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EMPLOYEE BENEFITS - Schedule of Funded Status (Details) - Pension Plan - USD ($) $ in Millions | Dec. 31, 2021 | Dec. 31, 2020
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Defined Benefit Plan Disclosure [Line Items] |  |
Accumulated benefit obligation | $ 6,337.3 | $ 6,669.4
The Connecticut Light and Power Company |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Accumulated benefit obligation | 1,241.1 | 1,356.4
NSTAR Electric Company |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Accumulated benefit obligation | 1,376.1 | 1,449.4
Public Service Company of New Hampshire |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Accumulated benefit obligation | $ 670.3 | $ 707.2

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- Definition Amount of actuarial present value of benefits attributed to employee service rendered, excluding assumptions about future compensation level. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920 + Details
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