v2.4.1.9

Derivative Instruments (Detail 5) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	$ 2,497us-gaap_DerivativeFairValueOfDerivativeAsset		$ 550us-gaap_DerivativeFairValueOfDerivativeAsset
Derivative Asset, Not Offset, Policy Election Deduction	(2,087)us-gaap_DerivativeAssetNotOffsetPolicyElectionDeduction		(480)us-gaap_DerivativeAssetNotOffsetPolicyElectionDeduction
Derivative, Collateral, Obligation to Return Cash	(269)us-gaap_DerivativeCollateralObligationToReturnCash	[1]	(14)us-gaap_DerivativeCollateralObligationToReturnCash	[1]
Derivative Asset, Fair Value, Amount Offset Against Collateral	141us-gaap_DerivativeFairValueOfDerivativeAssetAmountOffsetAgainstCollateral		56us-gaap_DerivativeFairValueOfDerivativeAssetAmountOffsetAgainstCollateral
Derivative Liability, Fair Value, Gross Liability	(2,226)us-gaap_DerivativeFairValueOfDerivativeLiability		(694)us-gaap_DerivativeFairValueOfDerivativeLiability
Derivative Liability, Not Offset, Policy Election Deduction	2,087us-gaap_DerivativeLiabilityNotOffsetPolicyElectionDeduction		480us-gaap_DerivativeLiabilityNotOffsetPolicyElectionDeduction
Derivative, Collateral, Right to Reclaim Cash	15us-gaap_DerivativeCollateralRightToReclaimCash	[1]	76us-gaap_DerivativeCollateralRightToReclaimCash	[1]
Derivative Liability, Fair Value, Amount Offset Against Collateral	(124)us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountOffsetAgainstCollateral		(138)us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountOffsetAgainstCollateral
Net derivative assets (liabilities)	271us-gaap_DerivativeFairValueOfDerivativeNet		(144)us-gaap_DerivativeFairValueOfDerivativeNet
Derivative Fair Value, Amount Not Offset Against Collateral, Net	0cpn_DerivativeFairValueAmountNotOffsetAgainstCollateralNet		0cpn_DerivativeFairValueAmountNotOffsetAgainstCollateralNet
Derivative, Collateral, Right to Reclaim Cash, Net	(254)cpn_DerivativeCollateralRightToReclaimCashNet	[1]	62cpn_DerivativeCollateralRightToReclaimCashNet	[1]
Derivative, Fair Value, Amount Offset Against Collateral, Net	17cpn_DerivativeAssetFairValueAmountOffsetAgainstCollateralNetOfDerivativeLiabilityFairValueAmountOffsetAgainstCollateral		(82)cpn_DerivativeAssetFairValueAmountOffsetAgainstCollateralNetOfDerivativeLiabilityFairValueAmountOffsetAgainstCollateral
Commodity Exchange Traded Futures and Swaps Contracts [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	2,134us-gaap_DerivativeFairValueOfDerivativeAsset / us-gaap_DerivativeInstrumentRiskAxis = cpn_CommodityExchangeTradedFuturesAndSwapsContractsMember		434us-gaap_DerivativeFairValueOfDerivativeAsset / us-gaap_DerivativeInstrumentRiskAxis = cpn_CommodityExchangeTradedFuturesAndSwapsContractsMember
Derivative Asset, Not Offset, Policy Election Deduction	(1,865)us-gaap_DerivativeAssetNotOffsetPolicyElectionDeduction / us-gaap_DerivativeInstrumentRiskAxis = cpn_CommodityExchangeTradedFuturesAndSwapsContractsMember		(420)us-gaap_DerivativeAssetNotOffsetPolicyElectionDeduction / us-gaap_DerivativeInstrumentRiskAxis = cpn_CommodityExchangeTradedFuturesAndSwapsContractsMember
Derivative, Collateral, Obligation to Return Cash	(269)us-gaap_DerivativeCollateralObligationToReturnCash / us-gaap_DerivativeInstrumentRiskAxis = cpn_CommodityExchangeTradedFuturesAndSwapsContractsMember	[1]	(14)us-gaap_DerivativeCollateralObligationToReturnCash / us-gaap_DerivativeInstrumentRiskAxis = cpn_CommodityExchangeTradedFuturesAndSwapsContractsMember	[1]
Derivative Asset, Fair Value, Amount Offset Against Collateral	0us-gaap_DerivativeFairValueOfDerivativeAssetAmountOffsetAgainstCollateral / us-gaap_DerivativeInstrumentRiskAxis = cpn_CommodityExchangeTradedFuturesAndSwapsContractsMember		0us-gaap_DerivativeFairValueOfDerivativeAssetAmountOffsetAgainstCollateral / us-gaap_DerivativeInstrumentRiskAxis = cpn_CommodityExchangeTradedFuturesAndSwapsContractsMember
