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Asset Retirement Obligations (Details) (USD $) In Millions, unless otherwise specified | 12 Months Ended
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Dec. 31, 2012
Asset Retirement Obligations [Abstract] |
Damages sought in USDOE claim | $ 112
Estimated award range from USDOE claim, Low | 65
Estimated award range from USDOE claim, High | 75
Asset Retirement Obligation Increase related to Boardman plant | 20
Asset Retirement Obligation Rate Recovery related to Trojan Plant | $ 4

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- Definition Asset Retirement Obligation Increase related to Boardman plant due to updated decommissioning study. + References No definition available. + Details
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- Definition Asset Retirement Obligation Rate Recovery related to Trojan Plant + References No definition available. + Details
Name: | por_AssetRetirementObligationRateRecoveryRelatedToTrojanPlant
Namespace Prefix: | por_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
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- Details
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- Definition Damages sought in USDOE claim + References No definition available. + Details
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Namespace Prefix: | por_
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- Definition High end of range for estimated award from USDOE claim + References No definition available. + Details
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- Definition Lower range of estimated award from USDOE claim + References No definition available. + Details
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Namespace Prefix: | por_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration