Revenue from Contract with Customer - MEC (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Disaggregation of Revenue [Line Items]
Total operating revenue	$ 26,337	$ 25,150	$ 20,952
MEC
Disaggregation of Revenue [Line Items]
Customer revenue	3,911	3,514	2,696
Other revenue	114	33	24
Total operating revenue	4,025	3,547	2,720
MEC | Retail
Disaggregation of Revenue [Line Items]
Customer revenue	3,175	2,987	2,429
MEC | Retail | Residential
Disaggregation of Revenue [Line Items]
Customer revenue	1,320	1,282	1,027
MEC | Retail | Commercial
Disaggregation of Revenue [Line Items]
Customer revenue	570	550	415
MEC | Retail | Industrial
Disaggregation of Revenue [Line Items]
Customer revenue	1,085	964	818
MEC | Retail | Natural gas transportation services
Disaggregation of Revenue [Line Items]
Customer revenue	44	39	36
MEC | Retail | Other retail
Disaggregation of Revenue [Line Items]
Customer revenue	156	152	133
MEC | Wholesale
Disaggregation of Revenue [Line Items]
Customer revenue	668	454	199
MEC | Multi-value transmission projects | Multi-value transmission projects
Disaggregation of Revenue [Line Items]
Customer revenue	61	58	60
MEC | Other
Disaggregation of Revenue [Line Items]
Customer revenue	7	15	8
Regulated assets | Retail Electric
Disaggregation of Revenue [Line Items]
Customer revenue	10,884	9,801	9,421
Regulated assets | Retail Gas
Disaggregation of Revenue [Line Items]
Customer revenue	1,022	974	619
Regulated assets | Wholesale
Disaggregation of Revenue [Line Items]
Customer revenue	1,024	727	366
Regulated assets | Other
Disaggregation of Revenue [Line Items]
Customer revenue	105	109	110
Regulated electric | Regulated assets | MEC
Disaggregation of Revenue [Line Items]
Customer revenue	2,876	2,498	2,117
Other revenue	112	31	22
Total operating revenue	2,988	2,529	2,139
Regulated electric | Regulated assets | MEC | Retail Electric
Disaggregation of Revenue [Line Items]
Customer revenue	2,320	2,128	1,924
Regulated electric | Regulated assets | MEC | Retail Electric | Residential
Disaggregation of Revenue [Line Items]
Customer revenue	765	718	685
Regulated electric | Regulated assets | MEC | Retail Electric | Commercial
Disaggregation of Revenue [Line Items]
Customer revenue	354	327	304
Regulated electric | Regulated assets | MEC | Retail Electric | Industrial
Disaggregation of Revenue [Line Items]
Customer revenue	1,047	934	804
Regulated electric | Regulated assets | MEC | Retail Electric | Other retail
Disaggregation of Revenue [Line Items]
Customer revenue	154	149	131
Regulated electric | Regulated assets | MEC | Wholesale
Disaggregation of Revenue [Line Items]
Customer revenue	495	312	133
Regulated electric | Regulated assets | MEC | Multi-value transmission projects | Multi-value transmission projects
Disaggregation of Revenue [Line Items]
Customer revenue	61	58	60
Regulated natural gas | Regulated assets | MEC
Disaggregation of Revenue [Line Items]
Customer revenue	1,028	1,001	571
Other revenue	2	2	2
Total operating revenue	1,030	1,003	573
Regulated natural gas | Regulated assets | MEC | Retail Gas
Disaggregation of Revenue [Line Items]
Customer revenue	855	859	505
Regulated natural gas | Regulated assets | MEC | Retail Gas | Residential
Disaggregation of Revenue [Line Items]
Customer revenue	555	564	342
Regulated natural gas | Regulated assets | MEC | Retail Gas | Commercial
Disaggregation of Revenue [Line Items]
Customer revenue	216	223	111
Regulated natural gas | Regulated assets | MEC | Retail Gas | Industrial
Disaggregation of Revenue [Line Items]
Customer revenue	38	30	14
Regulated natural gas | Regulated assets | MEC | Retail Gas | Natural gas transportation services
Disaggregation of Revenue [Line Items]
Customer revenue	44	39	36
Regulated natural gas | Regulated assets | MEC | Retail Gas | Other retail
Disaggregation of Revenue [Line Items]
Customer revenue	2	3	2
Regulated natural gas | Regulated assets | MEC | Wholesale
Disaggregation of Revenue [Line Items]
Customer revenue	173	142	66
Other | Nonregulated assets | MEC
Disaggregation of Revenue [Line Items]
Customer revenue	7	15	8
Other revenue	0	0	0
Total operating revenue	7	15	8
Other | Nonregulated assets | MEC | Other
Disaggregation of Revenue [Line Items]
Customer revenue	$ 7	$ 15	$ 8