v3.3.1.900

Debt (Corporate Revolving Facility and other Letters of Credit Facilities) (Details) - USD ($) $ in Millions | Jun. 27, 2018 | Dec. 31, 2015 | Dec. 31, 2014
--- | --- | --- | ---
Line of Credit Facility [Line Items] |  |  |
Letters of Credit Outstanding, Amount |  | $ 755 | $ 644
Corporate Revolving Facility [Member] |  |  |
Line of Credit Facility [Line Items] |  |  |
Letters of Credit Outstanding, Amount |  | 316 | 223
CDH [Member] |  |  |
Line of Credit Facility [Line Items] |  |  |
Letters of Credit Outstanding, Amount |  | 241 | 214
Various Project Financing Facilities [Member] |  |  |
Line of Credit Facility [Line Items] |  |  |
Letters of Credit Outstanding, Amount |  | $ 198 | $ 207
Subsequent Event [Member] | Corporate Revolving Facility [Member] |  |  |
Line of Credit Facility [Line Items] |  |  |
Future line of credit facility maximum borrowing capacity | $ 1,520 |  |

X
- Definition Future line of credit facility maximum borrowing capacity + References No definition available. + Details
Name: | cpn_Futurelineofcreditfacilitymaximumborrowingcapacity
Namespace Prefix: | cpn_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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- Definition The total amount of the contingent obligation under letters of credit outstanding as of the reporting date. + References No definition available. + Details
Name: | us-gaap_LettersOfCreditOutstandingAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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- 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_LineOfCreditFacilityLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Details
Name: | us-gaap_LineOfCreditFacilityAxis=cpn_CorporateRevolvingFacilityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LineOfCreditFacilityAxis=cpn_CdhMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LineOfCreditFacilityAxis=cpn_VariousProjectFinancingFacilitiesMember
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: |