Derivative Liability, Fair Value, Gross Liability	(1,870)us-gaap_DerivativeFairValueOfDerivativeLiability / us-gaap_DerivativeInstrumentRiskAxis = cpn_CommodityExchangeTradedFuturesAndSwapsContractsMember		(495)us-gaap_DerivativeFairValueOfDerivativeLiability / us-gaap_DerivativeInstrumentRiskAxis = cpn_CommodityExchangeTradedFuturesAndSwapsContractsMember
Derivative Liability, Not Offset, Policy Election Deduction	1,865us-gaap_DerivativeLiabilityNotOffsetPolicyElectionDeduction / us-gaap_DerivativeInstrumentRiskAxis = cpn_CommodityExchangeTradedFuturesAndSwapsContractsMember		420us-gaap_DerivativeLiabilityNotOffsetPolicyElectionDeduction / us-gaap_DerivativeInstrumentRiskAxis = cpn_CommodityExchangeTradedFuturesAndSwapsContractsMember
Derivative, Collateral, Right to Reclaim Cash	5us-gaap_DerivativeCollateralRightToReclaimCash / us-gaap_DerivativeInstrumentRiskAxis = cpn_CommodityExchangeTradedFuturesAndSwapsContractsMember	[1]	75us-gaap_DerivativeCollateralRightToReclaimCash / us-gaap_DerivativeInstrumentRiskAxis = cpn_CommodityExchangeTradedFuturesAndSwapsContractsMember	[1]
Derivative Liability, Fair Value, Amount Offset Against Collateral	0us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountOffsetAgainstCollateral / us-gaap_DerivativeInstrumentRiskAxis = cpn_CommodityExchangeTradedFuturesAndSwapsContractsMember		0us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountOffsetAgainstCollateral / us-gaap_DerivativeInstrumentRiskAxis = cpn_CommodityExchangeTradedFuturesAndSwapsContractsMember
Commodity Forward Contract [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	359us-gaap_DerivativeFairValueOfDerivativeAsset / us-gaap_DerivativeInstrumentRiskAxis = cpn_CommodityForwardContractMember		107us-gaap_DerivativeFairValueOfDerivativeAsset / us-gaap_DerivativeInstrumentRiskAxis = cpn_CommodityForwardContractMember
Derivative Asset, Not Offset, Policy Election Deduction	(222)us-gaap_DerivativeAssetNotOffsetPolicyElectionDeduction / us-gaap_DerivativeInstrumentRiskAxis = cpn_CommodityForwardContractMember		(60)us-gaap_DerivativeAssetNotOffsetPolicyElectionDeduction / us-gaap_DerivativeInstrumentRiskAxis = cpn_CommodityForwardContractMember
Derivative, Collateral, Obligation to Return Cash	0us-gaap_DerivativeCollateralObligationToReturnCash / us-gaap_DerivativeInstrumentRiskAxis = cpn_CommodityForwardContractMember	[1]	0us-gaap_DerivativeCollateralObligationToReturnCash / us-gaap_DerivativeInstrumentRiskAxis = cpn_CommodityForwardContractMember	[1]
Derivative Asset, Fair Value, Amount Offset Against Collateral	137us-gaap_DerivativeFairValueOfDerivativeAssetAmountOffsetAgainstCollateral / us-gaap_DerivativeInstrumentRiskAxis = cpn_CommodityForwardContractMember		47us-gaap_DerivativeFairValueOfDerivativeAssetAmountOffsetAgainstCollateral / us-gaap_DerivativeInstrumentRiskAxis = cpn_CommodityForwardContractMember
Derivative Liability, Fair Value, Gross Liability	(242)us-gaap_DerivativeFairValueOfDerivativeLiability / us-gaap_DerivativeInstrumentRiskAxis = cpn_CommodityForwardContractMember		(70)us-gaap_DerivativeFairValueOfDerivativeLiability / us-gaap_DerivativeInstrumentRiskAxis = cpn_CommodityForwardContractMember
Derivative Liability, Not Offset, Policy Election Deduction	222us-gaap_DerivativeLiabilityNotOffsetPolicyElectionDeduction / us-gaap_DerivativeInstrumentRiskAxis = cpn_CommodityForwardContractMember		60us-gaap_DerivativeLiabilityNotOffsetPolicyElectionDeduction / us-gaap_DerivativeInstrumentRiskAxis = cpn_CommodityForwardContractMember
