Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2022	Mar. 31, 2021
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 7,989	$ 7,929
Mark-to-market for economic hedging activities	2,277	721
Revenue	7,896	8,091
Less: Revenues accounted for under topics other than 606 and 815	2	2
Derivative revenue	2,263	725
Corporate/Eliminations
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	(3)	(3)
Revenue	17	(1)
Less: Revenues accounted for under topics other than 606 and 815	0	0
Retail revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	7,570	6,162
Retail revenue \| Corporate/Eliminations
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Energy revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	278	482
Derivative revenue	29	58
Energy revenue \| Corporate/Eliminations
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	5	1
Derivative revenue	4	2
Capacity revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	116	155
Derivative revenue	13	37
Capacity revenue \| Corporate/Eliminations
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	0	0
Derivative revenue	0	0
Derivative revenue
Disaggregation of Revenue [Line Items]
Mark-to-market for economic hedging activities	(133)	(32)
Less: Realized and unrealized ASC 815 revenue	(95)	160
Derivative revenue \| Corporate/Eliminations
Disaggregation of Revenue [Line Items]
Mark-to-market for economic hedging activities	17	1
Less: Realized and unrealized ASC 815 revenue	20	2
Other revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	74	1,324
Contract amortization	(9)
Other revenue \| Corporate/Eliminations
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	(5)	(3)
Contract amortization	0
Total operating revenue
Disaggregation of Revenue [Line Items]
Revenue	7,896	8,091
Total operating revenue \| Corporate/Eliminations
Disaggregation of Revenue [Line Items]
Revenue	17	(1)
Other revenue, derivative
Disaggregation of Revenue [Line Items]
Derivative revenue	(4)	97
Other revenue, derivative \| Corporate/Eliminations
Disaggregation of Revenue [Line Items]
Derivative revenue	(1)	(1)
Home \| Retail revenue
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	2,661	2,471
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	4,909	3,691
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	2,030	3,609
Revenue	2,023	3,702
Less: Revenues accounted for under topics other than 606 and 815	0	0
Texas \| Retail revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,952	2,114
Texas \| Energy revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	15	285
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	(2)	(1)
Less: Realized and unrealized ASC 815 revenue	(7)	93
Texas \| Other revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	58	1,304
Contract amortization	0
Texas \| Total operating revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	2,023	3,702
Texas \| Other revenue, derivative \| Operating Segments
Disaggregation of Revenue [Line Items]
Derivative revenue	(5)	94
Texas \| Other Ancillary \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers		1,200
Texas \| Home \| Retail revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,289	1,333
Texas \| Business \| Retail revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	663	781
East \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	4,793	3,396
Revenue	4,718	3,495
Less: Revenues accounted for under topics other than 606 and 815	(9)	0
East \| Retail revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	4,521	3,213
East \| Energy revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	204	126
Derivative revenue	45	60
East \| Capacity revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	115	141
Derivative revenue	13	37
East \| Derivative revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Mark-to-market for economic hedging activities	(130)	(4)
Less: Realized and unrealized ASC 815 revenue	(66)	99
East \| Other revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	17	19
Contract amortization	(9)
East \| Total operating revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	4,718	3,495
East \| Other revenue, derivative \| Operating Segments
Disaggregation of Revenue [Line Items]
Derivative revenue	6	6
East \| Home \| Retail revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	675	584
East \| Business \| Retail revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	3,846	2,629
West/Services/Other \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,169	927
Revenue	1,138	895
Less: Revenues accounted for under topics other than 606 and 815	11	2
West/Services/Other \| Retail revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,097	835
West/Services/Other \| Energy revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	54	70
Derivative revenue	(20)	(4)
West/Services/Other \| Capacity revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1	14
Derivative revenue	0	0
West/Services/Other \| Derivative revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Mark-to-market for economic hedging activities	(18)	(28)
Less: Realized and unrealized ASC 815 revenue	(42)	(34)
West/Services/Other \| Other revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	4	4
Contract amortization	0
West/Services/Other \| Total operating revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue	1,138	895
West/Services/Other \| Other revenue, derivative \| Operating Segments
Disaggregation of Revenue [Line Items]
Derivative revenue	(4)	(2)
West/Services/Other \| Home \| Retail revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	697	554
West/Services/Other \| Business \| Retail revenue \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 400	$ 281

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