v2.4.1.9

Assets and Liabilities with Recurring Fair Value Measurements Quantitative Information about Level 3 Fair Value Measurements (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Quantitative Information about Level 3 fair Value Measurements [Line Items]
Derivative, Fair Value, Net	$ 271,000,000us-gaap_DerivativeFairValueOfDerivativeNet	$ (144,000,000)us-gaap_DerivativeFairValueOfDerivativeNet
Physical Power [Member]
Quantitative Information about Level 3 fair Value Measurements [Line Items]
Derivative, Fair Value, Net	74,000,000us-gaap_DerivativeFairValueOfDerivativeNet / us-gaap_FairValueByLiabilityClassAxis = cpn_PhysicalPowerMember	7,000,000us-gaap_DerivativeFairValueOfDerivativeNet / us-gaap_FairValueByLiabilityClassAxis = cpn_PhysicalPowerMember
Natural Gas [Member]
Quantitative Information about Level 3 fair Value Measurements [Line Items]
Derivative, Fair Value, Net	5,000,000us-gaap_DerivativeFairValueOfDerivativeNet / us-gaap_FairValueByLiabilityClassAxis = us-gaap_NaturalGasReservesMember	0us-gaap_DerivativeFairValueOfDerivativeNet / us-gaap_FairValueByLiabilityClassAxis = us-gaap_NaturalGasReservesMember
Power Congestion Products [Member]
Quantitative Information about Level 3 fair Value Measurements [Line Items]
Derivative, Fair Value, Net	9,000,000us-gaap_DerivativeFairValueOfDerivativeNet / us-gaap_FairValueByLiabilityClassAxis = cpn_PowerCongestionProductsMember	7,000,000us-gaap_DerivativeFairValueOfDerivativeNet / us-gaap_FairValueByLiabilityClassAxis = cpn_PowerCongestionProductsMember
Minimum [Member] | Physical Power [Member]
Quantitative Information about Level 3 fair Value Measurements [Line Items]
Fair Value Inputs Quantitative Information	14.00cpn_FairValueInputsQuantitativeInformation / us-gaap_FairValueByLiabilityClassAxis = cpn_PhysicalPowerMember / us-gaap_RangeAxis = us-gaap_MinimumMember	28.92cpn_FairValueInputsQuantitativeInformation / us-gaap_FairValueByLiabilityClassAxis = cpn_PhysicalPowerMember / us-gaap_RangeAxis = us-gaap_MinimumMember
Minimum [Member] | Natural Gas [Member]
Quantitative Information about Level 3 fair Value Measurements [Line Items]
Fair Value Inputs Quantitative Information	1.00cpn_FairValueInputsQuantitativeInformation / us-gaap_FairValueByLiabilityClassAxis = us-gaap_NaturalGasReservesMember / us-gaap_RangeAxis = us-gaap_MinimumMember	0cpn_FairValueInputsQuantitativeInformation / us-gaap_FairValueByLiabilityClassAxis = us-gaap_NaturalGasReservesMember / us-gaap_RangeAxis = us-gaap_MinimumMember
Minimum [Member] | Power Congestion Products [Member]
Quantitative Information about Level 3 fair Value Measurements [Line Items]
Fair Value Inputs Quantitative Information	(19.56)cpn_FairValueInputsQuantitativeInformation / us-gaap_FairValueByLiabilityClassAxis = cpn_PowerCongestionProductsMember / us-gaap_RangeAxis = us-gaap_MinimumMember	(8.79)cpn_FairValueInputsQuantitativeInformation / us-gaap_FairValueByLiabilityClassAxis = cpn_PowerCongestionProductsMember / us-gaap_RangeAxis = us-gaap_MinimumMember
Maximum [Member] | Physical Power [Member]
Quantitative Information about Level 3 fair Value Measurements [Line Items]
Fair Value Inputs Quantitative Information	122.79cpn_FairValueInputsQuantitativeInformation / us-gaap_FairValueByLiabilityClassAxis = cpn_PhysicalPowerMember / us-gaap_RangeAxis = us-gaap_MaximumMember	53.15cpn_FairValueInputsQuantitativeInformation / us-gaap_FairValueByLiabilityClassAxis = cpn_PhysicalPowerMember / us-gaap_RangeAxis = us-gaap_MaximumMember
Maximum [Member] | Natural Gas [Member]
Quantitative Information about Level 3 fair Value Measurements [Line Items]
Fair Value Inputs Quantitative Information	10.86cpn_FairValueInputsQuantitativeInformation / us-gaap_FairValueByLiabilityClassAxis = us-gaap_NaturalGasReservesMember / us-gaap_RangeAxis = us-gaap_MaximumMember	0cpn_FairValueInputsQuantitativeInformation / us-gaap_FairValueByLiabilityClassAxis = us-gaap_NaturalGasReservesMember / us-gaap_RangeAxis = us-gaap_MaximumMember
Maximum [Member] | Power Congestion Products [Member]
Quantitative Information about Level 3 fair Value Measurements [Line Items]
Fair Value Inputs Quantitative Information	$ 19.56cpn_FairValueInputsQuantitativeInformation / us-gaap_FairValueByLiabilityClassAxis = cpn_PowerCongestionProductsMember / us-gaap_RangeAxis = us-gaap_MaximumMember	$ 11.53cpn_FairValueInputsQuantitativeInformation / us-gaap_FairValueByLiabilityClassAxis = cpn_PowerCongestionProductsMember / us-gaap_RangeAxis = us-gaap_MaximumMember

X

- Definition

Fair Value Inputs Quantitative Information

+ References

No definition available.

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X

- Definition

Fair value of the assets less the liabilities of a derivative or group of derivatives.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 10

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=35750535&loc=d3e13433-108611



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 45

-Paragraph 5

-URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41228-113958



Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 15

-URI http://asc.fasb.org/extlink&oid=35750535&loc=d3e13495-108611



Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 45

-Paragraph 6

-URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41271-113958

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- Details

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- Details

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- Details

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- Details

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