v2.4.1.9

Debt (Fair Value of Debt) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015		Dec. 31, 2014
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	$ 11,619us-gaap_LongTermDebt		$ 11,122us-gaap_LongTermDebt
Unsecured Debt [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	3,450us-gaap_LongTermDebt / us-gaap_LongtermDebtTypeAxis = us-gaap_UnsecuredDebtMember		2,800us-gaap_LongTermDebt / us-gaap_LongtermDebtTypeAxis = us-gaap_UnsecuredDebtMember
Loans Payable [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	2,792us-gaap_LongTermDebt / us-gaap_LongtermDebtTypeAxis = us-gaap_LoansPayableMember		2,799us-gaap_LongTermDebt / us-gaap_LongtermDebtTypeAxis = us-gaap_LoansPayableMember
Corporate Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	1,928us-gaap_LongTermDebt / us-gaap_LongtermDebtTypeAxis = us-gaap_CorporateDebtSecuritiesMember		2,075us-gaap_LongTermDebt / us-gaap_LongtermDebtTypeAxis = us-gaap_CorporateDebtSecuritiesMember
Secured Debt [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	1,592us-gaap_LongTermDebt / us-gaap_LongtermDebtTypeAxis = us-gaap_SecuredDebtMember		1,596us-gaap_LongTermDebt / us-gaap_LongtermDebtTypeAxis = us-gaap_SecuredDebtMember
Reported Value Measurement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	11,417us-gaap_LongTermDebt / us-gaap_FairValueByMeasurementBasisAxis = us-gaap_CarryingReportedAmountFairValueDisclosureMember		10,958us-gaap_LongTermDebt / us-gaap_FairValueByMeasurementBasisAxis = us-gaap_CarryingReportedAmountFairValueDisclosureMember
Reported Value Measurement [Member] | Unsecured Debt [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	3,450us-gaap_LongTermDebt / us-gaap_FairValueByMeasurementBasisAxis = us-gaap_CarryingReportedAmountFairValueDisclosureMember / us-gaap_LongtermDebtTypeAxis = us-gaap_UnsecuredDebtMember		2,800us-gaap_LongTermDebt / us-gaap_FairValueByMeasurementBasisAxis = us-gaap_CarryingReportedAmountFairValueDisclosureMember / us-gaap_LongtermDebtTypeAxis = us-gaap_UnsecuredDebtMember
Reported Value Measurement [Member] | Loans Payable [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	2,792us-gaap_LongTermDebt / us-gaap_FairValueByMeasurementBasisAxis = us-gaap_CarryingReportedAmountFairValueDisclosureMember / us-gaap_LongtermDebtTypeAxis = us-gaap_LoansPayableMember		2,799us-gaap_LongTermDebt / us-gaap_FairValueByMeasurementBasisAxis = us-gaap_CarryingReportedAmountFairValueDisclosureMember / us-gaap_LongtermDebtTypeAxis = us-gaap_LoansPayableMember
Reported Value Measurement [Member] | Corporate Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	1,928us-gaap_LongTermDebt / us-gaap_FairValueByMeasurementBasisAxis = us-gaap_CarryingReportedAmountFairValueDisclosureMember / us-gaap_LongtermDebtTypeAxis = us-gaap_CorporateDebtSecuritiesMember		2,075us-gaap_LongTermDebt / us-gaap_FairValueByMeasurementBasisAxis = us-gaap_CarryingReportedAmountFairValueDisclosureMember / us-gaap_LongtermDebtTypeAxis = us-gaap_CorporateDebtSecuritiesMember
Reported Value Measurement [Member] | Notes Payable, Other Payable excluding Capital Leases [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	1,655us-gaap_LongTermDebt / us-gaap_FairValueByMeasurementBasisAxis = us-gaap_CarryingReportedAmountFairValueDisclosureMember / us-gaap_LongtermDebtTypeAxis = cpn_NotesPayableOtherPayableexcludingCapitalLeasesMember	[1]	1,688us-gaap_LongTermDebt / us-gaap_FairValueByMeasurementBasisAxis = us-gaap_CarryingReportedAmountFairValueDisclosureMember / us-gaap_LongtermDebtTypeAxis = cpn_NotesPayableOtherPayableexcludingCapitalLeasesMember	[1]
Reported Value Measurement [Member] | Secured Debt [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	1,592us-gaap_LongTermDebt / us-gaap_FairValueByMeasurementBasisAxis = us-gaap_CarryingReportedAmountFairValueDisclosureMember / us-gaap_LongtermDebtTypeAxis = us-gaap_SecuredDebtMember		1,596us-gaap_LongTermDebt / us-gaap_FairValueByMeasurementBasisAxis = us-gaap_CarryingReportedAmountFairValueDisclosureMember / us-gaap_LongtermDebtTypeAxis = us-gaap_SecuredDebtMember
Fair Value, Inputs, Level 2 [Member] | Unsecured Debt [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	3,462us-gaap_LongTermDebt / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_LongtermDebtTypeAxis = us-gaap_UnsecuredDebtMember		2,832us-gaap_LongTermDebt / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_LongtermDebtTypeAxis = us-gaap_UnsecuredDebtMember
Fair Value, Inputs, Level 2 [Member] | Loans Payable [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	2,795us-gaap_LongTermDebt / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_LongtermDebtTypeAxis = us-gaap_LoansPayableMember		2,769us-gaap_LongTermDebt / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_LongtermDebtTypeAxis = us-gaap_LoansPayableMember
Fair Value, Inputs, Level 2 [Member] | Corporate Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	2,091us-gaap_LongTermDebt / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_LongtermDebtTypeAxis = us-gaap_CorporateDebtSecuritiesMember		2,247us-gaap_LongTermDebt / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_LongtermDebtTypeAxis = us-gaap_CorporateDebtSecuritiesMember
Fair Value, Inputs, Level 2 [Member] | Secured Debt [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	1,580us-gaap_LongTermDebt / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_LongtermDebtTypeAxis = us-gaap_SecuredDebtMember		1,540us-gaap_LongTermDebt / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member / us-gaap_LongtermDebtTypeAxis = us-gaap_SecuredDebtMember
Fair Value, Inputs, Level 3 [Member] | Notes Payable, Other Payable excluding Capital Leases [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	$ 1,691us-gaap_LongTermDebt / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_LongtermDebtTypeAxis = cpn_NotesPayableOtherPayableexcludingCapitalLeasesMember	[1]	$ 1,734us-gaap_LongTermDebt / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_LongtermDebtTypeAxis = cpn_NotesPayableOtherPayableexcludingCapitalLeasesMember	[1]
[1] Excludes a lease that is accounted for as a failed sale-leaseback transaction under U.S. GAAP.

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- Definition

Carrying amount of long-term debt, net of unamortized discount or premium, including current and noncurrent amounts. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 16

-Article 7



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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682



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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.16)

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878



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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 16

-Article 9



Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 20, 22

-Article 5



Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-03.16)

-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

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