v2.4.0.8

Variable Interest Entities and Unconsolidated Investments in Power Plants (VIE Texuals) (Details) (USD $) In Millions, unless otherwise specified | 3 Months Ended | 9 Months Ended |
--- | --- | --- | ---
Sep. 30, 2014 MW | Sep. 30, 2013 | Sep. 30, 2014 MW | Sep. 30, 2013 | Dec. 31, 2013 MW
Variable Interest Entity [Line Items] |  |  |  |  |
Power generation capacity | 10,365 |  | 10,365 |  | 9,427
Variable Interest Entity, Financial or Other Support, Amount | $ 7 | $ 0 | $ 47 | $ 0 |
Equity Method Investment, Summarized Financial Information, Debt | 362 |  | 362 |  | 395
Prorata Share of Equity Method Investment, Summarized Financial Information, Debt | 181 |  | 181 |  | 198
Greenfield [Member] |  |  |  |  |
Variable Interest Entity [Line Items] |  |  |  |  |
Power generation capacity | 1,038 |  | 1,038 |  |
Equity Method Investment, Ownership Percentage | 50.00% |  | 50.00% |  |
Distribution from equity method investee | 0 | 8 | 0 | 15 |
Whitby [Member] |  |  |  |  |
Variable Interest Entity [Line Items] |  |  |  |  |
Power generation capacity | 50 |  | 50 |  |
Equity Method Investment, Ownership Percentage | 50.00% |  | 50.00% |  |
Distribution from equity method investee | $ 0 | $ 0 | $ 13 | $ 9 |
Inland Empire Energy Center [Member] |  |  |  |  |
Variable Interest Entity [Line Items] |  |  |  |  |
Power generation capacity | 775 |  | 775 |  |
Put Option Exercise Period | 2,025 |  | 2,025 |  |
Inland Empire Energy Center [Member] | Minimum [Member] |  |  |  |  |
Variable Interest Entity [Line Items] |  |  |  |  |
Call Option Exercise Period | 2,017 |  | 2,017 |  |
Inland Empire Energy Center [Member] | Maximum [Member] |  |  |  |  |
Variable Interest Entity [Line Items] |  |  |  |  |
Call Option Exercise Period | 2,024 |  | 2,024 |  |

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

X
- Definition Distribution from equity method investee + References No definition available. + Details
Name: | cpn_DistributionFromEquityMethodInvestee
Namespace Prefix: | cpn_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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 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://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=6382943&loc=d3e33918-111571 + Details
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Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
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://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 50 -Paragraph 5A -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=28200181&loc=SL6759159-111685 + Details
Name: | us-gaap_VariableInterestEntityFinancialOrOtherSupportAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
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Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration