Revenue from Contracts with Customers - MEC (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Disaggregation of Revenue [Line Items]
Operating revenue	$ 6,346	$ 6,030
MEC
Disaggregation of Revenue [Line Items]
Total Customer Revenue	904	987
Other revenue	16	18
Operating revenue	920	1,005
MEC | Other
Disaggregation of Revenue [Line Items]
Total Customer Revenue	3	1
Regulated | Retail electric
Disaggregation of Revenue [Line Items]
Total Customer Revenue	2,688	2,256
Regulated | Retail gas
Disaggregation of Revenue [Line Items]
Total Customer Revenue	392	388
Regulated | Wholesale
Disaggregation of Revenue [Line Items]
Total Customer Revenue	191	236
Regulated | Other
Disaggregation of Revenue [Line Items]
Total Customer Revenue	34	22
Regulated | MEC | Retail
Disaggregation of Revenue [Line Items]
Total Customer Revenue	787	809
Regulated | MEC | Retail | Residential
Disaggregation of Revenue [Line Items]
Total Customer Revenue	366	393
Regulated | MEC | Retail | Commercial
Disaggregation of Revenue [Line Items]
Total Customer Revenue	153	162
Regulated | MEC | Retail | Industrial
Disaggregation of Revenue [Line Items]
Total Customer Revenue	221	207
Regulated | MEC | Retail | Natural gas transportation services
Disaggregation of Revenue [Line Items]
Total Customer Revenue	13	14
Regulated | MEC | Retail | Other retail
Disaggregation of Revenue [Line Items]
Total Customer Revenue	34	33
Regulated | MEC | Wholesale
Disaggregation of Revenue [Line Items]
Total Customer Revenue	100	162
Regulated | MEC | Multi-value transmission projects | Multi-value transmission projects
Disaggregation of Revenue [Line Items]
Total Customer Revenue	14	15
Regulated electric | MEC
Disaggregation of Revenue [Line Items]
Operating revenue	591	608
Regulated electric | Regulated | MEC
Disaggregation of Revenue [Line Items]
Total Customer Revenue	576	591
Other revenue	15	17
Operating revenue	591	608
Regulated electric | Regulated | MEC | Retail electric
Disaggregation of Revenue [Line Items]
Total Customer Revenue	491	472
Regulated electric | Regulated | MEC | Retail electric | Residential
Disaggregation of Revenue [Line Items]
Total Customer Revenue	167	168
Regulated electric | Regulated | MEC | Retail electric | Commercial
Disaggregation of Revenue [Line Items]
Total Customer Revenue	75	74
Regulated electric | Regulated | MEC | Retail electric | Industrial
Disaggregation of Revenue [Line Items]
Total Customer Revenue	214	198
Regulated electric | Regulated | MEC | Retail electric | Other retail
Disaggregation of Revenue [Line Items]
Total Customer Revenue	35	32
Regulated electric | Regulated | MEC | Wholesale
Disaggregation of Revenue [Line Items]
Total Customer Revenue	71	104
Regulated electric | Regulated | MEC | Multi-value transmission projects | Multi-value transmission projects
Disaggregation of Revenue [Line Items]
Total Customer Revenue	14	15
Regulated natural gas | MEC
Disaggregation of Revenue [Line Items]
Operating revenue	326	396
Regulated natural gas | Regulated | MEC
Disaggregation of Revenue [Line Items]
Total Customer Revenue	325	395
Other revenue	1	1
Operating revenue	326	396
Regulated natural gas | Regulated | MEC | Retail gas
Disaggregation of Revenue [Line Items]
Total Customer Revenue	296	337
Regulated natural gas | Regulated | MEC | Retail gas | Residential
Disaggregation of Revenue [Line Items]
Total Customer Revenue	199	225
Regulated natural gas | Regulated | MEC | Retail gas | Commercial
Disaggregation of Revenue [Line Items]
Total Customer Revenue	78	88
Regulated natural gas | Regulated | MEC | Retail gas | Industrial
Disaggregation of Revenue [Line Items]
Total Customer Revenue	7	9
Regulated natural gas | Regulated | MEC | Retail gas | Natural gas transportation services
Disaggregation of Revenue [Line Items]
Total Customer Revenue	13	14
Regulated natural gas | Regulated | MEC | Retail gas | Other retail
Disaggregation of Revenue [Line Items]
Total Customer Revenue	(1)	1
Regulated natural gas | Regulated | MEC | Wholesale
Disaggregation of Revenue [Line Items]
Total Customer Revenue	29	58
Other | MEC
Disaggregation of Revenue [Line Items]
Operating revenue	3	1
Other | Nonregulated | MEC
Disaggregation of Revenue [Line Items]
Total Customer Revenue	3	1
Other revenue	0	0
Operating revenue	3	1
Other | Nonregulated | MEC | Other
Disaggregation of Revenue [Line Items]
Total Customer Revenue	$ 3	$ 1