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Segment Information (Schedule Of Segment Reporting Information By Segment) (Details) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2023 USD ($) segment | Dec. 31, 2022 USD ($) | Dec. 31, 2021 USD ($)
Segment Reporting Information [Line Items] |  |  |
Number of reportable segments | segment | 4 |  |
External revenues | $ 7,500 | $ 7,957 | $ 6,394
Depreciation and amortization | 1,387 | 1,289 | 1,146
Interest income | 33 | 35 | 27
Interest Charges | 566 | 486 | 383
Income tax benefit | 183 | 176 | 157
Net Income (Loss) Available to Common Stockholders, Basic | 1,152 | 1,074 | 990
Capital expenditures | $ 3,597 | 3,351 | 3,479
Ameren Missouri |  |  |
Segment Reporting Information [Line Items] |  |  |
Number of reportable segments | segment | 1 |  |
Ameren Illinois |  |  |
Segment Reporting Information [Line Items] |  |  |
Number of reportable segments | segment | 3 |  |
External revenues | $ 3,482 | 3,756 | 2,895
Depreciation and amortization | 556 | 514 | 472
Interest income | 21 | 7 | 1
Interest Charges | 204 | 168 | 164
Income tax benefit | 209 | 179 | 143
Net Income Attributable to Ameren Common Shareholders | 607 | 513 | 425
Capital expenditures | 1,731 | 1,601 | 1,432
Operating Segments | Ameren Missouri |  |  |
Segment Reporting Information [Line Items] |  |  |
External revenues | 3,825 | 4,012 | 3,311
Depreciation and amortization | 783 | 732 | 632
Interest income | 11 | 28 | 26
Interest Charges | 227 | 213 | 137
Income tax benefit | (8) | (10) | 3
Net Income Attributable to Ameren Common Shareholders | 545 | 562 | 518
Capital expenditures | 1,760 | 1,690 | 2,015
Operating Segments | Ameren Illinois Electric Distribution |  |  |
Segment Reporting Information [Line Items] |  |  |
External revenues | 2,217 | 2,255 | 1,635
Depreciation and amortization | 351 | 332 | 309
Interest income | 19 | 7 | 1
Interest Charges | 89 | 74 | 74
Income tax benefit | 82 | 68 | 53
Net Income Attributable to Ameren Common Shareholders | 258 | 202 | 165
Capital expenditures | 752 | 621 | 579
Operating Segments | Ameren Illinois Gas |  |  |
Segment Reporting Information [Line Items] |  |  |
External revenues | 897 | 1,180 | 957
Depreciation and amortization | 108 | 98 | 90
Interest income | 1 | 0 | 0
Interest Charges | 55 | 44 | 42
Income tax benefit | 50 | 46 | 39
Net Income Attributable to Ameren Common Shareholders | 134 | 123 | 108
Capital expenditures | 299 | 308 | 278
Operating Segments | Ameren Transmission |  |  |
Segment Reporting Information [Line Items] |  |  |
External revenues | 561 | 510 | 491
Depreciation and amortization | 138 | 123 | 111
Interest income | 2 | 0 | 0
Interest Charges | 96 | 84 | 83
Income tax benefit | 106 | 92 | 82
Net Income Attributable to Ameren Common Shareholders | 296 | 263 | 230
Capital expenditures | 804 | 741 | 616
Operating Segments | Ameren Illinois | Ameren Illinois Electric Distribution |  |  |
Segment Reporting Information [Line Items] |  |  |
External revenues | 2,218 | 2,256 | 1,639
Depreciation and amortization | 351 | 332 | 309
Interest income | 19 | 7 | 1
Interest Charges | 89 | 74 | 74
Income tax benefit | 82 | 68 | 53
Net Income Attributable to Ameren Common Shareholders | 258 | 202 | 165
Capital expenditures | 752 | 621 | 579
Operating Segments | Ameren Illinois | Ameren Illinois Gas |  |  |
Segment Reporting Information [Line Items] |  |  |
External revenues | 897 | 1,180 | 957
Depreciation and amortization | 108 | 98 | 90
Interest income | 1 | 0 | 0
Interest Charges | 55 | 44 | 42
Income tax benefit | 50 | 46 | 39
Net Income Attributable to Ameren Common Shareholders | 134 | 123 | 108
Capital expenditures | 299 | 308 | 278
Operating Segments | Ameren Illinois | Ameren Illinois Transmission |  |  |
Segment Reporting Information [Line Items] |  |  |
External revenues | 367 | 320 | 299
Depreciation and amortization | 97 | 84 | 73
Interest income | 1 | 0 | 0
Interest Charges | 60 | 50 | 48
Income tax benefit | 77 | 65 | 51
Net Income Attributable to Ameren Common Shareholders | 215 | 188 | 152
Capital expenditures | 680 | 672 | 575
Segment Reconciling Items |  |  |
Segment Reporting Information [Line Items] |  |  |
Depreciation and amortization | 7 | 4 | 4
Interest income | 5 | 1 | 3
Interest Charges | 104 | 72 | 50
Income tax benefit | (47) | (20) | (20)
Net Income Attributable to Ameren Common Shareholders | (81) | (76) | (31)
Capital expenditures | 9 | 7 | 4
Intersegment Elimination |  |  |
Segment Reporting Information [Line Items] |  |  |
Intersegment revenues | 151 | 140 | 117
Depreciation and amortization | 0 | 0 | 0
Interest income | (5) | (1) | (3)
Interest Charges | (5) | (1) | (3)
Income tax benefit | 0 | 0 | 0
Capital expenditures | (27) | (16) | (13)
Intersegment Elimination | Ameren Missouri |  |  |
Segment Reporting Information [Line Items] |  |  |
Intersegment revenues | 34 | 34 | 42
Intersegment Elimination | Ameren Illinois Electric Distribution |  |  |
Segment Reporting Information [Line Items] |  |  |
Intersegment revenues | 1 | 1 | 4
Intersegment Elimination | Ameren Illinois Gas |  |  |
Segment Reporting Information [Line Items] |  |  |
Intersegment revenues | 0 | 0 | 0
Intersegment Elimination | Ameren Transmission |  |  |
Segment Reporting Information [Line Items] |  |  |
Intersegment revenues | 116 | 105 | 71
Intersegment Elimination | Ameren Illinois |  |  |
Segment Reporting Information [Line Items] |  |  |
Intersegment revenues | 113 | 104 | 66
Intersegment Elimination | Ameren Illinois | Ameren Illinois Electric Distribution |  |  |
Segment Reporting Information [Line Items] |  |  |
Intersegment revenues | 0 | 0 | 0
Intersegment Elimination | Ameren Illinois | Ameren Illinois Gas |  |  |
Segment Reporting Information [Line Items] |  |  |
Intersegment revenues | 0 | 0 | 0
Intersegment Elimination | Ameren Illinois | Ameren Illinois Transmission |  |  |
Segment Reporting Information [Line Items] |  |  |
Intersegment revenues | $ 113 | $ 104 | $ 66

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