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Earnings Per Share and Common Stock (Tables)

3 Months Ended

Mar. 31, 2021

Earnings Per Share [Abstract]

Reconciliation of Basic and Diluted Earnings Per Share [Table Text Block]

									2021																		2020
Reconciliation of Basic and Diluted									Dilutive																		Dilutive
Earnings Per Share			Basic						Securities						Diluted						Basic						Securities						Diluted
Millions Except Per Share Amounts
Three Months Ended March 31,
Net Income Attributable to ALLETE			$51.8												$51.8						$66.3												$66.3
Average Common Shares			52.1						0.1						52.2						51.7						0.1						51.8
Earnings Per Share			$0.99												$0.99						$1.28												$1.28

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- References

No definition available.

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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
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

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