| Three Months Ended June 30, | Six Months Ended June 30, | ||||||||||||||||||||||
| 2025 | 2024 | 2025 | 2024 | ||||||||||||||||||||
| Operating Revenues: | |||||||||||||||||||||||
| Electric | $ | 2,038 | $ | 1,521 | $ | 3,660 | $ | 2,885 | |||||||||||||||
| Natural gas | 183 | 172 | 658 | 624 | |||||||||||||||||||
| Total operating revenues | 2,221 | 1,693 | 4,318 | 3,509 | |||||||||||||||||||
| Operating Expenses: | |||||||||||||||||||||||
| Fuel and purchased power | 794 | 327 | 1,296 | 655 | |||||||||||||||||||
| Natural gas purchased for resale | 39 | 33 | 208 | 184 | |||||||||||||||||||
| Other operations and maintenance | 460 | 465 | 945 | 935 | |||||||||||||||||||
| Depreciation and amortization | 386 | 376 | 753 | 737 | |||||||||||||||||||
| Taxes other than income taxes | 131 | 131 | 275 | 266 | |||||||||||||||||||
| Total operating expenses | 1,810 | 1,332 | 3,477 | 2,777 | |||||||||||||||||||
| Operating Income | 411 | 361 | 841 | 732 | |||||||||||||||||||
| Other Income, Net | 96 | 103 | 181 | 192 | |||||||||||||||||||
| Interest Charges | 187 | 165 | 362 | 319 | |||||||||||||||||||
| Income Before Income Taxes | 320 | 299 | 660 | 605 | |||||||||||||||||||
| Income Taxes | 43 | 39 | 93 | 83 | |||||||||||||||||||
| Net Income | 277 | 260 | 567 | 522 | |||||||||||||||||||
| Less: Net Income Attributable to Noncontrolling Interests | 2 | 2 | 3 | 3 | |||||||||||||||||||
| Net Income Attributable to Ameren Common Shareholders | $ | 275 | $ | 258 | $ | 564 | $ | 519 | |||||||||||||||
| Earnings per Common Share - Basic | $ | 1.02 | $ | 0.97 | $ | 2.09 | $ | 1.95 | |||||||||||||||
| Earnings per Common Share – Diluted | $ | 1.01 | $ | 0.97 | $ | 2.08 | $ | 1.95 | |||||||||||||||
| Weighted-average Common Shares Outstanding – Basic | 270.3 | 266.7 | 270.1 | 266.5 | |||||||||||||||||||
| Weighted-average Common Shares Outstanding – Diluted | 271.6 | 266.8 | 271.5 | 266.8 | |||||||||||||||||||
| June 30, 2025 | December 31, 2024 | ||||||||||
| ASSETS | |||||||||||
| Current Assets: | |||||||||||
| Cash and cash equivalents | $ | 11 | $ | 7 | |||||||
| Accounts receivable - trade (less allowance for doubtful accounts) | 567 | 525 | |||||||||
| Unbilled revenue | 467 | 346 | |||||||||
| Miscellaneous accounts receivable | 101 | 96 | |||||||||
| Inventories | 738 | 762 | |||||||||
| Current regulatory assets | 332 | 366 | |||||||||
| Other current assets | 258 | 162 | |||||||||
| Total current assets | 2,474 | 2,264 | |||||||||
| Property, Plant, and Equipment, Net | 37,816 | 36,304 | |||||||||
| Investments and Other Assets: | |||||||||||
| Nuclear decommissioning trust fund | 1,414 | 1,342 | |||||||||
| Goodwill | 411 | 411 | |||||||||
| Regulatory assets | 2,666 | 2,397 | |||||||||
| Pension and other postretirement benefits | 734 | 757 | |||||||||
| Other assets | 1,110 | 1,123 | |||||||||
| Total investments and other assets | 6,335 | 6,030 | |||||||||
| TOTAL ASSETS | $ | 46,625 | $ | 44,598 | |||||||
| LIABILITIES AND EQUITY | |||||||||||
| Current Liabilities: | |||||||||||
| Current maturities of long-term debt | $ | 29 | $ | 317 | |||||||
| Short-term debt | 1,141 | 1,143 | |||||||||
| Accounts and wages payable | 882 | 1,059 | |||||||||
| Taxes accrued | 155 | 60 | |||||||||
| Interest accrued | 230 | 196 | |||||||||
