v3.26.1
Revenue from Contracts with Customers and Lease Income - Schedule of Contract Balances (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2026
Dec. 31, 2025
Disaggregation of Revenue [Line Items]      
Accounts Receivable $ 3,155 $ 3,155 $ 3,139
Contract Assets 354 354 294
Contract Liabilities 329 329 213
Revenue from contracts with customers recognized 26 80  
ALABAMA POWER CO      
Disaggregation of Revenue [Line Items]      
Accounts Receivable 860 860 716
Contract Assets 0 0 3
Contract Liabilities 7 7 6
Revenue from contracts with customers recognized 0 0  
GEORGIA POWER CO      
Disaggregation of Revenue [Line Items]      
Accounts Receivable 1,549 1,549 1,278
Contract Assets 189 189 160
Contract Liabilities 123 123 75
Revenue from contracts with customers recognized 7 18  
MISSISSIPPI POWER CO      
Disaggregation of Revenue [Line Items]      
Accounts Receivable 122 122 115
Contract Assets 4 4 0
Contract Liabilities 0 0 0
Revenue from contracts with customers recognized 0 0  
SOUTHERN POWER CO      
Disaggregation of Revenue [Line Items]      
Accounts Receivable 136 136 132
Contract Assets 0 0 0
Contract Liabilities 1 1 2
Revenue from contracts with customers recognized 0 0  
SOUTHERN Co GAS      
Disaggregation of Revenue [Line Items]      
Accounts Receivable 448 448 864
Contract Assets 67 67 67
Contract Liabilities 0 0 $ 0
Revenue from contracts with customers recognized $ 0 $ 0