Percentage of Ownership

No definition available.

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Namespace Prefix:	nrg_
Data Type:	num:percentItemType
Balance Type:	na
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- 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

- Definition

Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 45
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=68055307&loc=d3e2420-110228

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3602-108585

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=66011266&loc=d3e33918-111571

+ Details

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Period Type:	instant

- 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

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Balance Type:	na
Period Type:	duration

- Definition

The charge against earnings resulting from the write down of long lived assets other than goodwill due to the difference between the carrying value and lower fair value.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=64862545&loc=d3e2921-110230

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3602-108585

+ Details

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

- Definition

The amount of other than temporary impairment (OTTI) losses on equity securities, OTTI related to credit losses on debt securities, and OTTI losses on debt securities when the entity intends to sell the securities or it is more likely than not that the entity will be required to sell the securities before recovery of its amortized cost basis. Additionally, this item includes OTTI losses recognized during the period on investments accounted for under the cost method of accounting.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 8B
-URI http://asc.fasb.org/extlink&oid=73527792&loc=SL6284393-111563

+ Details

Name:	us-gaap_OtherThanTemporaryImpairmentLossesInvestmentsPortionRecognizedInEarningsNet
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The cash inflow from the sale of long-lived, physical assets that are used in the normal conduct of business to produce goods and services and not intended for resale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3179-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Investing Activities
-URI http://asc.fasb.org/extlink&oid=6516133

+ Details

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

Asset Impairments (Details) $ in Millions					3 Months Ended						12 Months Ended
Asset Impairments (Details) $ in Millions	Jul. 13, 2016 USD ($)	May 13, 2016 USD ($)	Feb. 03, 2016 USD ($)	Nov. 25, 2015 USD ($)	Dec. 31, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($) MW	Sep. 30, 2014 USD ($) MW	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($) MW	Sep. 30, 2016	May 12, 2016 MW	Nov. 24, 2015 MW	Dec. 31, 2009 MW
Asset Impairments
Impairment losses											$ 918	$ 5,030	$ 97
Other Asset Impairment Charges											48
Emission Allowances [Member]
Asset Impairments
Impairment losses					$ 23
Mandalay operating unit [Member]
Asset Impairments
Impairment losses						$ 16
Ormond Beach operating unit [Member]
Asset Impairments
Impairment losses					28	43
Elbow Creek [Member]
Asset Impairments
Impairment losses					117
Goat Wind [Member]
Asset Impairments
Impairment losses					60
Forward [Member]
Asset Impairments
Impairment losses					6
Long Beach [Member]
Asset Impairments
Impairment losses					36
Conemaugh [Member]
Asset Impairments
Impairment losses					97
Keystone [Member]
Asset Impairments
Impairment losses					10
Pittsburg [Member]
Asset Impairments
Impairment losses					20
Other Intangible Assets [Member]
Asset Impairments
Impairment losses					23
Solar Panels [Member]
Asset Impairments
Impairment losses					19					$ 10
Deferred Marketing Expenses [Member]
Asset Impairments
Impairment losses					18
Other [Member]
Asset Impairments
Impairment losses					153
Limestone [Member]
Asset Impairments
Impairment losses								$ 1,514
W.A. Parish [Member]
Asset Impairments
Impairment losses								$ 1,295
Huntley [Member]
Asset Impairments
Impairment losses												132
Dunkirk [Member]
Asset Impairments
Impairment losses												160
Gregory Power Partners, L.P. [Member]
Asset Impairments
Impairment losses												176
Coolwater [Member]
Asset Impairments
Impairment losses									$ 22
Osceola facility [Member]
Asset Impairments
Impairment losses										$ 60
Coolwater [Member]
Asset Impairments
Power Generation Capacity, Megawatts \| MW									636				636
Solar Panels [Member]
Asset Impairments
Impairment losses												29
Other [Member]
Asset Impairments
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net											$ 22
Petra Nova Parish Holdings [Member]
Asset Impairments
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net							$ 140
Equity Method Investment, Ownership Percentage														50.00%
Power Generation Capacity, Megawatts \| MW										75
Community Wind North, LLC [Member]
Asset Impairments
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net					36
Sherbino I Wind Farm LLC [Member]
Asset Impairments
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net					$ 70
Equity Method Investment, Ownership Percentage																	50.00%
Power Generation Capacity, Megawatts \| MW																	150
Osceola facility [Member]
Asset Impairments
Power Generation Capacity, Megawatts \| MW										463
Rockford [Member]
Asset Impairments
Percentage of Ownership															100.00%
Proceeds from Sale of Property, Plant, and Equipment	$ 56	$ 55
Impairment losses						$ 17
Power Generation Capacity, Megawatts \| MW															450
Seward Generating Station [Member]
Asset Impairments
Proceeds from Sale of Property, Plant, and Equipment			$ 75	$ 75
Impairment losses												$ 134
Power Generation Capacity, Megawatts \| MW																525