v2.4.1.9

Debt (Corporate Revolving Facility and other Letters of Credit Facilities) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Line of Credit Facility [Line Items]
Line of Credit Facility, Fair Value of Amount Outstanding	$ 644us-gaap_LineOfCreditFacilityFairValueOfAmountOutstanding	$ 630us-gaap_LineOfCreditFacilityFairValueOfAmountOutstanding
Corporate Revolving Facility [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Fair Value of Amount Outstanding	223us-gaap_LineOfCreditFacilityFairValueOfAmountOutstanding / us-gaap_LineOfCreditFacilityAxis = cpn_CorporateRevolvingFacilityMember	242us-gaap_LineOfCreditFacilityFairValueOfAmountOutstanding / us-gaap_LineOfCreditFacilityAxis = cpn_CorporateRevolvingFacilityMember
CDH [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Fair Value of Amount Outstanding	214us-gaap_LineOfCreditFacilityFairValueOfAmountOutstanding / us-gaap_LineOfCreditFacilityAxis = cpn_CdhMember	218us-gaap_LineOfCreditFacilityFairValueOfAmountOutstanding / us-gaap_LineOfCreditFacilityAxis = cpn_CdhMember
Various Project Financing Facilities [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Fair Value of Amount Outstanding	$ 207us-gaap_LineOfCreditFacilityFairValueOfAmountOutstanding / us-gaap_LineOfCreditFacilityAxis = cpn_VariousProjectFinancingFacilitiesMember	$ 170us-gaap_LineOfCreditFacilityFairValueOfAmountOutstanding / us-gaap_LineOfCreditFacilityAxis = cpn_VariousProjectFinancingFacilitiesMember

X

- Definition

Fair value of the amount outstanding under the credit facility.

+ 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 825

-SubTopic 10

-Section 50

-Paragraph 12

-URI http://asc.fasb.org/extlink&oid=35750535&loc=d3e13476-108611

+ Details

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

X

- Details

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

X

- Details

Name:	us-gaap_LineOfCreditFacilityAxis=cpn_CdhMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_LineOfCreditFacilityAxis=cpn_CorporateRevolvingFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_LineOfCreditFacilityAxis=cpn_VariousProjectFinancingFacilitiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: