v2.3.0.15

Commitments and Contingencies (Details) (USD $) In Millions, unless otherwise specified | 9 Months Ended |  |
--- | --- | --- | ---
Sep. 30, 2011 | Dec. 31, 2010 | Jul. 02, 2010
Commitments and Contingencies [Abstract] |  |  |
Environmental remediation liabilities related to Acquisition |  |  | $ 0
Amount of expenditures over which PHI is responsible for related to the Conectiv Acquisition |  |  | $ 10
Amount of shares remaining in reserve for distribution to holders of disputed claims | 21 |  |
Amount of shares authorized to settle unsecured claims | 485 |  |
Commitments and Contingencies [Line Items] |  |  |
Power generation capacity (in Megawatts) | 11,372 | 13,553 |

X
- Definition Amount Of Expenditures Third Party Is Responsible For Related To Acquisition + Details
Name: | cpn_AmountOfExpendituresThirdPartyIsResponsibleForRelatedToAcquisition
Namespace Prefix: | cpn
Data Type: | xbrli:monetaryItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount of shares authorized to settle unsecured claims + Details
Name: | cpn_AmountOfSharesAuthorizedToSettleUnsecuredClaims
Namespace Prefix: | cpn
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of shares remaining in reserve for distribution to holders of disputed claims + Details
Name: | cpn_AmountOfSharesRemainingInReserveForDistributionToHoldersOfDisputedClaims
Namespace Prefix: | cpn
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition Commitments and Contingencies Line Items + Details
Name: | cpn_CommitmentsAndContingenciesLineItems
Namespace Prefix: | cpn
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Environmental remediation liabilities related to Acquisition + Details
Name: | cpn_EnvironmentalRemediationLiabilitiesRelatedToAcquisition
Namespace Prefix: | cpn
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Power generation capacity + Details
Name: | cpn_PowerGenerationCapacity
Namespace Prefix: | cpn
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | us-gaap_CommitmentsAndContingenciesDisclosureAbstract
Namespace Prefix: | us-gaap
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration