SCHEDULE I - FINANCIAL INFORMATION OF REGISTRANT - BALANCE SHEET (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current Assets:
Cash	$ 15,432	$ 108,068
Prepayments and Other Current Assets	342,135	260,995
Total Current Assets	2,414,539	2,292,224
Deferred Debits and Other Assets:
Investments in Subsidiary Companies, at Equity	871,633	464,286
Goodwill	4,427,266	4,427,266
Other Long-Term Assets	512,238	398,407
Total Deferred Debits and Other Assets	11,123,906	10,338,604
Total Assets	41,123,915	38,241,256
Current Liabilities:
Notes Payable	889,084	910,000
Long-Term Debt – Current Portion	327,411	837,319
Other Current Liabilities	836,834	823,006
Total Current Liabilities	3,605,563	4,112,882
Total Deferred Credits and Other Liabilities	10,421,838	9,653,913
Capitalization:
Long-Term Debt	13,770,828	12,248,743
Common Shareholders' Equity:
Common Shares	1,729,292	1,669,392
Capital Surplus, Paid in	7,087,768	6,241,222
Retained Earnings	4,177,048	3,953,974
Accumulated Other Comprehensive Loss	(65,059)	(60,000)
Treasury Stock	(299,055)	(317,771)
Common Shareholders' Equity	12,629,994	11,486,817	$ 11,086,242	$ 10,711,734
Total Liabilities and Capitalization	41,123,915	38,241,256
Eversource
Current Assets:
Cash	1,469	591	$ 521	$ 93
Accounts Receivable from Subsidiaries	25,070	32,175
Notes Receivable from Subsidiaries	1,376,000	991,400
Prepayments and Other Current Assets	33,546	26,861
Total Current Assets	1,436,085	1,051,027
Deferred Debits and Other Assets:
Investments in Subsidiary Companies, at Equity	13,162,337	12,009,659
Notes Receivable from Subsidiaries	157,000	323,500
Accumulated Deferred Income Taxes	27,578	40,454
Goodwill	3,231,811	3,231,811
Other Long-Term Assets	92,394	73,669
Total Deferred Debits and Other Assets	16,671,120	15,679,093
Total Assets	18,107,205	16,730,120
Current Liabilities:
Notes Payable	878,584	631,500
Long-Term Debt – Current Portion	23,933	378,883
Accounts Payable to Subsidiaries	4,333	8,432
Other Current Liabilities	62,385	57,877
Total Current Liabilities	969,235	1,076,692
Total Deferred Credits and Other Liabilities	149,637	134,614
Capitalization:
Long-Term Debt	4,358,339	4,031,997
Common Shareholders' Equity:
Common Shares	1,729,292	1,669,392
Capital Surplus, Paid in	7,087,768	6,241,222
Retained Earnings	4,177,048	3,953,974
Accumulated Other Comprehensive Loss	(65,059)	(60,000)
Treasury Stock	(299,055)	(317,771)
Common Shareholders' Equity	12,629,994	11,486,817
Total Liabilities and Capitalization	$ 18,107,205	$ 16,730,120