NSTAR ELECTRIC COMPANY AND SUBSIDIARY CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating Revenues	$ 11,910,705	$ 12,289,336	$ 9,863,085
Operating Expenses:
Purchased Power and Transmission	5,168,241	5,014,074	3,372,344
Operations and Maintenance	1,895,703	1,865,328	1,739,685
Depreciation	1,305,840	1,194,246	1,103,008
Energy Efficiency Programs	691,344	658,051	592,775
Taxes Other Than Income Taxes	940,359	910,591	829,987
Total Operating Expenses	9,511,370	10,091,182	7,869,764
Operating Income	2,399,335	2,198,154	1,993,321
Interest Expense	855,441	678,274	582,334
Other Income, Net	348,069	346,088	161,282
(Loss)/Income Before Income Tax Expense	(275,037)	1,865,968	1,572,269
Income Tax Expense	159,684	453,574	344,223
Net (Loss)/Income	(434,700)	1,412,400	1,228,000
NSTAR Electric Company
Operating Revenues	3,515,539	3,583,070	3,056,350
Operating Expenses:
Purchased Power and Transmission	1,154,013	1,264,824	932,530
Operations and Maintenance	668,466	640,834	563,172
Depreciation	372,578	361,969	337,451
Amortization of Regulatory (Liabilities)/Assets, Net	16,150	83,855	55,774
Energy Efficiency Programs	325,593	332,247	288,612
Taxes Other Than Income Taxes	256,090	246,705	216,703
Total Operating Expenses	2,792,890	2,930,434	2,394,242
Operating Income	722,649	652,636	662,108
Interest Expense	189,254	162,892	146,048
Other Income, Net	164,129	142,661	74,844
(Loss)/Income Before Income Tax Expense	697,524	632,405	590,904
Income Tax Expense	152,996	139,977	114,335
Net (Loss)/Income	$ 544,528	$ 492,428	$ 476,569