REGULATORY ACCOUNTING - Components of Regulatory Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Regulatory Assets [Line Items]
Total Regulatory Assets	$ 7,070,700	$ 6,389,200
Less: Current Portion	2,189,660	1,674,196
Total Long-Term Regulatory Assets	4,880,974	4,714,970
Storm Costs, Net
Regulatory Assets [Line Items]
Total Regulatory Assets	2,039,400	1,785,900
Regulatory Tracking Mechanisms
Regulatory Assets [Line Items]
Total Regulatory Assets	1,781,600	1,319,200
Benefit Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	967,400	1,117,300
Income Taxes, Net
Regulatory Assets [Line Items]
Total Regulatory Assets	968,400	912,400
Securitized Stranded Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	349,300	392,500
Goodwill-related
Regulatory Assets [Line Items]
Total Regulatory Assets	247,200	264,100
Asset Retirement Obligations
Regulatory Assets [Line Items]
Total Regulatory Assets	150,200	137,900
Derivative Liabilities
Regulatory Assets [Line Items]
Total Regulatory Assets	57,200	120,900
Other Regulatory Assets
Regulatory Assets [Line Items]
Total Regulatory Assets	510,000	339,000
CL&P
Regulatory Assets [Line Items]
Total Regulatory Assets	2,325,500	2,143,200
Less: Current Portion	638,529	480,369
Total Long-Term Regulatory Assets	1,687,029	1,662,778
CL&P \| Storm Costs, Net
Regulatory Assets [Line Items]
Total Regulatory Assets	971,100	896,600
CL&P \| Regulatory Tracking Mechanisms
Regulatory Assets [Line Items]
Total Regulatory Assets	507,700	354,500
CL&P \| Benefit Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	168,800	197,400
CL&P \| Income Taxes, Net
Regulatory Assets [Line Items]
Total Regulatory Assets	521,000	512,600
CL&P \| Securitized Stranded Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	0	0
CL&P \| Goodwill-related
Regulatory Assets [Line Items]
Total Regulatory Assets	0	0
CL&P \| Asset Retirement Obligations
Regulatory Assets [Line Items]
Total Regulatory Assets	41,200	38,500
CL&P \| Derivative Liabilities
Regulatory Assets [Line Items]
Total Regulatory Assets	57,200	120,900
CL&P \| Other Regulatory Assets
Regulatory Assets [Line Items]
Total Regulatory Assets	58,500	22,700
NSTAR Electric
Regulatory Assets [Line Items]
Total Regulatory Assets	2,107,100	1,957,900
Less: Current Portion	902,770	676,083
Total Long-Term Regulatory Assets	1,204,337	1,281,836
NSTAR Electric \| Storm Costs, Net
Regulatory Assets [Line Items]
Total Regulatory Assets	609,800	609,100
NSTAR Electric \| Regulatory Tracking Mechanisms
Regulatory Assets [Line Items]
Total Regulatory Assets	650,000	482,900
NSTAR Electric \| Benefit Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	293,600	336,700
NSTAR Electric \| Income Taxes, Net
Regulatory Assets [Line Items]
Total Regulatory Assets	145,400	128,600
NSTAR Electric \| Securitized Stranded Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	0	0
NSTAR Electric \| Goodwill-related
Regulatory Assets [Line Items]
Total Regulatory Assets	212,300	226,700
NSTAR Electric \| Asset Retirement Obligations
Regulatory Assets [Line Items]
Total Regulatory Assets	78,300	72,300
NSTAR Electric \| Derivative Liabilities
Regulatory Assets [Line Items]
Total Regulatory Assets	0	0
NSTAR Electric \| Other Regulatory Assets
Regulatory Assets [Line Items]
Total Regulatory Assets	117,700	101,600
PSNH
Regulatory Assets [Line Items]
Total Regulatory Assets	1,065,700	963,300
Less: Current Portion	173,267	189,450
Total Long-Term Regulatory Assets	892,411	773,783
PSNH \| Storm Costs, Net
Regulatory Assets [Line Items]
Total Regulatory Assets	458,500	280,200
PSNH \| Regulatory Tracking Mechanisms
Regulatory Assets [Line Items]
Total Regulatory Assets	162,800	182,200
PSNH \| Benefit Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	65,600	79,300
PSNH \| Income Taxes, Net
Regulatory Assets [Line Items]
Total Regulatory Assets	20,700	16,400
PSNH \| Securitized Stranded Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	349,300	392,500
PSNH \| Goodwill-related
Regulatory Assets [Line Items]
Total Regulatory Assets	0	0
PSNH \| Asset Retirement Obligations
Regulatory Assets [Line Items]
Total Regulatory Assets	5,100	4,700
PSNH \| Derivative Liabilities
Regulatory Assets [Line Items]
Total Regulatory Assets	0	0
PSNH \| Other Regulatory Assets
Regulatory Assets [Line Items]
Total Regulatory Assets	$ 3,700	$ 8,000

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The amount for the individual regulatory asset as itemized in a table of regulatory assets as of the end of the period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 980
-SubTopic 340
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478742/980-340-50-1

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