Revenue from Contracts with Customers - PAC (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Disaggregation of Revenue [Line Items]
Total Customer Revenue	$ 5,138	$ 4,357	$ 14,049	$ 11,190
Operating revenue	6,968	6,193	19,113	15,332
Other revenue
Disaggregation of Revenue [Line Items]
Operating revenue	87	94	326	314
Regulated
Disaggregation of Revenue [Line Items]
Total Customer Revenue	4,430	3,927	12,111	10,109
Regulated | Retail electric
Disaggregation of Revenue [Line Items]
Total Customer Revenue	3,096	2,981	7,615	7,214
Regulated | Wholesale
Disaggregation of Revenue [Line Items]
Total Customer Revenue	203	130	504	266
Regulated | Transmission and distribution
Disaggregation of Revenue [Line Items]
Total Customer Revenue	521	455	1,512	1,336
Regulated | Other
Disaggregation of Revenue [Line Items]
Total Customer Revenue	24	42	80	89
PAC
Disaggregation of Revenue [Line Items]
Operating revenue	1,491	1,479	4,031	3,829
PAC | Other revenue
Disaggregation of Revenue [Line Items]
Operating revenue	0	1	25	54
PAC | Regulated
Disaggregation of Revenue [Line Items]
Total Customer Revenue	1,491	1,478	4,006	3,775
PAC | Regulated | Retail electric
Disaggregation of Revenue [Line Items]
Total Customer Revenue	1,352	1,344	3,685	3,532
PAC | Regulated | Wholesale
Disaggregation of Revenue [Line Items]
Total Customer Revenue	58	59	124	76
PAC | Regulated | Transmission and distribution
Disaggregation of Revenue [Line Items]
Total Customer Revenue	55	33	117	79
PAC | Regulated | Other
Disaggregation of Revenue [Line Items]
Total Customer Revenue	26	42	80	88
PAC | Regulated | Residential | Retail electric
Disaggregation of Revenue [Line Items]
Total Customer Revenue	530	519	1,442	1,363
PAC | Regulated | Commercial | Retail electric
Disaggregation of Revenue [Line Items]
Total Customer Revenue	428	418	1,180	1,122
PAC | Regulated | Industrial | Retail electric
Disaggregation of Revenue [Line Items]
Total Customer Revenue	296	293	849	838
PAC | Regulated | Other retail | Retail electric
Disaggregation of Revenue [Line Items]
Total Customer Revenue	$ 98	$ 114	$ 214	$ 209