This element represents the number of shares repurchased under an accelerated share repurchase agreement.

Name:	nrg_AcceleratedShareRepurchasesShareRepurchased
Namespace Prefix:	nrg
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

-- None. No documentation exists for this element. --

+ Details

Name:	nrg_CapitalAllocationPlanLineItems
Namespace Prefix:	nrg
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

This element represents the increase in the value of shares to be repurchased under the capital allocation plan authorization.

+ Details

Name:	nrg_IncreaseInTreasuryStockRepurchaseAuthorization
Namespace Prefix:	nrg
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Total Targeted Share Repurchases for Current Year

+ Details

Name:	nrg_TotalTargetedShareRepurchasesForCurrentYear
Namespace Prefix:	nrg
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

- Definition

Dollar amount of the cash payment to or cash received from the bank; or the stock issuance to (stock received from) the bank in the settlement of the accelerated share repurchase agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Emerging Issues Task Force (EITF)

-Number 99-7

-Paragraph 1

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Name:	us-gaap_AcceleratedShareRepurchasesSettlementPaymentOrReceipt
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The remaining repurchase amount authorized by an entity's Board of Directors under a stock repurchase plan.

+ Details

Name:	us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Changes in Capital Structure (Details 2) (Common Stock, 2011 Capital Allocation Plan, USD $) In Millions, except Share data	1 Months Ended					4 Months Ended	9 Months Ended
	Oct. 31, 2011	Aug. 31, 2011	Aug. 18, 2011	Aug. 04, 2011	Apr. 30, 2011	Jun. 30, 2011	Sep. 30, 2011
Common Stock \| 2011 Capital Allocation Plan
Capital Allocation Plan
Accelerated share repurchase agreement, amount of shares to be repurchased							$ 130
Shares received under ASR agreement (in shares)	8,646,224	2,650,000			6,229,574
Increase in capital allocation plan during the period			190	250		180
Total Targeted Share Repurchases for Current Year				430
Stock Repurchase Program, Remaining Authorized Repurchase Amount							$ 52