| Three Months Ended June 30, | Six Months Ended June 30, | ||||||||||||||||||||||
| 2026 | 2025 | 2026 | 2025 | ||||||||||||||||||||
| Operating Revenues: | |||||||||||||||||||||||
| Electric | $ | 1,887 | $ | 2,038 | $ | 3,548 | $ | 3,660 | |||||||||||||||
| Natural gas | 205 | 183 | 720 | 658 | |||||||||||||||||||
| Total operating revenues | 2,092 | 2,221 | 4,268 | 4,318 | |||||||||||||||||||
| Operating Expenses: | |||||||||||||||||||||||
| Fuel and purchased power | 507 | 794 | 940 | 1,296 | |||||||||||||||||||
| Natural gas purchased for resale | 39 | 39 | 210 | 208 | |||||||||||||||||||
| Other operations and maintenance | 521 | 460 | 1,012 | 945 | |||||||||||||||||||
| Depreciation and amortization | 420 | 386 | 818 | 753 | |||||||||||||||||||
| Taxes other than income taxes | 146 | 131 | 297 | 275 | |||||||||||||||||||
| Total operating expenses | 1,633 | 1,810 | 3,277 | 3,477 | |||||||||||||||||||
| Operating Income | 459 | 411 | 991 | 841 | |||||||||||||||||||
| Other Income, Net | 118 | 96 | 208 | 181 | |||||||||||||||||||
| Interest Charges | 209 | 187 | 413 | 362 | |||||||||||||||||||
| Income Before Income Taxes | 368 | 320 | 786 | 660 | |||||||||||||||||||
| Income Taxes | 52 | 43 | 112 | 93 | |||||||||||||||||||
| Net Income | 316 | 277 | 674 | 567 | |||||||||||||||||||
| Less: Net Income Attributable to Noncontrolling Interests | 2 | 2 | 3 | 3 | |||||||||||||||||||
| Net Income Attributable to Ameren Common Shareholders | $ | 314 | $ | 275 | $ | 671 | $ | 564 | |||||||||||||||
| Earnings per Common Share - Basic | $ | 1.14 | $ | 1.02 | $ | 2.43 | $ | 2.09 | |||||||||||||||
| Earnings per Common Share – Diluted | $ | 1.13 | $ | 1.01 | $ | 2.41 | $ | 2.08 | |||||||||||||||
| Weighted-average Common Shares Outstanding – Basic | 276.8 | 270.3 | 276.6 | 270.1 | |||||||||||||||||||
| Weighted-average Common Shares Outstanding – Diluted | 278.7 | 271.6 | 278.6 | 271.5 | |||||||||||||||||||
| June 30, 2026 | December 31, 2025 | ||||||||||
| ASSETS | |||||||||||
| Current Assets: | |||||||||||
| Cash and cash equivalents | $ | 12 | $ | 13 | |||||||
| Accounts receivable - trade (less allowance for doubtful accounts) | 600 | 665 | |||||||||
| Unbilled revenue | 478 | 415 | |||||||||
| Miscellaneous accounts receivable | 199 | 107 | |||||||||
| Inventories | 800 | 774 | |||||||||
| Current regulatory assets | 337 | 387 | |||||||||
| Other current assets | 218 | 210 | |||||||||
| Total current assets | 2,644 | 2,571 | |||||||||
| Property, Plant, and Equipment, Net | 41,372 | 39,313 | |||||||||
| Investments and Other Assets: | |||||||||||
| Nuclear decommissioning trust fund | 1,631 | 1,526 | |||||||||
| Goodwill | 411 | 411 | |||||||||
| Regulatory assets | 2,888 | 2,524 | |||||||||
| Pension and other postretirement benefits | 973 | 977 | |||||||||
| Other assets | 1,297 | 1,154 | |||||||||
| Total investments and other assets | 7,200 | 6,592 | |||||||||
| TOTAL ASSETS | $ | 51,216 | $ | 48,476 | |||||||
| LIABILITIES AND EQUITY | |||||||||||
| Current Liabilities: | |||||||||||
| Current maturities of long-term debt | $ | 1,524 | $ | 973 | |||||||
| Short-term debt | 1,220 | 643 | |||||||||
| Accounts and wages payable | 998 | 1,254 | |||||||||
| Interest accrued | 246 | 229 | |||||||||
| Customer deposits | 248 | 238 | |||||||||
| Other current liabilities | 742 | 570 | |||||||||
| Total current liabilities | 4,978 | 3,907 | |||||||||
| Long-term Debt, Net | 19,064 | 18,214 | |||||||||
| Deferred Credits and Other Liabilities: | |||||||||||
| Accumulated deferred income taxes and tax credits, net | 5,381 | 5,181 | |||||||||
| Regulatory liabilities | 6,437 | 6,255 | |||||||||
| Asset retirement obligations | 873 | 849 | |||||||||
| Other deferred credits and liabilities | 667 | 540 | |||||||||
| Total deferred credits and other liabilities | 13,358 | 12,825 | |||||||||
| Shareholders’ Equity: | |||||||||||
| Common stock | 3 | 3 | |||||||||
| Other paid-in capital, principally premium on common stock | 8,132 | 8,106 | |||||||||
| Retained earnings | 5,549 | 5,292 | |||||||||
| Accumulated other comprehensive income | 3 | — | |||||||||
| Total shareholders’ equity | 13,687 | 13,401 | |||||||||
| Noncontrolling Interests | 129 | 129 | |||||||||
| Total equity | 13,816 | 13,530 | |||||||||
| TOTAL LIABILITIES AND EQUITY | $ | 51,216 | $ | 48,476 | |||||||
| Six Months Ended June 30, | |||||||||||
| 2026 | 2025 | ||||||||||
| Cash Flows From Operating Activities: | |||||||||||
| Net income | $ | 674 | $ | 567 | |||||||
| Adjustments to reconcile net income to net cash provided by operating activities: | |||||||||||
| Depreciation and amortization | 841 | 793 | |||||||||
| Amortization of nuclear fuel | 43 | 20 | |||||||||
| Amortization of debt issuance costs and premium/discounts | 10 | 10 | |||||||||
| Deferred income taxes and tax credits, net | 127 | 172 | |||||||||
| Allowance for equity funds used during construction | (69) | (39) | |||||||||
| Stock-based compensation costs | 16 | 14 | |||||||||
| Other | (13) | 10 | |||||||||
| Changes in assets and liabilities | (438) | (254) | |||||||||
| Net cash provided by operating activities | 1,191 | 1,293 | |||||||||
| Cash Flows From Investing Activities: | |||||||||||
| Capital expenditures | (2,653) | (2,130) | |||||||||
| Nuclear fuel expenditures | (23) | (19) | |||||||||
| Purchases of securities – nuclear decommissioning trust fund | (168) | (244) | |||||||||
| Sales and maturities of securities – nuclear decommissioning trust fund | 158 | 223 | |||||||||
| Other | (20) | 59 | |||||||||
| Net cash used in investing activities | (2,706) | (2,111) | |||||||||
| Cash Flows From Financing Activities: | |||||||||||
| Dividends on common stock | (414) | (384) | |||||||||
| Dividends paid to noncontrolling interest holders | (3) | (3) | |||||||||
| Short-term debt, net | 577 | (2) | |||||||||
| Maturities and extinguishment of long-term debt | (378) | (324) | |||||||||
| Issuances of long-term debt | 1,794 | 1,599 | |||||||||
| Issuances of common stock | 22 | 25 | |||||||||
| Employee payroll taxes related to stock-based compensation | (14) | (13) | |||||||||
| Debt issuance costs | (19) | (14) | |||||||||
| Net cash provided by financing activities | 1,565 | 884 | |||||||||
| Net change in cash, cash equivalents, and restricted cash | 50 | 66 | |||||||||
Cash, cash equivalents, and restricted cash at beginning of year(a) | 420 | 328 | |||||||||
Cash, cash equivalents, and restricted cash at end of period(b) | $ | 470 | $ | 394 | |||||||