Derivative, Collateral, Right to Reclaim Cash	10us-gaap_DerivativeCollateralRightToReclaimCash / us-gaap_DerivativeInstrumentRiskAxis = cpn_CommodityForwardContractMember	[1]	1us-gaap_DerivativeCollateralRightToReclaimCash / us-gaap_DerivativeInstrumentRiskAxis = cpn_CommodityForwardContractMember	[1]
Derivative Liability, Fair Value, Amount Offset Against Collateral	(10)us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountOffsetAgainstCollateral / us-gaap_DerivativeInstrumentRiskAxis = cpn_CommodityForwardContractMember		(9)us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountOffsetAgainstCollateral / us-gaap_DerivativeInstrumentRiskAxis = cpn_CommodityForwardContractMember
Interest Rate Swap [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	4us-gaap_DerivativeFairValueOfDerivativeAsset / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember		9us-gaap_DerivativeFairValueOfDerivativeAsset / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember
Derivative Asset, Not Offset, Policy Election Deduction	0us-gaap_DerivativeAssetNotOffsetPolicyElectionDeduction / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember		0us-gaap_DerivativeAssetNotOffsetPolicyElectionDeduction / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember
Derivative, Collateral, Obligation to Return Cash	0us-gaap_DerivativeCollateralObligationToReturnCash / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember	[1]	0us-gaap_DerivativeCollateralObligationToReturnCash / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember	[1]
Derivative Asset, Fair Value, Amount Offset Against Collateral	4us-gaap_DerivativeFairValueOfDerivativeAssetAmountOffsetAgainstCollateral / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember		9us-gaap_DerivativeFairValueOfDerivativeAssetAmountOffsetAgainstCollateral / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember
Derivative Liability, Fair Value, Gross Liability	(114)us-gaap_DerivativeFairValueOfDerivativeLiability / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember		(129)us-gaap_DerivativeFairValueOfDerivativeLiability / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember
Derivative Liability, Not Offset, Policy Election Deduction	0us-gaap_DerivativeLiabilityNotOffsetPolicyElectionDeduction / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember		0us-gaap_DerivativeLiabilityNotOffsetPolicyElectionDeduction / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember
Derivative, Collateral, Right to Reclaim Cash	0us-gaap_DerivativeCollateralRightToReclaimCash / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember	[1]	0us-gaap_DerivativeCollateralRightToReclaimCash / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember	[1]
Derivative Liability, Fair Value, Amount Offset Against Collateral	(114)us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountOffsetAgainstCollateral / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember		(129)us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountOffsetAgainstCollateral / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember
Net derivative assets (liabilities)	$ (110)us-gaap_DerivativeFairValueOfDerivativeNet / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember		$ (120)us-gaap_DerivativeFairValueOfDerivativeNet / us-gaap_DerivativeInstrumentRiskAxis = us-gaap_InterestRateSwapMember
[1] Negative balances represent margin deposits posted with us by our counterparties related to our derivative activities that are subject to a master netting arrangement. Positive balances reflect margin deposits and natural gas and power prepayments posted by us with our counterparties related to our derivative activities that are subject to a master netting arrangement. See Note 9 for a further discussion of our collateral.

