v3.19.2

Variable Interest Entities and Unconsolidated Investments in Power Plants (VIE Texuals) (Details) $ in Millions | 3 Months Ended | 6 Months Ended |
--- | --- | --- | ---
Jun. 30, 2019 USD ($) yr MW | Jun. 30, 2018 USD ($) | Jun. 30, 2019 USD ($) yr MW | Jun. 30, 2018 USD ($) | Dec. 31, 2018 USD ($) MW
Variable Interest Entity [Line Items] |  |  |  |  |
Variable interest entity, financial or other support, amount | $ 0 | $ 0 | $ 0 | $ 0 |
Equity method investment, ownership percentage | 50.00% |  | 50.00% |  |
Equity method investment, summarized financial information, debt | $ 304 |  | $ 304 |  | $ 301
Prorata share of equity method investment, summarized financial information, debt | $ 152 |  | 152 |  | $ 151
Return on investments from unconsolidated subsidiaries |  |  | $ 11 | 5 |
Greenfield [Member] |  |  |  |  |
Variable Interest Entity [Line Items] |  |  |  |  |
Power generation capacity | MW | 1,038 |  | 1,038 |  |
Equity method investment, ownership percentage | 50.00% |  | 50.00% |  |
Return on investments from unconsolidated subsidiaries | $ 0 | 0 | $ 0 | 0 |
Whitby [Member] |  |  |  |  |
Variable Interest Entity [Line Items] |  |  |  |  |
Power generation capacity | MW | 50 |  | 50 |  |
Equity method investment, ownership percentage | 50.00% |  | 50.00% |  |
Return on investments from unconsolidated subsidiaries | $ 0 | $ 2 | $ 11 | $ 5 |
Calpine Receivables [Member] |  |  |  |  |
Variable Interest Entity [Line Items] |  |  |  |  |
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount | $ 67 |  | $ 67 |  |
Equity method investment, ownership percentage | 100.00% |  | 100.00% |  |
Variable Interest Entity, Primary Beneficiary [Member] |  |  |  |  |
Variable Interest Entity [Line Items] |  |  |  |  |
Power generation capacity | MW | 7,880 |  | 7,880 |  | 7,880
Put Option [Member] |  |  |  |  |
Variable Interest Entity [Line Items] |  |  |  |  |
Proceeds from sale of property, plant and equipment |  |  | $ 280 |  |
Call Option [Member] |  |  |  |  |
Variable Interest Entity [Line Items] |  |  |  |  |
Proceeds from sale of property, plant and equipment |  |  | $ 377 |  |
Inland Empire Energy Center [Member] |  |  |  |  |
Variable Interest Entity [Line Items] |  |  |  |  |
Power generation capacity | MW | 775 |  | 775 |  |
Put Option Exercise Period | yr | 2,025 |  | 2,025 |  |
Inland Empire Energy Center [Member] | Minimum [Member] |  |  |  |  |
Variable Interest Entity [Line Items] |  |  |  |  |
Call Option Exercise Period | yr | 2,017 |  | 2,017 |  |
Inland Empire Energy Center [Member] | Maximum [Member] |  |  |  |  |
Variable Interest Entity [Line Items] |  |  |  |  |
Call Option Exercise Period | yr | 2,024 |  | 2,024 |  |
OMEC [Member] |  |  |  |  |
Variable Interest Entity [Line Items] |  |  |  |  |
Debt Instrument, Face Amount | $ 220 |  | $ 220 |  |

X
- Definition Call Option Exercise Period + References No definition available. + Details
Name: | cpn_CallOptionExercisePeriod
Namespace Prefix: | cpn_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Equity Method Investment, Summarized Financial Information, Debt + References No definition available. + Details
Name: | cpn_EquityMethodInvestmentSummarizedFinancialInformationDebt
Namespace Prefix: | cpn_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
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 Prorata Share of Equity Method Investment, Summarized Financial Information, Debt + References No definition available. + Details
Name: | cpn_ProrataShareOfEquityMethodInvestmentSummarizedFinancialInformationDebt
Namespace Prefix: | cpn_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Put Option Exercise Period + References No definition available. + Details
Name: | cpn_PutOptionExercisePeriod
Namespace Prefix: | cpn_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Face (par) amount of debt instrument at time of issuance. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 55 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400 + Details
Name: | us-gaap_DebtInstrumentFaceAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of distribution received from equity method investee for return on investment, classified as operating activities. Excludes distribution for return of investment, classified as investing activities. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3602-108585 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04(10)) -URI http://asc.fasb.org/extlink&oid=116637232&loc=SL114874131-224263 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03(12)) -URI http://asc.fasb.org/extlink&oid=116634182&loc=SL114868664-224227 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 21D -URI http://asc.fasb.org/extlink&oid=118932676&loc=SL94080555-108585 + Details
Name: | us-gaap_EquityMethodInvestmentDividendsOrDistributions
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571 + Details
Name: | us-gaap_EquityMethodInvestmentOwnershipPercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition The cash inflow from the sale of long-lived, physical assets that are used in the normal conduct of business to produce goods and services and not intended for resale. + 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=118932676&loc=d3e3179-108585 + Details
Name: | us-gaap_ProceedsFromSaleOfPropertyPlantAndEquipment
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The reporting entity's maximum amount of exposure to loss as a result of its involvement with the Variable Interest Entity (VIE). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=118582676&loc=d3e5747-111685 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph b -URI http://asc.fasb.org/extlink&oid=118582676&loc=d3e5728-111685 + Details
Name: | us-gaap_VariableInterestEntityEntityMaximumLossExposureAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The amount of financial or other support the reporting entity has provided (explicitly or implicitly) to the Variable Interest Entity (VIE) that it was not previously contractually required to provide or that the reporting entity intends to provide, including, for example, situations in which the reporting entity assisted the VIE in obtaining another type of support. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 50 -Paragraph 5A -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=118582676&loc=SL6759159-111685 + Details
Name: | us-gaap_VariableInterestEntityFinancialOrOtherSupportAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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

X
- Details
Name: | srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=cpn_GreenfieldMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=cpn_WhitbyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=cpn_CalpineReceivablesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis=us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis=us-gaap_PutOptionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis=us-gaap_CallOptionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis=cpn_InlandEmpireEnergyCenterMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=cpn_OmecMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |