Revenue from Contracts with Customers - PAC (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Disaggregation of Revenue [Line Items]
Total Customer Revenue	$ 4,199	$ 3,317	$ 8,911	$ 6,833
Operating revenue	6,064	4,612	12,145	9,139
Other revenue
Disaggregation of Revenue [Line Items]
Operating revenue	102	102	239	220
Regulated
Disaggregation of Revenue [Line Items]
Total Customer Revenue	3,587	2,969	7,681	6,182
Regulated | Retail electric
Disaggregation of Revenue [Line Items]
Total Customer Revenue	2,411	2,172	4,519	4,233
Regulated | Wholesale
Disaggregation of Revenue [Line Items]
Total Customer Revenue	108	59	301	136
Regulated | Transmission and distribution
Disaggregation of Revenue [Line Items]
Total Customer Revenue	495	419	991	881
Regulated | Other
Disaggregation of Revenue [Line Items]
Total Customer Revenue	31	20	56	47
PAC
Disaggregation of Revenue [Line Items]
Operating revenue	1,298	1,144	2,540	2,350
PAC | Other revenue
Disaggregation of Revenue [Line Items]
Operating revenue	12	17	25	53
PAC | Regulated
Disaggregation of Revenue [Line Items]
Total Customer Revenue	1,286	1,127	2,515	2,297
PAC | Regulated | Retail electric
Disaggregation of Revenue [Line Items]
Total Customer Revenue	1,188	1,066	2,333	2,188
PAC | Regulated | Wholesale
Disaggregation of Revenue [Line Items]
Total Customer Revenue	30	17	66	17
PAC | Regulated | Transmission and distribution
Disaggregation of Revenue [Line Items]
Total Customer Revenue	37	24	62	46
PAC | Regulated | Other
Disaggregation of Revenue [Line Items]
Total Customer Revenue	31	20	54	46
PAC | Regulated | Residential | Retail electric
Disaggregation of Revenue [Line Items]
Total Customer Revenue	429	384	912	844
PAC | Regulated | Commercial | Retail electric
Disaggregation of Revenue [Line Items]
Total Customer Revenue	393	346	752	704
PAC | Regulated | Industrial | Retail electric
Disaggregation of Revenue [Line Items]
Total Customer Revenue	282	268	553	545
PAC | Regulated | Other retail | Retail electric
Disaggregation of Revenue [Line Items]
Total Customer Revenue	$ 84	$ 68	$ 116	$ 95