v2.4.0.8

Summary of Significant Accounting Policies (Details) (USD $) In Millions, unless otherwise specified | 3 Months Ended | 6 Months Ended |
--- | --- | --- | ---
Jun. 30, 2013 | Jun. 30, 2012 | Jun. 30, 2013 | Jun. 30, 2012 | Dec. 31, 2012
Restricted Cash and Cash Equivalents Items [Line Items] |  |  |  |  |  |  |  |
Held-to-maturity Securities, Restricted | $ 24 |  |  | $ 24 |  |  | $ 25 |
Current | 140 |  |  | 140 |  |  | 193 |
Non-current | 58 |  |  | 58 |  |  | 60 |
Total | 198 |  |  | 198 |  |  | 253 |
Basis Of Presentation and Summary of Significant Accounting Policies (Textuals) [Abstract] |  |  |  |  |  |  |  |
Cash and cash equivalents subject to project finance facilities and lease agreements | 127 |  |  | 127 |  |  | 131 |
Interest Costs Capitalized | 12 |  | 9 | 24 |  | 17 |  |
Inventory | 345 |  |  | 345 |  |  | 301 |
Treasury Stock, Value, Acquired, Cost Method |  |  |  | 362 |  |  |  |
Adjustments Related to Tax Withholding for Share-based Compensation |  |  |  | 6 |  |  |  |
Debt Service |  |  |  |  |  |  |  |
Restricted Cash and Cash Equivalents Items [Line Items] |  |  |  |  |  |  |  |
Current | 14 | [1] |  | 14 | [1] |  | 11 | [1]
Non-current | 42 | [1] |  | 42 | [1] |  | 41 | [1]
Total | 56 | [1] |  | 56 | [1] |  | 52 | [1]
Rent Reserve |  |  |  |  |  |  |  |
Restricted Cash and Cash Equivalents Items [Line Items] |  |  |  |  |  |  |  |
Current | 7 |  |  | 7 |  |  | 0 |
Non-current | 0 |  |  | 0 |  |  | 0 |
Total | 7 |  |  | 7 |  |  | 0 |
Construction Major Maintenance |  |  |  |  |  |  |  |
Restricted Cash and Cash Equivalents Items [Line Items] |  |  |  |  |  |  |  |
Current | 26 |  |  | 26 |  |  | 32 |
Non-current | 8 |  |  | 8 |  |  | 14 |
Total | 34 |  |  | 34 |  |  | 46 |
Security Project Insurance |  |  |  |  |  |  |  |
Restricted Cash and Cash Equivalents Items [Line Items] |  |  |  |  |  |  |  |
Current | 73 |  |  | 73 |  |  | 101 |
Non-current | 6 |  |  | 6 |  |  | 3 |
Total | 79 |  |  | 79 |  |  | 104 |
Other |  |  |  |  |  |  |  |
Restricted Cash and Cash Equivalents Items [Line Items] |  |  |  |  |  |  |  |
Current | 20 |  |  | 20 |  |  | 49 |
Non-current | 2 |  |  | 2 |  |  | 2 |
Total | 22 |  |  | 22 |  |  | 51 |
Geothermal Properties, Gross [Member] | Minimum [Member] |  |  |  |  |  |  |  |
Basis Of Presentation and Summary of Significant Accounting Policies (Textuals) [Abstract] |  |  |  |  |  |  |  |
Property, Plant and Equipment, Estimated Useful Lives |  |  |  | 13 years |  |  |  |
Geothermal Properties, Gross [Member] | Maximum [Member] |  |  |  |  |  |  |  |
Basis Of Presentation and Summary of Significant Accounting Policies (Textuals) [Abstract] |  |  |  |  |  |  |  |
Property, Plant and Equipment, Estimated Useful Lives |  |  |  | 59 years |  |  |  |
Property, Plant and Equipment, Other Types [Member] | Minimum [Member] |  |  |  |  |  |  |  |
Basis Of Presentation and Summary of Significant Accounting Policies (Textuals) [Abstract] |  |  |  |  |  |  |  |
Property, Plant and Equipment, Estimated Useful Lives |  |  |  | 3 years |  |  |  |
Property, Plant and Equipment, Other Types [Member] | Maximum [Member] |  |  |  |  |  |  |  |
Basis Of Presentation and Summary of Significant Accounting Policies (Textuals) [Abstract] |  |  |  |  |  |  |  |
Property, Plant and Equipment, Estimated Useful Lives |  |  |  | 47 years |  |  |  |
Building, Machinery and Equipment, Gross [Member] | Minimum [Member] |  |  |  |  |  |  |  |
Basis Of Presentation and Summary of Significant Accounting Policies (Textuals) [Abstract] |  |  |  |  |  |  |  |
Property, Plant and Equipment, Estimated Useful Lives |  |  |  | 3 years |  |  |  |
Building, Machinery and Equipment, Gross [Member] | Maximum [Member] |  |  |  |  |  |  |  |
Basis Of Presentation and Summary of Significant Accounting Policies (Textuals) [Abstract] |  |  |  |  |  |  |  |
Property, Plant and Equipment, Estimated Useful Lives |  |  |  | 47 years |  |  |  |
Income Statement [Member] |  |  |  |  |  |  |  |
Basis Of Presentation and Summary of Significant Accounting Policies (Textuals) [Abstract] |  |  |  |  |  |  |  |
Prior Period Reclassification Adjustment |  |  | 2 |  |  | 5 |  |
Cash Flow Statement [Member] |  |  |  |  |  |  |  |
Basis Of Presentation and Summary of Significant Accounting Policies (Textuals) [Abstract] |  |  |  |  |  |  |  |
Prior Period Reclassification Adjustment |  |  |  |  |  | $ 3 |  |
[1] | June 30, 2013 and December 31, 2012, amounts restricted for debt service included approximately $24 million and $25 million, respectively, of repurchase agreements with a financial institution containing maturity dates greater than one year.In

X
- Details
Name: | cpn_BasisOfPresentationAndSummaryOfSignificantAccountingPoliciesTextualsAbstract
Namespace Prefix: | cpn_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Cash and cash equivalents subject to project finance facilities and lease agreements + References No definition available. + Details
Name: | cpn_CashAndCashEquivalentsSubjectToProjectFinanceFacilitiesAndLeaseAgreements
Namespace Prefix: | cpn_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The amount of adjustment to stockholders' equity associated with an employee's income tax withholding obligation as part of a net-share settlement of a share-based award. + References No definition available. + Details
