v2.4.0.6

Commitments and Contingencies (Narrative) (Details) (USD $) Share data in Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Jul. 02, 2010
Commitments and Contingencies [Line Items]
Cash collateral outstanding related to bonds	4000000
Outstanding claims related to guarantees	0
Royalty Expense	$ 22,000,000	$ 25,000,000	$ 22,000,000
Power generation capacity	11,391	13,656
Environmental remediation liabilities related to Acquisition	0			10,000,000
Amount of shares authorized to settle unsecured claims	485
LTSA [Member]
Unrecorded Unconditional Purchase Obligation
Unrecorded Unconditional Purchase Obligation	70,000,000
Term of Unrecorded Unconditional Purchase Obligation Lower Limit	1
Term of Unrecorded Unconditional Purchase Obligation Upper Limit	7
Public Utilities, Inventory, Fuel [Member]
Unrecorded Unconditional Purchase Obligation
Unrecorded Unconditional Purchase Obligation	$ 4,600,000,000
Term of Unrecorded Unconditional Purchase Obligation Lower Limit	1
Term of Unrecorded Unconditional Purchase Obligation Upper Limit	15
Term of Unrecorded Unconditional Purchase Obligation Outlier	30

X

- Definition

Amount of shares authorized to settle unsecured claims

+ References

No definition available.

+ Details

Name:	cpn_AmountOfSharesAuthorizedToSettleUnsecuredClaims
Namespace Prefix:	cpn_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

X

- Details

Name:	cpn_CommitmentsAndContingenciesLineItems
Namespace Prefix:	cpn_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Environmental remediation liabilities related to Acquisition

+ References

No definition available.

+ Details

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

X

- Definition

Outstanding claims related to guarantees

+ References

No definition available.

+ Details

Name:	cpn_OutstandingClaimsRelatedToGuarantees
Namespace Prefix:	cpn_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Power generation capacity

+ References

No definition available.

+ Details

Name:	cpn_PowerGenerationCapacity
Namespace Prefix:	cpn_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

X

- Definition

Term of Unrecorded Unconditional Purchase Obligation Lower Limit

+ References

No definition available.

+ Details

Name:	cpn_TermOfUnrecordedUnconditionalPurchaseObligationLowerLimit
Namespace Prefix:	cpn_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

X

- Definition

Term of Unrecorded Unconditional Purchase Obligation Outlier

+ References

No definition available.

+ Details

Name:	cpn_TermOfUnrecordedUnconditionalPurchaseObligationOutlier
Namespace Prefix:	cpn_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

X

- Definition

Term of Unrecorded Unconditional Purchase Obligation Upper Limit

+ References

No definition available.

+ Details

Name:	cpn_TermOfUnrecordedUnconditionalPurchaseObligationUpperLimit
Namespace Prefix:	cpn_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

X

- Definition

Describes the nature of any assets held either as collateral or by third parties that, upon the occurrence of any triggering event or condition under the guarantee, the guarantor can obtain and liquidate to recover all or a portion of the amounts paid under the guarantee.

+ References

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

-Publisher FASB

-Name FASB Interpretation (FIN)

-Number 45

-Paragraph 13

-Subparagraph d

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.



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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 460

-SubTopic 10

-Section 50

-Paragraph 4

-Subparagraph (e)

-URI http://asc.fasb.org/extlink&oid=6851643&loc=d3e12069-110248

+ Details

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

X

- Definition

Amount of expense related to royalty payments under a contractual arrangement such as payment for mineral and drilling rights and use of technology or intellectual property.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.3)

-URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688

+ Details

Name:	us-gaap_RoyaltyExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Details

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

X

- Definition

The amount of the fixed and determinable portion of an unrecorded unconditional purchase obligation as of the balance sheet date.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 47

-Paragraph 7

-Subparagraph b

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.



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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 440

-SubTopic 10

-Section 50

-Paragraph 4

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6394976&loc=d3e25336-109308

+ Details

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