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v3.22.2.2

Segment Information (Disaggregation of Revenue) (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2022 | Sep. 30, 2021 | Sep. 30, 2022 | Sep. 30, 2021
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | $ 2,306 | $ 1,811 | $ 5,911 | $ 4,849
Revenues | 2,306 | 1,811 | 5,911 | 4,849
Revenues from alternative revenue programs | (83) | (95) | 2 | (6)
Other revenues not from contracts with customers | (43) | 13 | (74) | 82
Union Electric Company |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from alternative revenue programs | 14 | 6 | 8 | (9)
Other revenues not from contracts with customers | (45) | 7 | (81) | 71
Ameren Illinois Electric Distribution |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from alternative revenue programs | (83) | (97) | 13 | (2)
Other revenues not from contracts with customers | 2 | 6 | 5 | 9
Ameren Illinois Natural Gas |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from alternative revenue programs | (3) | (5) | (5) | 0
Other revenues not from contracts with customers | 0 | 0 | 2 | 2
Ameren Transmission |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from alternative revenue programs | (11) | 1 | (14) | 5
Other revenues not from contracts with customers | 0 | 0 | 0 | 0
Electric |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 2,140 | 1,668 | 4,971 | 4,108
Revenues | 2,140 | 1,668 | 4,971 | 4,108
Electric | Residential |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 971 | 795 | 2,221 | 1,882
Electric | Commercial |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 663 | 555 | 1,539 | 1,301
Electric | Industrial |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 146 | 124 | 374 | 315
Electric | Other |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 360 | 194 | 837 | 610
Natural gas |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 166 | 143 | 940 | 741
Revenues | 166 | 143 | 940 | 741
Natural gas | Residential |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 100 | 84 | 653 | 492
Natural gas | Commercial |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 31 | 27 | 188 | 139
Natural gas | Industrial |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 6 | 3 | 37 | 22
Natural gas | Other |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 29 | 29 | 62 | 88
Ameren Illinois Company |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 904 | 645 | 2,697 | 2,097
Revenues | 904 | 645 | 2,697 | 2,097
Revenues from alternative revenue programs | (96) | (99) | (4) | 2
Other revenues not from contracts with customers | 2 | 6 | 7 | 11
Ameren Illinois Company | Residential |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 496 | 333 | 1,529 | 1,143
Ameren Illinois Company | Commercial |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 258 | 166 | 723 | 518
Ameren Illinois Company | Industrial |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 52 | 29 | 178 | 114
Ameren Illinois Company | Other |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 98 | 117 | 267 | 322
Ameren Illinois Company | Ameren Illinois Electric Distribution |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from alternative revenue programs | (83) | (97) | 13 | (2)
Other revenues not from contracts with customers | 2 | 6 | 5 | 9
Ameren Illinois Company | Ameren Illinois Natural Gas |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from alternative revenue programs | (3) | (5) | (5) | 0
Other revenues not from contracts with customers | 0 | 0 | 2 | 2
Ameren Illinois Company | Ameren Illinois Transmission |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues from alternative revenue programs | (10) | 3 | (12) | 4
Other revenues not from contracts with customers | 0 | 0 | 0 | 0
Ameren Illinois Company | Electric |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 758 | 518 | 1,886 | 1,455
Ameren Illinois Company | Natural gas |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 146 | 127 | 811 | 642
Operating Segments | Union Electric Company |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 1,351 | 1,118 | 3,071 | 2,612
Revenues | 1,359 | 1,129 | 3,096 | 2,642
Operating Segments | Ameren Illinois Electric Distribution |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 672 | 425 | 1,640 | 1,222
Revenues | 672 | 428 | 1,641 | 1,227
Operating Segments | Ameren Illinois Natural Gas |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 146 | 127 | 811 | 642
Revenues | 146 | 127 | 811 | 642
Operating Segments | Ameren Transmission |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 137 | 141 | 389 | 373
Revenues | 169 | 160 | 465 | 426
Operating Segments | Electric | Union Electric Company |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 1,338 | 1,113 | 2,966 | 2,543
Operating Segments | Electric | Union Electric Company | Residential |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 564 | 537 | 1,267 | 1,177
Operating Segments | Electric | Union Electric Company | Commercial |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 430 | 412 | 968 | 899
Operating Segments | Electric | Union Electric Company | Industrial |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 99 | 98 | 229 | 221
Operating Segments | Electric | Union Electric Company | Other |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 245 | 66 | 502 | 246
Operating Segments | Electric | Ameren Illinois Electric Distribution |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 672 | 428 | 1,641 | 1,227
Operating Segments | Electric | Ameren Illinois Electric Distribution | Residential |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 407 | 258 | 954 | 705
Operating Segments | Electric | Ameren Illinois Electric Distribution | Commercial |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 233 | 143 | 571 | 402
Operating Segments | Electric | Ameren Illinois Electric Distribution | Industrial |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 47 | 26 | 145 | 94
Operating Segments | Electric | Ameren Illinois Electric Distribution | Other |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | (15) | 1 | (29) | 26
Operating Segments | Electric | Ameren Illinois Natural Gas |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 0 | 0 | 0 | 0
Operating Segments | Electric | Ameren Illinois Natural Gas | Residential |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 0 | 0 | 0 | 0
Operating Segments | Electric | Ameren Illinois Natural Gas | Commercial |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 0 | 0 | 0 | 0
Operating Segments | Electric | Ameren Illinois Natural Gas | Industrial |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 0 | 0 | 0 | 0
Operating Segments | Electric | Ameren Illinois Natural Gas | Other |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 0 | 0 | 0 | 0
Operating Segments | Electric | Ameren Transmission |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 169 | 160 | 465 | 426
Operating Segments | Electric | Ameren Transmission | Residential |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 0 | 0 | 0 | 0
Operating Segments | Electric | Ameren Transmission | Commercial |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 0 | 0 | 0 | 0
Operating Segments | Electric | Ameren Transmission | Industrial |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 0 | 0 | 0 | 0
Operating Segments | Electric | Ameren Transmission | Other |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 169 | 160 | 465 | 426
Operating Segments | Natural gas | Union Electric Company |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 21 | 16 | 130 | 99
Operating Segments | Natural gas | Union Electric Company | Residential |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 11 | 9 | 78 | 54
Operating Segments | Natural gas | Union Electric Company | Commercial |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 6 | 4 | 36 | 23
Operating Segments | Natural gas | Union Electric Company | Industrial |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 1 | 0 | 4 | 2
Operating Segments | Natural gas | Union Electric Company | Other |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 3 | 3 | 12 | 20
Operating Segments | Natural gas | Ameren Illinois Electric Distribution |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 0 | 0 | 0 | 0
Operating Segments | Natural gas | Ameren Illinois Electric Distribution | Residential |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 0 | 0 | 0 | 0
Operating Segments | Natural gas | Ameren Illinois Electric Distribution | Commercial |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 0 | 0 | 0 | 0
Operating Segments | Natural gas | Ameren Illinois Electric Distribution | Industrial |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 0 | 0 | 0 | 0
Operating Segments | Natural gas | Ameren Illinois Electric Distribution | Other |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 0 | 0 | 0 | 0
Operating Segments | Natural gas | Ameren Illinois Natural Gas |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 146 | 127 | 811 | 642
Operating Segments | Natural gas | Ameren Illinois Natural Gas | Residential |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 89 | 75 | 575 | 438
Operating Segments | Natural gas | Ameren Illinois Natural Gas | Commercial |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 25 | 23 | 152 | 116
Operating Segments | Natural gas | Ameren Illinois Natural Gas | Industrial |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 5 | 3 | 33 | 20
Operating Segments | Natural gas | Ameren Illinois Natural Gas | Other |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 27 | 26 | 51 | 68
Operating Segments | Natural gas | Ameren Transmission |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 0 | 0 | 0 | 0
Operating Segments | Natural gas | Ameren Transmission | Residential |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 0 | 0 | 0 | 0
Operating Segments | Natural gas | Ameren Transmission | Commercial |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 0 | 0 | 0 | 0
Operating Segments | Natural gas | Ameren Transmission | Industrial |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 0 | 0 | 0 | 0
Operating Segments | Natural gas | Ameren Transmission | Other |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 0 | 0 | 0 | 0
Operating Segments | Ameren Illinois Company | Ameren Illinois Electric Distribution |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 672 | 428 | 1,641 | 1,227
Operating Segments | Ameren Illinois Company | Ameren Illinois Natural Gas |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 146 | 127 | 811 | 642
Operating Segments | Ameren Illinois Company | Ameren Illinois Transmission |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 86 | 90 | 245 | 228
Operating Segments | Ameren Illinois Company | Electric | Ameren Illinois Electric Distribution |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 672 | 428 | 1,641 | 1,227
Operating Segments | Ameren Illinois Company | Electric | Ameren Illinois Electric Distribution | Residential |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 407 | 258 | 954 | 705
Operating Segments | Ameren Illinois Company | Electric | Ameren Illinois Electric Distribution | Commercial |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 233 | 143 | 571 | 402
Operating Segments | Ameren Illinois Company | Electric | Ameren Illinois Electric Distribution | Industrial |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 47 | 26 | 145 | 94
Operating Segments | Ameren Illinois Company | Electric | Ameren Illinois Electric Distribution | Other |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | (15) | 1 | (29) | 26
Operating Segments | Ameren Illinois Company | Electric | Ameren Illinois Transmission |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 117 | 108 | 320 | 277
Operating Segments | Ameren Illinois Company | Electric | Ameren Illinois Transmission | Residential |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 0 | 0 | 0 | 0
Operating Segments | Ameren Illinois Company | Electric | Ameren Illinois Transmission | Commercial |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 0 | 0 | 0 | 0
Operating Segments | Ameren Illinois Company | Electric | Ameren Illinois Transmission | Industrial |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 0 | 0 | 0 | 0
Operating Segments | Ameren Illinois Company | Electric | Ameren Illinois Transmission | Other |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 117 | 108 | 320 | 277
Operating Segments | Ameren Illinois Company | Natural gas | Ameren Illinois Natural Gas |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 146 | 127 | 811 | 642
Operating Segments | Ameren Illinois Company | Natural gas | Ameren Illinois Natural Gas | Residential |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 89 | 75 | 575 | 438
Operating Segments | Ameren Illinois Company | Natural gas | Ameren Illinois Natural Gas | Commercial |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 25 | 23 | 152 | 116
Operating Segments | Ameren Illinois Company | Natural gas | Ameren Illinois Natural Gas | Industrial |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 5 | 3 | 33 | 20
Operating Segments | Ameren Illinois Company | Natural gas | Ameren Illinois Natural Gas | Other |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 27 | 26 | 51 | 68
Intersegment Eliminations |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | (40) | (33) | (102) | (88)
Revenues | (40) | (33) | (102) | (88)
Intersegment Eliminations | Union Electric Company |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | (8) | (11) | (25) | (30)
Intersegment Eliminations | Ameren Illinois Electric Distribution |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 0 | (3) | (1) | (5)
Intersegment Eliminations | Ameren Illinois Natural Gas |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 0 | 0 | 0 | 0
Intersegment Eliminations | Ameren Transmission |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | (32) | (19) | (76) | (53)
Intersegment Eliminations | Electric |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | (39) | (33) | (101) | (88)
Intersegment Eliminations | Electric | Residential |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 0 | 0 | 0 | 0
Intersegment Eliminations | Electric | Commercial |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 0 | 0 | 0 | 0
Intersegment Eliminations | Electric | Industrial |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 0 | 0 | 0 | 0
Intersegment Eliminations | Electric | Other |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | (39) | (33) | (101) | (88)
Intersegment Eliminations | Natural gas |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | (1) | 0 | (1) | 0
Intersegment Eliminations | Natural gas | Residential |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 0 | 0 | 0 | 0
Intersegment Eliminations | Natural gas | Commercial |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 0 | 0 | 0 | 0
Intersegment Eliminations | Natural gas | Industrial |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 0 | 0 | 0 | 0
Intersegment Eliminations | Natural gas | Other |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | (1) | 0 | (1) | 0
Intersegment Eliminations | Ameren Illinois Company |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | (31) | (18) | (75) | (49)
Revenues | (31) | (18) | (75) | (49)
Intersegment Eliminations | Ameren Illinois Company | Residential |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 0 | 0 | 0 | 0
Intersegment Eliminations | Ameren Illinois Company | Commercial |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 0 | 0 | 0 | 0
Intersegment Eliminations | Ameren Illinois Company | Industrial |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 0 | 0 | 0 | 0
Intersegment Eliminations | Ameren Illinois Company | Other |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | (31) | (18) | (75) | (49)
Intersegment Eliminations | Ameren Illinois Company | Ameren Illinois Electric Distribution |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 0 | 0 | 0 | 0
Intersegment Eliminations | Ameren Illinois Company | Ameren Illinois Natural Gas |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | 0 | 0 | 0 | 0
Intersegment Eliminations | Ameren Illinois Company | Ameren Illinois Transmission |  |  |  |
Disaggregation of Revenue [Line Items] |  |  |  |
Revenues | $ (31) | $ (18) | $ (75) | $ (49)

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