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Operations and Significant Accounting Policies - Other Non-Current Liabilities (Details) - USD ($) $ in Millions | Dec. 31, 2024 | Dec. 31, 2023
--- | --- | ---
Business Segments [Line Items] |  |
Asset Retirement Obligation | $ 261.3 | $ 202.9
PSAs | 15.1 | 20.9
Other | 36.4 | 40.5
Total Other Non-Current Liabilities | 312.8 | 264.3
BNI Energy |  |
Business Segments [Line Items] |  |
Other receivables | $ 42.3 | $ 37.2

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