SCHEDULE I - FINANCIAL INFORMATION OF REGISTRANT - BALANCE SHEET (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current Assets:
Cash	$ 66,773	$ 106,599
Prepayments and Other Current Assets	369,759	252,439
Total Current Assets	3,270,120	3,130,143
Deferred Debits and Other Assets:
Investments in Subsidiary Companies, at Equity	1,436,293	1,107,143
Goodwill	4,477,269	4,445,988	$ 4,427,000
Other Long-Term Assets	883,756	583,854
Total Deferred Debits and Other Assets	11,844,374	12,086,932
Total Assets (as of)	48,492,144	46,099,598
Current Liabilities:
Notes Payable	1,505,450	1,249,325
Long-Term Debt – Current Portion	1,193,097	1,053,186
Other Current Liabilities	830,620	809,214
Total Current Liabilities	5,847,039	4,915,012
Deferred Credits and Other Liabilities	10,412,412	11,342,662
Capitalization:
Long-Term Debt	17,023,577	15,125,876
Common Shareholders' Equity:
Common Shares	1,789,092	1,789,092
Capital Surplus, Paid in	8,098,514	8,015,663
Retained Earnings	5,005,391	4,613,201
Accumulated Other Comprehensive Loss	(42,275)	(76,411)
Treasury Stock	(250,878)	(277,979)
Stockholders' equity	14,599,844	14,063,566	$ 12,629,994	$ 11,486,817
Total Liabilities and Capitalization	48,492,144	46,099,598
Eversource
Current Assets:
Cash	175	434
Accounts Receivable from Subsidiaries	43,403	39,645
Notes Receivable from Subsidiaries	1,245,900	996,300
Prepayments and Other Current Assets	11,974	19,043
Total Current Assets	1,301,452	1,055,422
Deferred Debits and Other Assets:
Investments in Subsidiary Companies, at Equity	16,108,190	15,483,263
Notes Receivable from Subsidiaries	1,001,000	1,110,400
Accumulated Deferred Income Taxes	17,409	33,469
Goodwill	3,852,524	3,231,811
Other Long-Term Assets	101,710	90,735
Total Deferred Debits and Other Assets	21,080,833	19,949,678
Total Assets (as of)	22,382,285	21,005,100
Current Liabilities:
Notes Payable	1,342,950	1,054,325
Long-Term Debt – Current Portion	767,681	473,933
Accounts Payable to Subsidiaries	37,609	18,424
Other Current Liabilities	87,745	103,477
Total Current Liabilities	2,235,985	1,650,159
Deferred Credits and Other Liabilities	150,616	163,053
Capitalization:
Long-Term Debt	5,395,840	5,128,322
Common Shareholders' Equity:
Common Shares	1,789,092	1,789,092
Capital Surplus, Paid in	8,098,514	8,015,663
Retained Earnings	5,005,391	4,613,201
Accumulated Other Comprehensive Loss	(42,275)	(76,411)
Treasury Stock	(250,878)	(277,979)
Stockholders' equity	14,599,844	14,063,566
Total Liabilities and Capitalization	$ 22,382,285	$ 21,005,100