SCHEDULE I - FINANCIAL INFORMATION OF REGISTRANT - STATEMENTS OF INCOME (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Condensed Income Statements, Captions [Line Items]
Operating Revenues	$ 12,289,336	$ 9,863,085	$ 8,904,430
Operating Expenses:
Other	1,865,328	1,739,685	1,480,252
Operating Income (Loss)	2,198,154	1,993,321	1,988,734
Interest Expense	678,274	582,334	538,452
Other Income, Net:
Equity in Earnings of Subsidiaries	22,900	14,200	14,200
Other Income, Net	346,088	161,282	108,590
Income Before Income Tax Expense	1,865,968	1,572,269	1,558,872
Income Tax Benefit	453,574	344,223	346,186
Net Income	$ 1,412,394	$ 1,228,046	$ 1,212,686
Basic Earnings Per Common Share (in dollars per share)	$ 4.05	$ 3.55	$ 3.56
Diluted Earnings Per Common Share (in dollars per share)	$ 4.05	$ 3.54	$ 3.55
Weighted Average Common Shares Outstanding:
Basic (in shares)	346,783,444	343,972,926	338,836,147
Diluted (in shares)	347,246,768	344,631,056	339,847,062
Eversource
Condensed Income Statements, Captions [Line Items]
Operating Revenues	$ 0	$ 0	$ 0
Operating Expenses:
Other	26,708	43,048	28,645
Operating Income (Loss)	(26,708)	(43,048)	(28,645)
Interest Expense	237,773	163,613	160,887
Other Income, Net:
Equity in Earnings of Subsidiaries	1,565,474	1,345,199	1,309,630
Other, Net	79,383	47,802	38,546
Other Income, Net	1,644,857	1,393,001	1,348,176
Income Before Income Tax Expense	1,380,376	1,186,340	1,158,644
Income Tax Benefit	(24,499)	(34,187)	(46,523)
Net Income	$ 1,404,875	$ 1,220,527	$ 1,205,167
Basic Earnings Per Common Share (in dollars per share)	$ 4.05	$ 3.55	$ 3.56
Diluted Earnings Per Common Share (in dollars per share)	$ 4.05	$ 3.54	$ 3.55
Weighted Average Common Shares Outstanding:
Basic (in shares)	346,783,444	343,972,926	338,836,147
Diluted (in shares)	347,246,768	344,631,056	339,847,062