First Mortgage Bonds - maximum rate

No definition available.

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- Definition

First mortgage Bonds - minimum rate

+ References

No definition available.

+ Details

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- Definition

Long-term Pollution Control Bond, Rate

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	instant

- Definition

Pollution Control Bonds Retired

+ References

No definition available.

+ Details

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Namespace Prefix:	por_
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Balance Type:	debit
Period Type:	duration

- Definition

Pollution Control Revenue Bonds owned by PGE

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
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Period Type:	instant

- Definition

Remarketable Pollution Control Bonds held by the Company.

+ References

No definition available.

+ Details

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Period Type:	instant

- Definition

Unsecured term bank loan rate - maximum

+ References

No definition available.

+ Details

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Namespace Prefix:	por_
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Balance Type:	na
Period Type:	instant

- Definition

Unsecured term bank loan rate - minimum

+ References

No definition available.

+ Details

Name:	por_Unsecuredtermbankloanrateminimum
Namespace Prefix:	por_
Data Type:	num:percentItemType
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Period Type:	instant

- Definition

The reference rate for the variable rate of the debt instrument, such as LIBOR or the US Treasury rate and the maturity of the reference rate used, such as three months or six months LIBOR.

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	duration

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22(a)(1))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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- Details

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- Definition

Weighted average interest rate of debt outstanding.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtWeightedAverageInterestRate
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Data Type:	num:percentItemType
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Period Type:	instant

- Definition

The cash inflow from amounts received from a long-term debt instrument secured by a first mortgage deed of trust, containing a pledge of real property. The lender has the highest claim on the property in case of default.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Financing Activities

-URI http://asc.fasb.org/extlink&oid=6513228

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 14

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3255-108585

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

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

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
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Period Type:	duration

- Definition

Carrying value as of the balance sheet date of the portion of long-term, uncollateralized debt obligations due within one year or the normal operating cycle, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.20)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 20

-Article 5

+ Details

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Balance Type:	credit
Period Type:	instant

- Details

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Long term debt (Details) (USD $) In Millions, unless otherwise specified	1 Months Ended	3 Months Ended			12 Months Ended			1 Months Ended
	Nov. 30, 2014	Dec. 31, 2014	Sep. 30, 2014	Mar. 31, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jan. 31, 2015
Debt Instrument [Line Items]
Proceeds from Issuance of First Mortgage Bond					$ 280
Long-term Pollution Control Bond		21por_RemarketablePollutionControlBonds			21por_RemarketablePollutionControlBonds
Pollution Control Bonds Retired				(6)por_PollutionControlBondsRetired
Debt Instrument, Interest Rate, Stated Percentage	3.51%	4.44%	4.39%		4.44%
Proceeds from Issuance of Long-term Debt	80	100	100		585	380	0
Unsecured Debt, Current		305us-gaap_UnsecuredDebtCurrent			305us-gaap_UnsecuredDebtCurrent	0us-gaap_UnsecuredDebtCurrent
Debt Instrument, Description of Variable Rate Basis					70
First mortgage Bonds - minimum rate		3.46%por_FirstMortgageBondsMinimumRate			3.46%por_FirstMortgageBondsMinimumRate	3.46%por_FirstMortgageBondsMinimumRate
First Mortgage Bonds - maximum rate		9.31%por_FirstMortgageBondsMaximumRate			9.31%por_FirstMortgageBondsMaximumRate	9.31%por_FirstMortgageBondsMaximumRate
Debt, Weighted Average Interest Rate		5.42%us-gaap_DebtWeightedAverageInterestRate			5.42%us-gaap_DebtWeightedAverageInterestRate	5.62%us-gaap_DebtWeightedAverageInterestRate
Unsecured term bank loan rate - minimum		0.86%por_Unsecuredtermbankloanrateminimum			0.86%por_Unsecuredtermbankloanrateminimum
Unsecured term bank loan rate - maximum		0.93%por_Unsecuredtermbankloanratemaximum			0.93%por_Unsecuredtermbankloanratemaximum
Pollution Control Revenue Bonds owned by PGE		21			21	27
Long-term Pollution Control Bond, Rate		5.00%por_LongTermPollutionControlBondRate			5.00%por_LongTermPollutionControlBondRate	5.00%por_LongTermPollutionControlBondRate
Subsequent Event [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage								3.55%
Proceeds from Issuance of Long-term Debt								$ 75