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Regulatory Matters (Regulatory Liabilities) (Details) - USD ($) $ in Millions | Dec. 31, 2023 | Dec. 31, 2022
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Regulated Operations [Line Items] |  |
Regulatory Liabilities | $ 1,789.3 | $ 2,012.6
Regulatory Liability, Current | 278.6 | 236.8
Regulatory Liability, Noncurrent | $ 1,510.7 | 1,775.8
Remaining Recovery Period of Regulatory Assets for which No Return on Investment During Recovery Period is Provided | 69 years |
Deferred Derivative Gain (Loss) |  |
Regulated Operations [Line Items] |  |
Regulatory Liabilities | $ 23.3 | 90.0
Customer Assistance Programs |  |
Regulated Operations [Line Items] |  |
Regulatory Liabilities | 19.8 | 32.9
Rate Refunds |  |
Regulated Operations [Line Items] |  |
Regulatory Liabilities | 16.1 | 51.4
Off-Systems sales sharing |  |
Regulated Operations [Line Items] |  |
Regulatory Liabilities | 19.0 | 12.3
HLBV Adjustments under ASC 980 |  |
Regulated Operations [Line Items] |  |
Regulatory Liabilities | 18.1 | 5.4
Overrecovered Gas And Fuel Costs |  |
Regulated Operations [Line Items] |  |
Regulatory Liabilities | 144.5 | 20.6
Cost Of Removal |  |
Regulated Operations [Line Items] |  |
Regulatory Liabilities | 597.2 | 675.9
Regulatory Effects Of Accounting For Income Taxes |  |
Regulated Operations [Line Items] |  |
Regulatory Liabilities | 849.9 | 996.3
Other Postretirement Costs |  |
Regulated Operations [Line Items] |  |
Regulatory Liabilities | 54.0 | 66.8
Other Liabilities |  |
Regulated Operations [Line Items] |  |
Regulatory Liabilities | $ 47.4 | $ 61.0

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- Definition The amount for the individual regulatory liability as itemized in a table of regulatory liabilities as of the end of the period. + References 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//1943274/2147481854/980-405-25-1 + Details
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- Definition 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://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.24) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1 + Details
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