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INCOME TAXES - Schedule of Unrecognized Tax Benefits Roll Forward (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022
Unrecognized Tax Benefits [Roll Forward] |  |  |
Beginning Balance | $ 81.3 | $ 67.1 | $ 65.8
Gross Increases - Current Year | 14.2 | 23.4 | 11.5
Gross Increases - Prior Year | 11.0 | 0.1 |
Gross Decreases - Prior Year | (0.2) | (0.1) | (2.4)
Lapse of Statute of Limitations | (12.6) | (9.2) | (7.8)
Ending Balance | 93.7 | 81.3 | 67.1
CL&P |  |  |
Unrecognized Tax Benefits [Roll Forward] |  |  |
Beginning Balance | 25.8 | 25.5 | 26.2
Gross Increases - Current Year | 2.9 | 4.0 | 3.5
Gross Increases - Prior Year | 0.0 | 0.1 |
Gross Decreases - Prior Year | (0.2) | 0.0 | (0.9)
Lapse of Statute of Limitations | (6.6) | (3.8) | (3.3)
Ending Balance | $ 21.9 | $ 25.8 | $ 25.5

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- Definition A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. + References No definition available. + Details
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- Definition Amount of unrecognized tax benefits. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 740 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 217 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482663/740-10-55-217 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 740 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 15A -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482685/740-10-50-15A Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 740 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 10B -Publisher FASB -URI https://asc.fasb.org/1943274/2147482525/740-10-45-10B + Details
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