Restructuring and Related Cost, Annualized Services

No definition available.

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

- Definition

Restructuring and Related Cost, Credit Applied

+ References

No definition available.

+ Details

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

- Definition

Service Agreement, Notice Of Termination, Period

+ References

No definition available.

+ Details

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

- Definition

Revenue, comprised of base and incentive revenue derived from the management of joint ventures, managing third-party properties, or another entity's operations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1(d))
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

+ Details

Name:	us-gaap_ManagementFeesRevenue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

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.

+ References

No definition available.

+ Details

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

- Definition

Reflects the sum of all other revenue and income realized from sales and other transactions (excluding transactions that are eliminated in consolidated or combined financial statements) with related party during the period.

+ References

No definition available.

+ Details

Name:	us-gaap_RelatedPartyTransactionOtherRevenuesFromTransactionsWithRelatedParty
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of selling, general and administrative expenses resulting from transactions, excluding transactions that are eliminated in consolidated or combined financial statements, with related party.

+ References

No definition available.

+ Details

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

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=nrg_ServicesAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RestructuringPlanAxis=nrg_RestructuringSupportAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=us-gaap_AffiliatedEntityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=nrg_TransitionServicesAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Related Party Transactions - Service Agreement and Transition Services Agreement with GenOn (Details) - USD ($) $ in Millions		1 Months Ended	3 Months Ended		12 Months Ended
	Jun. 12, 2017	Dec. 31, 2017	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Related Party Transaction [Line Items]
Notice of termination, period		60 days
Other income - affiliate			$ 0	$ 48
Services Agreement \| Restructuring Support Agreement
Related Party Transaction [Line Items]
Shared services, annualized rate		$ 84			$ 84
Credit applied					28
GenOn \| Services Agreement
Related Party Transaction [Line Items]
Service fees			193
Shared services, annualized rate		$ 84			$ 84
Credit applied	$ 28
GenOn \| Transition Services Agreement \| Restructuring Support Agreement
Related Party Transaction [Line Items]
Selling, general and administrative expenses			$ 21