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Commitments and Guarantees Unrecorded Unconditional Purchase Obligations (Details) (USD $) In Millions, unless otherwise specified | Dec. 31, 2014
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Capital Additions [Member] |
Unrecorded Unconditional Purchase Obligation [Line Items] |
Unrecorded Unconditional Purchase Obligation | $ 343 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceSheetAmount / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = us-gaap_CapitalAdditionsMember
Unrecorded Unconditional Purchase Obligation, Due within One Year | 242 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFirstAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = us-gaap_CapitalAdditionsMember
Unrecorded Unconditional Purchase Obligation, Due within Two Years | 21 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnSecondAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = us-gaap_CapitalAdditionsMember
Unrecorded Unconditional Purchase Obligation, Due within Three Years | 2 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnThirdAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = us-gaap_CapitalAdditionsMember
Unrecorded Unconditional Purchase Obligation, Due within Four Years | 2 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFourthAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = us-gaap_CapitalAdditionsMember
Unrecorded Unconditional Purchase Obligation, Due within Five Years | 2 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFifthAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = us-gaap_CapitalAdditionsMember
Unrecorded Unconditional Purchase Obligation, Due after Five Years | 74 us-gaap_UnrecordedUnconditionalPurchaseObligationDueAfterFiveYears / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = us-gaap_CapitalAdditionsMember
Long-term Contract for Purchase of Electric Power [Domain] |
Unrecorded Unconditional Purchase Obligation [Line Items] |
Unrecorded Unconditional Purchase Obligation | 1,605 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceSheetAmount / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = us-gaap_LongTermContractForPurchaseOfElectricPowerDomain
Unrecorded Unconditional Purchase Obligation, Due within One Year | 179 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFirstAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = us-gaap_LongTermContractForPurchaseOfElectricPowerDomain
Unrecorded Unconditional Purchase Obligation, Due within Two Years | 167 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnSecondAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = us-gaap_LongTermContractForPurchaseOfElectricPowerDomain
Unrecorded Unconditional Purchase Obligation, Due within Three Years | 140 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnThirdAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = us-gaap_LongTermContractForPurchaseOfElectricPowerDomain
Unrecorded Unconditional Purchase Obligation, Due within Four Years | 143 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFourthAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = us-gaap_LongTermContractForPurchaseOfElectricPowerDomain
Unrecorded Unconditional Purchase Obligation, Due within Five Years | 143 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFifthAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = us-gaap_LongTermContractForPurchaseOfElectricPowerDomain
Unrecorded Unconditional Purchase Obligation, Due after Five Years | 833 us-gaap_UnrecordedUnconditionalPurchaseObligationDueAfterFiveYears / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = us-gaap_LongTermContractForPurchaseOfElectricPowerDomain
Electric Transmission [Member] |
Unrecorded Unconditional Purchase Obligation [Line Items] |
Unrecorded Unconditional Purchase Obligation | 90 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceSheetAmount / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = us-gaap_ElectricTransmissionMember
Unrecorded Unconditional Purchase Obligation, Due within One Year | 27 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFirstAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = us-gaap_ElectricTransmissionMember
Unrecorded Unconditional Purchase Obligation, Due within Two Years | 26 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnSecondAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = us-gaap_ElectricTransmissionMember
Unrecorded Unconditional Purchase Obligation, Due within Three Years | 6 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnThirdAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = us-gaap_ElectricTransmissionMember
Unrecorded Unconditional Purchase Obligation, Due within Four Years | 6 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFourthAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = us-gaap_ElectricTransmissionMember
Unrecorded Unconditional Purchase Obligation, Due within Five Years | 5 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFifthAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = us-gaap_ElectricTransmissionMember
Unrecorded Unconditional Purchase Obligation, Due after Five Years | 20 us-gaap_UnrecordedUnconditionalPurchaseObligationDueAfterFiveYears / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = us-gaap_ElectricTransmissionMember
Public Utility Districts [Member] |
Unrecorded Unconditional Purchase Obligation [Line Items] |
Unrecorded Unconditional Purchase Obligation | 49 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceSheetAmount / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = por_PublicUtilityDistrictsMember
Unrecorded Unconditional Purchase Obligation, Due within One Year | 8 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFirstAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = por_PublicUtilityDistrictsMember
Unrecorded Unconditional Purchase Obligation, Due within Two Years | 7 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnSecondAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = por_PublicUtilityDistrictsMember
Unrecorded Unconditional Purchase Obligation, Due within Three Years | 5 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnThirdAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = por_PublicUtilityDistrictsMember
Unrecorded Unconditional Purchase Obligation, Due within Four Years | 4 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFourthAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = por_PublicUtilityDistrictsMember
Unrecorded Unconditional Purchase Obligation, Due within Five Years | 2 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFifthAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = por_PublicUtilityDistrictsMember
Unrecorded Unconditional Purchase Obligation, Due after Five Years | 23 us-gaap_UnrecordedUnconditionalPurchaseObligationDueAfterFiveYears / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = por_PublicUtilityDistrictsMember
Natural gas [Member] |
Unrecorded Unconditional Purchase Obligation [Line Items] |
Unrecorded Unconditional Purchase Obligation | 453 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceSheetAmount / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = us-gaap_PublicUtilitiesInventoryFuelMember
Unrecorded Unconditional Purchase Obligation, Due within One Year | 56 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFirstAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = us-gaap_PublicUtilitiesInventoryFuelMember
Unrecorded Unconditional Purchase Obligation, Due within Two Years | 37 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnSecondAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = us-gaap_PublicUtilitiesInventoryFuelMember
Unrecorded Unconditional Purchase Obligation, Due within Three Years | 40 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnThirdAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = us-gaap_PublicUtilitiesInventoryFuelMember
