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INCOME TAXES - Reconciliation of Unrecognized Tax Benefit (Details) - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward] |  |  |
Beginning Balance | $ 61.8 | $ 55.0 | $ 45.9
Gross Increases - Current Year | 11.3 | 11.9 | 12.1
Gross Increases - Prior Year |  | 1.4 | 3.4
Gross Decreases - Prior Year | (0.3) |  |
Lapse of Statute of Limitations | (7.0) | (6.5) | (6.4)
Ending Balance | 65.8 | 61.8 | 55.0
The Connecticut Light and Power Company |  |  |
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward] |  |  |
Beginning Balance | 25.8 | 23.1 | 18.2
Gross Increases - Current Year | 3.8 | 4.6 | 4.0
Gross Increases - Prior Year |  | 0.7 | 3.3
Gross Decreases - Prior Year | (0.6) |  |
Lapse of Statute of Limitations | (2.8) | (2.6) | (2.4)
Ending Balance | $ 26.2 | $ 25.8 | $ 23.1

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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/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 45 -Paragraph 10B -URI http://asc.fasb.org/extlink&oid=123427490&loc=SL37586934-109318 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 15A -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121826272&loc=SL6600010-109319 + Details
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- Definition Amount of decrease in unrecognized tax benefits resulting from tax positions taken in prior period tax returns. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 15A -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=121826272&loc=SL6600010-109319 + Details
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- Definition Amount of increase in unrecognized tax benefits resulting from tax positions that have been or will be taken in current period tax return. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 15A -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=121826272&loc=SL6600010-109319 + Details
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