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Subsequent Event - Agreement and Plan of Merger - Narrative (Details) - Alloy Parent and Alloy Merger Sub - Forecast $ / shares in Units, $ in Millions | 8 Months Ended
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Dec. 31, 2024 USD ($) $ / shares
Subsequent Event |
Subsequent Event [Line Items] |
Conversion price, cash (in usd per share) | $ / shares | $ 67.00
Equity value of ALLETE common stock acquired | $ 3,900
Alloy Parent |
Subsequent Event [Line Items] |
Required amount to purchase of preferred stock | $ 300

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