REGULATORY ASSETS AND LIABILITIES - REGULATORY LIABILITIES (Details) - USD ($) $ in Millions	Sep. 30, 2026	Dec. 31, 2025
Regulatory liabilities
Other current liabilities	$ 85.7	$ 88.9
Regulatory liabilities	4,292.2	4,121.3
Total regulatory liabilities	4,377.9	4,210.2
Income tax related items
Regulatory liabilities
Total regulatory liabilities	1,770.4	1,802.4
Removal costs
Regulatory liabilities
Total regulatory liabilities	1,689.2	1,584.7
Pension and OPEB benefits
Regulatory liabilities
Total regulatory liabilities	296.3	301.5
Energy costs refundable through rate adjustments
Regulatory liabilities
Total regulatory liabilities	147.0	119.2
Settlement related to QIP and UEA riders
Regulatory liabilities
Total regulatory liabilities	125.0	125.0
Uncollectible expense
Regulatory liabilities
Total regulatory liabilities	93.4	73.1
Earnings sharing mechanisms
Regulatory liabilities
Total regulatory liabilities	48.1	35.8
Derivatives
Regulatory liabilities
Total regulatory liabilities	38.5	27.4
MERC property tax tracker
Regulatory liabilities
Total regulatory liabilities	29.2	23.1
We Power escrowed costs
Regulatory liabilities
Total regulatory liabilities	20.1	15.1
Other, net
Regulatory liabilities
Total regulatory liabilities	$ 120.7	$ 102.9

The amount for the individual regulatory liability as itemized in a table of regulatory liabilities as of the end of the period.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 980
-SubTopic 405
-Name Accounting Standards Codification
-Section 25
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477571/980-405-25-1

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The amount for the individual regulatory current liability as itemized in a table of regulatory current liabilities as of the end of the period.

+ References

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The amount for the individual regulatory noncurrent liability as itemized in a table of regulatory noncurrent liabilities as of the end of the period.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(24))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

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