Revenue Recognition - Disaggregated Revenues (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	$ 26,777	$ 8,690	$ 7,991
Mark-to-market for economic hedging activities	2,716	(119)	(20)
Revenues	26,989	9,093	9,821
Less: Lease revenue	8	18	20
Derivative revenue	2,684	(124)	0
Retail Revenue | Home
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	9,676	6,331	6,254
Retail Revenue | Business
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	13,885	1,129	1,279
Total retail revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	23,561	7,460	7,533
Energy revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	1,215	539	1,169
Derivative revenue	136	105	1,595
Capacity revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	775	680	700
Derivative revenue	149	156	109
Derivative revenue
Disaggregation of Revenue [Line Items]
Mark-to-market for economic hedging activities	(164)	95	33
Derivative revenue	234	385	1,810
Other revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	1,632	319	386
Contract amortization	(30)
Total operating revenues
Disaggregation of Revenue [Line Items]
Revenues	26,989	9,093	9,821
Other derivative revenue
Disaggregation of Revenue [Line Items]
Derivative revenue	113	29	73
Corporate/Eliminations
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	(6)	(7)	(5)
Revenues	10	(4)	(7)
Less: Lease revenue	0	0	0
Corporate/Eliminations | Retail Revenue | Home
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	(1)	(2)	(3)
Corporate/Eliminations | Retail Revenue | Business
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0	0	0
Corporate/Eliminations | Total retail revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	(1)	(2)	(3)
Corporate/Eliminations | Energy revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	7	(1)	0
Derivative revenue	3	(5)	(1)
Corporate/Eliminations | Capacity revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0	(1)	0
Derivative revenue	0	0	0
Corporate/Eliminations | Derivative revenue
Disaggregation of Revenue [Line Items]
Mark-to-market for economic hedging activities	13	8	(1)
Derivative revenue	16	3	(2)
Corporate/Eliminations | Other revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	(9)	(8)	(3)
Contract amortization	0
Corporate/Eliminations | Total operating revenues
Disaggregation of Revenue [Line Items]
Revenues	10	(4)	(7)
Corporate/Eliminations | Other derivative revenue
Disaggregation of Revenue [Line Items]
Derivative revenue	0	0	0
Texas | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	10,163	6,279	5,507
Revenues	10,293	6,309	7,069
Less: Lease revenue	0	0	0
Texas | Operating Segments | Retail Revenue | Home
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	5,665	5,027	5,027
Texas | Operating Segments | Retail Revenue | Business
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	2,745	1,034	1,205
Texas | Operating Segments | Total retail revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	8,410	6,061	6,232
Texas | Operating Segments | Energy revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	329	24	529
Derivative revenue	0	0	1,459
Texas | Operating Segments | Capacity revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0	0	0
Derivative revenue	0	0	0
Texas | Operating Segments | Derivative revenue
Disaggregation of Revenue [Line Items]
Mark-to-market for economic hedging activities	(3)	2	47
Derivative revenue	130	30	1,562
Texas | Operating Segments | Other revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	1,557	222	261
Contract amortization	0
Texas | Operating Segments | Total operating revenues
Disaggregation of Revenue [Line Items]
Revenues	10,293	6,309	7,069
Texas | Operating Segments | Other ancillary revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	1,300
Texas | Operating Segments | Other derivative revenue
Disaggregation of Revenue [Line Items]
Derivative revenue	133	28	56
Texas | Corporate/Eliminations
Disaggregation of Revenue [Line Items]
Revenues	(5)	(6)	(1)
East | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	12,874	1,943	2,078
Revenues	13,033	2,258	2,262
Less: Lease revenue	1	1	1
East | Operating Segments | Retail Revenue | Home
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	1,959	1,210	1,173
East | Operating Segments | Retail Revenue | Business
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	9,903	95	74
East | Operating Segments | Total retail revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	11,862	1,305	1,247
East | Operating Segments | Energy revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	508	183	322
Derivative revenue	131	67	98
East | Operating Segments | Capacity revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	718	620	664
Derivative revenue	149	156	109
East | Operating Segments | Derivative revenue
Disaggregation of Revenue [Line Items]
Mark-to-market for economic hedging activities	(88)	88	(29)
Derivative revenue	184	314	183
East | Operating Segments | Other revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	59	62	58
Contract amortization	(26)
East | Operating Segments | Total operating revenues
Disaggregation of Revenue [Line Items]
Revenues	13,033	2,258	2,262
East | Operating Segments | Other derivative revenue
Disaggregation of Revenue [Line Items]
Derivative revenue	(8)	3	5
East | Corporate/Eliminations
Disaggregation of Revenue [Line Items]
Revenues	18	6	(8)
West/Services/Other | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	3,746	475	411
Less: Lease revenue	7	17	19
West/Services/Other | Operating Segments | Retail Revenue | Home
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	2,053	96	57
West/Services/Other | Operating Segments | Retail Revenue | Business
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	1,237	0	0
West/Services/Other | Operating Segments | Total retail revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	3,290	96	57
West/Services/Other | Operating Segments | Energy revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	371	333	318
Derivative revenue	2	43	39
West/Services/Other | Operating Segments | Capacity revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	57	61	36
Derivative revenue	0	0	0
West/Services/Other | Operating Segments | Derivative revenue
Disaggregation of Revenue [Line Items]
Mark-to-market for economic hedging activities	(86)	(3)	16
Derivative revenue	(96)	38	67
West/Services/Other | Operating Segments | Other revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	25	43	70
Contract amortization	(4)
West/Services/Other | Operating Segments | Total operating revenues
Disaggregation of Revenue [Line Items]
Revenues	3,653	530	497
West/Services/Other | Operating Segments | Other derivative revenue
Disaggregation of Revenue [Line Items]
Derivative revenue	$ (12)	$ (2)	$ 12