Price Risk Management Net volumes related to price risk management activities (Details) (CAD) In Millions, unless otherwise specified	Mar. 31, 2013 MMBTU MWh	Dec. 31, 2012 MWh MMBTU
Commodity contracts:
Electricity	13,000,000	11,000,000
Natural gas	87,000,000	86,000,000
Oil	3,000,000	0
Foreign currency	8	7

- Details

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

- Definition

Net volume associated with the reporting entity's derivative instruments recorded as of the balance sheet date having arisen from price risk management activities related to natural gas.

+ References

No definition available.

+ Details

Name:	por_VolumeRelatedToDerivativeInstrumentsAtBalanceSheetDateCommodityContractsNaturalGas
Namespace Prefix:	por_
Data Type:	num:energyItemType
Balance Type:	na
Period Type:	instant

- Definition

VolumeRelatedToDerivativeInstrumentsAtBalanceSheetDateCommodityContractsOil

+ References

No definition available.

+ Details

Name:	por_Volumerelatedtoderivativeinstrumentsatbalancesheetdatecommoditycontractsoil
Namespace Prefix:	por_
Data Type:	num:energyItemType
Balance Type:	na
Period Type:	instant

- Definition

Net volume related to the reporting entity's derivative instruments as of the balance sheet date having arisen from price risk management activities.

+ References

No definition available.

+ Details

Name:	por_VolumeRelatedToDerivativeInstrumentsHeldAtBalanceSheetDateCommodityContractsElectricity
Namespace Prefix:	por_
Data Type:	num:energyItemType
Balance Type:	na
Period Type:	instant

- Definition

Aggregate notional amount of foreign currency exchange rate derivatives. Notional amount refers to the number of currency units specified in the foreign currency derivative contract.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Notional Amount

-URI http://asc.fasb.org/extlink&oid=6519104

+ Details

Name:	us-gaap_NotionalAmountOfForeignCurrencyDerivatives
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant