v2.4.1.9
Assets and Liabilities with Recurring Fair Value Measurements (Details) (USD $)
In Millions, unless otherwise specified
Dec. 31, 2014
Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash equivalents $ 896us-gaap_CashAndCashEquivalentsFairValueDisclosure [1] $ 1,134us-gaap_CashAndCashEquivalentsFairValueDisclosure [1]
Margin Deposit Assets 96us-gaap_MarginDepositAssets [2] 261us-gaap_MarginDepositAssets [2]
Commodity futures contracts 2,134cpn_CommodityFuturesContractsAssetsFairValueDisclosure 434cpn_CommodityFuturesContractsAssetsFairValueDisclosure
Commodity forward contracts 359cpn_CommodityForwardContractsAssetsFairValueDisclosure [3] 107cpn_CommodityForwardContractsAssetsFairValueDisclosure [3]
Interest rate swaps 4cpn_InterestRateSwapAssetsFairValueDisclosure 9cpn_InterestRateSwapAssetsFairValueDisclosure
Total assets 3,489us-gaap_AssetsFairValueDisclosure 1,945us-gaap_AssetsFairValueDisclosure
Security Deposit Liability 47us-gaap_SecurityDepositLiability [2],[4] 5us-gaap_SecurityDepositLiability [2],[4]
Commodity futures contracts 1,870cpn_CommodityFuturesContractsLiabilitiesFairValueDisclosure 495cpn_CommodityFuturesContractsLiabilitiesFairValueDisclosure
Commodity forward contracts 242cpn_CommodityForwardContractsLiabilitiesFairValueDisclosure [3] 70cpn_CommodityForwardContractsLiabilitiesFairValueDisclosure [3]
Interest rate swaps 114cpn_InterestRateSwapLiabilitiesFairValueDisclosure 129cpn_InterestRateSwapLiabilitiesFairValueDisclosure
Total liabilities 2,273us-gaap_LiabilitiesFairValueDisclosure 699us-gaap_LiabilitiesFairValueDisclosure
Fair Value, Inputs, Level 1 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash equivalents 896us-gaap_CashAndCashEquivalentsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member		 [1] 1,134us-gaap_CashAndCashEquivalentsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member		 [1]
Margin Deposit Assets 96us-gaap_MarginDepositAssets
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member		 261us-gaap_MarginDepositAssets
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
Commodity futures contracts 2,134cpn_CommodityFuturesContractsAssetsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member		 434cpn_CommodityFuturesContractsAssetsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
Commodity forward contracts 0cpn_CommodityForwardContractsAssetsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member		 [3] 0cpn_CommodityForwardContractsAssetsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member		 [3]
Interest rate swaps 0cpn_InterestRateSwapAssetsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member		 0cpn_InterestRateSwapAssetsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
Total assets 3,126us-gaap_AssetsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member		 1,829us-gaap_AssetsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
Security Deposit Liability 47us-gaap_SecurityDepositLiability
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member		 5us-gaap_SecurityDepositLiability
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
Commodity futures contracts 1,870cpn_CommodityFuturesContractsLiabilitiesFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member		 495cpn_CommodityFuturesContractsLiabilitiesFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
Commodity forward contracts 0cpn_CommodityForwardContractsLiabilitiesFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member		 [3] 0cpn_CommodityForwardContractsLiabilitiesFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member		 [3]
Interest rate swaps 0cpn_InterestRateSwapLiabilitiesFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member		 0cpn_InterestRateSwapLiabilitiesFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
Total liabilities 1,917us-gaap_LiabilitiesFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member		 500us-gaap_LiabilitiesFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
Fair Value, Inputs, Level 2 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash equivalents 0us-gaap_CashAndCashEquivalentsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member		 [1] 0us-gaap_CashAndCashEquivalentsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member		 [1]
Margin Deposit Assets 0us-gaap_MarginDepositAssets
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member		 0us-gaap_MarginDepositAssets
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
Commodity futures contracts 0cpn_CommodityFuturesContractsAssetsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member		 0cpn_CommodityFuturesContractsAssetsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
Commodity forward contracts 195cpn_CommodityForwardContractsAssetsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member		 [3] 75cpn_CommodityForwardContractsAssetsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member		 [3]
Interest rate swaps 4cpn_InterestRateSwapAssetsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member		 9cpn_InterestRateSwapAssetsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
Total assets 199us-gaap_AssetsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member		 84us-gaap_AssetsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
Security Deposit Liability 0us-gaap_SecurityDepositLiability
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member		 0us-gaap_SecurityDepositLiability
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
Commodity futures contracts 0cpn_CommodityFuturesContractsLiabilitiesFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member		 0cpn_CommodityFuturesContractsLiabilitiesFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
Commodity forward contracts 163cpn_CommodityForwardContractsLiabilitiesFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member		 [3] 52cpn_CommodityForwardContractsLiabilitiesFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member		 [3]
Interest rate swaps 114cpn_InterestRateSwapLiabilitiesFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member		 129cpn_InterestRateSwapLiabilitiesFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
Total liabilities 277us-gaap_LiabilitiesFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member		 181us-gaap_LiabilitiesFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
Fair Value, Inputs, Level 3 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash equivalents 0us-gaap_CashAndCashEquivalentsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member		 [1] 0us-gaap_CashAndCashEquivalentsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member		 [1]
Margin Deposit Assets 0us-gaap_MarginDepositAssets
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member		 0us-gaap_MarginDepositAssets
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
Commodity futures contracts 0cpn_CommodityFuturesContractsAssetsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member		 0cpn_CommodityFuturesContractsAssetsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
Commodity forward contracts 164cpn_CommodityForwardContractsAssetsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member		 [3] 32cpn_CommodityForwardContractsAssetsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member		 [3]
Interest rate swaps 0cpn_InterestRateSwapAssetsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member		 0cpn_InterestRateSwapAssetsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
Total assets 164us-gaap_AssetsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member		 32us-gaap_AssetsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
Security Deposit Liability 0us-gaap_SecurityDepositLiability
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member		 0us-gaap_SecurityDepositLiability
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
Commodity futures contracts 0cpn_CommodityFuturesContractsLiabilitiesFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member		 0cpn_CommodityFuturesContractsLiabilitiesFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
Commodity forward contracts 79cpn_CommodityForwardContractsLiabilitiesFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member		 [3] 18cpn_CommodityForwardContractsLiabilitiesFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member		 [3]
Interest rate swaps 0cpn_InterestRateSwapLiabilitiesFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member		 0cpn_InterestRateSwapLiabilitiesFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
Total liabilities $ 79us-gaap_LiabilitiesFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member		 $ 18us-gaap_LiabilitiesFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
[1] As of December 31, 2014 and 2013, we had cash equivalents of $679 million and $889 million included in cash and cash equivalents and $217 million and $245 million included in restricted cash, respectively.
[2] Balances are subject to master netting arrangements and presented on a gross basis on our Consolidated Balance Sheets. We do not offset fair value amounts recognized for derivative instruments executed with the same counterparty under a master netting arrangement for financial statement presentation, and we do not offset amounts recognized for the right to reclaim, or the obligation to return, cash collateral with corresponding derivative instrument fair values. See Note 8 for further discussion of our derivative instruments subject to master netting arrangements.
[3] Includes OTC swaps and options.
[4] Included in other current liabilities on our Consolidated Balance Sheets.