v2.4.1.9
Segment and Significant Customer Information (Details) (USD $)
In Millions, unless otherwise specified
3 Months Ended 12 Months Ended
Dec. 31, 2014
Sep. 30, 2014
Jun. 30, 2014
Mar. 31, 2014
Dec. 31, 2013
Sep. 30, 2013
Jun. 30, 2013
Mar. 31, 2013
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Revenues from External Customers and Long-Lived Assets [Line Items]                      
Operating revenues $ 1,939us-gaap_Revenues $ 2,187us-gaap_Revenues $ 1,939us-gaap_Revenues $ 1,965us-gaap_Revenues $ 1,438us-gaap_Revenues $ 2,050us-gaap_Revenues $ 1,572us-gaap_Revenues $ 1,241us-gaap_Revenues $ 8,030us-gaap_Revenues $ 6,301us-gaap_Revenues $ 5,478us-gaap_Revenues
Commodity Margin                 2,759cpn_CommodityMargin [1] 2,568cpn_CommodityMargin [1] 2,538cpn_CommodityMargin [1],[2],[3]
Mark-to-Market Commodity Activity, Net and Other Revenue                 379cpn_MarkToMarketCommodityActivityNetAndOtherRevenue [4] (3)cpn_MarkToMarketCommodityActivityNetAndOtherRevenue [4] (84)cpn_MarkToMarketCommodityActivityNetAndOtherRevenue [4]
Plant operating expense                 969us-gaap_OperatingCostsAndExpenses 895us-gaap_OperatingCostsAndExpenses 922us-gaap_OperatingCostsAndExpenses
Depreciation and amortization expense                 603us-gaap_DepreciationAndAmortization 593us-gaap_DepreciationAndAmortization 562us-gaap_DepreciationAndAmortization
Sales, general and other administrative expense                 144us-gaap_SellingGeneralAndAdministrativeExpense 136us-gaap_SellingGeneralAndAdministrativeExpense 140us-gaap_SellingGeneralAndAdministrativeExpense
Other Cost and Expense, Operating                 88us-gaap_OtherCostAndExpenseOperating 81us-gaap_OtherCostAndExpenseOperating 78us-gaap_OtherCostAndExpenseOperating
Impairment losses                 123us-gaap_AssetImpairmentCharges 16us-gaap_AssetImpairmentCharges 0us-gaap_AssetImpairmentCharges
Gain (Loss) on Disposition of Assets                 (753)us-gaap_GainLossOnDispositionOfAssets1 0us-gaap_GainLossOnDispositionOfAssets1 (222)us-gaap_GainLossOnDispositionOfAssets1
(Income) from unconsolidated investments in power plants                 (25)us-gaap_IncomeLossFromEquityMethodInvestments (30)us-gaap_IncomeLossFromEquityMethodInvestments (28)us-gaap_IncomeLossFromEquityMethodInvestments
Income from operations 390us-gaap_OperatingIncomeLoss 1,126us-gaap_OperatingIncomeLoss 329us-gaap_OperatingIncomeLoss 144us-gaap_OperatingIncomeLoss 151us-gaap_OperatingIncomeLoss 597us-gaap_OperatingIncomeLoss 122us-gaap_OperatingIncomeLoss 4us-gaap_OperatingIncomeLoss 1,989us-gaap_OperatingIncomeLoss 874us-gaap_OperatingIncomeLoss 1,002us-gaap_OperatingIncomeLoss
Interest expense, net of interest income                 639us-gaap_InterestRevenueExpenseNet 690us-gaap_InterestRevenueExpenseNet 725us-gaap_InterestRevenueExpenseNet
Loss on interest rate derivatives                 0us-gaap_GainLossOnInterestRateDerivativeInstrumentsNotDesignatedAsHedgingInstruments 0us-gaap_GainLossOnInterestRateDerivativeInstrumentsNotDesignatedAsHedgingInstruments 14us-gaap_GainLossOnInterestRateDerivativeInstrumentsNotDesignatedAsHedgingInstruments
Debt Extinguishment Costs and Other (Income) Expense, Net                 367cpn_DebtExtinguishmentCostsAndOtherIncomeExpenseNet 164cpn_DebtExtinguishmentCostsAndOtherIncomeExpenseNet 45cpn_DebtExtinguishmentCostsAndOtherIncomeExpenseNet
Income before income taxes                 983cpn_IncomeLossBeforeReorganizationItemsIncomeTaxesAndDiscontinuedOperations 20cpn_IncomeLossBeforeReorganizationItemsIncomeTaxesAndDiscontinuedOperations 218cpn_IncomeLossBeforeReorganizationItemsIncomeTaxesAndDiscontinuedOperations
Commodity Margin for Six Southeast Power Plants Sold                 81cpn_CommodityMarginforSixSoutheastPowerPlantsSold 152cpn_CommodityMarginforSixSoutheastPowerPlantsSold 131cpn_CommodityMarginforSixSoutheastPowerPlantsSold
Lease levelization                 (5)cpn_LeaseLevelization 6cpn_LeaseLevelization 1cpn_LeaseLevelization
Contract amortization                 14cpn_ContractAmortization 14cpn_ContractAmortization 14cpn_ContractAmortization
Commodity Margin Broad River Energy Center                     52cpn_CommodityMarginBroadRiverEnergyCenter
Commodity Margin Riverside Energy Center                     73cpn_CommodityMarginRiversideEnergyCenter
Number of significant customers                 one two  
West [Member]                      
Revenues from External Customers and Long-Lived Assets [Line Items]                      
Operating revenues                 2,358us-gaap_Revenues
/ us-gaap_StatementGeographicalAxis
= cpn_WestMember
1,942us-gaap_Revenues
/ us-gaap_StatementGeographicalAxis
= cpn_WestMember
1,678us-gaap_Revenues
/ us-gaap_StatementGeographicalAxis
= cpn_WestMember
Commodity Margin                 1,050cpn_CommodityMargin
/ us-gaap_StatementGeographicalAxis
= cpn_WestMember
[1] 1,020cpn_CommodityMargin
/ us-gaap_StatementGeographicalAxis
= cpn_WestMember
[1] 994cpn_CommodityMargin
/ us-gaap_StatementGeographicalAxis
= cpn_WestMember
[1],[2],[3]
Mark-to-Market Commodity Activity, Net and Other Revenue                 220cpn_MarkToMarketCommodityActivityNetAndOtherRevenue
/ us-gaap_StatementGeographicalAxis
= cpn_WestMember
[4] (50)cpn_MarkToMarketCommodityActivityNetAndOtherRevenue
/ us-gaap_StatementGeographicalAxis
= cpn_WestMember
[4] (93)cpn_MarkToMarketCommodityActivityNetAndOtherRevenue
/ us-gaap_StatementGeographicalAxis
= cpn_WestMember
[4]
Plant operating expense                 385us-gaap_OperatingCostsAndExpenses
/ us-gaap_StatementGeographicalAxis
= cpn_WestMember
365us-gaap_OperatingCostsAndExpenses
/ us-gaap_StatementGeographicalAxis
= cpn_WestMember
368us-gaap_OperatingCostsAndExpenses
/ us-gaap_StatementGeographicalAxis
= cpn_WestMember
Depreciation and amortization expense                 245us-gaap_DepreciationAndAmortization
/ us-gaap_StatementGeographicalAxis
= cpn_WestMember
227us-gaap_DepreciationAndAmortization
/ us-gaap_StatementGeographicalAxis
= cpn_WestMember
203us-gaap_DepreciationAndAmortization
/ us-gaap_StatementGeographicalAxis
= cpn_WestMember
Sales, general and other administrative expense                 41us-gaap_SellingGeneralAndAdministrativeExpense
/ us-gaap_StatementGeographicalAxis
= cpn_WestMember
37us-gaap_SellingGeneralAndAdministrativeExpense
/ us-gaap_StatementGeographicalAxis
= cpn_WestMember
36us-gaap_SellingGeneralAndAdministrativeExpense
/ us-gaap_StatementGeographicalAxis
= cpn_WestMember
Other Cost and Expense, Operating                 50us-gaap_OtherCostAndExpenseOperating
/ us-gaap_StatementGeographicalAxis
= cpn_WestMember
45us-gaap_OtherCostAndExpenseOperating
/ us-gaap_StatementGeographicalAxis
= cpn_WestMember
42us-gaap_OtherCostAndExpenseOperating
/ us-gaap_StatementGeographicalAxis
= cpn_WestMember
Impairment losses                 0us-gaap_AssetImpairmentCharges
/ us-gaap_StatementGeographicalAxis
= cpn_WestMember
16us-gaap_AssetImpairmentCharges
/ us-gaap_StatementGeographicalAxis
= cpn_WestMember
 
Gain (Loss) on Disposition of Assets                 0us-gaap_GainLossOnDispositionOfAssets1
/ us-gaap_StatementGeographicalAxis
= cpn_WestMember
  0us-gaap_GainLossOnDispositionOfAssets1
/ us-gaap_StatementGeographicalAxis
= cpn_WestMember
(Income) from unconsolidated investments in power plants                 0us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_StatementGeographicalAxis
= cpn_WestMember
0us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_StatementGeographicalAxis
= cpn_WestMember
0us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_StatementGeographicalAxis
= cpn_WestMember
Income from operations                 549us-gaap_OperatingIncomeLoss
/ us-gaap_StatementGeographicalAxis
= cpn_WestMember
280us-gaap_OperatingIncomeLoss
/ us-gaap_StatementGeographicalAxis
= cpn_WestMember
252us-gaap_OperatingIncomeLoss
/ us-gaap_StatementGeographicalAxis
= cpn_WestMember
Texas [Member]                      
Revenues from External Customers and Long-Lived Assets [Line Items]                      
Operating revenues                 3,252us-gaap_Revenues
/ us-gaap_StatementGeographicalAxis
= stpr_TX
2,343us-gaap_Revenues
/ us-gaap_StatementGeographicalAxis
= stpr_TX
1,918us-gaap_Revenues
/ us-gaap_StatementGeographicalAxis
= stpr_TX
Commodity Margin                 760cpn_CommodityMargin
/ us-gaap_StatementGeographicalAxis
= stpr_TX
[1] 632cpn_CommodityMargin
/ us-gaap_StatementGeographicalAxis
= stpr_TX
[1] 570cpn_CommodityMargin
/ us-gaap_StatementGeographicalAxis
= stpr_TX
[1],[2],[3]
Mark-to-Market Commodity Activity, Net and Other Revenue                 142cpn_MarkToMarketCommodityActivityNetAndOtherRevenue
/ us-gaap_StatementGeographicalAxis
= stpr_TX
[4] 51cpn_MarkToMarketCommodityActivityNetAndOtherRevenue
/ us-gaap_StatementGeographicalAxis
= stpr_TX
[4] 87cpn_MarkToMarketCommodityActivityNetAndOtherRevenue
/ us-gaap_StatementGeographicalAxis
= stpr_TX
[4]
Plant operating expense                 313us-gaap_OperatingCostsAndExpenses
/ us-gaap_StatementGeographicalAxis
= stpr_TX
269us-gaap_OperatingCostsAndExpenses
/ us-gaap_StatementGeographicalAxis
= stpr_TX
247us-gaap_OperatingCostsAndExpenses
/ us-gaap_StatementGeographicalAxis
= stpr_TX
Depreciation and amortization expense                 191us-gaap_DepreciationAndAmortization
/ us-gaap_StatementGeographicalAxis
= stpr_TX
165us-gaap_DepreciationAndAmortization
/ us-gaap_StatementGeographicalAxis
= stpr_TX
142us-gaap_DepreciationAndAmortization
/ us-gaap_StatementGeographicalAxis
= stpr_TX
Sales, general and other administrative expense                 64us-gaap_SellingGeneralAndAdministrativeExpense
/ us-gaap_StatementGeographicalAxis
= stpr_TX
56us-gaap_SellingGeneralAndAdministrativeExpense
/ us-gaap_StatementGeographicalAxis
= stpr_TX
47us-gaap_SellingGeneralAndAdministrativeExpense
/ us-gaap_StatementGeographicalAxis
= stpr_TX
Other Cost and Expense, Operating                 5us-gaap_OtherCostAndExpenseOperating
/ us-gaap_StatementGeographicalAxis
= stpr_TX
3us-gaap_OtherCostAndExpenseOperating
/ us-gaap_StatementGeographicalAxis
= stpr_TX
5us-gaap_OtherCostAndExpenseOperating
/ us-gaap_StatementGeographicalAxis
= stpr_TX
Impairment losses                 0us-gaap_AssetImpairmentCharges
/ us-gaap_StatementGeographicalAxis
= stpr_TX
0us-gaap_AssetImpairmentCharges
/ us-gaap_StatementGeographicalAxis
= stpr_TX
 
Gain (Loss) on Disposition of Assets                 0us-gaap_GainLossOnDispositionOfAssets1
/ us-gaap_StatementGeographicalAxis
= stpr_TX
  0us-gaap_GainLossOnDispositionOfAssets1
/ us-gaap_StatementGeographicalAxis
= stpr_TX
(Income) from unconsolidated investments in power plants                 0us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_StatementGeographicalAxis
= stpr_TX
0us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_StatementGeographicalAxis
= stpr_TX
0us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_StatementGeographicalAxis
= stpr_TX
Income from operations                 329us-gaap_OperatingIncomeLoss
/ us-gaap_StatementGeographicalAxis
= stpr_TX
190us-gaap_OperatingIncomeLoss
/ us-gaap_StatementGeographicalAxis
= stpr_TX
216us-gaap_OperatingIncomeLoss
/ us-gaap_StatementGeographicalAxis
= stpr_TX
East [Member]                      
Revenues from External Customers and Long-Lived Assets [Line Items]                      
Operating revenues                 2,496us-gaap_Revenues
/ us-gaap_StatementGeographicalAxis
= cpn_EastMember
2,134us-gaap_Revenues
/ us-gaap_StatementGeographicalAxis
= cpn_EastMember
1,991us-gaap_Revenues
/ us-gaap_StatementGeographicalAxis
= cpn_EastMember
Commodity Margin                 949cpn_CommodityMargin
/ us-gaap_StatementGeographicalAxis
= cpn_EastMember
[1] 916cpn_CommodityMargin
/ us-gaap_StatementGeographicalAxis
= cpn_EastMember
[1] 974cpn_CommodityMargin
/ us-gaap_StatementGeographicalAxis
= cpn_EastMember
[1],[2],[3]
Mark-to-Market Commodity Activity, Net and Other Revenue                 48cpn_MarkToMarketCommodityActivityNetAndOtherRevenue
/ us-gaap_StatementGeographicalAxis
= cpn_EastMember
[4] 27cpn_MarkToMarketCommodityActivityNetAndOtherRevenue
/ us-gaap_StatementGeographicalAxis
= cpn_EastMember
[4] (47)cpn_MarkToMarketCommodityActivityNetAndOtherRevenue
/ us-gaap_StatementGeographicalAxis
= cpn_EastMember
[4]
Plant operating expense                 302us-gaap_OperatingCostsAndExpenses
/ us-gaap_StatementGeographicalAxis
= cpn_EastMember
292us-gaap_OperatingCostsAndExpenses
/ us-gaap_StatementGeographicalAxis
= cpn_EastMember
337us-gaap_OperatingCostsAndExpenses
/ us-gaap_StatementGeographicalAxis
= cpn_EastMember
Depreciation and amortization expense                 168us-gaap_DepreciationAndAmortization
/ us-gaap_StatementGeographicalAxis
= cpn_EastMember
203us-gaap_DepreciationAndAmortization
/ us-gaap_StatementGeographicalAxis
= cpn_EastMember
219us-gaap_DepreciationAndAmortization
/ us-gaap_StatementGeographicalAxis
= cpn_EastMember
Sales, general and other administrative expense                 39us-gaap_SellingGeneralAndAdministrativeExpense
/ us-gaap_StatementGeographicalAxis
= cpn_EastMember
42us-gaap_SellingGeneralAndAdministrativeExpense
/ us-gaap_StatementGeographicalAxis
= cpn_EastMember
57us-gaap_SellingGeneralAndAdministrativeExpense
/ us-gaap_StatementGeographicalAxis
= cpn_EastMember
Other Cost and Expense, Operating                 32us-gaap_OtherCostAndExpenseOperating
/ us-gaap_StatementGeographicalAxis
= cpn_EastMember
33us-gaap_OtherCostAndExpenseOperating
/ us-gaap_StatementGeographicalAxis
= cpn_EastMember
34us-gaap_OtherCostAndExpenseOperating
/ us-gaap_StatementGeographicalAxis
= cpn_EastMember
Impairment losses                 123us-gaap_AssetImpairmentCharges
/ us-gaap_StatementGeographicalAxis
= cpn_EastMember
0us-gaap_AssetImpairmentCharges
/ us-gaap_StatementGeographicalAxis
= cpn_EastMember
 
Gain (Loss) on Disposition of Assets                 (753)us-gaap_GainLossOnDispositionOfAssets1
/ us-gaap_StatementGeographicalAxis
= cpn_EastMember
  (222)us-gaap_GainLossOnDispositionOfAssets1
/ us-gaap_StatementGeographicalAxis
= cpn_EastMember
(Income) from unconsolidated investments in power plants                 (25)us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_StatementGeographicalAxis
= cpn_EastMember
(30)us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_StatementGeographicalAxis
= cpn_EastMember
(28)us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_StatementGeographicalAxis
= cpn_EastMember
Income from operations                 1,111us-gaap_OperatingIncomeLoss
/ us-gaap_StatementGeographicalAxis
= cpn_EastMember
403us-gaap_OperatingIncomeLoss
/ us-gaap_StatementGeographicalAxis
= cpn_EastMember
530us-gaap_OperatingIncomeLoss
/ us-gaap_StatementGeographicalAxis
= cpn_EastMember
Geography Consolidation and Elimination [Member]                      
Revenues from External Customers and Long-Lived Assets [Line Items]                      
Operating revenues                 (76)us-gaap_Revenues
/ us-gaap_StatementGeographicalAxis
= cpn_GeographyConsolidationandEliminationMember
(118)us-gaap_Revenues
/ us-gaap_StatementGeographicalAxis
= cpn_GeographyConsolidationandEliminationMember
(109)us-gaap_Revenues
/ us-gaap_StatementGeographicalAxis
= cpn_GeographyConsolidationandEliminationMember
Commodity Margin                 0cpn_CommodityMargin
/ us-gaap_StatementGeographicalAxis
= cpn_GeographyConsolidationandEliminationMember
0cpn_CommodityMargin
/ us-gaap_StatementGeographicalAxis
= cpn_GeographyConsolidationandEliminationMember
0cpn_CommodityMargin
/ us-gaap_StatementGeographicalAxis
= cpn_GeographyConsolidationandEliminationMember
Mark-to-Market Commodity Activity, Net and Other Revenue                 (31)cpn_MarkToMarketCommodityActivityNetAndOtherRevenue
/ us-gaap_StatementGeographicalAxis
= cpn_GeographyConsolidationandEliminationMember
(31)cpn_MarkToMarketCommodityActivityNetAndOtherRevenue
/ us-gaap_StatementGeographicalAxis
= cpn_GeographyConsolidationandEliminationMember
(31)cpn_MarkToMarketCommodityActivityNetAndOtherRevenue
/ us-gaap_StatementGeographicalAxis
= cpn_GeographyConsolidationandEliminationMember
Plant operating expense                 (31)us-gaap_OperatingCostsAndExpenses
/ us-gaap_StatementGeographicalAxis
= cpn_GeographyConsolidationandEliminationMember
(31)us-gaap_OperatingCostsAndExpenses
/ us-gaap_StatementGeographicalAxis
= cpn_GeographyConsolidationandEliminationMember
(30)us-gaap_OperatingCostsAndExpenses
/ us-gaap_StatementGeographicalAxis
= cpn_GeographyConsolidationandEliminationMember
Depreciation and amortization expense                 (1)us-gaap_DepreciationAndAmortization
/ us-gaap_StatementGeographicalAxis
= cpn_GeographyConsolidationandEliminationMember
(2)us-gaap_DepreciationAndAmortization
/ us-gaap_StatementGeographicalAxis
= cpn_GeographyConsolidationandEliminationMember
(2)us-gaap_DepreciationAndAmortization
/ us-gaap_StatementGeographicalAxis
= cpn_GeographyConsolidationandEliminationMember
Sales, general and other administrative expense                 0us-gaap_SellingGeneralAndAdministrativeExpense
/ us-gaap_StatementGeographicalAxis
= cpn_GeographyConsolidationandEliminationMember
1us-gaap_SellingGeneralAndAdministrativeExpense
/ us-gaap_StatementGeographicalAxis
= cpn_GeographyConsolidationandEliminationMember
0us-gaap_SellingGeneralAndAdministrativeExpense
/ us-gaap_StatementGeographicalAxis
= cpn_GeographyConsolidationandEliminationMember
Other Cost and Expense, Operating                 1us-gaap_OtherCostAndExpenseOperating
/ us-gaap_StatementGeographicalAxis
= cpn_GeographyConsolidationandEliminationMember
0us-gaap_OtherCostAndExpenseOperating
/ us-gaap_StatementGeographicalAxis
= cpn_GeographyConsolidationandEliminationMember
(3)us-gaap_OtherCostAndExpenseOperating
/ us-gaap_StatementGeographicalAxis
= cpn_GeographyConsolidationandEliminationMember
Impairment losses                 0us-gaap_AssetImpairmentCharges
/ us-gaap_StatementGeographicalAxis
= cpn_GeographyConsolidationandEliminationMember
0us-gaap_AssetImpairmentCharges
/ us-gaap_StatementGeographicalAxis
= cpn_GeographyConsolidationandEliminationMember
 
Gain (Loss) on Disposition of Assets                 0us-gaap_GainLossOnDispositionOfAssets1
/ us-gaap_StatementGeographicalAxis
= cpn_GeographyConsolidationandEliminationMember
  0us-gaap_GainLossOnDispositionOfAssets1
/ us-gaap_StatementGeographicalAxis
= cpn_GeographyConsolidationandEliminationMember
(Income) from unconsolidated investments in power plants                 0us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_StatementGeographicalAxis
= cpn_GeographyConsolidationandEliminationMember
0us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_StatementGeographicalAxis
= cpn_GeographyConsolidationandEliminationMember
0us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_StatementGeographicalAxis
= cpn_GeographyConsolidationandEliminationMember
Income from operations                 0us-gaap_OperatingIncomeLoss
/ us-gaap_StatementGeographicalAxis
= cpn_GeographyConsolidationandEliminationMember
1us-gaap_OperatingIncomeLoss
/ us-gaap_StatementGeographicalAxis
= cpn_GeographyConsolidationandEliminationMember
4us-gaap_OperatingIncomeLoss
/ us-gaap_StatementGeographicalAxis
= cpn_GeographyConsolidationandEliminationMember
PJM Settlement, Inc. [Member]                      
Revenues from External Customers and Long-Lived Assets [Line Items]                      
Operating revenues                 1,024us-gaap_Revenues
/ us-gaap_MajorCustomersAxis
= cpn_PjmSettlementIncMember
820us-gaap_Revenues
/ us-gaap_MajorCustomersAxis
= cpn_PjmSettlementIncMember
713us-gaap_Revenues
/ us-gaap_MajorCustomersAxis
= cpn_PjmSettlementIncMember
Pacific Gas & Electric Company [Member]                      
Revenues from External Customers and Long-Lived Assets [Line Items]                      
Operating revenues                   694us-gaap_Revenues
/ us-gaap_MajorCustomersAxis
= cpn_PacificGasElectricCompanyMember
 
Operating Segments [Member]                      
Revenues from External Customers and Long-Lived Assets [Line Items]                      
Operating revenues                 8,030us-gaap_Revenues
/ us-gaap_ConsolidationItemsAxis
= us-gaap_OperatingSegmentsMember
6,301us-gaap_Revenues
/ us-gaap_ConsolidationItemsAxis
= us-gaap_OperatingSegmentsMember
5,478us-gaap_Revenues
/ us-gaap_ConsolidationItemsAxis
= us-gaap_OperatingSegmentsMember
Operating Segments [Member] | West [Member]                      
Revenues from External Customers and Long-Lived Assets [Line Items]                      
Operating revenues                 2,352us-gaap_Revenues
/ us-gaap_ConsolidationItemsAxis