X

- Definition

Derivative Asset, Fair Value, Amount Offset Against Collateral Net Of Derivative Liability, Fair Value, Amount Offset Against Collateral

+ References

No definition available.

+ Details

Name:	cpn_DerivativeAssetFairValueAmountOffsetAgainstCollateralNetOfDerivativeLiabilityFairValueAmountOffsetAgainstCollateral
Namespace Prefix:	cpn_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Derivative, Collateral, Right to Reclaim Cash, Net

+ References

No definition available.

+ Details

Name:	cpn_DerivativeCollateralRightToReclaimCashNet
Namespace Prefix:	cpn_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Derivative Fair Value, Amount Not Offset Against Collateral, Net

+ References

No definition available.

+ Details

Name:	cpn_DerivativeFairValueAmountNotOffsetAgainstCollateralNet
Namespace Prefix:	cpn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Definition

Fair value of financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, elected not to be offset, deducted from derivative assets.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 55

-Paragraph 13

-URI http://asc.fasb.org/extlink&oid=36459792&loc=SL20226016-175313



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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 50

-Paragraph 3

-Subparagraph (d)(1)(i)

-URI http://asc.fasb.org/extlink&oid=34720828&loc=SL20225862-175312

+ Details

Name:	us-gaap_DerivativeAssetNotOffsetPolicyElectionDeduction
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Definition

Amount of obligation to return cash collateral under master netting arrangements that have not been offset against derivative assets.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 55

-Paragraph 13

-URI http://asc.fasb.org/extlink&oid=36459792&loc=SL20226016-175313



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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 50

-Paragraph 3

-Subparagraph (d)(2)

-URI http://asc.fasb.org/extlink&oid=34720828&loc=SL20225862-175312



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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 8

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=35706170&loc=d3e41678-113959

+ Details

Name:	us-gaap_DerivativeCollateralObligationToReturnCash
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Definition

Amount of right to receive cash collateral under master netting arrangements that have not been offset against derivative liabilities.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 55

-Paragraph 13

-URI http://asc.fasb.org/extlink&oid=36459792&loc=SL20226016-175313



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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 50

-Paragraph 3

-Subparagraph (d)(2)

-URI http://asc.fasb.org/extlink&oid=34720828&loc=SL20225862-175312



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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 8

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=35706170&loc=d3e41678-113959

+ Details

Name:	us-gaap_DerivativeCollateralRightToReclaimCash
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 50

-Paragraph 3

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=34720828&loc=SL20225862-175312



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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4B

-Subparagraph (a),(c)

-URI http://asc.fasb.org/extlink&oid=35706170&loc=SL5624163-113959



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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 55

-Paragraph 7

-URI http://asc.fasb.org/extlink&oid=36459792&loc=SL20226000-175313

+ Details

Name:	us-gaap_DerivativeFairValueOfDerivativeAsset
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Fair value, after effects of master netting arrangements, of financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset offset against an obligation to return collateral. Includes assets not subject to a master netting arrangement and not elected to be offset.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 55

-Paragraph 13

-URI http://asc.fasb.org/extlink&oid=36459792&loc=SL20226016-175313



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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 50

-Paragraph 3

-Subparagraph (e)

-URI http://asc.fasb.org/extlink&oid=34720828&loc=SL20225862-175312



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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 8

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=35706170&loc=d3e41678-113959

+ Details

Name:	us-gaap_DerivativeFairValueOfDerivativeAssetAmountOffsetAgainstCollateral
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Fair value, before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 50

-Paragraph 3

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=34720828&loc=SL20225862-175312



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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4B

-Subparagraph (a),(c)

-URI http://asc.fasb.org/extlink&oid=35706170&loc=SL5624163-113959



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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 55

-Paragraph 7

-URI http://asc.fasb.org/extlink&oid=36459792&loc=SL20226000-175313

+ Details

Name:	us-gaap_DerivativeFairValueOfDerivativeLiability
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Definition

Fair value, after effects of master netting arrangements, of financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset offset against the right to receive collateral. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 55

-Paragraph 13

-URI http://asc.fasb.org/extlink&oid=36459792&loc=SL20226016-175313



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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 50

-Paragraph 3

-Subparagraph (e)

-URI http://asc.fasb.org/extlink&oid=34720828&loc=SL20225862-175312



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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 8

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=35706170&loc=d3e41678-113959

+ Details

Name:	us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountOffsetAgainstCollateral
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

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

+ Details

Name:	us-gaap_DerivativeFairValueOfDerivativeNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Fair value of financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, elected not to be offset, deducted from derivative liabilities.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 55

-Paragraph 13

-URI http://asc.fasb.org/extlink&oid=36459792&loc=SL20226016-175313



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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 50

-Paragraph 3

-Subparagraph (d)(1)(i)

-URI http://asc.fasb.org/extlink&oid=34720828&loc=SL20225862-175312

+ Details

Name:	us-gaap_DerivativeLiabilityNotOffsetPolicyElectionDeduction
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Details

Name:	us-gaap_DerivativeLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=cpn_CommodityExchangeTradedFuturesAndSwapsContractsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=cpn_CommodityForwardContractMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_InterestRateSwapMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: