v3.19.1

Revenue from Contracts with Customers Performance Obligations and Contract Balances (Details) - Environmental Credits [Member] - USD ($) $ in Millions | 12 Months Ended |
--- | --- | ---
Dec. 31, 2018 | Dec. 31, 2017
Deferred Revenue, Current | $ 14 | $ 15
Deferred Revenue, Revenue Recognized | $ 15 |

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- Definition The carrying amount of consideration received or receivable as of the balance sheet date on potential earnings that were not recognized as revenue in conformity with GAAP, and which are expected to be recognized as such within one year or the normal operating cycle, if longer, including sales, license fees, and royalties, but excluding interest income. + References Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section 45 -Paragraph 8 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=82887183&loc=d3e6935-107765 + Details
Name: | us-gaap_DeferredRevenueCurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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- Definition Amount of revenue recognized that was previously reported as deferred or unearned revenue. + References No definition available. + Details
Name: | us-gaap_DeferredRevenueRevenueRecognized1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

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- Details
Name: | srt_ProductOrServiceAxis=cpn_EnvironmentalCreditsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |