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REGULATORY ACCOUNTING - Components of Regulatory Liabilities (Details) - USD ($) $ in Thousands | Mar. 31, 2025 | Dec. 31, 2024
--- | --- | ---
Regulatory Liabilities [Line Items] |  |
Total Regulatory Liabilities | $ 4,842,800 | $ 4,664,900
Less: Current Portion | 774,549 | 632,282
Total Long-Term Regulatory Liabilities | 4,068,329 | 4,032,564
EDIT due to Tax Cuts and Jobs Act of 2017 |  |
Regulatory Liabilities [Line Items] |  |
Total Regulatory Liabilities | 2,432,400 | 2,442,700
Regulatory Tracking Mechanisms |  |
Regulatory Liabilities [Line Items] |  |
Total Regulatory Liabilities | 840,500 | 702,400
Cost of Removal |  |
Regulatory Liabilities [Line Items] |  |
Total Regulatory Liabilities | 711,000 | 684,100
Deferred Portion of Non-Service Income Components of Pension, SERP and PBOP |  |
Regulatory Liabilities [Line Items] |  |
Total Regulatory Liabilities | 448,100 | 427,100
AFUDC - Transmission |  |
Regulatory Liabilities [Line Items] |  |
Total Regulatory Liabilities | 160,300 | 154,800
Benefit Costs |  |
Regulatory Liabilities [Line Items] |  |
Total Regulatory Liabilities | 63,400 | 69,300
Other Regulatory Liabilities |  |
Regulatory Liabilities [Line Items] |  |
Total Regulatory Liabilities | 187,100 | 184,500
CL&P |  |
Regulatory Liabilities [Line Items] |  |
Total Regulatory Liabilities | 1,581,800 | 1,520,000
Less: Current Portion | 169,066 | 124,122
Total Long-Term Regulatory Liabilities | 1,412,685 | 1,395,883
CL&P | EDIT due to Tax Cuts and Jobs Act of 2017 |  |
Regulatory Liabilities [Line Items] |  |
Total Regulatory Liabilities | 954,600 | 956,600
CL&P | Regulatory Tracking Mechanisms |  |
Regulatory Liabilities [Line Items] |  |
Total Regulatory Liabilities | 221,800 | 180,300
CL&P | Cost of Removal |  |
Regulatory Liabilities [Line Items] |  |
Total Regulatory Liabilities | 226,800 | 212,800
CL&P | Deferred Portion of Non-Service Income Components of Pension, SERP and PBOP |  |
Regulatory Liabilities [Line Items] |  |
Total Regulatory Liabilities | 64,500 | 61,600
CL&P | AFUDC - Transmission |  |
Regulatory Liabilities [Line Items] |  |
Total Regulatory Liabilities | 66,600 | 65,100
CL&P | Benefit Costs |  |
Regulatory Liabilities [Line Items] |  |
Total Regulatory Liabilities | 4,700 | 4,500
CL&P | Other Regulatory Liabilities |  |
Regulatory Liabilities [Line Items] |  |
Total Regulatory Liabilities | 42,800 | 39,100
NSTAR Electric |  |
Regulatory Liabilities [Line Items] |  |
Total Regulatory Liabilities | 2,151,800 | 2,079,400
Less: Current Portion | 497,405 | 436,312
Total Long-Term Regulatory Liabilities | 1,654,352 | 1,643,079
NSTAR Electric | EDIT due to Tax Cuts and Jobs Act of 2017 |  |
Regulatory Liabilities [Line Items] |  |
Total Regulatory Liabilities | 872,000 | 877,600
NSTAR Electric | Regulatory Tracking Mechanisms |  |
Regulatory Liabilities [Line Items] |  |
Total Regulatory Liabilities | 475,000 | 413,600
NSTAR Electric | Cost of Removal |  |
Regulatory Liabilities [Line Items] |  |
Total Regulatory Liabilities | 457,600 | 451,300
NSTAR Electric | Deferred Portion of Non-Service Income Components of Pension, SERP and PBOP |  |
Regulatory Liabilities [Line Items] |  |
Total Regulatory Liabilities | 222,300 | 211,600
NSTAR Electric | AFUDC - Transmission |  |
Regulatory Liabilities [Line Items] |  |
Total Regulatory Liabilities | 93,700 | 89,700
NSTAR Electric | Benefit Costs |  |
Regulatory Liabilities [Line Items] |  |
Total Regulatory Liabilities | 17,100 | 21,400
NSTAR Electric | Other Regulatory Liabilities |  |
Regulatory Liabilities [Line Items] |  |
Total Regulatory Liabilities | 14,100 | 14,200
PSNH |  |
Regulatory Liabilities [Line Items] |  |
Total Regulatory Liabilities | 504,000 | 516,100
Less: Current Portion | 103,097 | 121,058
Total Long-Term Regulatory Liabilities | 400,903 | 394,982
PSNH | EDIT due to Tax Cuts and Jobs Act of 2017 |  |
Regulatory Liabilities [Line Items] |  |
Total Regulatory Liabilities | 328,600 | 330,600
PSNH | Regulatory Tracking Mechanisms |  |
Regulatory Liabilities [Line Items] |  |
Total Regulatory Liabilities | 96,100 | 114,400
PSNH | Cost of Removal |  |
Regulatory Liabilities [Line Items] |  |
Total Regulatory Liabilities | 26,600 | 20,100
PSNH | Deferred Portion of Non-Service Income Components of Pension, SERP and PBOP |  |
Regulatory Liabilities [Line Items] |  |
Total Regulatory Liabilities | 44,100 | 42,600
PSNH | AFUDC - Transmission |  |
Regulatory Liabilities [Line Items] |  |
Total Regulatory Liabilities | 0 | 0
PSNH | Benefit Costs |  |
Regulatory Liabilities [Line Items] |  |
Total Regulatory Liabilities | 4,000 | 3,900
PSNH | Other Regulatory Liabilities |  |
Regulatory Liabilities [Line Items] |  |
Total Regulatory Liabilities | $ 4,600 | $ 4,500

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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/1943274/2147477571/980-405-25-1 + Details
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