v3.26.1
Revenue from Contracts with Customers - SPPC (Details) - USD ($)
$ in Millions
3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Disaggregation of Revenue [Line Items]    
Operating revenue $ 6,672 $ 6,366
Regulated | Regulated retail electric    
Disaggregation of Revenue [Line Items]    
Total Customer Revenue 2,968 2,824
Regulated | Regulated retail gas    
Disaggregation of Revenue [Line Items]    
Total Customer Revenue 369 358
SPPC    
Disaggregation of Revenue [Line Items]    
Other revenue 0 0
Operating revenue 272 285
SPPC | Electric    
Disaggregation of Revenue [Line Items]    
Other revenue 0 0
Operating revenue 235 236
SPPC | Natural Gas    
Disaggregation of Revenue [Line Items]    
Other revenue 0 0
Operating revenue 37 49
SPPC | Regulated    
Disaggregation of Revenue [Line Items]    
Total Customer Revenue 272 285
SPPC | Regulated | Wholesale, transmission and other    
Disaggregation of Revenue [Line Items]    
Total Customer Revenue 22 18
SPPC | Regulated | Electric    
Disaggregation of Revenue [Line Items]    
Total Customer Revenue 235 236
SPPC | Regulated | Electric | Wholesale, transmission and other    
Disaggregation of Revenue [Line Items]    
Total Customer Revenue 19 18
SPPC | Regulated | Natural Gas    
Disaggregation of Revenue [Line Items]    
Total Customer Revenue 37 49
SPPC | Regulated | Natural Gas | Wholesale, transmission and other    
Disaggregation of Revenue [Line Items]    
Total Customer Revenue 3 0
SPPC | Regulated | Total retail    
Disaggregation of Revenue [Line Items]    
Total Customer Revenue 250 267
SPPC | Regulated | Total retail | Electric | Regulated retail electric    
Disaggregation of Revenue [Line Items]    
Total Customer Revenue 216 218
SPPC | Regulated | Total retail | Natural Gas | Regulated retail gas    
Disaggregation of Revenue [Line Items]    
Total Customer Revenue 34 49
SPPC | Regulated | Customer Revenue    
Disaggregation of Revenue [Line Items]    
Total Customer Revenue 248 265
SPPC | Regulated | Customer Revenue | Residential    
Disaggregation of Revenue [Line Items]    
Total Customer Revenue 112 125
SPPC | Regulated | Customer Revenue | Commercial    
Disaggregation of Revenue [Line Items]    
Total Customer Revenue 81 86
SPPC | Regulated | Customer Revenue | Industrial    
Disaggregation of Revenue [Line Items]    
Total Customer Revenue 54 52
SPPC | Regulated | Customer Revenue | Other retail    
Disaggregation of Revenue [Line Items]    
Total Customer Revenue 1 2
SPPC | Regulated | Customer Revenue | Electric | Regulated retail electric    
Disaggregation of Revenue [Line Items]    
Total Customer Revenue 214 216
SPPC | Regulated | Customer Revenue | Electric | Regulated retail electric | Residential    
Disaggregation of Revenue [Line Items]    
Total Customer Revenue 89 93
SPPC | Regulated | Customer Revenue | Electric | Regulated retail electric | Commercial    
Disaggregation of Revenue [Line Items]    
Total Customer Revenue 72 73
SPPC | Regulated | Customer Revenue | Electric | Regulated retail electric | Industrial    
Disaggregation of Revenue [Line Items]    
Total Customer Revenue 52 48
SPPC | Regulated | Customer Revenue | Electric | Regulated retail electric | Other retail    
Disaggregation of Revenue [Line Items]    
Total Customer Revenue 1 2
SPPC | Regulated | Customer Revenue | Natural Gas | Regulated retail gas    
Disaggregation of Revenue [Line Items]    
Total Customer Revenue 34 49
SPPC | Regulated | Customer Revenue | Natural Gas | Regulated retail gas | Residential    
Disaggregation of Revenue [Line Items]    
Total Customer Revenue 23 32
SPPC | Regulated | Customer Revenue | Natural Gas | Regulated retail gas | Commercial    
Disaggregation of Revenue [Line Items]    
Total Customer Revenue 9 13
SPPC | Regulated | Customer Revenue | Natural Gas | Regulated retail gas | Industrial    
Disaggregation of Revenue [Line Items]    
Total Customer Revenue 2 4
SPPC | Regulated | Customer Revenue | Natural Gas | Regulated retail gas | Other retail    
Disaggregation of Revenue [Line Items]    
Total Customer Revenue 0 0
SPPC | Regulated | Distribution only service    
Disaggregation of Revenue [Line Items]    
Total Customer Revenue 2 2
SPPC | Regulated | Distribution only service | Electric | Regulated retail electric    
Disaggregation of Revenue [Line Items]    
Total Customer Revenue 2 2
SPPC | Regulated | Distribution only service | Natural Gas | Regulated retail gas    
Disaggregation of Revenue [Line Items]    
Total Customer Revenue $ 0 $ 0