v3.2.0.727

Acquisition (Details) $ in Millions | Jul. 20, 2015 USD ($) MWh | Jun. 30, 2015 MW | Dec. 31, 2014 USD ($) MW
--- | --- | --- | ---
Business Acquisition [Line Items] |  |  |
Power generation capacity |  | 10,266 | 10,365
Fore River Energy Center [Member] |  |  |
Business Acquisition [Line Items] |  |  |
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net | $ |  |  | $ 530
Power generation capacity |  |  | 809
Subsequent Event [Member] |  |  |
Business Acquisition [Line Items] |  |  |
Electricity Sales Volume | MWh | 22,000,000 |  |
Subsequent Event [Member] | Champion Energy Holding, LLC [Member] |  |  |
Business Acquisition [Line Items] |  |  |
Ownership Percentage of Acquiree | 75.00% |  |
Subsequent Event [Member] | EDF Trading North America, LLC [Member] |  |  |
Business Acquisition [Line Items] |  |  |
Ownership Percentage of Acquiree | 25.00% |  |
Subsequent Event [Member] | Champion Energy Marketing, LLC [Member] |  |  |
Business Acquisition [Line Items] |  |  |
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net | $ | $ 240 |  |

X
- Definition Electricity Sales Volume + References No definition available. + Details
Name: | cpn_ElectricitySalesVolume
Namespace Prefix: | cpn_
Data Type: | num:energyItemType
Balance Type: | na
Period Type: | instant

X
- Definition Ownership Percentage of Acquiree + References No definition available. + Details
Name: | cpn_OwnershipPercentageofAcquiree
Namespace Prefix: | cpn_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Power generation capacity + References No definition available. + Details
Name: | cpn_PowerGenerationCapacity
Namespace Prefix: | cpn_
Data Type: | num:powerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_BusinessAcquisitionLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount recognized as of the acquisition date for the identifiable assets acquired in excess of (less than) the aggregate liabilities assumed. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 55 -Paragraph 37 -URI http://asc.fasb.org/extlink&oid=35744172&loc=d3e2207-128464 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=56956791&loc=d3e4845-128472 + Details
Name: | us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=cpn_ForeRiverEnergyCenterMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=cpn_ChampionEnergyHoldingLLCMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=cpn_EDFTradingNorthAmericaLLCMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=cpn_ChampionEnergyMarketingLLCMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |