v3.2.0.727

Debt (Letter of Credit) (Details) - USD ($) $ in Millions | Jun. 30, 2015 | Dec. 31, 2014
--- | --- | ---
Line of Credit Facility [Line Items] |  |  |
Letters of Credit Outstanding, Amount |  | $ 642 | $ 644
Corporate Revolving Facility [Member] |  |  |
Line of Credit Facility [Line Items] |  |  |
Letters of Credit Outstanding, Amount | [1] | 179 | 223
CDH [Member] |  |  |
Line of Credit Facility [Line Items] |  |  |
Letters of Credit Outstanding, Amount |  | 244 | 214
Various Project Financing Facilities [Member] |  |  |
Line of Credit Facility [Line Items] |  |  |
Letters of Credit Outstanding, Amount |  | $ 219 | $ 207
[1] | The Corporate Revolving Facility represents our primary revolving facility.

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_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: |