v2.4.0.8

Assets and Liabilities with Recurring Fair Value Measurements Quantitative Info on Level 3 (Details) (USD $) | Jun. 30, 2013 | Dec. 31, 2012
--- | --- | ---
Minimum [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |
Fair Value Inputs Quantitative Information Power | $ 31.00 | $ 23.75
Maximum [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |
Fair Value Inputs Quantitative Information Power | 50.00 | 53.82
Physical Power [Member] |  |
Fair Value Inputs, Assets, Quantitative Information [Line Items] |  |
Fair Value Inputs Quantitative Information Power | $ 6,000,000 | $ 11,000,000

X
- Definition Fair Value Inputs Quantitative Information Power + References No definition available. + Details
Name: | cpn_FairValueInputsQuantitativeInformationPower
Namespace Prefix: | cpn_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | us-gaap_FairValueInputsAssetsQuantitativeInformationLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration