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Earnings Per Share and Common Stock (Tables) | 3 Months Ended
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Mar. 31, 2024
Earnings Per Share [Abstract] |
Reconciliation of Basic and Diluted Earnings Per Share | The difference between basic and diluted earnings per share, if any, arises from non-vested restricted stock units and performance share awards granted under our Executive Long-Term Incentive Compensation Plan.
Three Months Ended March 31, |  |  | 2024 |  |  |  |  |  | 2023 |  |
Reconciliation of Basic and Diluted |  |  | Dilutive |  |  |  |  |  | Dilutive |  |
Earnings Per Share | Basic |  | Securities |  | Diluted |  | Basic |  | Securities |  | Diluted
Millions Except Per Share Amounts |  |  |  |  |  |  |  |  |  |  |
Net Income Attributable to ALLETE | $50.7 |  |  |  |  | $50.7 |  |  | $58.2 |  |  |  |  | $58.2 |
Average Common Shares | 57.6 |  |  | 0.1 |  |  | 57.7 |  |  | 57.3 |  |  | — |  |  | 57.3 |
Earnings Per Share | $0.88 |  |  |  |  | $0.88 |  |  | $1.02 |  |  |  |  | $1.02 |

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- Definition Tabular disclosure of an entity's basic and diluted earnings per share calculations, including a reconciliation of numerators and denominators of the basic and diluted per-share computations for income from continuing operations. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 260 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147482662/260-10-50-1 + Details
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