Price Risk Management Net volumes related to price risk management activities (Details) (CAD) In Millions, unless otherwise specified	Sep. 30, 2013 MMBTU MWh	Dec. 31, 2012 MWh MMBTU
Commodity contracts:
Electricity	12,000,000	11,000,000
Natural gas	104,000,000	86,000,000
Oil	(1,000,000)	0
Foreign currency	7	7

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.

No definition available.

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