Call Option Exercise Period

No definition available.

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- Definition

Equity Method Investment, Summarized Financial Information, Debt

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Minority Interest Ownership Percentage By Noncontrolling Third Party Owners

+ References

No definition available.

+ Details

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Period Type:	instant

- Definition

Power generation capacity

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	instant

- Definition

Prorata Share of Equity Method Investment, Summarized Financial Information, Debt

+ References

No definition available.

+ Details

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Period Type:	instant

- Definition

Put Option Exercise Period

+ References

No definition available.

+ Details

Name:	cpn_PutOptionExercisePeriod
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Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 323

-SubTopic 10

-Section 50

-Paragraph 3

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=6382943&loc=d3e33918-111571

+ Details

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Balance Type:	na
Period Type:	instant

- Details

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Balance Type:	na
Period Type:	duration

- Definition

The amount of financial or other support the reporting entity has provided (explicitly or implicitly) to the Variable Interest Entity (VIE) that it was not previously contractually required to provide or that the reporting entity intends to provide, including, for example, situations in which the reporting entity assisted the VIE in obtaining another type of support.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 810

-SubTopic 10

-Section 50

-Paragraph 5A

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=28200181&loc=SL6759159-111685

+ Details

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Balance Type:	debit
Period Type:	duration

- Details

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- Details

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- Details

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- Details

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- Details

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Variable Interest Entities and Unconsolidated Investments (VIE Textuals) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014 MW	Dec. 31, 2013 MW	Dec. 31, 2012
Schedule of Equity Method Investments [Line Items]
Power generation capacity	10,365cpn_PowerGenerationCapacity	9,427cpn_PowerGenerationCapacity
Variable Interest Entity, Financial or Other Support, Amount	$ 47,000,000	$ 0	$ 20,000,000
Equity Method Investment, Summarized Financial Information, Debt	342,000,000	395,000,000
Prorata Share of Equity Method Investment, Summarized Financial Information, Debt	$ 171,000,000	$ 198,000,000
Russell City Energy [Member]
Schedule of Equity Method Investments [Line Items]
Minority Interest Ownership Percentage By Noncontrolling Third Party Owners	25.00%
Equity Method Investment, Ownership Percentage	75.00%
Inland Empire Energy Center [Member]
Schedule of Equity Method Investments [Line Items]
Power generation capacity	775
Put Option Exercise Period	2,025
Minimum [Member] \| Inland Empire Energy Center [Member]
Schedule of Equity Method Investments [Line Items]
Call Option Exercise Period	2,017
Maximum [Member] \| Inland Empire Energy Center [Member]
Schedule of Equity Method Investments [Line Items]
Call Option Exercise Period	2,024
Greenfield [Member]
Schedule of Equity Method Investments [Line Items]
Power generation capacity	1,038
Equity Method Investment, Ownership Percentage	50.00%
Whitby [Member]
Schedule of Equity Method Investments [Line Items]
Power generation capacity	50
Equity Method Investment, Ownership Percentage	50.00%