| Three Months Ended September 30, | Nine Months Ended September 30, | ||||||||||||||||||||||
| 2024 | 2023 | 2024 | 2023 | ||||||||||||||||||||
| Operating Revenues: | |||||||||||||||||||||||
| Electric | $ | 2,035 | $ | 1,921 | $ | 4,920 | $ | 5,096 | |||||||||||||||
| Natural gas | 138 | 139 | 762 | 786 | |||||||||||||||||||
| Total operating revenues | 2,173 | 2,060 | 5,682 | 5,882 | |||||||||||||||||||
| Operating Expenses: | |||||||||||||||||||||||
| Fuel and purchased power | 499 | 430 | 1,154 | 1,518 | |||||||||||||||||||
| Natural gas purchased for resale | 30 | 30 | 214 | 280 | |||||||||||||||||||
| Other operations and maintenance | 520 | 470 | 1,455 | 1,368 | |||||||||||||||||||
| Depreciation and amortization | 388 | 369 | 1,125 | 1,024 | |||||||||||||||||||
| Taxes other than income taxes | 150 | 147 | 416 | 398 | |||||||||||||||||||
| Total operating expenses | 1,587 | 1,446 | 4,364 | 4,588 | |||||||||||||||||||
| Operating Income | 586 | 614 | 1,318 | 1,294 | |||||||||||||||||||
| Other Income, Net | 101 | 101 | 293 | 261 | |||||||||||||||||||
| Interest Charges | 173 | 152 | 492 | 413 | |||||||||||||||||||
| Income Before Income Taxes | 514 | 563 | 1,119 | 1,142 | |||||||||||||||||||
| Income Taxes | 57 | 69 | 140 | 144 | |||||||||||||||||||
| Net Income | 457 | 494 | 979 | 998 | |||||||||||||||||||
| Less: Net Income Attributable to Noncontrolling Interests | 1 | 1 | 4 | 4 | |||||||||||||||||||
| Net Income Attributable to Ameren Common Shareholders | $ | 456 | $ | 493 | $ | 975 | $ | 994 | |||||||||||||||
| Earnings per Common Share – Basic | $ | 1.71 | $ | 1.88 | $ | 3.66 | $ | 3.79 | |||||||||||||||
| Earnings per Common Share – Diluted | $ | 1.70 | $ | 1.87 | $ | 3.65 | $ | 3.78 | |||||||||||||||
| Weighted-average Common Shares Outstanding – Basic | 266.8 | 262.8 | 266.6 | 262.5 | |||||||||||||||||||
| Weighted-average Common Shares Outstanding – Diluted | 267.3 | 263.4 | 266.9 | 263.2 | |||||||||||||||||||
| September 30, 2024 | December 31, 2023 | ||||||||||
| ASSETS | |||||||||||
| Current Assets: | |||||||||||
| Cash and cash equivalents | $ | 17 | $ | 25 | |||||||
| Accounts receivable - trade (less allowance for doubtful accounts) | 651 | 494 | |||||||||
| Unbilled revenue | 348 | 319 | |||||||||
| Miscellaneous accounts receivable | 70 | 106 | |||||||||
| Inventories | 792 | 733 | |||||||||
| Current regulatory assets | 226 | 365 | |||||||||
| Other current assets | 153 | 139 | |||||||||
| Total current assets | 2,257 | 2,181 | |||||||||
| Property, Plant, and Equipment, Net | 35,720 | 33,776 | |||||||||
| Investments and Other Assets: | |||||||||||
| Nuclear decommissioning trust fund | 1,333 | 1,150 | |||||||||
| Goodwill | 411 | 411 | |||||||||
| Regulatory assets | 1,915 | 1,810 | |||||||||
| Pension and other postretirement benefits | 581 | 581 | |||||||||
| Other assets | 1,081 | 921 | |||||||||
| Total investments and other assets | 5,321 | 4,873 | |||||||||
| TOTAL ASSETS | $ | 43,298 | $ | 40,830 | |||||||
| LIABILITIES AND EQUITY | |||||||||||
| Current Liabilities: | |||||||||||
| Current maturities of long-term debt | $ | 300 | $ | 849 | |||||||
| Short-term debt | 1,539 | 536 | |||||||||
| Accounts and wages payable | 717 | 1,136 | |||||||||
| Taxes accrued | 206 | 54 | |||||||||
| Customer deposits | 205 | 176 | |||||||||
| Other current liabilities | 600 | 594 | |||||||||
| Total current liabilities | 3,567 | 3,345 | |||||||||
| Long-term Debt, Net | 16,422 | 15,121 | |||||||||
| Deferred Credits and Other Liabilities: | |||||||||||
| Accumulated deferred income taxes and tax credits, net | 4,477 | 4,176 | |||||||||
| Regulatory liabilities | 5,562 | 5,512 | |||||||||
| Asset retirement obligations | 798 | 772 | |||||||||
| Other deferred credits and liabilities | 510 | 426 | |||||||||
| Total deferred credits and other liabilities | 11,347 | 10,886 | |||||||||
| Shareholders’ Equity: | |||||||||||
| Common stock | 3 | 3 | |||||||||
| Other paid-in capital, principally premium on common stock | 7,264 | 7,216 | |||||||||
| Retained earnings | 4,576 | 4,136 | |||||||||
| Accumulated other comprehensive loss | (10) | (6) | |||||||||
| Total shareholders’ equity | 11,833 | 11,349 | |||||||||
| Noncontrolling Interests | 129 | 129 | |||||||||
| Total equity | 11,962 | 11,478 | |||||||||
| TOTAL LIABILITIES AND EQUITY | $ | 43,298 | $ | 40,830 | |||||||
| Nine Months Ended September 30, | |||||||||||
| 2024 | 2023 | ||||||||||
| Cash Flows From Operating Activities: | |||||||||||
| Net income | $ | 979 | $ | 998 | |||||||
| Adjustments to reconcile net income to net cash provided by operating activities: | |||||||||||
| Depreciation and amortization | 1,142 | 1,063 | |||||||||
| Amortization of nuclear fuel | 59 | 56 | |||||||||
| Amortization of debt issuance costs and premium/discounts | 14 | 12 | |||||||||
| Deferred income taxes and investment tax credits, net | 145 | 128 | |||||||||
| Allowance for equity funds used during construction | (48) | (39) | |||||||||
| Stock-based compensation costs | 22 | 21 | |||||||||
| Other | 84 | 12 | |||||||||
| Changes in assets and liabilities | (451) | (220) | |||||||||
| Net cash provided by operating activities | 1,946 | 2,031 | |||||||||
| Cash Flows From Investing Activities: | |||||||||||
| Capital expenditures | (3,029) | (2,571) | |||||||||
| Nuclear fuel expenditures | (57) | (63) | |||||||||
| Purchases of securities – nuclear decommissioning trust fund | (499) | (156) | |||||||||
| Sales and maturities of securities – nuclear decommissioning trust fund | 480 | 136 | |||||||||
| Other | (1) | (2) | |||||||||
| Net cash used in investing activities | (3,106) | (2,656) | |||||||||
| Cash Flows From Financing Activities: | |||||||||||
| Dividends on common stock | (535) | (496) | |||||||||
| Dividends paid to noncontrolling interest holders | (4) | (4) | |||||||||
| Short-term debt, net | 1,002 | 272 | |||||||||
| Maturities of long-term debt | (849) | (100) | |||||||||
| Issuances of long-term debt | 1,610 | 997 | |||||||||
| Issuances of common stock | 30 | 28 | |||||||||
| Employee payroll taxes related to stock-based compensation | (8) | (20) | |||||||||
| Debt issuance costs | (19) | (12) | |||||||||
| Other | (15) | (10) | |||||||||
| Net cash provided by financing activities | 1,212 | 655 | |||||||||
| Net change in cash, cash equivalents, and restricted cash | 52 | 30 | |||||||||
Cash, cash equivalents, and restricted cash at beginning of year(a) | 272 | 216 | |||||||||
Cash, cash equivalents, and restricted cash at end of period(b) | $ | 324 | $ | 246 | |||||||