v2.4.0.8

Variable Interest Entities and Unconsolidated Investments (VIE Textuals) (Details) (USD $)	12 Months Ended
	Dec. 31, 2013 MW	Dec. 31, 2012 MW	Dec. 31, 2011
Schedule of Equity Method Investments [Line Items]
Power generation capacity	9,027	8,255
Variable Interest Entity, Financial or Other Support, Amount	$ 0	$ 20,000,000	$ 87,000,000
Equity Method Investment, Summarized Financial Information, Debt	395,000,000	448,000,000
Prorata Share of Equity Method Investment, Summarized Financial Information, Debt	$ 198,000,000	$ 224,000,000
Russell City Energy [Member]
Schedule of Equity Method Investments [Line Items]
Minority Interest Ownership Percentage By Noncontrolling Third Party Owners	25.00%
Equity Method Investment, Ownership Percentage	75.00%
Inland Empire Energy Center [Member]
Schedule of Equity Method Investments [Line Items]
Power generation capacity	775
Put Option Exercise Period	2,025
Minimum [Member] | Inland Empire Energy Center [Member]
Schedule of Equity Method Investments [Line Items]
Call Option Exercise Period	2,017
Maximum [Member] | Inland Empire Energy Center [Member]
Schedule of Equity Method Investments [Line Items]
Call Option Exercise Period	2,024
Greenfield [Member]
Schedule of Equity Method Investments [Line Items]
Power generation capacity	1,038
Equity Method Investment, Ownership Percentage	50.00%
Whitby [Member]
Schedule of Equity Method Investments [Line Items]
Power generation capacity	50
Equity Method Investment, Ownership Percentage	50.00%

X

- Definition

Call Option Exercise Period

+ References

No definition available.

+ Details

Name:	cpn_CallOptionExercisePeriod
Namespace Prefix:	cpn_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

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

Minority Interest Ownership Percentage By Noncontrolling Third Party Owners

+ References

No definition available.

+ Details

Name:	cpn_MinorityInterestOwnershipPercentageByNoncontrollingThirdPartyOwners
Namespace Prefix:	cpn_
Data Type:	num:percentItemType
Balance Type:	na
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

Name:	us-gaap_EquityMethodInvestmentOwnershipPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

X

- Details

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

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