v2.4.1.9

Variable Interest Entities and Unconsolidated Investments in Power Plants (Unconsolidated VIEs) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Schedule of Equity Method Investments [Line Items]
Equity Method Investments	$ 88us-gaap_EquityMethodInvestments	$ 95us-gaap_EquityMethodInvestments
Greenfield [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investments	69us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = cpn_GreenfieldMember	78us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = cpn_GreenfieldMember
Equity Method Investment, Ownership Percentage	50.00%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = cpn_GreenfieldMember
Whitby [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investments	$ 19us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = cpn_WhitbyMember	$ 17us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = cpn_WhitbyMember
Equity Method Investment, Ownership Percentage	50.00%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = cpn_WhitbyMember

X

- 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

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Namespace Prefix:	us-gaap_
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X

- Definition

This item represents the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment (OTTI) losses recognized.

+ 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 210.5-02.12)

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



Reference 2: 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

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X

- Details

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X

- Details

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X

- Details

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