v2.4.1.9

Variable Interest Entities and Unconsolidated Investments (Unconsolidated Investements) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Loss from Unconsolidated Investments in Power Plants and Distributions [Line Items]
(Income) from unconsolidated investments in power plants	$ (25)us-gaap_IncomeLossFromEquityMethodInvestments	$ (30)us-gaap_IncomeLossFromEquityMethodInvestments	$ (28)us-gaap_IncomeLossFromEquityMethodInvestments
Distributions from Equity Method Investments	13cpn_DistributionsfromEquityMethodInvestments	27cpn_DistributionsfromEquityMethodInvestments	29cpn_DistributionsfromEquityMethodInvestments
Greenfield [Member]
Income Loss from Unconsolidated Investments in Power Plants and Distributions [Line Items]
(Income) from unconsolidated investments in power plants	(10)us-gaap_IncomeLossFromEquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = cpn_GreenfieldMember	(16)us-gaap_IncomeLossFromEquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = cpn_GreenfieldMember	(17)us-gaap_IncomeLossFromEquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = cpn_GreenfieldMember
Distributions from Equity Method Investments	0cpn_DistributionsfromEquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = cpn_GreenfieldMember	18cpn_DistributionsfromEquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = cpn_GreenfieldMember	22cpn_DistributionsfromEquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = cpn_GreenfieldMember
Whitby [Member]
Income Loss from Unconsolidated Investments in Power Plants and Distributions [Line Items]
(Income) from unconsolidated investments in power plants	(15)us-gaap_IncomeLossFromEquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = cpn_WhitbyMember	(14)us-gaap_IncomeLossFromEquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = cpn_WhitbyMember	(11)us-gaap_IncomeLossFromEquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = cpn_WhitbyMember
Distributions from Equity Method Investments	$ 13cpn_DistributionsfromEquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = cpn_WhitbyMember	$ 9cpn_DistributionsfromEquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = cpn_WhitbyMember	$ 7cpn_DistributionsfromEquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = cpn_WhitbyMember

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- Definition

Distributions from Equity Method Investments

+ References

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- Definition

This item represents the entity's proportionate share for the period of the net income (loss) of its investee (such as unconsolidated subsidiaries and joint ventures) to which the equity method of accounting is applied. This item includes income or expense related to stock-based compensation based on the investor's grant of stock to employees of an equity method investee.

+ 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 SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 9

-Article 5



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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 323

-SubTopic 10

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=35755396&loc=d3e33749-111570



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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.12)

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688



Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph 11

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