v3.20.1

Debt (Letter of Credit) (Details) - USD ($) $ in Millions | Mar. 31, 2020 | Dec. 31, 2019
--- | --- | ---
Line of Credit Facility [Line Items] |  |  |
Letters of Credit Outstanding, Amount |  | $ 1,119 | $ 1,085
Revolving facilities |  |  |
Line of Credit Facility [Line Items] |  |  |
Letters of Credit Outstanding, Amount | [1] | 636 | 604
CDHI |  |  |
Line of Credit Facility [Line Items] |  |  |
Letters of Credit Outstanding, Amount | [2] | 3 | 3
Various project financing facilities |  |  |
Line of Credit Facility [Line Items] |  |  |
Letters of Credit Outstanding, Amount |  | 185 | 184
Other corporate facilities |  |  |
Line of Credit Facility [Line Items] |  |  |
Letters of Credit Outstanding, Amount | [3] | $ 295 | $ 294
[1] | The Corporate Revolving Facility represents our primary revolving facility and matures on March 8, 2023.
[2] | (2)On April 9, 2020, we amended one of our unsecured letter of credit facilities to partially extend the maturity of $100 million in commitments from June 20, 2020 to June 20, 2022.
[3] | (2)On January 21, 2020, we redeemed the outstanding $184 million in aggregate principal amount of our 2024 First Lien Notes, which was included in debt, current portion on our Consolidated Condensed Balance Sheet at December 31, 2019, with the proceeds from the 2028 First Lien Notes which was included in cash and cash equivalents on our Consolidated Condensed Balance Sheet at December 31, 2019.

X
- 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

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

X
- Details
Name: | us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

X
- Details
Name: | us-gaap_CreditFacilityAxis=cpn_VariousProjectFinancingFacilitiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CreditFacilityAxis=cpn_OtherCorporateFacilitiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |