Property, Plant and Equipment, Net Property, Plant and Equipment, Net - Change in Accounting Estimate (Details) (Depreciable Assets [Member], USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2014	Sep. 30, 2014
Depreciable Assets [Member]
Change in Accounting Estimate [Line Items]
Change in Accounting Estimates, Impact on Period of Change	$ 8	$ 17

Disclosure of the financial effect on the period of change from a change in accounting estimate.

No definition available.

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