| Customer deposits | 240 | 223 | |||||||||
| Other current liabilities | 410 | 415 | |||||||||
| Total current liabilities | 3,087 | 3,413 | |||||||||
| Long-term Debt, Net | 18,811 | 17,262 | |||||||||
| Deferred Credits and Other Liabilities: | |||||||||||
| Accumulated deferred income taxes and tax credits, net | 4,881 | 4,474 | |||||||||
| Regulatory liabilities | 6,014 | 5,897 | |||||||||
| Asset retirement obligations | 838 | 822 | |||||||||
| Other deferred credits and liabilities | 551 | 487 | |||||||||
| Total deferred credits and other liabilities | 12,284 | 11,680 | |||||||||
| Shareholders’ Equity: | |||||||||||
| Common stock | 3 | 3 | |||||||||
| Other paid-in capital, principally premium on common stock | 7,541 | 7,513 | |||||||||
| Retained earnings | 4,784 | 4,604 | |||||||||
| Accumulated other comprehensive loss | (14) | (6) | |||||||||
| Total shareholders’ equity | 12,314 | 12,114 | |||||||||
| Noncontrolling Interests | 129 | 129 | |||||||||
| Total equity | 12,443 | 12,243 | |||||||||
| TOTAL LIABILITIES AND EQUITY | $ | 46,625 | $ | 44,598 | |||||||
| Six Months Ended June 30, | |||||||||||
| 2025 | 2024 | ||||||||||
| Cash Flows From Operating Activities: | |||||||||||
| Net income | $ | 567 | $ | 522 | |||||||
| Adjustments to reconcile net income to net cash provided by operating activities: | |||||||||||
| Depreciation and amortization | 793 | 760 | |||||||||
| Amortization of nuclear fuel | 20 | 38 | |||||||||
| Amortization of debt issuance costs and premium/discounts | 10 | 9 | |||||||||
| Deferred income taxes and tax credits, net | 172 | 76 | |||||||||
| Allowance for equity funds used during construction | (39) | (25) | |||||||||
| Stock-based compensation costs | 14 | 14 | |||||||||
| Other | 10 | 13 | |||||||||
| Changes in assets and liabilities | (254) | (358) | |||||||||
| Net cash provided by operating activities | 1,293 | 1,049 | |||||||||
| Cash Flows From Investing Activities: | |||||||||||
| Capital expenditures | (2,130) | (1,892) | |||||||||
| Nuclear fuel expenditures | (19) | (37) | |||||||||
| Purchases of securities – nuclear decommissioning trust fund | (244) | (323) | |||||||||
| Sales and maturities of securities – nuclear decommissioning trust fund | 223 | 309 | |||||||||
| Other | 59 | 11 | |||||||||
| Net cash used in investing activities | (2,111) | (1,932) | |||||||||
| Cash Flows From Financing Activities: | |||||||||||
| Dividends on common stock | (384) | (356) | |||||||||
| Dividends paid to noncontrolling interest holders | (3) | (3) | |||||||||
| Short-term debt, net | (2) | 156 | |||||||||
| Maturities and extinguishment of long-term debt | (324) | (350) | |||||||||
| Issuances of long-term debt | 1,599 | 1,470 | |||||||||
| Issuances of common stock | 25 | 21 | |||||||||
| Employee payroll taxes related to stock-based compensation | (13) | (8) | |||||||||
| Debt issuance costs | (14) | (18) | |||||||||
| Net cash provided by financing activities | 884 | 912 | |||||||||
| Net change in cash, cash equivalents, and restricted cash | 66 | 29 | |||||||||
Cash, cash equivalents, and restricted cash at beginning of year(a) | 328 | 272 | |||||||||
Cash, cash equivalents, and restricted cash at end of period(b) | $ | 394 | $ | 301 | |||||||