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v3.25.1

Segment Information (Disaggregation of Revenue) (Details) - USD ($) $ in Millions | 3 Months Ended
--- | ---
Mar. 31, 2025 | Mar. 31, 2024
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | $ 2,097 | $ 1,816
Revenues | 2,097 | 1,816
Revenues from alternative revenue programs | 18 | 61
Other revenues not from contracts with customers | 5 | 4
Union Electric Company |  |
Disaggregation of Revenue [Line Items] |  |
Revenues from alternative revenue programs | (5) | (6)
Other revenues not from contracts with customers | 1 | 1
Ameren Illinois Electric Distribution |  |
Disaggregation of Revenue [Line Items] |  |
Revenues from alternative revenue programs | 21 | 39
Other revenues not from contracts with customers | 3 | 2
Ameren Illinois Natural Gas |  |
Disaggregation of Revenue [Line Items] |  |
Revenues from alternative revenue programs | 3 | 19
Other revenues not from contracts with customers | 1 | 1
Ameren Transmission |  |
Disaggregation of Revenue [Line Items] |  |
Revenues from alternative revenue programs | (1) | 9
Other revenues not from contracts with customers | 0 | 0
Electric |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 1,622 | 1,364
Revenues | 1,622 | 1,364
Electric | Residential |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 718 | 638
Electric | Commercial |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 453 | 424
Electric | Industrial |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 116 | 106
Electric | Other |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 335 | 196
Natural gas |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 475 | 452
Revenues | 475 | 452
Natural gas | Residential |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 352 | 327
Natural gas | Commercial |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 96 | 84
Natural gas | Industrial |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 6 | 6
Natural gas | Other |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 21 | 35
Ameren Illinois Company |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 1,100 | 1,000
Revenues | 1,100 | 1,000
Revenues from alternative revenue programs | 23 | 66
Other revenues not from contracts with customers | 4 | 3
Ameren Illinois Company | Residential |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 651 | 584
Ameren Illinois Company | Commercial |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 257 | 233
Ameren Illinois Company | Industrial |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 54 | 49
Ameren Illinois Company | Other |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 138 | 134
Ameren Illinois Company | Ameren Illinois Electric Distribution |  |
Disaggregation of Revenue [Line Items] |  |
Revenues from alternative revenue programs | 21 | 39
Other revenues not from contracts with customers | 3 | 2
Ameren Illinois Company | Ameren Illinois Natural Gas |  |
Disaggregation of Revenue [Line Items] |  |
Revenues from alternative revenue programs | 3 | 19
Other revenues not from contracts with customers | 1 | 1
Ameren Illinois Company | Ameren Illinois Transmission |  |
Disaggregation of Revenue [Line Items] |  |
Revenues from alternative revenue programs | (1) | 8
Other revenues not from contracts with customers | 0 | 0
Ameren Illinois Company | Electric |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 689 | 609
Ameren Illinois Company | Natural gas |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 411 | 391
Operating Segments | Union Electric Company |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 950 | 768
Revenues | 957 | 775
Operating Segments | Ameren Illinois Electric Distribution |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 570 | 506
Revenues | 572 | 506
Operating Segments | Ameren Illinois Natural Gas |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 411 | 391
Revenues | 411 | 391
Operating Segments | Ameren Transmission |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 166 | 151
Revenues | 210 | 185
Operating Segments | Electric | Union Electric Company |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 893 | 714
Operating Segments | Electric | Union Electric Company | Residential |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 376 | 341
Operating Segments | Electric | Union Electric Company | Commercial |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 273 | 259
Operating Segments | Electric | Union Electric Company | Industrial |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 66 | 61
Operating Segments | Electric | Union Electric Company | Other |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 178 | 53
Operating Segments | Electric | Ameren Illinois Electric Distribution |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 572 | 506
Operating Segments | Electric | Ameren Illinois Electric Distribution | Residential |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 342 | 297
Operating Segments | Electric | Ameren Illinois Electric Distribution | Commercial |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 180 | 165
Operating Segments | Electric | Ameren Illinois Electric Distribution | Industrial |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 50 | 45
Operating Segments | Electric | Ameren Illinois Electric Distribution | Other |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 0 | (1)
Operating Segments | Electric | Ameren Illinois Natural Gas |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 0 | 0
Operating Segments | Electric | Ameren Illinois Natural Gas | Residential |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 0 | 0
Operating Segments | Electric | Ameren Illinois Natural Gas | Commercial |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 0 | 0
Operating Segments | Electric | Ameren Illinois Natural Gas | Industrial |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 0 | 0
Operating Segments | Electric | Ameren Illinois Natural Gas | Other |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 0 | 0
Operating Segments | Electric | Ameren Transmission |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 210 | 185
Operating Segments | Electric | Ameren Transmission | Residential |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 0 | 0
Operating Segments | Electric | Ameren Transmission | Commercial |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 0 | 0
Operating Segments | Electric | Ameren Transmission | Industrial |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 0 | 0
Operating Segments | Electric | Ameren Transmission | Other |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 210 | 185
Operating Segments | Natural gas | Union Electric Company |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 64 | 61
Operating Segments | Natural gas | Union Electric Company | Residential |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 43 | 40
Operating Segments | Natural gas | Union Electric Company | Commercial |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 19 | 16
Operating Segments | Natural gas | Union Electric Company | Industrial |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 2 | 2
Operating Segments | Natural gas | Union Electric Company | Other |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 0 | 3
Operating Segments | Natural gas | Ameren Illinois Electric Distribution |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 0 | 0
Operating Segments | Natural gas | Ameren Illinois Electric Distribution | Residential |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 0 | 0
Operating Segments | Natural gas | Ameren Illinois Electric Distribution | Commercial |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 0 | 0
Operating Segments | Natural gas | Ameren Illinois Electric Distribution | Industrial |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 0 | 0
Operating Segments | Natural gas | Ameren Illinois Electric Distribution | Other |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 0 | 0
Operating Segments | Natural gas | Ameren Illinois Natural Gas |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 411 | 391
Operating Segments | Natural gas | Ameren Illinois Natural Gas | Residential |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 309 | 287
Operating Segments | Natural gas | Ameren Illinois Natural Gas | Commercial |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 77 | 68
Operating Segments | Natural gas | Ameren Illinois Natural Gas | Industrial |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 4 | 4
Operating Segments | Natural gas | Ameren Illinois Natural Gas | Other |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 21 | 32
Operating Segments | Natural gas | Ameren Transmission |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 0 | 0
Operating Segments | Natural gas | Ameren Transmission | Residential |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 0 | 0
Operating Segments | Natural gas | Ameren Transmission | Commercial |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 0 | 0
Operating Segments | Natural gas | Ameren Transmission | Industrial |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 0 | 0
Operating Segments | Natural gas | Ameren Transmission | Other |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 0 | 0
Operating Segments | Ameren Illinois Company | Ameren Illinois Electric Distribution |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 572 | 506
Revenues | 572 | 506
Operating Segments | Ameren Illinois Company | Ameren Illinois Natural Gas |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 411 | 391
Revenues | 411 | 391
Operating Segments | Ameren Illinois Company | Ameren Illinois Transmission |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 117 | 103
Revenues | 154 | 131
Operating Segments | Ameren Illinois Company | Electric | Ameren Illinois Electric Distribution |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 572 | 506
Operating Segments | Ameren Illinois Company | Electric | Ameren Illinois Electric Distribution | Residential |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 342 | 297
Operating Segments | Ameren Illinois Company | Electric | Ameren Illinois Electric Distribution | Commercial |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 180 | 165
Operating Segments | Ameren Illinois Company | Electric | Ameren Illinois Electric Distribution | Industrial |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 50 | 45
Operating Segments | Ameren Illinois Company | Electric | Ameren Illinois Electric Distribution | Other |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 0 | (1)
Operating Segments | Ameren Illinois Company | Electric | Ameren Illinois Transmission |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 154 | 131
Operating Segments | Ameren Illinois Company | Electric | Ameren Illinois Transmission | Residential |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 0 | 0
Operating Segments | Ameren Illinois Company | Electric | Ameren Illinois Transmission | Commercial |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 0 | 0
Operating Segments | Ameren Illinois Company | Electric | Ameren Illinois Transmission | Industrial |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 0 | 0
Operating Segments | Ameren Illinois Company | Electric | Ameren Illinois Transmission | Other |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 154 | 131
Operating Segments | Ameren Illinois Company | Natural gas | Ameren Illinois Natural Gas |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 411 | 391
Operating Segments | Ameren Illinois Company | Natural gas | Ameren Illinois Natural Gas | Residential |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 309 | 287
Operating Segments | Ameren Illinois Company | Natural gas | Ameren Illinois Natural Gas | Commercial |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 77 | 68
Operating Segments | Ameren Illinois Company | Natural gas | Ameren Illinois Natural Gas | Industrial |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 4 | 4
Operating Segments | Ameren Illinois Company | Natural gas | Ameren Illinois Natural Gas | Other |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 21 | 32
Intersegment Eliminations |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | (53) | (41)
Revenues | (53) | (41)
Intersegment Eliminations | Union Electric Company |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | (7) | (7)
Intersegment Eliminations | Ameren Illinois Electric Distribution |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | (2) | 0
Intersegment Eliminations | Ameren Illinois Natural Gas |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 0 | 0
Intersegment Eliminations | Ameren Transmission |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | (44) | (34)
Intersegment Eliminations | Electric |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | (53) | (41)
Intersegment Eliminations | Electric | Residential |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 0 | 0
Intersegment Eliminations | Electric | Commercial |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 0 | 0
Intersegment Eliminations | Electric | Industrial |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 0 | 0
Intersegment Eliminations | Electric | Other |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | (53) | (41)
Intersegment Eliminations | Natural gas |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 0 | 0
Intersegment Eliminations | Natural gas | Residential |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 0 | 0
Intersegment Eliminations | Natural gas | Commercial |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 0 | 0
Intersegment Eliminations | Natural gas | Industrial |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 0 | 0
Intersegment Eliminations | Natural gas | Other |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 0 | 0
Intersegment Eliminations | Ameren Illinois Company |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | (37) | (28)
Revenues | (37) | (28)
Intersegment Eliminations | Ameren Illinois Company | Residential |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 0 | 0
Intersegment Eliminations | Ameren Illinois Company | Commercial |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 0 | 0
Intersegment Eliminations | Ameren Illinois Company | Industrial |  |
Disaggregation of Revenue [Line Items] |  |
Operating Revenues | 0 | 0
Intersegment Eliminations | Ameren Illinois Company | Other |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | (37) | (28)
Intersegment Eliminations | Ameren Illinois Company | Ameren Illinois Electric Distribution |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 0 | 0
Intersegment Eliminations | Ameren Illinois Company | Ameren Illinois Natural Gas |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 0 | 0
Intersegment Eliminations | Ameren Illinois Company | Ameren Illinois Transmission |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | $ (37) | $ (28)

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