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v3.23.1

Segment Information (Disaggregation of Revenue) (Details) - USD ($) $ in Millions | 3 Months Ended
--- | ---
Mar. 31, 2023 | Mar. 31, 2022
Disaggregation of Revenue [Line Items] |  |
Revenues | $ 2,062 | $ 1,879
Revenues | 2,062 | 1,879
Revenues from alternative revenue programs | 98 | 45
Other revenues not from contracts with customers | (3) | 3
Union Electric Company |  |
Disaggregation of Revenue [Line Items] |  |
Revenues from alternative revenue programs | (2) | (6)
Other revenues not from contracts with customers | (6) | 0
Ameren Illinois Electric Distribution |  |
Disaggregation of Revenue [Line Items] |  |
Revenues from alternative revenue programs | 64 | 55
Other revenues not from contracts with customers | 2 | 2
Ameren Illinois Natural Gas |  |
Disaggregation of Revenue [Line Items] |  |
Revenues from alternative revenue programs | 28 | (5)
Other revenues not from contracts with customers | 1 | 1
Ameren Transmission |  |
Disaggregation of Revenue [Line Items] |  |
Revenues from alternative revenue programs | 8 | 1
Other revenues not from contracts with customers | 0 | 0
Electric |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 1,590 | 1,318
Revenues | 1,590 | 1,318
Electric | Residential |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 706 | 595
Electric | Commercial |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 447 | 398
Electric | Industrial |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 109 | 102
Electric | Other |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 328 | 223
Natural gas |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 472 | 561
Revenues | 472 | 561
Natural gas | Residential |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 348 | 420
Natural gas | Commercial |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 100 | 119
Natural gas | Industrial |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 9 | 19
Natural gas | Other |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 15 | 3
Ameren Illinois Company |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 1,101 | 1,024
Revenues | 1,101 | 1,024
Revenues from alternative revenue programs | 99 | 51
Other revenues not from contracts with customers | 3 | 3
Ameren Illinois Company | Residential |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 678 | 632
Ameren Illinois Company | Commercial |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 277 | 255
Ameren Illinois Company | Industrial |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 55 | 62
Ameren Illinois Company | Other |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 91 | 75
Ameren Illinois Company | Ameren Illinois Electric Distribution |  |
Disaggregation of Revenue [Line Items] |  |
Revenues from alternative revenue programs | 64 | 55
Other revenues not from contracts with customers | 2 | 2
Ameren Illinois Company | Ameren Illinois Natural Gas |  |
Disaggregation of Revenue [Line Items] |  |
Revenues from alternative revenue programs | 28 | (5)
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 | 7 | 1
Other revenues not from contracts with customers | 0 | 0
Ameren Illinois Company | Electric |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 710 | 543
Ameren Illinois Company | Natural gas |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 391 | 481
Operating Segments | Union Electric Company |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 913 | 808
Revenues | 923 | 818
Operating Segments | Ameren Illinois Electric Distribution |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 624 | 464
Revenues | 624 | 465
Operating Segments | Ameren Illinois Natural Gas |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 391 | 481
Revenues | 391 | 481
Operating Segments | Ameren Transmission |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 134 | 126
Revenues | 163 | 146
Operating Segments | Electric | Union Electric Company |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 841 | 738
Operating Segments | Electric | Union Electric Company | Residential |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 324 | 332
Operating Segments | Electric | Union Electric Company | Commercial |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 247 | 240
Operating Segments | Electric | Union Electric Company | Industrial |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 61 | 57
Operating Segments | Electric | Union Electric Company | Other |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 209 | 109
Operating Segments | Electric | Ameren Illinois Electric Distribution |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 624 | 465
Operating Segments | Electric | Ameren Illinois Electric Distribution | Residential |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 382 | 263
Operating Segments | Electric | Ameren Illinois Electric Distribution | Commercial |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 200 | 158
Operating Segments | Electric | Ameren Illinois Electric Distribution | Industrial |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 48 | 45
Operating Segments | Electric | Ameren Illinois Electric Distribution | Other |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | (6) | (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] |  |
Revenues | 0 | 0
Operating Segments | Electric | Ameren Illinois Natural Gas | Commercial |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 0 | 0
Operating Segments | Electric | Ameren Illinois Natural Gas | Industrial |  |
Disaggregation of Revenue [Line Items] |  |
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 | 163 | 146
Operating Segments | Electric | Ameren Transmission | Residential |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 0 | 0
Operating Segments | Electric | Ameren Transmission | Commercial |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 0 | 0
Operating Segments | Electric | Ameren Transmission | Industrial |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 0 | 0
Operating Segments | Electric | Ameren Transmission | Other |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 163 | 146
Operating Segments | Natural gas | Union Electric Company |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 82 | 80
Operating Segments | Natural gas | Union Electric Company | Residential |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 52 | 51
Operating Segments | Natural gas | Union Electric Company | Commercial |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 23 | 22
Operating Segments | Natural gas | Union Electric Company | Industrial |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 2 | 2
Operating Segments | Natural gas | Union Electric Company | Other |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 5 | 5
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] |  |
Revenues | 0 | 0
Operating Segments | Natural gas | Ameren Illinois Electric Distribution | Commercial |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 0 | 0
Operating Segments | Natural gas | Ameren Illinois Electric Distribution | Industrial |  |
Disaggregation of Revenue [Line Items] |  |
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 | 391 | 481
Operating Segments | Natural gas | Ameren Illinois Natural Gas | Residential |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 296 | 369
Operating Segments | Natural gas | Ameren Illinois Natural Gas | Commercial |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 77 | 97
Operating Segments | Natural gas | Ameren Illinois Natural Gas | Industrial |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 7 | 17
Operating Segments | Natural gas | Ameren Illinois Natural Gas | Other |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 11 | (2)
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] |  |
Revenues | 0 | 0
Operating Segments | Natural gas | Ameren Transmission | Commercial |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 0 | 0
Operating Segments | Natural gas | Ameren Transmission | Industrial |  |
Disaggregation of Revenue [Line Items] |  |
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] |  |
Revenues | 624 | 465
Operating Segments | Ameren Illinois Company | Ameren Illinois Natural Gas |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 391 | 481
Operating Segments | Ameren Illinois Company | Ameren Illinois Transmission |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 86 | 78
Operating Segments | Ameren Illinois Company | Electric | Ameren Illinois Electric Distribution |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 624 | 465
Operating Segments | Ameren Illinois Company | Electric | Ameren Illinois Electric Distribution | Residential |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 382 | 263
Operating Segments | Ameren Illinois Company | Electric | Ameren Illinois Electric Distribution | Commercial |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 200 | 158
Operating Segments | Ameren Illinois Company | Electric | Ameren Illinois Electric Distribution | Industrial |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 48 | 45
Operating Segments | Ameren Illinois Company | Electric | Ameren Illinois Electric Distribution | Other |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | (6) | (1)
Operating Segments | Ameren Illinois Company | Electric | Ameren Illinois Transmission |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 114 | 98
Operating Segments | Ameren Illinois Company | Electric | Ameren Illinois Transmission | Residential |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 0 | 0
Operating Segments | Ameren Illinois Company | Electric | Ameren Illinois Transmission | Commercial |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 0 | 0
Operating Segments | Ameren Illinois Company | Electric | Ameren Illinois Transmission | Industrial |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 0 | 0
Operating Segments | Ameren Illinois Company | Electric | Ameren Illinois Transmission | Other |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 114 | 98
Operating Segments | Ameren Illinois Company | Natural gas | Ameren Illinois Natural Gas |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 391 | 481
Operating Segments | Ameren Illinois Company | Natural gas | Ameren Illinois Natural Gas | Residential |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 296 | 369
Operating Segments | Ameren Illinois Company | Natural gas | Ameren Illinois Natural Gas | Commercial |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 77 | 97
Operating Segments | Ameren Illinois Company | Natural gas | Ameren Illinois Natural Gas | Industrial |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 7 | 17
Operating Segments | Ameren Illinois Company | Natural gas | Ameren Illinois Natural Gas | Other |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 11 | (2)
Intersegment Eliminations |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | (39) | (31)
Revenues | (39) | (31)
Intersegment Eliminations | Union Electric Company |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | (10) | (10)
Intersegment Eliminations | Ameren Illinois Electric Distribution |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 0 | (1)
Intersegment Eliminations | Ameren Illinois Natural Gas |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 0 | 0
Intersegment Eliminations | Ameren Transmission |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | (29) | (20)
Intersegment Eliminations | Electric |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | (38) | (31)
Intersegment Eliminations | Electric | Residential |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 0 | 0
Intersegment Eliminations | Electric | Commercial |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 0 | 0
Intersegment Eliminations | Electric | Industrial |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 0 | 0
Intersegment Eliminations | Electric | Other |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | (38) | (31)
Intersegment Eliminations | Natural gas |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | (1) | 0
Intersegment Eliminations | Natural gas | Residential |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 0 | 0
Intersegment Eliminations | Natural gas | Commercial |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 0 | 0
Intersegment Eliminations | Natural gas | Industrial |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 0 | 0
Intersegment Eliminations | Natural gas | Other |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | (1) | 0
Intersegment Eliminations | Ameren Illinois Company |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | (28) | (20)
Revenues | (28) | (20)
Intersegment Eliminations | Ameren Illinois Company | Residential |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 0 | 0
Intersegment Eliminations | Ameren Illinois Company | Commercial |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 0 | 0
Intersegment Eliminations | Ameren Illinois Company | Industrial |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | 0 | 0
Intersegment Eliminations | Ameren Illinois Company | Other |  |
Disaggregation of Revenue [Line Items] |  |
Revenues | (28) | (20)
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 | $ (28) | $ (20)

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