= us-gaap_OperatingSegmentsMember
/ us-gaap_StatementGeographicalAxis
= cpn_WestMember
1,937us-gaap_Revenues
/ us-gaap_ConsolidationItemsAxis
= us-gaap_OperatingSegmentsMember
/ us-gaap_StatementGeographicalAxis
= cpn_WestMember
1,668us-gaap_Revenues
/ us-gaap_ConsolidationItemsAxis
= us-gaap_OperatingSegmentsMember
/ us-gaap_StatementGeographicalAxis
= cpn_WestMember
Operating Segments [Member] | Texas [Member]                      
Revenues from External Customers and Long-Lived Assets [Line Items]                      
Operating revenues                 3,229us-gaap_Revenues
/ us-gaap_ConsolidationItemsAxis
= us-gaap_OperatingSegmentsMember
/ us-gaap_StatementGeographicalAxis
= stpr_TX
2,347us-gaap_Revenues
/ us-gaap_ConsolidationItemsAxis
= us-gaap_OperatingSegmentsMember
/ us-gaap_StatementGeographicalAxis
= stpr_TX
1,857us-gaap_Revenues
/ us-gaap_ConsolidationItemsAxis
= us-gaap_OperatingSegmentsMember
/ us-gaap_StatementGeographicalAxis
= stpr_TX
Operating Segments [Member] | East [Member]                      
Revenues from External Customers and Long-Lived Assets [Line Items]                      
Operating revenues                 2,449us-gaap_Revenues
/ us-gaap_ConsolidationItemsAxis
= us-gaap_OperatingSegmentsMember
/ us-gaap_StatementGeographicalAxis
= cpn_EastMember
2,017us-gaap_Revenues
/ us-gaap_ConsolidationItemsAxis
= us-gaap_OperatingSegmentsMember
/ us-gaap_StatementGeographicalAxis
= cpn_EastMember
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Operating Segments [Member] | Geography Consolidation and Elimination [Member]                      
Revenues from External Customers and Long-Lived Assets [Line Items]                      
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Intersegment Eliminations [Member]                      
Revenues from External Customers and Long-Lived Assets [Line Items]                      
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Intersegment Eliminations [Member] | West [Member]                      
Revenues from External Customers and Long-Lived Assets [Line Items]                      
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Intersegment Eliminations [Member] | Texas [Member]                      
Revenues from External Customers and Long-Lived Assets [Line Items]                      
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Revenues from External Customers and Long-Lived Assets [Line Items]                      
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Revenues from External Customers and Long-Lived Assets [Line Items]                      
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[1] Our East segment includes Commodity Margin of $81 million, $152 million and $131 million for the years ended December 31, 2014, 2013 and 2012, respectively, related to the six power plants in our East segment that were sold in July 2014.
[2] Our East segment includes Commodity Margin of $73 million for the year ended December 31, 2012, related to Riverside Energy Center, LLC, which was sold in December 2012.
[3] Our East segment includes Commodity Margin of $52 million for the year ended December 31, 2012, related to Broad River, which was sold in December 2012.
[4] Includes $(5) million, $6 million and $1 million of lease levelization and $14 million, $14 million and $14 million of amortization expense for the years ended December 31, 2014, 2013 and 2012, respectively.