Unrecorded Unconditional Purchase Obligation, Due within Four Years | 40 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFourthAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = us-gaap_PublicUtilitiesInventoryFuelMember
Unrecorded Unconditional Purchase Obligation, Due within Five Years | 36 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFifthAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = us-gaap_PublicUtilitiesInventoryFuelMember
Unrecorded Unconditional Purchase Obligation, Due after Five Years | 244 us-gaap_UnrecordedUnconditionalPurchaseObligationDueAfterFiveYears / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = us-gaap_PublicUtilitiesInventoryFuelMember
Coal and transportationSupply Agreements [Member] |
Unrecorded Unconditional Purchase Obligation [Line Items] |
Unrecorded Unconditional Purchase Obligation | 58 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceSheetAmount / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = us-gaap_CoalSupplyAgreementsMember
Unrecorded Unconditional Purchase Obligation, Due within One Year | 23 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFirstAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = us-gaap_CoalSupplyAgreementsMember
Unrecorded Unconditional Purchase Obligation, Due within Two Years | 14 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnSecondAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = us-gaap_CoalSupplyAgreementsMember
Unrecorded Unconditional Purchase Obligation, Due within Three Years | 11 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnThirdAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = us-gaap_CoalSupplyAgreementsMember
Unrecorded Unconditional Purchase Obligation, Due within Four Years | 5 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFourthAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = us-gaap_CoalSupplyAgreementsMember
Unrecorded Unconditional Purchase Obligation, Due within Five Years | 5 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFifthAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = us-gaap_CoalSupplyAgreementsMember
Unrecorded Unconditional Purchase Obligation, Due after Five Years | 0 us-gaap_UnrecordedUnconditionalPurchaseObligationDueAfterFiveYears / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = us-gaap_CoalSupplyAgreementsMember
Operatomg leases [Member] |
Unrecorded Unconditional Purchase Obligation [Line Items] |
Unrecorded Unconditional Purchase Obligation | 244 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceSheetAmount / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = us-gaap_LeaseAgreementsMember
Unrecorded Unconditional Purchase Obligation, Due within One Year | 10 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFirstAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = us-gaap_LeaseAgreementsMember
Unrecorded Unconditional Purchase Obligation, Due within Two Years | 11 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnSecondAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = us-gaap_LeaseAgreementsMember
Unrecorded Unconditional Purchase Obligation, Due within Three Years | 12 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnThirdAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = us-gaap_LeaseAgreementsMember
Unrecorded Unconditional Purchase Obligation, Due within Four Years | 11 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFourthAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = us-gaap_LeaseAgreementsMember
Unrecorded Unconditional Purchase Obligation, Due within Five Years | 8 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFifthAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = us-gaap_LeaseAgreementsMember
Unrecorded Unconditional Purchase Obligation, Due after Five Years | 192 us-gaap_UnrecordedUnconditionalPurchaseObligationDueAfterFiveYears / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = us-gaap_LeaseAgreementsMember
Commitments [Member] |
Unrecorded Unconditional Purchase Obligation [Line Items] |
Unrecorded Unconditional Purchase Obligation | 2,842 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceSheetAmount / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = us-gaap_CommitmentsMember
Unrecorded Unconditional Purchase Obligation, Due within One Year | 545 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFirstAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = us-gaap_CommitmentsMember
Unrecorded Unconditional Purchase Obligation, Due within Two Years | 283 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnSecondAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = us-gaap_CommitmentsMember
Unrecorded Unconditional Purchase Obligation, Due within Three Years | 216 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnThirdAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = us-gaap_CommitmentsMember
Unrecorded Unconditional Purchase Obligation, Due within Four Years | 211 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFourthAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = us-gaap_CommitmentsMember
Unrecorded Unconditional Purchase Obligation, Due within Five Years | 201 us-gaap_UnrecordedUnconditionalPurchaseObligationBalanceOnFifthAnniversary / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = us-gaap_CommitmentsMember
Unrecorded Unconditional Purchase Obligation, Due after Five Years | $ 1,386 us-gaap_UnrecordedUnconditionalPurchaseObligationDueAfterFiveYears / us-gaap_UnrecordedUnconditionalPurchaseObligationByCategoryOfItemPurchasedAxis = us-gaap_CommitmentsMember

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- Definition Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing in the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 440 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6394976&loc=d3e25336-109308 + Details
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X
- Definition Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing in the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 440 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6394976&loc=d3e25336-109308 + Details
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- Definition Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing in the fourth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 440 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6394976&loc=d3e25336-109308 + Details
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X
- Definition Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing in the second fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 440 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6394976&loc=d3e25336-109308 + Details
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- Definition Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing in the third fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 440 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6394976&loc=d3e25336-109308 + Details
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- Definition Amount of the unrecorded obligation to transfer funds in the future for fixed or minimum amounts or quantities of goods or services at fixed or minimum prices (for example, as in take-or-pay contracts or throughput contracts). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 440 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6394976&loc=d3e25336-109308 + Details
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X
- Definition Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing after the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 440 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6394976&loc=d3e25336-109308 + Details
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