Name:	nrg_AmountOfNetCounterpartyCreditRiskExposureToCertainCounterparties
Namespace Prefix:	nrg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Carrying amount as of the balance sheet date of cash collateral and letters of credit received by the entity on deposit from third parties in support of energy risk management.

No definition available.

Name:	nrg_CollateralHeldCashAndLettersOfCredit
Namespace Prefix:	nrg_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The percentage of net counterparty credit exposure that rolls-off by the end of 2012.

No definition available.

Name:	nrg_CounterpartyCreditRiskExposurePercentageOfCreditRiskRollOff
Namespace Prefix:	nrg_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Represents the threshold percentage for disclosure of counterparty credit exposure.

No definition available.

Name:	nrg_CounterpartyCreditRiskExposurePercentageThreshold
Namespace Prefix:	nrg_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Represents the percentage of net counterparty credit exposure of the entity.

No definition available.

Name:	nrg_CreditDerivativeMaximumNetExposurePercentage
Namespace Prefix:	nrg_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

This element represents the estimated amount of the counterparty credit risk exposure.

No definition available.

Name:	nrg_EstimatedCounterpartyCreditRiskExposureToCertainCounterparties
Namespace Prefix:	nrg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Estimated Counterparty Credit Risk Exposure to Certain Counterparties, Period

No definition available.

Name:	nrg_EstimatedCounterpartyCreditRiskExposureToCertainCounterpartiesPeriod
Namespace Prefix:	nrg_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Represents the net exposure of the entity determined as total credit exposure to all counterparties less collateral (cash and letters of credit) held against those positions as of the reporting date.

No definition available.

Name:	nrg_NetCreditExposure
Namespace Prefix:	nrg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Number Of Wholesale Counterparties With Credit Risk Exposure

No definition available.

Name:	nrg_NumberOfWholesaleCounterpartiesWithCreditRiskExposure
Namespace Prefix:	nrg_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

Maximum amount of loss due to credit risk that, based on the gross fair value of the financial instrument, the entity would incur if parties to the financial instruments that make up the concentration failed completely to perform according to the terms of the contracts and the collateral or other security, if any, for the amount due proved to be of no value to the entity.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 21
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118260190&loc=d3e13537-108611

Name:	us-gaap_ConcentrationRiskCreditRiskFinancialInstrumentMaximumExposure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

Name:	us-gaap_FairValueConcentrationOfRiskFinancialStatementCaptionsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Name:	invest_InvestmentAxis=nrg_IvanpauAndAguaCalienteMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_LongTermContractForPurchaseOfElectricPowerAxis=us-gaap_LongTermContractWithCustomerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	nrg_CounterpartyRiskByInvestmentGradeAxis=us-gaap_ExternalCreditRatingInvestmentGradeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	nrg_CounterpartyRiskByInvestmentGradeAxis=nrg_ExternalCreditRatingNotRatedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	nrg_CounterpartyRiskByInstitutionAxis=nrg_UtilitiesEnergyMerchantsMarketersAndOtherMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: