Applicable margin range percentage above base rate

No definition available.

Name:	cpn_ApplicableMarginRangePercentageAboveBaseRate
Namespace Prefix:	cpn_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Applicable margin range percentage added to the British Bankers' Association Interest Settlement Rates

+ References

No definition available.

+ Details

Name:	cpn_ApplicableMarginRangePercentageAboveBritishBankersAssociationInterestSettlementRates
Namespace Prefix:	cpn_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Excess amount of asset sales requiring mandatory prepayments

+ References

No definition available.

+ Details

Name:	cpn_ExcessAmountOfAssetSalesRequiringMandatoryPrepayments
Namespace Prefix:	cpn_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Interest periods for LIBOR rate borrowings

+ References

No definition available.

+ Details

Name:	cpn_InterestPeriodsForLiborRateBorrowings
Namespace Prefix:	cpn_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Lease Assets, Accumulated Depreciation

+ References

No definition available.

+ Details

Name:	cpn_LeaseAssetsAccumulatedDepreciation
Namespace Prefix:	cpn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Lease Assets, Historical Cost

+ References

No definition available.

+ Details

Name:	cpn_LeaseAssetsHistoricalCost
Namespace Prefix:	cpn_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Letter of Credit Total

+ References

No definition available.

+ Details

Name:	cpn_LetterOfCreditTotal
Namespace Prefix:	cpn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Maximum Remaining Lease Term

+ References

No definition available.

+ Details

Name:	cpn_MaximumRemainingLeaseTerm
Namespace Prefix:	cpn_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage added to Federal Funds Effective Rate to arrive at base rate

+ References

No definition available.

+ Details

Name:	cpn_PercentageAddedToFederalFundsEffectiveRateToArriveAtBaseRate
Namespace Prefix:	cpn_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of the principal amount of the Term Loan to be paid quarterly

+ References

No definition available.

+ Details

Name:	cpn_PercentageOfPrincipalAmountOfTermLoanToBePaidQuarterly
Namespace Prefix:	cpn_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Repayment time for drawings under letters of credit

+ References

No definition available.

+ Details

Name:	cpn_RepaymentTimeForDrawingsUnderLettersOfCredit
Namespace Prefix:	cpn_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Term loan interest rate spread option Federal Funds effective rate

+ References

No definition available.

+ Details

Name:	cpn_TermloaninterestratespreadoptionFederalFundseffectiverate
Namespace Prefix:	cpn_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Term loan interest rate spread option Prime Rate

+ References

No definition available.

+ Details

Name:	cpn_TermloaninterestratespreadoptionPrimeRate
Namespace Prefix:	cpn_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum contractual interest rate for funds borrowed, under the debt agreement.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

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(a)(1))

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

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentageRateRangeMaximum
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Minimum contractual interest rate for funds borrowed, under the debt agreement.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

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(a)(2))

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

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentageRateRangeMinimum
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Details

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

- Definition

Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 470

-SubTopic 50

-Section 40

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6850294&loc=d3e12317-112629

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 470

-SubTopic 50

-Section 40

-Paragraph 4

-URI http://asc.fasb.org/extlink&oid=6850294&loc=d3e12355-112629

+ Details

Name:	us-gaap_GainsLossesOnExtinguishmentOfDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of increase (decrease) of the credit facility.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 235

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.4-08.(f))

-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 08

-Paragraph f

-Article 4

+ Details

Name:	us-gaap_LineOfCreditFacilityIncreaseDecreaseForPeriodNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.19(b),22(b))

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

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

+ Details

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

- Definition

The fee, expressed as a percentage of the line of credit facility, for available but unused credit capacity under the credit facility.

+ References

No definition available.

+ Details

Name:	us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	cpn_InterestPeriodsAxis=cpn_NineMonthsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	cpn_InterestPeriodsAxis=cpn_OneMonthMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	cpn_InterestPeriodsAxis=cpn_SixMonthsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	cpn_InterestPeriodsAxis=cpn_ThreeMonthsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	cpn_InterestPeriodsAxis=cpn_TwelveMonthsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	cpn_InterestPeriodsAxis=cpn_TwoMonthsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

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

- Details

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

Debt (Textuals) (Details) (USD $)	12 Months Ended			3 Months Ended
Debt (Textuals) (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Sep. 30, 2014
Debt Instrument [Line Items]
Gains (Losses) on Extinguishment of Debt	$ (346,000,000)	$ (144,000,000)	$ (30,000,000)
Maximum Remaining Lease Term	34 years
Lease Assets, Historical Cost	933,000,000cpn_LeaseAssetsHistoricalCost	862,000,000cpn_LeaseAssetsHistoricalCost
Lease Assets, Accumulated Depreciation	395,000,000cpn_LeaseAssetsAccumulatedDepreciation	343,000,000cpn_LeaseAssetsAccumulatedDepreciation
First Lien Term Loans [Member]
Debt Instrument [Line Items]
Term loan interest rate spread option Federal Funds effective rate	0.50%
Term loan interest rate spread option Prime Rate	2.00%
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Maximum	3.00%
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Minimum	1.00%
Percentage of principal amount of Term Loan to be paid quarterly	0.25%
Corporate Revolving Facility [Member]
Debt Instrument [Line Items]
Percentage added to Federal Funds Effective Rate to arrive at base rate	0.50%
Repayment time for drawings under letters of credit	2 days
Excess amount of asset sales requiring mandatory prepayments	3,000,000,000
Corporate Revolving Facility [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Applicable margin range percentage above base rate	1.00%
Applicable Margin Range Percentage Above British Bankers' Association Interest Settlement Rates	2.00%
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	0.25%
Corporate Revolving Facility [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Applicable margin range percentage above base rate	1.25%
Applicable Margin Range Percentage Above British Bankers' Association Interest Settlement Rates	2.25%
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	0.50%
CDHI [Member]
Debt Instrument [Line Items]
Letter of Credit Total	300,000,000
One Month [Member] \| Corporate Revolving Facility [Member]
Debt Instrument [Line Items]
Interest periods for LIBOR rate borrowings	1 month
Two Months [Member] \| Corporate Revolving Facility [Member]
Debt Instrument [Line Items]
Interest periods for LIBOR rate borrowings	2 months
Three Months [Member] \| Corporate Revolving Facility [Member]
Debt Instrument [Line Items]
Interest periods for LIBOR rate borrowings	3 months
Six Months [Member] \| Corporate Revolving Facility [Member]
Debt Instrument [Line Items]
Interest periods for LIBOR rate borrowings	6 months
Nine Months [Member] \| Corporate Revolving Facility [Member]
Debt Instrument [Line Items]
Interest periods for LIBOR rate borrowings	9 months
Twelve Months [Member] \| Corporate Revolving Facility [Member]
Debt Instrument [Line Items]
Interest periods for LIBOR rate borrowings	12 months
Corporate Revolving Facility [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Increase (Decrease), Net				500,000,000
Line of Credit Facility, Maximum Borrowing Capacity				$ 1,500,000,000