EARNINGS PER SHARE AND COMMON STOCK (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Basic
Net Income Attributable to ALLETE	$ 31.9	$ 33.0	$ 88.0	$ 83.7
Average Common Shares (in shares)	58.0	57.7	58.0	57.7
Earnings Per Share (in usd per share)	$ 0.55	$ 0.57	$ 1.52	$ 1.45
Diluted
Net Income Attributable to ALLETE	$ 31.9	$ 33.0	$ 88.0	$ 83.7
Average Common Shares Diluted Securities (in shares)	0.1	0.1	0.0	0.0
Average Common Shares (in shares)	58.1	57.8	58.0	57.7
Earnings Per Share (in usd per share)	$ 0.55	$ 0.57	$ 1.52	$ 1.45

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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+ Details

- Definition

The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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+ Details

- Definition

Amount, after deduction of tax, noncontrolling interests, dividends on preferred stock and participating securities; of income (loss) available to common shareholders.

+ References

+ Details

- Definition

Amount, after deduction of tax, noncontrolling interests, dividends on preferred stock and participating securities, and addition from assumption of issuance of common shares for dilutive potential common shares; of income (loss) available to common shareholders.

+ References + Details

ALLETE INC 10-Q