v3.26.1
Revenue from Contracts with Customers - NPC (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
NPC    
Disaggregation of Revenue [Line Items]    
Other revenue 1 1
Operating revenue 491 431
NPC | Regulated    
Disaggregation of Revenue [Line Items]    
Total Customer Revenue 490 430
NPC | Regulated | Regulated retail electric    
Disaggregation of Revenue [Line Items]    
Total Customer Revenue 478 416
NPC | Regulated | Wholesale, transmission and other    
Disaggregation of Revenue [Line Items]    
Total Customer Revenue 12 14
NPC | Customer Revenue | Regulated | Regulated retail electric    
Disaggregation of Revenue [Line Items]    
Total Customer Revenue 474 412
NPC | Customer Revenue | Regulated | Regulated retail electric | Residential    
Disaggregation of Revenue [Line Items]    
Total Customer Revenue 234 217
NPC | Customer Revenue | Regulated | Regulated retail electric | Commercial    
Disaggregation of Revenue [Line Items]    
Total Customer Revenue 118 98
NPC | Customer Revenue | Regulated | Regulated retail electric | Industrial    
Disaggregation of Revenue [Line Items]    
Total Customer Revenue 118 97
NPC | Customer Revenue | Regulated | Regulated retail electric | Other retail    
Disaggregation of Revenue [Line Items]    
Total Customer Revenue 4 0
NPC | Distribution only service | Regulated | Regulated retail electric    
Disaggregation of Revenue [Line Items]    
Total Customer Revenue $ 4 $ 4