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OPERATIONS AND SIGNIFICANT ACCOUNTING POLICIES - Other Non-Current Liabilities (Details) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024
Business Segments [Line Items]
Asset Retirement Obligation	$ 265.4	$ 261.3
PSAs	13.6	15.1
Other	35.8	36.4
Total Other Non-Current Liabilities	314.8	312.8
BNI Energy
Business Segments [Line Items]
Other receivables	$ 42.3	$ 42.3

X

- Definition

The fair value adjustment for the price of power per MW at market rates compared to those at contract rate at the time of acquisition through the end of the contract term present valued to acquisition date resulting in a noncurrent liability.

+ References

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- Definition

Noncurrent portion of the carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 410
-SubTopic 20
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-Section 50
-Paragraph 1
-Subparagraph (c)
-Publisher FASB
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- Definition

Amount of expenses incurred but not yet paid classified as other, due after one year or the normal operating cycle, if longer.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-SubTopic 10
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Amount of liabilities classified as other, due after one year or the normal operating cycle, if longer.

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Amount due from parties in nontrade transactions, classified as other.

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Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 280
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Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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