v3.19.2
Revenue from Contracts with Customers - Disaggregate Revenue Sources (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2019
Jun. 30, 2018
Jun. 30, 2019
Jun. 30, 2018
Disaggregation of Revenue [Line Items]        
Total operating revenues $ 5,098 $ 5,627 $ 10,510 $ 11,999
Revenue from leases 184   326  
Total retail electric and gas distribution revenues        
Disaggregation of Revenue [Line Items]        
Total operating revenues 4,103 4,378 8,347 9,146
Total retail electric revenues        
Disaggregation of Revenue [Line Items]        
Revenue from leases 8 18 16 36
Increase (decrease) in revenue from cost recovery mechanisms (14) 68 (117) 101
Residential        
Disaggregation of Revenue [Line Items]        
Total operating revenues 1,488 1,579 2,776 3,118
Commercial        
Disaggregation of Revenue [Line Items]        
Total operating revenues 1,258 1,315 2,350 2,557
Industrial        
Disaggregation of Revenue [Line Items]        
Total operating revenues 763 814 1,440 1,569
Other        
Disaggregation of Revenue [Line Items]        
Total operating revenues 31 32 57 64
Natural gas distribution revenues        
Disaggregation of Revenue [Line Items]        
Total operating revenues 562 642 1,724 1,865
Revenues not accounted for under ASC 606 5 5 8 8
Alternative revenue programs        
Disaggregation of Revenue [Line Items]        
Total operating revenues 1 (4) 0 (27)
Wholesale energy revenues        
Disaggregation of Revenue [Line Items]        
Total operating revenues 410 464 777 937
Revenue from leases 115 118 182 187
Revenue from transactions accounted for as derivatives 30 61 82 155
Wholesale capacity revenues        
Disaggregation of Revenue [Line Items]        
Total operating revenues 132 152 264 302
Revenue from leases 22 31 47 61
Other natural gas revenues        
Disaggregation of Revenue [Line Items]        
Total operating revenues 126 68 439 476
Revenue from leases 8   16  
Revenues not accounted for under ASC 606 10   27  
Other revenues        
Disaggregation of Revenue [Line Items]        
Total operating revenues 327 565 683 1,138
Revenue from leases 28 33 59 66
Revenues not accounted for under ASC 606 89 89 180 183
ALABAMA POWER CO        
Disaggregation of Revenue [Line Items]        
Total operating revenues 1,513 1,503 2,921 2,976
ALABAMA POWER CO | Total retail electric revenues        
Disaggregation of Revenue [Line Items]        
Total operating revenues 1,378 1,338 2,592 2,624
Increase (decrease) in revenue from cost recovery mechanisms (11) 78 (68) 125
ALABAMA POWER CO | Residential        
Disaggregation of Revenue [Line Items]        
Total operating revenues 588 557 1,128 1,127
ALABAMA POWER CO | Commercial        
Disaggregation of Revenue [Line Items]        
Total operating revenues 418 402 772 774
ALABAMA POWER CO | Industrial        
Disaggregation of Revenue [Line Items]        
Total operating revenues 366 372 679 710
ALABAMA POWER CO | Other        
Disaggregation of Revenue [Line Items]        
Total operating revenues 6 7 13 13
ALABAMA POWER CO | Wholesale energy revenues        
Disaggregation of Revenue [Line Items]        
Total operating revenues 41 71 135 172
Revenue from transactions accounted for as derivatives 3 4 6 9
ALABAMA POWER CO | Wholesale capacity revenues        
Disaggregation of Revenue [Line Items]        
Total operating revenues 25 25 51 49
ALABAMA POWER CO | Other revenues        
Disaggregation of Revenue [Line Items]        
Total operating revenues 69 69 143 131
Revenues not accounted for under ASC 606 31 26 59 52
GEORGIA POWER CO        
Disaggregation of Revenue [Line Items]        
Total operating revenues 2,117 2,048 3,951 4,008
Revenue from leases 19   39  
GEORGIA POWER CO | Total retail electric revenues        
Disaggregation of Revenue [Line Items]        
Total operating revenues 1,946 1,889 3,614 3,688
Revenue from leases 8 18 16 36
Increase (decrease) in revenue from cost recovery mechanisms (5) 3 (52) 12
GEORGIA POWER CO | Residential        
Disaggregation of Revenue [Line Items]        
Total operating revenues 831 785 1,519 1,529
GEORGIA POWER CO | Commercial        
Disaggregation of Revenue [Line Items]        
Total operating revenues 767 749 1,440 1,466
GEORGIA POWER CO | Industrial        
Disaggregation of Revenue [Line Items]        
Total operating revenues 327 335 616 650
GEORGIA POWER CO | Other        
Disaggregation of Revenue [Line Items]        
Total operating revenues 21 20 39 43
GEORGIA POWER CO | Wholesale energy revenues        
Disaggregation of Revenue [Line Items]        
Total operating revenues 14 26 27 66
Revenue from transactions accounted for as derivatives 4 5 8 13
GEORGIA POWER CO | Wholesale capacity revenues        
Disaggregation of Revenue [Line Items]        
Total operating revenues 22 13 40 27
GEORGIA POWER CO | Other revenues        
Disaggregation of Revenue [Line Items]        
Total operating revenues 135 120 270 227
Revenue from leases 11 33 23 66
Revenues not accounted for under ASC 606 30 26 61 53
MISSISSIPPI POWER CO        
Disaggregation of Revenue [Line Items]        
Total operating revenues 313 297 600 598
Revenue from leases 2   5  
MISSISSIPPI POWER CO | Total retail electric revenues        
Disaggregation of Revenue [Line Items]        
Total operating revenues 215 212 418 406
Increase (decrease) in revenue from cost recovery mechanisms 2 (1) 3 (8)
MISSISSIPPI POWER CO | Residential        
Disaggregation of Revenue [Line Items]        
Total operating revenues 69 65 129 125
MISSISSIPPI POWER CO | Commercial        
Disaggregation of Revenue [Line Items]        
Total operating revenues 73 68 138 130
MISSISSIPPI POWER CO | Industrial        
Disaggregation of Revenue [Line Items]        
Total operating revenues 70 76 145 146
MISSISSIPPI POWER CO | Other        
Disaggregation of Revenue [Line Items]        
Total operating revenues 3 3 6 5
MISSISSIPPI POWER CO | Wholesale energy revenues        
Disaggregation of Revenue [Line Items]        
Total operating revenues 93 77 170 176
Revenue from transactions accounted for as derivatives 1 1 1 2
MISSISSIPPI POWER CO | Wholesale capacity revenues        
Disaggregation of Revenue [Line Items]        
Total operating revenues 1 1 2 5
MISSISSIPPI POWER CO | Other revenues        
Disaggregation of Revenue [Line Items]        
Total operating revenues 4 7 10 11
SOUTHERN POWER CO        
Disaggregation of Revenue [Line Items]        
Total operating revenues 510 555 953 1,064
Revenue from leases 164   278  
SOUTHERN POWER CO | Other revenues        
Disaggregation of Revenue [Line Items]        
Total operating revenues 3 3 6 5
SOUTHERN POWER CO | PPA capacity revenues        
Disaggregation of Revenue [Line Items]        
Total operating revenues 125 144 252 282
Revenue from leases 39 47 80 94
SOUTHERN POWER CO | PPA energy revenues        
Disaggregation of Revenue [Line Items]        
Total operating revenues 291 302 518 556
Revenue from leases 125 127 198 203
SOUTHERN POWER CO | Non-PPA revenues        
Disaggregation of Revenue [Line Items]        
Total operating revenues 91 106 177 221
Revenue from transactions accounted for as derivatives 22 50 67 129
SOUTHERN Co GAS        
Disaggregation of Revenue [Line Items]        
Total operating revenues 689 730 2,163 2,369
Revenue from leases 9   17  
SOUTHERN Co GAS | Wholesale Gas Services | Third Party Gross Revenues        
Disaggregation of Revenue [Line Items]        
Revenue from transactions accounted for as derivatives 800 700 2,000 1,800
SOUTHERN Co GAS | Operating Segments        
Disaggregation of Revenue [Line Items]        
Total operating revenues 682 724 2,177 2,381
SOUTHERN Co GAS | Operating Segments | Wholesale Gas Services        
Disaggregation of Revenue [Line Items]        
Total operating revenues 48 (16) 134 150
SOUTHERN Co GAS | Operating Segments | Wholesale Gas Services | Third Party Gross Revenues        
Disaggregation of Revenue [Line Items]        
Total operating revenues 1,223 1,336 3,148 3,274
SOUTHERN Co GAS | Natural gas distribution revenues        
Disaggregation of Revenue [Line Items]        
Total operating revenues 563 638 1,724 1,838
Revenues not accounted for under ASC 606 5 5 8 8
SOUTHERN Co GAS | Residential        
Disaggregation of Revenue [Line Items]        
Total operating revenues 229 273 830 933
SOUTHERN Co GAS | Commercial        
Disaggregation of Revenue [Line Items]        
Total operating revenues 65 76 235 268
SOUTHERN Co GAS | Transportation        
Disaggregation of Revenue [Line Items]        
Total operating revenues 213 228 469 505
SOUTHERN Co GAS | Industrial        
Disaggregation of Revenue [Line Items]        
Total operating revenues 5 7 22 24
SOUTHERN Co GAS | Other        
Disaggregation of Revenue [Line Items]        
Total operating revenues 50 58 168 135
SOUTHERN Co GAS | Alternative revenue programs        
Disaggregation of Revenue [Line Items]        
Total operating revenues 1 (4) 0 (27)
SOUTHERN Co GAS | Other natural gas revenues | Wholesale Gas Services | Third Party Gross Revenues        
Disaggregation of Revenue [Line Items]        
Total operating revenues 1,200 1,300 3,100 3,300
SOUTHERN Co GAS | Other revenues        
Disaggregation of Revenue [Line Items]        
Total operating revenues 12 10 22 25
SOUTHERN Co GAS | Wholesale Gas Services        
Disaggregation of Revenue [Line Items]        
Total operating revenues 48 (15) 114 131
SOUTHERN Co GAS | Gas pipeline investments        
Disaggregation of Revenue [Line Items]        
Total operating revenues 8 8 16 16
Revenue from leases 8   16  
SOUTHERN Co GAS | Gas marketing services        
Disaggregation of Revenue [Line Items]        
Total operating revenues 58 $ 89 287 359
Revenues not accounted for under ASC 606 $ 2   $ 11 $ 4