| Three Months Ended September 30, | Nine Months Ended September 30, | ||||||||||||||||||||||
| 2023 | 2022 | 2023 | 2022 | ||||||||||||||||||||
| Operating Revenues: | |||||||||||||||||||||||
| Electric | $ | 1,921 | $ | 2,140 | $ | 5,096 | $ | 4,971 | |||||||||||||||
| Natural gas | 139 | 166 | 786 | 940 | |||||||||||||||||||
| Total operating revenues | 2,060 | 2,306 | 5,882 | 5,911 | |||||||||||||||||||
| Operating Expenses: | |||||||||||||||||||||||
| Fuel | 158 | 117 | 423 | 376 | |||||||||||||||||||
| Purchased power | 272 | 563 | 1,095 | 1,058 | |||||||||||||||||||
| Natural gas purchased for resale | 30 | 58 | 280 | 431 | |||||||||||||||||||
| Other operations and maintenance | 470 | 475 | 1,368 | 1,427 | |||||||||||||||||||
| Depreciation and amortization | 369 | 350 | 1,024 | 965 | |||||||||||||||||||
| Taxes other than income taxes | 147 | 144 | 398 | 415 | |||||||||||||||||||
| Total operating expenses | 1,446 | 1,707 | 4,588 | 4,672 | |||||||||||||||||||
| Operating Income | 614 | 599 | 1,294 | 1,239 | |||||||||||||||||||
| Other Income, Net | 101 | 58 | 261 | 180 | |||||||||||||||||||
| Interest Charges | 152 | 126 | 413 | 356 | |||||||||||||||||||
| Income Before Income Taxes | 563 | 531 | 1,142 | 1,063 | |||||||||||||||||||
| Income Taxes | 69 | 78 | 144 | 148 | |||||||||||||||||||
| Net Income | 494 | 453 | 998 | 915 | |||||||||||||||||||
| Less: Net Income Attributable to Noncontrolling Interests | 1 | 1 | 4 | 4 | |||||||||||||||||||
| Net Income Attributable to Ameren Common Shareholders | $ | 493 | $ | 452 | $ | 994 | $ | 911 | |||||||||||||||
| Earnings per Common Share – Basic | $ | 1.88 | $ | 1.75 | $ | 3.79 | $ | 3.53 | |||||||||||||||
| Earnings per Common Share – Diluted | $ | 1.87 | $ | 1.74 | $ | 3.78 | $ | 3.51 | |||||||||||||||
| Weighted-average Common Shares Outstanding – Basic | 262.8 | 258.4 | 262.5 | 258.2 | |||||||||||||||||||
| Weighted-average Common Shares Outstanding – Diluted | 263.4 | 259.5 | 263.2 | 259.3 | |||||||||||||||||||
| September 30, 2023 | December 31, 2022 | ||||||||||
| ASSETS | |||||||||||
| Current Assets: | |||||||||||
| Cash and cash equivalents | $ | 8 | $ | 10 | |||||||
| Accounts receivable - trade (less allowance for doubtful accounts) | 597 | 600 | |||||||||
| Unbilled revenue | 360 | 446 | |||||||||
| Miscellaneous accounts receivable | 65 | 54 | |||||||||
| Inventories | 760 | 667 | |||||||||
| Current regulatory assets | 157 | 354 | |||||||||
| Investment in industrial development revenue bonds | — | 240 | |||||||||
| Current collateral assets | 13 | 142 | |||||||||
| Other current assets | 124 | 155 | |||||||||
| Total current assets | 2,084 | 2,668 | |||||||||
| Property, Plant, and Equipment, Net | 32,938 | 31,262 | |||||||||
| Investments and Other Assets: | |||||||||||
| Nuclear decommissioning trust fund | 1,042 | 958 | |||||||||
| Goodwill | 411 | 411 | |||||||||
| Regulatory assets | 1,772 | 1,426 | |||||||||
| Pension and other postretirement benefits | 470 | 411 | |||||||||
| Other assets | 882 | 768 | |||||||||
| Total investments and other assets | 4,577 | 3,974 | |||||||||
| TOTAL ASSETS | $ | 39,599 | $ | 37,904 | |||||||
| LIABILITIES AND EQUITY | |||||||||||
| Current Liabilities: | |||||||||||
| Current maturities of long-term debt | $ | 849 | $ | 340 | |||||||
| Short-term debt | 1,340 | 1,070 | |||||||||
| Accounts and wages payable | 955 | 1,159 | |||||||||
| Taxes accrued | 209 | 59 | |||||||||
| Other current liabilities | 664 | 738 | |||||||||
| Total current liabilities | 4,017 | 3,366 | |||||||||
| Long-term Debt, Net | 13,829 | 13,685 | |||||||||
| Deferred Credits and Other Liabilities: | |||||||||||
| Accumulated deferred income taxes and tax credits, net | 4,068 | 3,804 | |||||||||
| Regulatory liabilities | 5,336 | 5,309 | |||||||||
| Asset retirement obligations | 761 | 763 | |||||||||
| Other deferred credits and liabilities | 416 | 340 | |||||||||
| Total deferred credits and other liabilities | 10,581 | 10,216 | |||||||||
| Shareholders’ Equity: | |||||||||||
| Common stock | 3 | 3 | |||||||||
| Other paid-in capital, principally premium on common stock | 6,900 | 6,860 | |||||||||
| Retained earnings | 4,144 | 3,646 | |||||||||
| Accumulated other comprehensive loss | (4) | (1) | |||||||||
| Total shareholders’ equity | 11,043 | 10,508 | |||||||||
| Noncontrolling Interests | 129 | 129 | |||||||||
| Total equity | 11,172 | 10,637 | |||||||||
| TOTAL LIABILITIES AND EQUITY | $ | 39,599 | $ | 37,904 | |||||||
| Nine Months Ended September 30, | |||||||||||
| 2023 | 2022 | ||||||||||
| Cash Flows From Operating Activities: | |||||||||||
| Net income | $ | 998 | $ | 915 | |||||||
| Adjustments to reconcile net income to net cash provided by operating activities: | |||||||||||
| Depreciation and amortization | 1,063 | 1,016 | |||||||||
| Amortization of nuclear fuel | 56 | 46 | |||||||||
| Amortization of debt issuance costs and premium/discounts | 12 | 17 | |||||||||
| Deferred income taxes and investment tax credits, net | 128 | 137 | |||||||||
| Allowance for equity funds used during construction | (39) | (31) | |||||||||
| Stock-based compensation costs | 21 | 18 | |||||||||
| Other | 12 | 63 | |||||||||
| Changes in assets and liabilities | (220) | (582) | |||||||||
| Net cash provided by operating activities | 2,031 | 1,599 | |||||||||
| Cash Flows From Investing Activities: | |||||||||||
| Capital expenditures | (2,571) | (2,437) | |||||||||
| Nuclear fuel expenditures | (63) | (22) | |||||||||
| Purchases of securities – nuclear decommissioning trust fund | (156) | (176) | |||||||||
| Sales and maturities of securities – nuclear decommissioning trust fund | 136 | 163 | |||||||||
| Other | (2) | 14 | |||||||||
| Net cash used in investing activities | (2,656) | (2,458) | |||||||||
| Cash Flows From Financing Activities: | |||||||||||
| Dividends on common stock | (496) | (457) | |||||||||
| Dividends paid to noncontrolling interest holders | (4) | (4) | |||||||||
| Short-term debt, net | 272 | 675 | |||||||||
| Maturities of long-term debt | (100) | (450) | |||||||||
| Issuances of long-term debt | 997 | 1,118 | |||||||||
| Issuances of common stock | 28 | 29 | |||||||||
| Employee payroll taxes related to stock-based compensation | (20) | (16) | |||||||||
| Debt issuance costs | (12) | (11) | |||||||||
| Other | (10) | — | |||||||||
| Net cash provided by financing activities | 655 | 884 | |||||||||
| Net change in cash, cash equivalents, and restricted cash | 30 | 25 | |||||||||
| Cash, cash equivalents, and restricted cash at beginning of year | 216 | 155 | |||||||||
| Cash, cash equivalents, and restricted cash at end of period | $ | 246 | $ | 180 | |||||||