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v3.21.2

Business Segments (Details) $ in Millions | 3 Months Ended | 6 Months Ended |
--- | --- | --- | ---
Jun. 30, 2021 USD ($) a | Jun. 30, 2020 USD ($) | Jun. 30, 2021 USD ($) a Segments | Jun. 30, 2020 USD ($) | Dec. 31, 2020 USD ($)
Business Segments [Line Items] |  |  |  |  |
Number of Reportable Segments | Segments |  |  | 2 |  |
Operating Revenue | $ 335.6 | $ 243.2 | $ 674.8 | $ 554.8 |
Net Income Attributable to ALLETE | 27.9 | 20.1 | 79.7 | 86.4 |
Assets | 6,293.3 |  | $ 6,293.3 |  | $ 6,084.6
Regulated Operations [Member] |  |  |  |  |
Business Segments [Line Items] |  |  |  |  |
Number of Operating Segments | Segments |  |  | 3 |  |
Operating Revenue | 290.4 | 200.8 | $ 583.4 | 466.1 |
Net Income Attributable to ALLETE | 21.5 | 11.1 | 66.5 | 68.6 |
Assets | 4,200.1 |  | 4,200.1 |  | 4,196.8
Regulated Operations [Member] | Residential [Member] |  |  |  |  |
Business Segments [Line Items] |  |  |  |  |
Operating Revenue | 35.4 | 27.4 | 81.0 | 68.3 |
Regulated Operations [Member] | Commercial [Member] |  |  |  |  |
Business Segments [Line Items] |  |  |  |  |
Operating Revenue | 40.7 | 28.8 | 80.4 | 66.1 |
Regulated Operations [Member] | Municipal [Member] |  |  |  |  |
Business Segments [Line Items] |  |  |  |  |
Operating Revenue | 11.5 | 9.0 | 24.1 | 19.3 |
Regulated Operations [Member] | Industrial [Member] |  |  |  |  |
Business Segments [Line Items] |  |  |  |  |
Operating Revenue | 139.1 | 88.0 | 268.1 | 206.8 |
Regulated Operations [Member] | Other Power Suppliers [Member] |  |  |  |  |
Business Segments [Line Items] |  |  |  |  |
Operating Revenue | 37.3 | 27.4 | 75.7 | 65.7 |
Regulated Operations [Member] | Other [Member] |  |  |  |  |
Business Segments [Line Items] |  |  |  |  |
Operating Revenue | 26.4 | 20.2 | 54.1 | 39.9 |
ALLETE Clean Energy [Member] |  |  |  |  |
Business Segments [Line Items] |  |  |  |  |
Operating Revenue | 21.6 | 17.6 | 42.5 | 37.7 |
Net Income Attributable to ALLETE | 5.1 | 4.0 | 12.5 | 15.7 |
Assets | 1,653.5 |  | 1,653.5 |  | 1,483.3
ALLETE Clean Energy [Member] | Long-term PSA [Member] |  |  |  |  |
Business Segments [Line Items] |  |  |  |  |
Operating Revenue | 18.7 | 14.8 | 36.8 | 32.1 |
ALLETE Clean Energy [Member] | Other [Member] |  |  |  |  |
Business Segments [Line Items] |  |  |  |  |
Operating Revenue, Other Than Customer Revenue | $ 2.9 | 2.8 | $ 5.7 | 5.6 |
Corporate and Other [Member] |  |  |  |  |
Business Segments [Line Items] |  |  |  |  |
Number of Operating Segments | Segments |  |  | 2 |  |
Land in Minnesota (Acres) | a | 4,000 |  | 4,000 |  |
Operating Revenue | $ 23.6 | 24.8 | $ 48.9 | 51.0 |
Net Income Attributable to ALLETE | 1.3 | 5.0 | 0.7 | 2.1 |
Assets | 439.7 |  | 439.7 |  | $ 404.5
Corporate and Other [Member] | Long-term Contract [Member] |  |  |  |  |
Business Segments [Line Items] |  |  |  |  |
Operating Revenue | 21.4 | 22.5 | 43.1 | 44.9 |
Corporate and Other [Member] | Other [Member] |  |  |  |  |
Business Segments [Line Items] |  |  |  |  |
Operating Revenue | $ 2.2 | $ 2.3 | $ 5.8 | $ 6.1 |

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