v3.19.1

Divestitures (Details) - Subsequent Event [Member] $ in Millions | 3 Months Ended |
--- | --- | ---
Sep. 30, 2019 USD ($) | Apr. 08, 2019 MW
Garrison Energy Center and RockGen Energy LLC [Member] |  |
Business Acquisition [Line Items] |  |
Ownership percentage of acquiree |  | 100.00%
Proceeds from Sale of Productive Assets | $ | $ 360 |
Garrison Energy Center LLC [Member] |  |
Business Acquisition [Line Items] |  |
Power generation capacity |  | 309
RockGen Energy LLC [Member] |  |
Business Acquisition [Line Items] |  |
Power generation capacity |  | 503

X
- Definition Ownership Percentage of Divestee + References No definition available. + Details
Name: | cpn_OwnershipPercentageofDivestee
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 The cash inflow from the sale of property, plant and equipment (capital expenditures), software, and other intangible assets. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 12 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3179-108585 + Details
Name: | us-gaap_ProceedsFromSaleOfProductiveAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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_GarrisonEnergyCenterandRockGenEnergyLLCMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

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