XML 95 R65.htm IDEA: XBRL DOCUMENT v3.8.0.1

Nature of Business (Details)	3 Months Ended	12 Months Ended
	Jun. 30, 2017 USD ($)	Dec. 31, 2017 USD ($) MW	Dec. 31, 2016 USD ($)	Jun. 14, 2017 USD ($)
Power Generation Facilities
Generation capacity (in MW) | MW		30,000
Discontinued Operations | GenOn
Power Generation Facilities
Investment in GenOn recorded under cost method at fair value				$ 0
Loss on deconsolidation	$ 208,000,000	$ 634,000,000	$ 0

X

- Definition

The generation capacity of the entity's power generation facilities as of the balance sheet date, expressed in megawatts.

+ References

No definition available.

+ Details

Name:	nrg_PowerGenerationCapacityMegawatts
Namespace Prefix:	nrg_
Data Type:	num:powerItemType
Balance Type:	na
Period Type:	instant

X

- References

No definition available.

+ Details

Name:	nrg_PowerGenerationFacilitiesLineItems
Namespace Prefix:	nrg_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Fair value portion of investments accounted under the cost method.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 325
-SubTopic 20
-Section 25
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=75030709&loc=d3e39828-111592

+ Details

Name:	us-gaap_CostMethodInvestmentsFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Amount after tax of gain (loss) not previously recognized resulting from the disposal of a discontinued operation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=64827811&loc=d3e1361-107760

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 45
-Paragraph 3B
-URI http://asc.fasb.org/extlink&oid=65878427&loc=SL51721525-107759

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 5C
-Subparagraph (b)(2)
-URI http://asc.fasb.org/extlink&oid=64827811&loc=SL51721675-107760

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=65878427&loc=d3e957-107759

+ Details

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

X

- Details

Name:	us-gaap_DisposalGroupClassificationAxis=us-gaap_SegmentDiscontinuedOperationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis=nrg_GenOnMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: