \| SiEnergy secured senior notes \| Secured Debt \| NWN Water
Short-term Debt [Line Items]
Stated interest rate (as percent)	5.58%
Maximum \| NW Holdings Unsecured Senior Bonds \| Unsecured Debt
Short-term Debt [Line Items]
Stated interest rate (as percent)	5.86%