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EMPLOYEE BENEFITS - Schedule of Other Retirement Benefits (Details) - USD ($) $ in Millions | Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019
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Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |
Actuarially-Determined Liability | $ 42.8 | $ 45.7 | $ 52.0
Other Retirement Benefits Expense | 2.2 | 3.3 | 2.7
The Connecticut Light and Power Company |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |
Actuarially-Determined Liability | 0.2 | 0.2 | 0.2
Other Retirement Benefits Expense | 0.7 | 1.2 | 1.0
NSTAR Electric Company |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |
Actuarially-Determined Liability | 0.1 | 0.1 | 0.1
Other Retirement Benefits Expense | 0.7 | 1.1 | 0.9
Public Service Company of New Hampshire |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |
Actuarially-Determined Liability | 1.5 | 1.7 | 1.7
Other Retirement Benefits Expense | $ 0.3 | $ 0.5 | $ 0.4

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- Definition Other retirement benefits are accounted for on an accrual basis and expensed over the service lives of the employees in accordance with accounting guidance for deferred compensation contracts. + References No definition available. + Details
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- Definition Aggregate carrying value as of the balance sheet date of the liabilities for deferred compensation arrangements payable after one year (or the normal operating cycle, if longer). Represents currently earned compensation under cash arrangements (such as a profit-sharing plan, rabbi trust, and employee contract--excluding equity-based arrangements) that is not actually paid until a later date. + References No definition available. + Details
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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