Early Tender Offer Amount

No definition available.

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

- Definition

Amount of short-term and long-term debt and lease obligation.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.13,16)
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+ Details

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

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

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-Publisher FASB
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Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
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+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- 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

- Definition

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

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Name:	us-gaap_GainsLossesOnExtinguishmentOfDebt
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

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-Publisher FASB
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-Topic 210
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-Section S99
-Paragraph 1
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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of long-term debt and lease obligation, classified as noncurrent.

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-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

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

- Definition

Amount of long-term debt and lease obligation, classified as current.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.20)
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Name:	us-gaap_LongTermDebtAndCapitalLeaseObligationsCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of cash outflow for the payment of debt classified as other, maturing after one year or the operating cycle, if longer.

+ References

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-Publisher FASB
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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Debt (Debt) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
Debt (Debt) (Details) - USD ($) $ in Millions	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Aug. 10, 2020	Jun. 09, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Gain (Loss) on Extinguishment of Debt	$ (8)	$ (3)	$ (8)	$ 1
Subtotal	11,105		11,105				$ 11,706
Less: Current maturities	231		231				1,268
Total long-term debt	10,874		10,874				10,438
Repayments of Other Long-term Debt			412	$ 77
First Lien Term Loans
Debt Instrument [Line Items]
Subtotal	3,155		3,155				3,167
Senior Unsecured Notes
Debt Instrument [Line Items]
Subtotal	3,042		3,042				3,663
Senior Unsecured Notes
Debt Instrument [Line Items]
Gain (Loss) on Extinguishment of Debt	8
First Lien Notes
Debt Instrument [Line Items]
Subtotal	2,408		2,408				2,835
Project financing, notes payable and other
Debt Instrument [Line Items]
Subtotal	481		481				879
CCFC Term Loan
Debt Instrument [Line Items]
Subtotal	962		962				967
GPC Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount						$ 900
Subtotal	867		867				0
Line of Credit Facility, Maximum Borrowing Capacity						$ 200
Finance lease obligations
Debt Instrument [Line Items]
Subtotal	68		68				73
Revolving facilities
Debt Instrument [Line Items]
Subtotal	$ 122		$ 122				$ 122
Subsequent Event \| 2024 Senior Unsecured Notes(2)
Debt Instrument [Line Items]
Early Tender Offer Amount					$ 255
Subsequent Event \| 2029 Senior Unsecured Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount					$ 650
Debt Instrument, Interest Rate, Stated Percentage					4.625%
Subsequent Event \| 2025 Senior Unsecured Notes(2)
Debt Instrument [Line Items]
Early Tender Offer Amount					$ 1,045
Subsequent Event \| 2031 Senior Unsecured Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount					$ 850
Debt Instrument, Interest Rate, Stated Percentage					5.00%
London Interbank Offered Rate (LIBOR) [Member] \| GPC Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	2.00%
Increase in GPC Loan Rate Every Three Years [Member] \| GPC Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.125%
Federal Funds Effective Rate [Member] \| GPC Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.50%
Prime Rate or The Eurodollar Rate For A One-Month Interest Period [Member] \| GPC Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.00%
Increase In LIBOR Plus Rate Every Three Years [Member] \| GPC Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.125%
Minimum [Member] \| GPC Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage						0.00%
Steamboat [Member]
Debt Instrument [Line Items]
Repayments of Other Long-term Debt	$ 342