v2.4.1.9

Debt Debt (First Lien Term Loans) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013
First Lien Term Loans 2018 [Member]
Debt Instrument [Line Items]
Long-term Debt	$ 1,597us-gaap_LongTermDebt / us-gaap_LongtermDebtTypeAxis = cpn_FirstLienTermLoans2018Member		$ 1,614us-gaap_LongTermDebt / us-gaap_LongtermDebtTypeAxis = cpn_FirstLienTermLoans2018Member
Debt Instrument, Interest Rate, Effective Percentage	4.30%us-gaap_DebtInstrumentInterestRateEffectivePercentage / us-gaap_LongtermDebtTypeAxis = cpn_FirstLienTermLoans2018Member	[1]	4.30%us-gaap_DebtInstrumentInterestRateEffectivePercentage / us-gaap_LongtermDebtTypeAxis = cpn_FirstLienTermLoans2018Member	[1]
First Lien Term Loan 2019 [Member]
Debt Instrument [Line Items]
Long-term Debt	816us-gaap_LongTermDebt / us-gaap_LongtermDebtTypeAxis = cpn_FirstLienTermLoan2019Member		824us-gaap_LongTermDebt / us-gaap_LongtermDebtTypeAxis = cpn_FirstLienTermLoan2019Member
Debt Instrument, Interest Rate, Effective Percentage	4.40%us-gaap_DebtInstrumentInterestRateEffectivePercentage / us-gaap_LongtermDebtTypeAxis = cpn_FirstLienTermLoan2019Member	[1]	4.50%us-gaap_DebtInstrumentInterestRateEffectivePercentage / us-gaap_LongtermDebtTypeAxis = cpn_FirstLienTermLoan2019Member	[1]
2020 First Lien Term Loan [Member]
Debt Instrument [Line Items]
Long-term Debt	386us-gaap_LongTermDebt / us-gaap_LongtermDebtTypeAxis = cpn_A2020FirstLienTermLoanMember		390us-gaap_LongTermDebt / us-gaap_LongtermDebtTypeAxis = cpn_A2020FirstLienTermLoanMember
Debt Instrument, Interest Rate, Effective Percentage	4.30%us-gaap_DebtInstrumentInterestRateEffectivePercentage / us-gaap_LongtermDebtTypeAxis = cpn_A2020FirstLienTermLoanMember	[1]	4.30%us-gaap_DebtInstrumentInterestRateEffectivePercentage / us-gaap_LongtermDebtTypeAxis = cpn_A2020FirstLienTermLoanMember	[1]
Loans Payable [Member]
Debt Instrument [Line Items]
Long-term Debt	$ 2,799us-gaap_LongTermDebt / us-gaap_LongtermDebtTypeAxis = us-gaap_LoansPayableMember		$ 2,828us-gaap_LongTermDebt / us-gaap_LongtermDebtTypeAxis = us-gaap_LoansPayableMember
[1] Our weighted average interest rate calculation includes the amortization of deferred financing costs and debt discount.

X

- Definition

Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399



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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5



Reference 3: 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(a)(1))

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

+ Details

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X

- Details

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- 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

+ Details

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

X

- Details

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Namespace Prefix:
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X

- Details

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Balance Type:
Period Type:

X

- Details

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X

- Details

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Period Type: