SCHEDULE I - FINANCIAL INFORMATION OF REGISTRANT - STATEMENTS OF INCOME(LOSS) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Condensed Income Statements, Captions [Line Items]
Revenues	$ 13,547,244	$ 11,900,809	$ 11,910,705
Operating Expenses:
Other	2,073,778	2,012,926	1,895,703
Loss on Pending Sale of Aquarion	0	297,000	0
Total Operating Expenses	10,558,655	9,492,100	9,511,370
Operating Income (Loss)	2,988,589	2,408,709	2,399,335
Interest Expense	1,243,266	1,111,336	855,441
Other Income, Net:
Equity in Earnings/(Losses) of Subsidiaries	19,900	51,900	15,500
Other Income/(Loss), Net	378,854	410,482	348,069
Income/(Loss) Before Income Tax Benefit	1,840,177	1,243,836	(275,037)
Income tax expense (benefit)	$ 140,286	$ 424,664	$ 159,684
Basic Earnings/(Loss) Per Common Share (in dollars per share)	$ 4.56	$ 2.27	$ (1.27)
Diluted Earnings/(Loss) Per Common Share (in dollars per share)	$ 4.56	$ 2.27	$ (1.26)
Weighted Average Common Shares Outstanding:
Basic (in shares)	370,852,601	357,482,965	349,580,638
Diluted (in shares)	371,259,264	357,779,408	349,840,481
Eversource
Condensed Income Statements, Captions [Line Items]
Revenues	$ 2,067	$ 4,442	$ 840
Operating Expenses:
Acquisition and Integration Costs Allowed for Recovery	(82,346)	0	0
Other	10,458	20	12,769
Loss on Pending Sale of Aquarion	0	297,000	0
Total Operating Expenses	(71,888)	297,020	12,769
Operating Income (Loss)	73,955	(292,578)	(11,929)
Interest Expense	548,723	549,511	397,281
Other Income, Net:
Equity in Earnings/(Losses) of Subsidiaries	1,923,453	1,359,297	(312,040)
Other, Net	166,600	214,444	188,003
Other Income/(Loss), Net	2,090,053	1,573,741	(124,037)
Income/(Loss) Before Income Tax Benefit	1,615,285	731,652	(533,247)
Income tax expense (benefit)	(77,087)	(80,001)	(91,007)
Net Income/(Loss)	$ 1,692,372	$ 811,653	$ (442,240)
Basic Earnings/(Loss) Per Common Share (in dollars per share)	$ 4.56	$ 2.27	$ (1.27)
Diluted Earnings/(Loss) Per Common Share (in dollars per share)	$ 4.56	$ 2.27	$ (1.26)
Weighted Average Common Shares Outstanding:
Basic (in shares)	370,852,601	357,482,965	349,580,638
Diluted (in shares)	371,259,264	357,779,408	349,840,481