Price Risk Management Net volumes related to price risk management activities (Details) (CAD) In Millions, unless otherwise specified	Mar. 31, 2015 MMBTU MWh	Dec. 31, 2014 MWh MMBTU
Commodity contracts:
Electricity	15,000,000	16,000,000
Natural gas	126,000,000	127,000,000
Foreign currency	7	7

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

No definition available.

Name:	por_VolumeRelatedtoDerivativeInstrumentsHeldatBalanceSheetDateForeignCurrency
Namespace Prefix:	por_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant