Guarantees (Details) (USD $) In Millions	6 Months Ended
Jun. 30, 2011	Dec. 31, 2010
Guarantee Obligations Abstract
Guarantee obligations maximum exposure	$ 365
Guarantee obligations unlimited exposure	Certain indemnifications have no limitations as to time or maximum potential future payments
Indemnification charge	65
Replacement power costs	12
Guarantee obligations current carrying value	90	31
Guarantee obligations related party	$ 300

Name:	pgn_GuaranteeObligationsAbstract
Namespace Prefix:	pgn
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Disclosures for those guarantees that are issued to benefit entities meeting the definition of a related party.

+ Details

Name:	pgn_GuaranteeObligationsRelatedParty
Namespace Prefix:	pgn
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Total amount of indemnification liability related to current and future years.

+ Details

Name:	pgn_IndemnificationCharge
Namespace Prefix:	pgn
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The total amount of replacement power costs provided under an indemnification agreement.

+ Details

Name:	pgn_ReplacementPowerCosts
Namespace Prefix:	pgn
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The current carrying amount of the liability for the freestanding or embedded guarantor's obligations under the guarantee or each group of similar guarantees.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 5
-Paragraph 9

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name FASB Interpretation (FIN)
-Number 45
-Paragraph 13
-Subparagraph c

+ Details

Name:	us-gaap_GuaranteeObligationsCurrentCarryingValue
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name FASB Interpretation (FIN)
-Number 45
-Paragraph 13
-Subparagraph b

+ Details

Name:	us-gaap_GuaranteeObligationsMaximumExposure
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Discloses whether the terms of the guarantee (or each group of similar guarantees) provide for no limitation to the maximum potential future payments under the guarantee.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name FASB Interpretation (FIN)
-Number 45
-Paragraph 13
-Subparagraph b

+ Details

Name:	us-gaap_GuaranteeObligationsUnlimitedExposure
Namespace Prefix:	us-gaap
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration