Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2024	Mar. 31, 2023
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 7,380	$ 7,515
Mark-to-market for economic hedging activities	472	(1,944)
Revenue	7,429	7,722
Less: Revenues accounted for under topics other than ASC 606 and ASC 815	16	8
Derivative revenue	468	(1,932)
Corporate/Eliminations
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	(3)	(1)
Revenue	(6)	(10)
Less: Revenues accounted for under topics other than ASC 606 and ASC 815	0	0
Retail revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	7,229	7,363
Derivative revenue	10	27
Retail revenue \| Corporate/Eliminations
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Derivative revenue	0	0
Energy revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	152	128
Derivative revenue	62	66
Energy revenue \| Corporate/Eliminations
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	(3)	2
Derivative revenue	(3)	2
Capacity revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	42	42
Derivative revenue	22	6
Capacity revenue \| Corporate/Eliminations
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	(1)	0
Derivative revenue	0	0
Derivative revenue
Disaggregation of Revenue [Line Items]
Mark-to-market for economic hedging activities	(60)	91
Less: Realized and unrealized ASC 815 revenue	33	199
Derivative revenue \| Corporate/Eliminations
Disaggregation of Revenue [Line Items]
Mark-to-market for economic hedging activities	0	(11)
Less: Realized and unrealized ASC 815 revenue	(3)	(9)
Other revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	76	109
Contract amortization	(10)	(11)
Other revenue \| Corporate/Eliminations
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	(2)	(1)
Contract amortization	0	0
Total operating revenue
Disaggregation of Revenue [Line Items]
Revenue	7,429	7,722
Total operating revenue \| Corporate/Eliminations
Disaggregation of Revenue [Line Items]
Revenue	(6)	(10)
Other revenue, derivative
Disaggregation of Revenue [Line Items]
Derivative revenue	(1)	9
Other revenue, derivative \| Corporate/Eliminations
Disaggregation of Revenue [Line Items]
Derivative revenue	0	0
Home \| Retail revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	3,129	2,660
Home \| Retail revenue \| Corporate/Eliminations
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Business \| Retail revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	4,100	4,703
Business \| Retail revenue \| Corporate/Eliminations
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Texas \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	2,231	2,036
Revenue	2,233	2,034
Less: Revenues accounted for under topics other than ASC 606 and ASC 815	0	0
Texas \| Retail revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	2,178	1,958
Derivative revenue	0	0
Texas \| Energy revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	7	4
Derivative revenue	0	0
Texas \| Capacity revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Derivative revenue	0	0
Texas \| Derivative revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Mark-to-market for economic hedging activities	0	0
Less: Realized and unrealized ASC 815 revenue	2	(2)
Texas \| Other revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	48	72
Contract amortization	0	0
Texas \| Total operating revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	2,233	2,034
Texas \| Other revenue, derivative \| Operating Segments
Disaggregation of Revenue [Line Items]
Derivative revenue	2	(2)
Texas \| Home \| Retail revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,360	1,236
Texas \| Business \| Retail revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	818	722
East \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	3,481	4,064
Revenue	3,515	4,176
Less: Revenues accounted for under topics other than ASC 606 and ASC 815	10	(1)
East \| Retail revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	3,428	4,016
Derivative revenue	10	27
East \| Energy revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	81	74
Derivative revenue	43	47
East \| Capacity revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	41	41
Derivative revenue	22	6
East \| Derivative revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Mark-to-market for economic hedging activities	(51)	35
Less: Realized and unrealized ASC 815 revenue	24	113
East \| Other revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	26	21
Contract amortization	(10)	(11)
East \| Total operating revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	3,515	4,176
East \| Other revenue, derivative \| Operating Segments
Disaggregation of Revenue [Line Items]
Derivative revenue	0	(2)
East \| Home \| Retail revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	702	651
East \| Business \| Retail revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	2,726	3,365
West/Services/Other \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,203	1,268
Revenue	1,219	1,374
Less: Revenues accounted for under topics other than ASC 606 and ASC 815	6	9
West/Services/Other \| Retail revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,155	1,241
Derivative revenue	0	0
West/Services/Other \| Energy revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	67	48
Derivative revenue	22	17
West/Services/Other \| Capacity revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	2	1
Derivative revenue	0	0
West/Services/Other \| Derivative revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Mark-to-market for economic hedging activities	(9)	67
Less: Realized and unrealized ASC 815 revenue	10	97
West/Services/Other \| Other revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	4	17
Contract amortization	0	0
West/Services/Other \| Total operating revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	1,219	1,374
West/Services/Other \| Other revenue, derivative \| Operating Segments
Disaggregation of Revenue [Line Items]
Derivative revenue	(3)	13
West/Services/Other \| Home \| Retail revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	599	625
West/Services/Other \| Business \| Retail revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	556	616
Vivint Smart Home \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	468	148
Revenue	468	148
Less: Revenues accounted for under topics other than ASC 606 and ASC 815	0	0
Vivint Smart Home \| Retail revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	468	148
Derivative revenue	0	0
Vivint Smart Home \| Energy revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Derivative revenue	0	0
Vivint Smart Home \| Capacity revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Derivative revenue	0	0
Vivint Smart Home \| Derivative revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Mark-to-market for economic hedging activities	0	0
Less: Realized and unrealized ASC 815 revenue	0	0
Vivint Smart Home \| Other revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Contract amortization	0	0
Vivint Smart Home \| Total operating revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	468	148
Vivint Smart Home \| Other revenue, derivative \| Operating Segments
Disaggregation of Revenue [Line Items]
Derivative revenue	0	0
Vivint Smart Home \| Home \| Retail revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	468	148
Vivint Smart Home \| Business \| Retail revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 0	$ 0

Unrealized Gain (Loss) on Derivatives, Mark To Market, Economic Hedging Activities

No definition available.

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

- Definition

Amount of amortization expense for asset recognized from cost incurred to obtain or fulfill contract with customer.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 340
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479483/340-40-50-3

+ Details

Name:	us-gaap_CapitalizedContractCostAmortization
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.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-5

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 91
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479777/606-10-55-91

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 91
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479777/606-10-55-91

Reference 4: http://www.xbrl.org/2003/role/exampleRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 91
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479777/606-10-55-91

Reference 5: http://www.xbrl.org/2003/role/exampleRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 91
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479777/606-10-55-91

Reference 6: http://www.xbrl.org/2003/role/exampleRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 91
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479777/606-10-55-91

Reference 7: http://www.xbrl.org/2003/role/exampleRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 91
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479777/606-10-55-91

Reference 8: http://www.xbrl.org/2003/role/exampleRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 91
-Subparagraph (g)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479777/606-10-55-91

+ Details

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

- Definition

Aggregate net gain (loss) on all derivative instruments recognized in earnings during the period, before tax effects.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4A
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480434/815-10-50-4A

+ Details

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

- Definition

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 924
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 11.L)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479941/924-10-S99-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-5

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 30
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-30

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 42
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-42

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 22
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-22

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-32

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 40
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-40

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 22
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-22

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-32

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 41
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-41

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-4

+ Details

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

- Definition

Amount of revenue that is not accounted for under Topic 606, classified as other.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(1)(e))
-SubTopic 10
-Topic 220
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483621/220-10-S99-2

+ Details

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

- Definition

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(g)(1)(ii))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 323
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481687/323-10-50-3

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 825
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 28
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482907/825-10-50-28

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(1))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483621/220-10-S99-2

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1A
-Subparagraph (SX 210.13-01(a)(4)(i))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1A

Reference 6: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1A
-Subparagraph (SX 210.13-01(a)(4)(ii))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1A

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1A
-Subparagraph (SX 210.13-01(a)(4)(iii)(A))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1A

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1A
-Subparagraph (SX 210.13-01(a)(4)(iv))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1A

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1A
-Subparagraph (SX 210.13-01(a)(5))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1A

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1B
-Subparagraph (SX 210.13-02(a)(4)(i))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1B

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1B
-Subparagraph (SX 210.13-02(a)(4)(iii)(A))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1B

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1B
-Subparagraph (SX 210.13-02(a)(4)(iii)(B))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1B

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1B
-Subparagraph (SX 210.13-02(a)(4)(iv))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1B

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1B
-Subparagraph (SX 210.13-02(a)(5))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480097/470-10-S99-1B

Reference 15: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 30
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-30

Reference 16: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 42
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-42

Reference 17: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 22
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-22

Reference 18: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-32

Reference 19: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 40
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-40

Reference 20: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 22
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-22

Reference 21: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-32

Reference 22: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 41
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-41

Reference 23: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 235
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-05(b)(2))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479557/942-235-S99-1

+ Details

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

- Definition

The net change in the difference between the fair value and the carrying value, or in the comparative fair values, of derivative instruments, including options, swaps, futures, and forward contracts, held at each balance sheet date, that was included in earnings for the period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 45
-Paragraph 28
-Subparagraph (b)
-SubTopic 10
-Topic 230
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482740/230-10-45-28

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(7)(c)(3))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483575/946-220-S99-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(7)(c)(5))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483575/946-220-S99-1

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(7)(c)(6))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483575/946-220-S99-1

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(7)(c)(7))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483575/946-220-S99-1

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 320
-Name Accounting Standards Codification
-Section S99
-Paragraph 5A
-Subparagraph (SX 210.12-13A(Column F))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480032/946-320-S99-5A

+ Details

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

- Details

Name:	srt_ConsolidationItemsAxis=us-gaap_IntersegmentEliminationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ProductOrServiceAxis=nrg_ProductsAndServicesRetailRevenueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ProductOrServiceAxis=nrg_EnergyRevenueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ProductOrServiceAxis=nrg_CapacityRevenueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ProductOrServiceAxis=nrg_ProductsAndServicesDerivativeRevenueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ProductOrServiceAxis=nrg_ProductsAndServicesOtherMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ProductOrServiceAxis=nrg_OperatingRevenuesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ProductOrServiceAxis=nrg_ProductsAndServicesOtherDerivativeRevenueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_MajorCustomersAxis=nrg_HomeCustomerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_MajorCustomersAxis=nrg_BusinessSolutionsCustomersMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=nrg_TexasSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ConsolidationItemsAxis=us-gaap_OperatingSegmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=nrg_EastSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=nrg_WestServicesAndOtherSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=nrg_VivintSmartHomeSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: