v2.4.1.9

Assets and Liabilities with Recurring Fair Value Measurements Quantitative Info on Level 3 (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Derivative, Fair Value, Net	$ 354,000,000us-gaap_DerivativeFairValueOfDerivativeNet	$ 271,000,000us-gaap_DerivativeFairValueOfDerivativeNet
Power Contracts [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Derivative, Fair Value, Net	201,000,000us-gaap_DerivativeFairValueOfDerivativeNet / us-gaap_FairValueByLiabilityClassAxis = cpn_PhysicalPowerMember	74,000,000us-gaap_DerivativeFairValueOfDerivativeNet / us-gaap_FairValueByLiabilityClassAxis = cpn_PhysicalPowerMember
Power Contracts [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs Quantitative Information	13.43cpn_FairValueInputsQuantitativeInformation / us-gaap_FairValueByLiabilityClassAxis = cpn_PhysicalPowerMember / us-gaap_RangeAxis = us-gaap_MinimumMember	14.00cpn_FairValueInputsQuantitativeInformation / us-gaap_FairValueByLiabilityClassAxis = cpn_PhysicalPowerMember / us-gaap_RangeAxis = us-gaap_MinimumMember
Power Contracts [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs Quantitative Information	123.25cpn_FairValueInputsQuantitativeInformation / us-gaap_FairValueByLiabilityClassAxis = cpn_PhysicalPowerMember / us-gaap_RangeAxis = us-gaap_MaximumMember	122.79cpn_FairValueInputsQuantitativeInformation / us-gaap_FairValueByLiabilityClassAxis = cpn_PhysicalPowerMember / us-gaap_RangeAxis = us-gaap_MaximumMember
Natural Gas [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Derivative, Fair Value, Net	0us-gaap_DerivativeFairValueOfDerivativeNet / us-gaap_FairValueByLiabilityClassAxis = us-gaap_NaturalGasReservesMember	5,000,000us-gaap_DerivativeFairValueOfDerivativeNet / us-gaap_FairValueByLiabilityClassAxis = us-gaap_NaturalGasReservesMember
Natural Gas [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs Quantitative Information		1.00cpn_FairValueInputsQuantitativeInformation / us-gaap_FairValueByLiabilityClassAxis = us-gaap_NaturalGasReservesMember / us-gaap_RangeAxis = us-gaap_MinimumMember
Natural Gas [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs Quantitative Information		10.86cpn_FairValueInputsQuantitativeInformation / us-gaap_FairValueByLiabilityClassAxis = us-gaap_NaturalGasReservesMember / us-gaap_RangeAxis = us-gaap_MaximumMember
Power Congestion Products [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Derivative, Fair Value, Net	0us-gaap_DerivativeFairValueOfDerivativeNet / us-gaap_FairValueByLiabilityClassAxis = cpn_PowerCongestionProductsMember	9,000,000us-gaap_DerivativeFairValueOfDerivativeNet / us-gaap_FairValueByLiabilityClassAxis = cpn_PowerCongestionProductsMember
Power Congestion Products [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs Quantitative Information		(19.56)cpn_FairValueInputsQuantitativeInformation / us-gaap_FairValueByLiabilityClassAxis = cpn_PowerCongestionProductsMember / us-gaap_RangeAxis = us-gaap_MinimumMember
Power Congestion Products [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs Quantitative Information		$ 19.56cpn_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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- 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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