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Basis of Presentation (Details) retail_customers in Thousands, mi² in Thousands	Sep. 30, 2025 mi² retail_customers
Basis of Presentation [Abstract]
Service Area Sq Miles | mi²	4
Incorporated Cities	51
Number of Retail Customers | retail_customers	957

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- Definition

Basis of Presentation [Abstract]

+ References

No definition available.

+ Details

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Namespace Prefix:	por_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

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- Definition

Number of incorporated cities in service area.

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No definition available.

+ Details

Name:	por_IncorporatedCities
Namespace Prefix:	por_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

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- Definition

Includes residential, commercial and industrial.

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No definition available.

+ Details

Name:	por_NumberOfRetailCustomers
Namespace Prefix:	por_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

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- Definition

Approximate square miles of service area.

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No definition available.

+ Details

Name:	por_ServiceAreaSqMiles
Namespace Prefix:	por_
Data Type:	dtr-types:areaItemType
Balance Type:	na
Period Type:	instant