| Fiscal period | 2025 | 2024 | 2023 | 2022 | 2021 | 2020 | 2019 | 2018 | 2017 | 2016 |
| Period End Date | 12/31/2025 | 12/31/2024 | 12/31/2023 | 12/31/2022 | 12/31/2021 | 12/31/2020 | 12/31/2019 | 12/31/2018 | 12/31/2017 | 12/31/2016 |
| Operating Revenues | 5,339.94 | 5,124.92 | 4,695.99 | 4,324.39 | 3,803.84 | 3,586.98 | 3,471.21 | 3,691.25 | 3,565.30 | 3,498.68 |
| Revenues : Marketing and trading | -- | -- | -- | -- | -- | -- | -- | -- | -- | -- |
| Revenues : Real estate segment | -- | -- | -- | -- | -- | -- | -- | -- | -- | -- |
| Revenues : Regulated electricity segment | -- | -- | -- | -- | -- | -- | -- | -- | -- | -- |
| Revenues : Other revenues | -- | -- | -- | -- | -- | -- | -- | -- | -- | -- |
| Total Revenue | 5,339.94 | 5,124.92 | 4,695.99 | 4,324.39 | 3,803.84 | 3,586.98 | 3,471.21 | 3,691.25 | 3,565.30 | -- |
| Regulated electricity segment fuel and purchased power | 1,933.42 | 1,822.57 | 1,792.66 | 1,629.34 | 1,152.55 | 993.42 | 1,042.24 | 1,076.12 | 981.30 | 1,075.51 |
| Marketing and trading segment fuel and purchased power | -- | -- | -- | -- | -- | -- | -- | -- | -- | -- |
| Operations and maintenance | 1,185.07 | 1,165.16 | 1,058.73 | 987.07 | 954.07 | 958.91 | 941.62 | 1,036.74 | 924.44 | 911.32 |
| Depreciation and amortization | 915.34 | 895.35 | 794.04 | 753.20 | 650.88 | 614.38 | 590.93 | 582.35 | 534.12 | 485.83 |
| Taxes other than income taxes | 234.80 | 227.40 | 224.01 | 220.37 | 234.64 | 224.84 | 218.58 | 212.85 | 184.35 | 166.50 |
| Real estate segment operations | -- | -- | -- | -- | -- | -- | -- | -- | -- | -- |
| Regulatory disallowance | -- | -- | -- | -- | -- | -- | -- | -- | -- | -- |
| Other expenses | (3.68) | (2.39) | (1.91) | (2.49) | (6.39) | (7.29) | (5.89) | (9.50) | (6.66) | (3.54) |
| Real estate impairment charge | -- | -- | -- | -- | -- | -- | -- | -- | -- | -- |
| Total Operating Expenses | 4,272.31 | 4,112.85 | 3,871.35 | 3,592.47 | 2,998.53 | 2,798.83 | 2,799.25 | 2,917.56 | 2,630.87 | 2,642.70 |
| Operating income (loss) | 1,067.63 | 1,012.06 | 824.64 | 731.91 | 805.31 | 788.15 | 671.96 | 773.69 | 934.43 | 855.98 |
| Interest charges | 469.70 | 425.74 | 374.89 | 283.57 | 254.31 | 247.50 | 235.25 | 243.47 | 219.80 | 205.72 |
| Capitalized interest | -- | -- | -- | -- | -- | -- | -- | -- | -- | -- |
| Allowance for equity funds used during construction | 61.15 | 38.62 | 53.12 | 45.26 | 41.74 | 33.78 | 31.43 | 52.32 | 47.01 | 42.14 |
| Allowance for borrowed funds used during construction | 47.73 | 48.27 | 43.56 | 28.03 | 21.05 | 18.53 | 18.53 | 25.18 | 22.11 | 19.97 |
| Other Income | 49.41 | 48.61 | 33.67 | 7.92 | 45.10 | 56.70 | 50.26 | 24.90 | 4.01 | 0.90 |
| Other expense | (30.27) | (34.14) | (25.06) | (52.39) | (25.40) | (57.78) | (17.88) | (17.97) | (21.54) | (15.34) |
| Pension and other postretirement non-service credits - net | 12.42 | 48.87 | 40.65 | 98.49 | 112.54 | 56.34 | 22.99 | 49.79 | -- | -- |
| Income from Continuing Operations Before Income Taxes | 738.37 | 736.56 | 595.69 | 575.65 | 746.03 | 648.23 | 542.04 | 664.44 | 766.22 | 697.94 |
| Provision for Income taxes | 106.73 | 110.53 | 76.91 | 74.83 | 110.09 | 78.17 | (15.77) | 133.90 | 258.27 | 236.41 |
| Income from continuing operations | -- | -- | -- | -- | -- | -- | -- | -- | -- | -- |
| INCOME (LOSS)FROM DISCONTINUED OPERATIONS | -- | -- | -- | -- | -- | -- | -- | -- | -- | -- |
| Cumulative effect of a change in accounting for trading activities | -- | -- | -- | -- | -- | -- | -- | -- | -- | -- |
| Cumulative Effect of a Change in Accounting for Derivatives | -- | -- | -- | -- | -- | -- | -- | -- | -- | -- |
| Consolidated Net Income (Loss) | 631.64 | 626.03 | 518.78 | 500.83 | 635.94 | 570.05 | 557.81 | 530.54 | 507.95 | 461.53 |
| Net loss attributable to noncontrolling interests | 15.11 | 17.22 | 17.22 | 17.22 | 17.22 | 19.49 | 19.49 | 19.49 | 19.49 | 19.49 |
| Net Income (Loss) Available to Common Shareholders | 616.53 | 608.81 | 501.56 | 483.60 | 618.72 | 550.56 | 538.32 | 511.05 | 488.46 | 442.03 |
| Income from continuing operations - basic | -- | -- | -- | -- | -- | -- | -- | -- | -- | -- |
| Income from Discontinued operations - basic | -- | -- | -- | -- | -- | -- | -- | -- | -- | -- |
| Net income - basic | 5.15 | 5.35 | 4.42 | 4.27 | 5.48 | 4.89 | 4.79 | 4.56 | 4.37 | 3.97 |
| Income from continuing operations - diluted | -- | -- | -- | -- | -- | -- | -- | -- | -- | -- |
| Income from Discontinued operation - diluted | -- | -- | -- | -- | -- | -- | -- | -- | -- | -- |
| Net income - diluted | 5.05 | 5.24 | 4.41 | 4.26 | 5.47 | 4.87 | 4.77 | 4.54 | 4.35 | 3.95 |
| Weighted Average Shares Outstanding (Basic) | 119.69 | 113.85 | 113.44 | 113.20 | 112.91 | 112.67 | 112.44 | 112.13 | 111.84 | 111.41 |
| Weighted Average Shares Outstanding (Diluted) | 121.97 | 116.23 | 113.80 | 113.42 | 113.19 | 112.94 | 112.76 | 112.55 | 112.37 | 112.05 |