XML 72 R46.htm IDEA: XBRL DOCUMENT v3.21.1
Regulatory Matters - MPC (Details) - MISSISSIPPI POWER CO
$ in Millions
Apr. 06, 2021
USD ($)
Mar. 15, 2021
USD ($)
Apr. 15, 2021
MW
Mar. 31, 2021
USD ($)
Dec. 31, 2020
MW
Loss Contingencies [Line Items]          
Requested revenues increase percentage   1.80%      
Requested revenues increase amount | $   $ 16      
Required fossil-stream generation retirements (in MWs) | MW         950
Plant Daniel Units 1 and 2          
Loss Contingencies [Line Items]          
Remaining net book value | $       $ 531  
Subsequent Event          
Loss Contingencies [Line Items]          
Requested revenues increase amount | $ $ 28        
Public utilities, valorem taxes previously recovered, amount | $ $ 19        
Subsequent Event | Plant Watson Unit 4          
Loss Contingencies [Line Items]          
Required fossil-stream generation retirements (in MWs) | MW     268    
Subsequent Event | Plant Greene County Units 1 and 2          
Loss Contingencies [Line Items]          
Required fossil-stream generation retirements (in MWs) | MW     103    
Subsequent Event | Plant Greene County Units 1 and 2 | ALABAMA POWER CO          
Loss Contingencies [Line Items]          
Proportionate ownership share     40.00%    
Subsequent Event | Plant Daniel Units 1 and 2          
Loss Contingencies [Line Items]          
Required fossil-stream generation retirements (in MWs) | MW     502    
Proportionate ownership share     50.00%