v3.26.3
Operating Segments - Virginia Power (Narrative) (Detail) - USD ($)
$ in Millions
 9 Months Ended
Sep. 30, 2026
Sep. 30, 2025
Segment Reporting Information [Line Items]    
Gains (loss) on investments $ 453 $ 442
Operating Segments    
Segment Reporting Information [Line Items]    
After- tax net income (expenses) (572) 81
Gains (loss) on investments 438 415
Gains (loss) on investments, after tax $ 293 $ 255
Investment, Type [Extensible Enumeration] Nuclear Decommissioning Trust Fund [Member] Nuclear Decommissioning Trust Fund [Member]
Operating Segments | Corporate and Other    
Segment Reporting Information [Line Items]    
After- tax net income (expenses) $ (826) $ (108)
After- tax net income (expenses) for specific items (577) 58
Virginia Electric and Power Company    
Segment Reporting Information [Line Items]    
Gains (loss) on investments 58 65
Virginia Electric and Power Company | Operating Segments    
Segment Reporting Information [Line Items]    
Loss associated with severe weather events 119 106
Loss associated with severe weather events, after-tax 88 79
Share of costs not expected to be recovered from customers on the CVOW commercial project 65 112
Share of costs not expected to be recovered from customers on the CVOW commercial project, after tax 48 84
Charge for the disallowance of certain strategic undergrounding costs 24  
Charge for the disallowance of certain strategic undergrounding costs, net of tax 18  
Gains (loss) on investments 63 59
Gains (loss) on investments, after tax $ 37 $ 34
Investment, Type [Extensible Enumeration] Nuclear Decommissioning Trust Fund [Member] Nuclear Decommissioning Trust Fund [Member]
Virginia Electric and Power Company | Operating Segments | Corporate and Other    
Segment Reporting Information [Line Items]    
After- tax net income (expenses) $ (102) $ (101)
After- tax net income (expenses) for specific items $ (126) $ (127)