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v3.23.3

Business Segments - (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended |
--- | --- | --- | ---
Sep. 30, 2023 | Sep. 30, 2022 | Sep. 30, 2023 | Sep. 30, 2022 | Dec. 31, 2022
Business Segments [Line Items] |  |  |  |  |
Total Operating Revenue | $ 378.8 | $ 388.3 | $ 1,477.1 | $ 1,144.9 |
Net Income (Loss) Attributable to ALLETE | 85.9 | 33.7 | 195.6 | 137.6 |
Gain from legal settlements |  |  | 44.3 |  |
Income tax expense from settlement proceeds |  |  | 3.8 |  |
Assets | 6,644.8 |  | 6,644.8 |  | $ 6,845.6
Corporate and Other |  |  |  |  |
Business Segments [Line Items] |  |  |  |  |
Total Operating Revenue | 378.8 | 388.3 | 1,477.1 | 1,144.9 |
Regulated Operations |  |  |  |  |
Business Segments [Line Items] |  |  |  |  |
Net Income (Loss) Attributable to ALLETE | 34.0 | 38.3 | 112.4 | 119.4 |
Assets | 4,272.4 |  | 4,272.4 |  | 4,291.4
Regulated Operations | Operating Segments |  |  |  |  |
Business Segments [Line Items] |  |  |  |  |
Total Operating Revenue | 314.3 | 322.6 | 919.1 | 960.3 |
Regulated Operations | Residential | Operating Segments |  |  |  |  |
Business Segments [Line Items] |  |  |  |  |
Operating Revenue | 37.9 | 40.1 | 123.3 | 136.7 |
Regulated Operations | Commercial | Operating Segments |  |  |  |  |
Business Segments [Line Items] |  |  |  |  |
Operating Revenue | 49.2 | 49.0 | 140.9 | 141.7 |
Regulated Operations | Municipal | Operating Segments |  |  |  |  |
Business Segments [Line Items] |  |  |  |  |
Operating Revenue | 8.7 | 9.8 | 25.2 | 31.9 |
Regulated Operations | Industrial | Operating Segments |  |  |  |  |
Business Segments [Line Items] |  |  |  |  |
Operating Revenue | 154.3 | 147.3 | 439.4 | 445.7 |
Regulated Operations | Other Power Suppliers | Operating Segments |  |  |  |  |
Business Segments [Line Items] |  |  |  |  |
Operating Revenue | 31.0 | 46.7 | 103.2 | 124.6 |
Regulated Operations | Other | Operating Segments |  |  |  |  |
Business Segments [Line Items] |  |  |  |  |
Operating Revenue | 33.2 | 29.7 | 87.1 | 79.7 |
ALLETE Clean Energy |  |  |  |  |
Business Segments [Line Items] |  |  |  |  |
Net Income (Loss) Attributable to ALLETE | 54.8 | (7.3) | 66.4 | 15.0 |
Assets | 1,599.7 |  | 1,599.7 |  | 1,873.3
ALLETE Clean Energy | Operating Segments |  |  |  |  |
Business Segments [Line Items] |  |  |  |  |
Total Operating Revenue | 14.2 | 15.6 | 396.8 | 65.0 |
ALLETE Clean Energy | Long-term PSA | Operating Segments |  |  |  |  |
Business Segments [Line Items] |  |  |  |  |
Operating Revenue | 12.9 | 14.4 | 44.5 | 58.7 |
ALLETE Clean Energy | Sale of Wind Energy Facilities | Operating Segments |  |  |  |  |
Business Segments [Line Items] |  |  |  |  |
Operating Revenue | 0.0 | 0.0 | 348.4 | 0.0 |
ALLETE Clean Energy | Other | Operating Segments |  |  |  |  |
Business Segments [Line Items] |  |  |  |  |
Operating revenue, other than customer revenue | 1.3 | 1.2 | 3.9 | 6.3 |
Corporate and Other |  |  |  |  |
Business Segments [Line Items] |  |  |  |  |
Net Income (Loss) Attributable to ALLETE | (2.9) | 2.7 | 16.8 | 3.2 |
Assets | 772.7 |  | 772.7 |  | $ 680.9
Corporate and Other | Corporate and Other |  |  |  |  |
Business Segments [Line Items] |  |  |  |  |
Total Operating Revenue | 50.3 | 50.1 | 161.2 | 119.6 |
Corporate and Other | New Energy |  |  |  |  |
Business Segments [Line Items] |  |  |  |  |
Purchase price accounting impact |  |  |  | 5.7 |
Transaction costs |  |  |  | 2.6 |
Corporate and Other | Long-term Contract | Corporate and Other |  |  |  |  |
Business Segments [Line Items] |  |  |  |  |
Operating Revenue | 24.6 | 23.5 | 74.0 | 67.5 |
Corporate and Other | Sale of Renewable Development Projects | Corporate and Other |  |  |  |  |
Business Segments [Line Items] |  |  |  |  |
Operating Revenue | 20.8 | 22.1 | 73.2 | 36.6 |
Corporate and Other | Other | Corporate and Other |  |  |  |  |
Business Segments [Line Items] |  |  |  |  |
Operating Revenue | $ 4.9 | $ 4.5 | $ 14.0 | $ 15.5 |

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