Revenue from Contracts with Customers - MEC (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Disaggregation of Revenue [Line Items]
Operating revenue	$ 6,404	$ 6,229	$ 12,515	$ 12,575
MEC
Disaggregation of Revenue [Line Items]
Total Customer Revenue	705	725	1,533	1,629
Other revenue	25	34	40	50
Operating revenue	730	759	1,573	1,679
MEC | Other customer revenue
Disaggregation of Revenue [Line Items]
Total Customer Revenue	0		2	4
Regulated | Regulated retail electric
Disaggregation of Revenue [Line Items]
Total Customer Revenue	3,001	2,844	5,715	5,532
Regulated | Regulated retail gas
Disaggregation of Revenue [Line Items]
Total Customer Revenue	122	133	461	525
Regulated | Regulated wholesale
Disaggregation of Revenue [Line Items]
Total Customer Revenue	50	89	168	280
Regulated | Other customer revenue
Disaggregation of Revenue [Line Items]
Total Customer Revenue	30	23	57	57
Regulated | MEC | Retail
Disaggregation of Revenue [Line Items]
Total Customer Revenue	667	659	1,406	1,446
Regulated | MEC | Retail | Residential
Disaggregation of Revenue [Line Items]
Total Customer Revenue	237	231	564	597
Regulated | MEC | Retail | Commercial
Disaggregation of Revenue [Line Items]
Total Customer Revenue	102	103	238	256
Regulated | MEC | Retail | Industrial
Disaggregation of Revenue [Line Items]
Total Customer Revenue	276	276	500	497
Regulated | MEC | Retail | Natural gas transportation services
Disaggregation of Revenue [Line Items]
Total Customer Revenue	11	10	25	23
Regulated | MEC | Retail | Other retail
Disaggregation of Revenue [Line Items]
Total Customer Revenue	41	39	79	73
Regulated | MEC | Regulated wholesale
Disaggregation of Revenue [Line Items]
Total Customer Revenue	25	52	97	152
Regulated | MEC | Multi-value transmission projects | Multi-value transmission projects
Disaggregation of Revenue [Line Items]
Total Customer Revenue	13	13	28	27
Nonregulated | MEC | Other customer revenue
Disaggregation of Revenue [Line Items]
Total Customer Revenue		1
Regulated electric | MEC
Disaggregation of Revenue [Line Items]
Operating revenue	635	661	1,200	1,252
Regulated electric | Regulated | MEC
Disaggregation of Revenue [Line Items]
Total Customer Revenue	610	627	1,161	1,203
Other revenue	25	34	39	49
Operating revenue	635	661	1,200	1,252
Regulated electric | Regulated | MEC | Regulated retail electric
Disaggregation of Revenue [Line Items]
Total Customer Revenue	579	569	1,064	1,060
Regulated electric | Regulated | MEC | Regulated retail electric | Residential
Disaggregation of Revenue [Line Items]
Total Customer Revenue	179	173	339	340
Regulated electric | Regulated | MEC | Regulated retail electric | Commercial
Disaggregation of Revenue [Line Items]
Total Customer Revenue	86	86	158	161
Regulated electric | Regulated | MEC | Regulated retail electric | Industrial
Disaggregation of Revenue [Line Items]
Total Customer Revenue	274	272	492	486
Regulated electric | Regulated | MEC | Regulated retail electric | Other retail
Disaggregation of Revenue [Line Items]
Total Customer Revenue	40	38	75	73
Regulated electric | Regulated | MEC | Regulated wholesale
Disaggregation of Revenue [Line Items]
Total Customer Revenue	18	45	69	116
Regulated electric | Regulated | MEC | Multi-value transmission projects | Multi-value transmission projects
Disaggregation of Revenue [Line Items]
Total Customer Revenue	13	13	28	27
Regulated natural gas | MEC
Disaggregation of Revenue [Line Items]
Operating revenue	95	97	371	423
Regulated natural gas | Regulated | MEC
Disaggregation of Revenue [Line Items]
Total Customer Revenue	95	97	370	422
Other revenue	0	0	1	1
Operating revenue	95	97	371	423
Regulated natural gas | Regulated | MEC | Regulated retail gas
Disaggregation of Revenue [Line Items]
Total Customer Revenue	88	90	342	386
Regulated natural gas | Regulated | MEC | Regulated retail gas | Residential
Disaggregation of Revenue [Line Items]
Total Customer Revenue	58	58	225	257
Regulated natural gas | Regulated | MEC | Regulated retail gas | Commercial
Disaggregation of Revenue [Line Items]
Total Customer Revenue	16	17	80	95
Regulated natural gas | Regulated | MEC | Regulated retail gas | Industrial
Disaggregation of Revenue [Line Items]
Total Customer Revenue	2	4	8	11
Regulated natural gas | Regulated | MEC | Regulated retail gas | Natural gas transportation services
Disaggregation of Revenue [Line Items]
Total Customer Revenue	11	10	25	23
Regulated natural gas | Regulated | MEC | Regulated retail gas | Other retail
Disaggregation of Revenue [Line Items]
Total Customer Revenue	1	1	4	0
Regulated natural gas | Regulated | MEC | Regulated wholesale
Disaggregation of Revenue [Line Items]
Total Customer Revenue	7	7	28	36
Other | MEC
Disaggregation of Revenue [Line Items]
Operating revenue	0	1	2	4
Other | Nonregulated | MEC
Disaggregation of Revenue [Line Items]
Total Customer Revenue	0	1	2	4
Other revenue	0	0	0	0
Operating revenue	0	1	2	4
Other | Nonregulated | MEC | Other customer revenue
Disaggregation of Revenue [Line Items]
Total Customer Revenue	$ 0	$ 1	$ 2	$ 4