| Three Months Ended December 31, | Year Ended December 31, | ||||||||||||||||||||||
| 2022 | 2021 | 2022 | 2021 | ||||||||||||||||||||
| Operating Revenues: | |||||||||||||||||||||||
| Electric | $ | 1,610 | $ | 1,189 | $ | 6,581 | $ | 5,297 | |||||||||||||||
| Natural gas | 436 | 356 | 1,376 | 1,097 | |||||||||||||||||||
| Total operating revenues | 2,046 | 1,545 | 7,957 | 6,394 | |||||||||||||||||||
| Operating Expenses: | |||||||||||||||||||||||
| Fuel | 97 | 159 | 473 | 581 | |||||||||||||||||||
| Purchased power | 489 | 127 | 1,547 | 606 | |||||||||||||||||||
| Natural gas purchased for resale | 226 | 167 | 657 | 442 | |||||||||||||||||||
| Other operations and maintenance | 510 | 485 | 1,937 | 1,774 | |||||||||||||||||||
| Depreciation and amortization | 324 | 290 | 1,289 | 1,146 | |||||||||||||||||||
| Taxes other than income taxes | 124 | 120 | 539 | 512 | |||||||||||||||||||
| Total operating expenses | 1,770 | 1,348 | 6,442 | 5,061 | |||||||||||||||||||
| Operating Income | 276 | 197 | 1,515 | 1,333 | |||||||||||||||||||
| Other Income, Net | 46 | 51 | 226 | 202 | |||||||||||||||||||
| Interest Charges | 130 | 93 | 486 | 383 | |||||||||||||||||||
| Income Before Income Taxes | 192 | 155 | 1,255 | 1,152 | |||||||||||||||||||
| Income Taxes | 28 | 29 | 176 | 157 | |||||||||||||||||||
| Net Income | 164 | 126 | 1,079 | 995 | |||||||||||||||||||
| Less: Net Income Attributable to Noncontrolling Interests | 1 | 1 | 5 | 5 | |||||||||||||||||||
| Net Income Attributable to Ameren Common Shareholders | $ | 163 | $ | 125 | $ | 1,074 | $ | 990 | |||||||||||||||
| Earnings per Common Share – Basic | $ | 0.63 | $ | 0.48 | $ | 4.16 | $ | 3.86 | |||||||||||||||
| Earnings per Common Share – Diluted | $ | 0.63 | $ | 0.48 | $ | 4.14 | $ | 3.84 | |||||||||||||||
| Weighted-average Common Shares Outstanding – Basic | 259.1 | 257.6 | 258.4 | 256.3 | |||||||||||||||||||
| Weighted-average Common Shares Outstanding – Diluted | 260.2 | 258.9 | 259.5 | 257.6 | |||||||||||||||||||
| December 31, 2022 | December 31, 2021 | ||||||||||
| ASSETS | |||||||||||
| Current Assets: | |||||||||||
| Cash and cash equivalents | $ | 10 | $ | 8 | |||||||
| Accounts receivable - trade (less allowance for doubtful accounts) | 600 | 434 | |||||||||
| Unbilled revenue | 446 | 301 | |||||||||
| Miscellaneous accounts receivable | 54 | 85 | |||||||||
| Inventories | 667 | 592 | |||||||||
| Current regulatory assets | 354 | 319 | |||||||||
| Investments in industrial development revenue bonds | 240 | 8 | |||||||||
| Current collateral assets | 142 | 66 | |||||||||
| Other current assets | 155 | 155 | |||||||||
| Total current assets | 2,668 | 1,968 | |||||||||
| Property, Plant, and Equipment, Net | 31,262 | 29,261 | |||||||||
| Investments and Other Assets: | |||||||||||
| Nuclear decommissioning trust fund | 958 | 1,159 | |||||||||
| Goodwill | 411 | 411 | |||||||||
| Regulatory assets | 1,426 | 1,289 | |||||||||
| Pension and other postretirement benefits | 411 | 756 | |||||||||
| Other assets | 768 | 891 | |||||||||
| Total investments and other assets | 3,974 | 4,506 | |||||||||
| TOTAL ASSETS | $ | 37,904 | $ | 35,735 | |||||||
| LIABILITIES AND EQUITY | |||||||||||
| Current Liabilities: | |||||||||||
| Current maturities of long-term debt | $ | 340 | $ | 505 | |||||||
| Short-term debt | 1,070 | 545 | |||||||||
| Accounts and wages payable | 1,159 | 1,095 | |||||||||
| Other current liabilities | 797 | 681 | |||||||||
| Total current liabilities | 3,366 | 2,826 | |||||||||
| Long-term Debt, Net | 13,685 | 12,562 | |||||||||
| Deferred Credits and Other Liabilities: | |||||||||||
| Accumulated deferred income taxes and investment tax credits, net | 3,804 | 3,499 | |||||||||
| Regulatory liabilities | 5,309 | 5,848 | |||||||||
| Asset retirement obligations | 763 | 757 | |||||||||
| Other deferred credits and liabilities | 340 | 414 | |||||||||
| Total deferred credits and other liabilities | 10,216 | 10,518 | |||||||||
| Shareholders’ Equity: | |||||||||||
| Common stock | 3 | 3 | |||||||||
| Other paid-in capital, principally premium on common stock | 6,860 | 6,502 | |||||||||
| Retained earnings | 3,646 | 3,182 | |||||||||
| Accumulated other comprehensive income (loss) | (1) | 13 | |||||||||
| Total shareholders’ equity | 10,508 | 9,700 | |||||||||
| Noncontrolling Interests | 129 | 129 | |||||||||
| Total equity | 10,637 | 9,829 | |||||||||
| TOTAL LIABILITIES AND EQUITY | $ | 37,904 | $ | 35,735 | |||||||
| Year Ended December 31, | |||||||||||
| 2022 | 2021 | ||||||||||
| Cash Flows From Operating Activities: | |||||||||||
| Net income | $ | 1,079 | $ | 995 | |||||||
| Adjustments to reconcile net income to net cash provided by operating activities: | |||||||||||
| Depreciation and amortization | 1,438 | 1,277 | |||||||||
| Amortization of debt issuance costs and premium/discounts | 21 | 23 | |||||||||
| Deferred income taxes and investment tax credits, net | 170 | 156 | |||||||||
| Allowance for equity funds used during construction | (43) | (43) | |||||||||
| Stock-based compensation costs | 24 | 22 | |||||||||
| Other | 68 | 19 | |||||||||
| Changes in assets and liabilities | (494) | (788) | |||||||||
| Net cash provided by operating activities | 2,263 | 1,661 | |||||||||
| Cash Flows From Investing Activities: | |||||||||||
| Capital expenditures | (3,351) | (3,479) | |||||||||
| Nuclear fuel expenditures | (29) | (44) | |||||||||
| Purchases of securities – nuclear decommissioning trust fund | (229) | (452) | |||||||||
| Sales and maturities of securities – nuclear decommissioning trust fund | 216 | 439 | |||||||||
| Other | 23 | 8 | |||||||||
| Net cash used in investing activities | (3,370) | (3,528) | |||||||||
| Cash Flows From Financing Activities: | |||||||||||
| Dividends on common stock | (610) | (565) | |||||||||
| Dividends paid to noncontrolling interest holders | (5) | (5) | |||||||||
| Short-term debt, net | 522 | 55 | |||||||||
| Maturities of long-term debt | (505) | (8) | |||||||||
| Issuances of long-term debt | 1,467 | 1,997 | |||||||||
| Issuances of common stock | 333 | 308 | |||||||||
| Redemptions of Ameren Illinois preferred stock | — | (13) | |||||||||
| Employee payroll taxes related to stock-based compensation | (16) | (17) | |||||||||
| Debt issuance costs | (18) | (18) | |||||||||
| Other | — | (13) | |||||||||
| Net cash provided by financing activities | 1,168 | 1,721 | |||||||||
| Net change in cash, cash equivalents, and restricted cash | 61 | (146) | |||||||||
| Cash, cash equivalents, and restricted cash at beginning of year | 155 | 301 | |||||||||
| Cash, cash equivalents, and restricted cash at end of year | $ | 216 | $ | 155 | |||||||