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Acquisitions and Dispositions - Southern Power Narrative (Details) - USD ($)
$ in Millions
3 Months Ended
Mar. 31, 2021
Mar. 31, 2020
Dec. 31, 2020
Business Acquisition [Line Items]      
Construction work in progress $ 9,525   $ 8,697
Gain on equipment contribution 44 $ 39  
SOUTHERN POWER CO      
Business Acquisition [Line Items]      
Construction work in progress 219   $ 127
Gain on equipment contribution 39 $ 39  
SOUTHERN POWER CO | Series of Construction Projects      
Business Acquisition [Line Items]      
Construction work in progress 158    
SOUTHERN POWER CO | Series of Construction Projects | Minimum      
Business Acquisition [Line Items]      
Estimated future construction payments 392    
SOUTHERN POWER CO | Series of Construction Projects | Maximum      
Business Acquisition [Line Items]      
Estimated future construction payments $ 460