Commitments and Contingencies Commitments and Contingencies - Hydroelectric Commitments (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Capital expenditures required by hydroelectric licenses	$ 203

Estimated capital expenditures related to hydroelectric facilities required by certain hydroelectric licenses over the next 10 years.

No definition available.

Name:	pcorp_CapitalExpendituresRequiredByHydroelectricLicenses
Namespace Prefix:	pcorp_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration