Revenue Recognition - Disaggregated Revenues (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	$ 30,347	$ 27,748	$ 28,256
Mark-to-market for economic hedging activities	(346)	206	(2,863)
Contract amortization	(510)	(332)	(168)
Revenues	30,713	28,130	28,823
Less: Revenues accounted for under topics other than ASC 606 and ASC 815	164	117	52
Retail revenue
Disaggregation of Revenue [Line Items]
Derivative revenue	37	36
Retail revenue | Home
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	12,967	12,946	12,171
Retail revenue | Business
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	16,576	14,203	15,296
Total retail revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	29,543	27,149	27,467
Energy revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	590	500	553
Derivative revenue	54	130	176
Capacity revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	280	177	197
Derivative revenue	63	76	73
Derivative revenue
Disaggregation of Revenue [Line Items]
Mark-to-market for economic hedging activities	12	(3)	144
Less: Realized and unrealized ASC 815 revenue	202	265	515
Other revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	294	336	494
Contract amortization	(6)	(29)	(32)
Total operating revenue
Disaggregation of Revenue [Line Items]
Revenues	30,713	28,130	28,823
Other derivative revenue
Disaggregation of Revenue [Line Items]
Derivative revenue	36	26	48
Operating Segments
Disaggregation of Revenue [Line Items]
Revenues			1,589
Corporate/Eliminations
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	(29)	(31)	(13)
Revenues	(35)	(40)	(30)
Less: Revenues accounted for under topics other than ASC 606 and ASC 815	0	(1)	0
Corporate/Eliminations | Retail revenue
Disaggregation of Revenue [Line Items]
Derivative revenue	0	0	74
Corporate/Eliminations | Retail revenue | Home
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	(18)	(17)	0
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	(18)	(17)	0
Corporate/Eliminations | Energy revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	(1)	(12)	0
Derivative revenue	(1)	(12)	1
Corporate/Eliminations | Capacity revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	(1)	(3)	(2)
Derivative revenue	0	0	0
Corporate/Eliminations | Derivative revenue
Disaggregation of Revenue [Line Items]
Mark-to-market for economic hedging activities	(5)	4	(17)
Less: Realized and unrealized ASC 815 revenue	(6)	(8)	(17)
Corporate/Eliminations | Other revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	(10)	(12)	(11)
Contract amortization	0	0	0
Corporate/Eliminations | Total operating revenue
Disaggregation of Revenue [Line Items]
Revenues	(35)	(40)	(30)
Corporate/Eliminations | Other derivative revenue
Disaggregation of Revenue [Line Items]
Derivative revenue	0	0	(1)
Texas | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	11,108	10,621	10,445
Revenues	11,139	10,651	10,474
Less: Revenues accounted for under topics other than ASC 606 and ASC 815	0	0	0
Texas | Operating Segments | Retail revenue
Disaggregation of Revenue [Line Items]
Derivative revenue	0	0	0
Texas | Operating Segments | Retail revenue | Home
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	7,172	6,836	6,538
Texas | Operating Segments | Retail revenue | Business
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	3,724	3,564	3,492
Texas | Operating Segments | Total retail revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	10,896	10,400	10,030
Texas | Operating Segments | Energy revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	49	41	77
Derivative revenue	0	0	0
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	0	0	0
Less: Realized and unrealized ASC 815 revenue	31	30	29
Texas | Operating Segments | Other revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	194	210	367
Contract amortization	0	0	0
Texas | Operating Segments | Total operating revenue
Disaggregation of Revenue [Line Items]
Revenues	11,139	10,651	10,474
Texas | Operating Segments | Other derivative revenue
Disaggregation of Revenue [Line Items]
Derivative revenue	31	30	29
Texas | Corporate/Eliminations
Disaggregation of Revenue [Line Items]
Revenues	(23)	(22)	(5)
East | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	14,060	11,484	12,168
Revenues	14,263	11,709	12,549
Less: Revenues accounted for under topics other than ASC 606 and ASC 815	36	57	17
East | Operating Segments | Retail revenue
Disaggregation of Revenue [Line Items]
Derivative revenue	37	36	74
East | Operating Segments | Retail revenue | Home
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	2,502	2,453	2,195
East | Operating Segments | Retail revenue | Business
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	10,965	8,794	9,751
East | Operating Segments | Total retail revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	13,467	11,247	11,946
East | Operating Segments | Energy revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	441	242	291
Derivative revenue	55	79	162
East | Operating Segments | Capacity revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	267	156	197
Derivative revenue	63	76	73
East | Operating Segments | Derivative revenue
Disaggregation of Revenue [Line Items]
Mark-to-market for economic hedging activities	7	(23)	57
Less: Realized and unrealized ASC 815 revenue	167	168	364
East | Operating Segments | Other revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	87	114	90
Contract amortization	(6)	(27)	(32)
East | Operating Segments | Total operating revenue
Disaggregation of Revenue [Line Items]
Revenues	14,263	11,709	12,549
East | Operating Segments | Other derivative revenue
Disaggregation of Revenue [Line Items]
Derivative revenue	5	0	(2)
East | Corporate/Eliminations
Disaggregation of Revenue [Line Items]
Revenues	(6)	0	(9)
West/Other | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	3,184	3,738	4,095
Less: Revenues accounted for under topics other than ASC 606 and ASC 815	8	6	7
West/Other | Operating Segments | Retail revenue
Disaggregation of Revenue [Line Items]
Derivative revenue	0	0	0
West/Other | Operating Segments | Retail revenue | Home
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	1,167	1,683	1,849
West/Other | Operating Segments | Retail revenue | Business
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	1,887	1,845	2,053
West/Other | Operating Segments | Total retail revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	3,054	3,528	3,902
West/Other | Operating Segments | Energy revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	101	229	185
Derivative revenue	0	63	13
West/Other | Operating Segments | Capacity revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	14	24	2
Derivative revenue	0	0	0
West/Other | Operating Segments | Derivative revenue
Disaggregation of Revenue [Line Items]
Mark-to-market for economic hedging activities	10	16	104
Less: Realized and unrealized ASC 815 revenue	10	75	139
West/Other | Operating Segments | Other revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	23	24	48
Contract amortization	0	(2)	0
West/Other | Operating Segments | Total operating revenue
Disaggregation of Revenue [Line Items]
Revenues	3,202	3,819	4,241
West/Other | Operating Segments | Other derivative revenue
Disaggregation of Revenue [Line Items]
Derivative revenue	0	(4)	22
Vivint Smart Home | Operating Segments
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	2,024	1,936	1,561
Revenues	2,144	1,991
Less: Revenues accounted for under topics other than ASC 606 and ASC 815	120	55	28
Vivint Smart Home | Operating Segments | Retail revenue
Disaggregation of Revenue [Line Items]
Derivative revenue	0	0	0
Vivint Smart Home | Operating Segments | Retail revenue | Home
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	2,144	1,991	1,589
Vivint Smart Home | Operating Segments | Retail revenue | Business
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0	0	0
Vivint Smart Home | Operating Segments | Total retail revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	2,144	1,991	1,589
Vivint Smart Home | Operating Segments | Energy revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0	0	0
Derivative revenue	0	0	0
Vivint Smart Home | Operating Segments | Capacity revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0	0	0
Derivative revenue	0	0	0
Vivint Smart Home | Operating Segments | Derivative revenue
Disaggregation of Revenue [Line Items]
Mark-to-market for economic hedging activities	0	0	0
Less: Realized and unrealized ASC 815 revenue	0	0	0
Vivint Smart Home | Operating Segments | Other revenue
Disaggregation of Revenue [Line Items]
Revenue from contract with customer	0	0	0
Contract amortization	0	0	0
Vivint Smart Home | Operating Segments | Total operating revenue
Disaggregation of Revenue [Line Items]
Revenues	2,144	1,991	1,589
Vivint Smart Home | Operating Segments | Other derivative revenue
Disaggregation of Revenue [Line Items]
Derivative revenue	0	0	0
Vivint Smart Home | Corporate/Eliminations
Disaggregation of Revenue [Line Items]
Revenues	$ 0	$ 0	$ 0