v3.2.0.727

Debt (First Lien Term Loans) (Details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Long-term Debt	$ 11,398	$ 11,122
First Lien Term Loans 2018 [Member]
Debt Instrument [Line Items]
Long-term Debt	0	1,597
First Lien Term Loan 2019 [Member]
Debt Instrument [Line Items]
Long-term Debt	812	816
2020 First Lien Term Loan [Member]
Debt Instrument [Line Items]
Long-term Debt	384	386
2022 First Lien Term Loan [Member]
Debt Instrument [Line Items]
Long-term Debt	1,591	0
First Lien Term Loans [Member]
Debt Instrument [Line Items]
Long-term Debt	$ 2,787	$ 2,799

X

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
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 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 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 944



-SubTopic 210



-Section S99



-Paragraph 1



-Subparagraph (SX 210.7-03.16)



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



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



-Publisher SEC



-Name Regulation S-X (SX)



-Number 210



-Section 02



-Paragraph 20, 22



-Article 5

+ Details

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

X

- Details

Name:	us-gaap_LongtermDebtTypeAxis=cpn_FirstLienTermLoans2018Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_LongtermDebtTypeAxis=cpn_FirstLienTermLoan2019Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_LongtermDebtTypeAxis=cpn_A2020FirstLienTermLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_LongtermDebtTypeAxis=cpn_A2022FirstLienTermLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_LoansPayableMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: