Revenue from Contracts with Customers - MEC (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Disaggregation of Revenue [Line Items]
Operating revenue	$ 6,111	$ 6,346
MEC
Disaggregation of Revenue [Line Items]
Total Customer Revenue	828	904
Other revenue	15	16
Operating revenue	843	920
MEC | Other customer revenue
Disaggregation of Revenue [Line Items]
Total Customer Revenue	2	3
Regulated | Regulated retail electric
Disaggregation of Revenue [Line Items]
Total Customer Revenue	2,714	2,688
Regulated | Regulated retail gas
Disaggregation of Revenue [Line Items]
Total Customer Revenue	339	392
Regulated | Regulated wholesale
Disaggregation of Revenue [Line Items]
Total Customer Revenue	118	191
Regulated | Other customer revenue
Disaggregation of Revenue [Line Items]
Total Customer Revenue	27	34
Regulated | MEC | Retail
Disaggregation of Revenue [Line Items]
Total Customer Revenue	739	787
Regulated | MEC | Retail | Residential
Disaggregation of Revenue [Line Items]
Total Customer Revenue	327	366
Regulated | MEC | Retail | Commercial
Disaggregation of Revenue [Line Items]
Total Customer Revenue	136	153
Regulated | MEC | Retail | Industrial
Disaggregation of Revenue [Line Items]
Total Customer Revenue	224	221
Regulated | MEC | Retail | Natural gas transportation services
Disaggregation of Revenue [Line Items]
Total Customer Revenue	14	13
Regulated | MEC | Retail | Other retail
Disaggregation of Revenue [Line Items]
Total Customer Revenue	38	34
Regulated | MEC | Regulated wholesale
Disaggregation of Revenue [Line Items]
Total Customer Revenue	72	100
Regulated | MEC | Multi-value transmission projects | Multi-value transmission projects
Disaggregation of Revenue [Line Items]
Total Customer Revenue	15	14
Regulated electric | MEC
Disaggregation of Revenue [Line Items]
Operating revenue	565	591
Regulated electric | Regulated | MEC
Disaggregation of Revenue [Line Items]
Total Customer Revenue	551	576
Other revenue	14	15
Operating revenue	565	591
Regulated electric | Regulated | MEC | Regulated retail electric
Disaggregation of Revenue [Line Items]
Total Customer Revenue	485	491
Regulated electric | Regulated | MEC | Regulated retail electric | Residential
Disaggregation of Revenue [Line Items]
Total Customer Revenue	160	167
Regulated electric | Regulated | MEC | Regulated retail electric | Commercial
Disaggregation of Revenue [Line Items]
Total Customer Revenue	72	75
Regulated electric | Regulated | MEC | Regulated retail electric | Industrial
Disaggregation of Revenue [Line Items]
Total Customer Revenue	218	214
Regulated electric | Regulated | MEC | Regulated retail electric | Other retail
Disaggregation of Revenue [Line Items]
Total Customer Revenue	35	35
Regulated electric | Regulated | MEC | Regulated wholesale
Disaggregation of Revenue [Line Items]
Total Customer Revenue	51	71
Regulated electric | Regulated | MEC | Multi-value transmission projects | Multi-value transmission projects
Disaggregation of Revenue [Line Items]
Total Customer Revenue	15	14
Regulated natural gas | MEC
Disaggregation of Revenue [Line Items]
Operating revenue	276	326
Regulated natural gas | Regulated | MEC
Disaggregation of Revenue [Line Items]
Total Customer Revenue	275	325
Other revenue	1	1
Operating revenue	276	326
Regulated natural gas | Regulated | MEC | Regulated retail gas
Disaggregation of Revenue [Line Items]
Total Customer Revenue	254	296
Regulated natural gas | Regulated | MEC | Regulated retail gas | Residential
Disaggregation of Revenue [Line Items]
Total Customer Revenue	167	199
Regulated natural gas | Regulated | MEC | Regulated retail gas | Commercial
Disaggregation of Revenue [Line Items]
Total Customer Revenue	64	78
Regulated natural gas | Regulated | MEC | Regulated retail gas | Industrial
Disaggregation of Revenue [Line Items]
Total Customer Revenue	6	7
Regulated natural gas | Regulated | MEC | Regulated retail gas | Natural gas transportation services
Disaggregation of Revenue [Line Items]
Total Customer Revenue	14	13
Regulated natural gas | Regulated | MEC | Regulated retail gas | Other retail
Disaggregation of Revenue [Line Items]
Total Customer Revenue	3	(1)
Regulated natural gas | Regulated | MEC | Regulated wholesale
Disaggregation of Revenue [Line Items]
Total Customer Revenue	21	29
Other | MEC
Disaggregation of Revenue [Line Items]
Operating revenue	2	3
Other | Nonregulated | MEC
Disaggregation of Revenue [Line Items]
Total Customer Revenue	2	3
Other revenue	0	0
Operating revenue	2	3
Other | Nonregulated | MEC | Other customer revenue
Disaggregation of Revenue [Line Items]
Total Customer Revenue	$ 2	$ 3