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

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

- Definition

Represents the number of defined benefit plans sponsored and operated by the entity.

+ Details

Name:	nrg_DefinedBenefitPensionAndOtherPostretirementPlansSponsoredAndOperatedNumber
Namespace Prefix:	nrg
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

The entity's ownership interest in jointly owned project.

+ Details

Name:	nrg_OwnershipInterestInJointlyOwnedProject
Namespace Prefix:	nrg
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

This element represents the percentage of contribution to the retirement plan obligation reimbursed by the entity.

+ Details

Name:	nrg_PercentageOfContributionToRetirementPlanObligationsReimbursedByEntity
Namespace Prefix:	nrg
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The increase in the fair value of plan assets from contributions made by the employer.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 132R

-Paragraph 5

-Subparagraph b

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (b)(3)

-URI http://asc.fasb.org/extlink&oid=6962843&loc=d3e1928-114920

+ Details

Name:	us-gaap_DefinedBenefitPlanContributionsByEmployer
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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.

+ Details

Name:	us-gaap_DefinedBenefitPlanDisclosureLineItems
Namespace Prefix:	us-gaap
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The total amount of net periodic benefit cost for defined benefit plans for the period. Periodic benefit costs include the following components: service cost, interest cost, expected return on plan assets, gain (loss), prior service cost or credit, transition asset or obligation, and gain (loss) due to settlements or curtailments.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 132R

-Paragraph 5

-Subparagraph h

-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.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (h)

-URI http://asc.fasb.org/extlink&oid=6962843&loc=d3e1928-114920

+ Details

Name:	us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Benefit Plans and Other Postretirement Benefits (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Benefit Plans and Other Postretirement Benefits Disclosure [Abstract]
Number of sponsored and operated defined benefit plan	3		3
Benefit Plans and Other Postretirement Benefits
Employer contributions to defined benefit plan, including reimbursements to STPNOC			$ 29
South Texas Project Units 1 and 2, Bay, City, TX
Benefit Plans and Other Postretirement Benefits
Undivided ownership interest in STP (as a percent)			44.00%
Percentage of contribution to the retirement plan obligation reimbursed (as a percent)			44.00%
Net periodic benefit cost	$ 10	$ 9	$ 29	$ 24