Name: | us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The carrying amount of securities categorized as held-to-maturity which serve as security for borrowings or other arrangements. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 6 -Article 9 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 08 -Paragraph b -Article 4 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=28368275&loc=d3e5086-111524 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX210.4-08(b)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.1) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.6) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 + Details
Name: | us-gaap_HeldToMaturitySecuritiesRestricted
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of interest capitalized during the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Allowance for Funds Used during Construction -URI http://asc.fasb.org/extlink&oid=6504829 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6450988&loc=d3e26243-108391 + Details
Name: | us-gaap_InterestCostsCapitalized
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount after valuation and LIFO reserves of inventory expected to be sold, or consumed within one year or operating cycle, if longer. + 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 210.5-02.6(a)) -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 330 -SubTopic 10 -Section 35 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6386567&loc=d3e3927-108312 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section 45 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=28358313&loc=d3e6676-107765 + Details
Name: | us-gaap_InventoryNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The amount of a reclassification adjustment made to prior period financial statement amounts. + References No definition available. + Details
Name: | us-gaap_PriorPeriodReclassificationAdjustment
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment. + References No definition available. + Details
Name: | us-gaap_PropertyPlantAndEquipmentUsefulLife
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition The carrying amounts of cash and cash equivalent items which are restricted as to withdrawal or usage. Restrictions may include legally restricted deposits held as compensating balances against borrowing arrangements, contracts entered into with others, or entity statements of intention with regard to particular deposits; however, time deposits and short-term certificates of deposit are not generally included in legally restricted deposits. Excludes compensating balance arrangements that are not agreements which legally restrict the use of cash amounts shown on the balance sheet. This element is for unclassified presentations; for classified presentations there is a separate and distinct element. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 1 -Article 5 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.1) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_RestrictedCashAndCashEquivalents
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The carrying amounts of cash and cash equivalent items which are restricted as to withdrawal or usage. Restrictions may include legally restricted deposits held as compensating balances against short-term borrowing arrangements, contracts entered into with others, or entity statements of intention with regard to particular deposits; however, time deposits and short-term certificates of deposit are not generally included in legally restricted deposits. Excludes compensating balance arrangements that are not agreements which legally restrict the use of cash amounts shown on the balance sheet. For a classified balance sheet represents the current portion only (the noncurrent portion has a separate concept); there is a separate and distinct element for unclassified presentations. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 1 -Article 5 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.1) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_RestrictedCashAndCashEquivalentsAtCarryingValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_RestrictedCashAndCashEquivalentsItemsLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Cash and equivalents whose use in whole or in part is restricted for the long-term, generally by contractual agreements or regulatory requirements. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 1 -Article 5 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.1) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_RestrictedCashAndCashEquivalentsNoncurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Equity impact of the cost of common and preferred stock that were repurchased during the period. Recorded using the cost method. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Article 3 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 30 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6405813&loc=d3e23239-112655 + Details
Name: | us-gaap_TreasuryStockValueAcquiredCostMethod
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration