Pay vs Performance Disclosure - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Pay vs Performance Disclosure
Net Income (Loss) Attributable to ALLETE	$ 33.0	$ 51.5	$ 83.7	$ 109.7

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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+ Details