Risk Management Future Year Net Unrealized Gain/Loss Recorded at Balance Sheet Date Expected to Become Realized (Details) $ in Millions	Mar. 31, 2025 USD ($)
Electricity [Member]
Commodity contracts:
2022	$ (2)
2023	5
2024	4
2025	3
2026	3
Thereafter	20
Total	33
Natural Gas [Member]
Commodity contracts:
2022	(62)
2023	42
2024	5
2025	1
2026	0
Thereafter	0
Total	110
Net Unrealized Loss/(gain)[Member]
Commodity contracts:
2022	(60)
2023	47
2024	9
2025	4
2026	3
Thereafter	20
Total	$ 143

Commodity contracts: [Abstract]

No definition available.

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- Definition

Minimum amount of other commitment not otherwise specified in the taxonomy. Excludes commitments explicitly modeled in the taxonomy, including but not limited to, long-term and short-term purchase commitments, recorded and unrecorded purchase obligations, supply commitments, registration payment arrangements, leases, debt, product warranties, guarantees, environmental remediation obligations, and pensions.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of commitment classified as other to be paid after fifth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of commitment classified as other to be paid in fifth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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- Definition

Amount of commitment classified as other to be paid in fourth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of commitment classified as other to be paid in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of commitment classified as other to be paid in second fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of commitment classified as other to be paid in third fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=srt_NaturalGasReservesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=por_UnrealizedGainLossOnDerivativesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: