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Accounting For Asset Retirement And Environmental Obligations - Additional Information (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2021
Dec. 31, 2019
Dec. 31, 2020
Asset Retirement And Environmental Obligations [Line Items]      
Increase (decrease) in asset retirement obligations   $ 37.6  
North Anna [Member]      
Asset Retirement And Environmental Obligations [Line Items]      
North Anna's nuclear decommissioning asset retirement obligation $ 161.5   $ 156.9
Decommission study period 4 years    
Asset retirement obligations cash flow estimates useful life 20 years    
Asset retirement obligations cash flow estimates related to application for additional operating license extension 20 years