NSTAR ELECTRIC COMPANY AND SUBSIDIARY CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Net Income	$ 1,228,046	$ 1,212,686	$ 916,572
Other Comprehensive Income/(Loss), Net of Tax:
Changes in Funded Status of SERP Benefit Plan	33,835	(13,290)	(7,618)
Qualified Cash Flow Hedging Instruments	972	1,596	1,393
Changes in Unrealized (Losses)/Gains on Marketable Securities	(671)	342	1,166
Other Comprehensive Income/(Loss), Net of Tax	34,136	(11,352)	(5,059)
Comprehensive Income Attributable to Common Shareholders	1,254,663	1,193,815	903,994
NSTAR Electric Company
Net Income	476,569	445,001	431,956
Other Comprehensive Income/(Loss), Net of Tax:
Changes in Funded Status of SERP Benefit Plan	(100)	(286)	1,084
Qualified Cash Flow Hedging Instruments	298	437	437
Changes in Unrealized (Losses)/Gains on Marketable Securities	(6)	3	12
Other Comprehensive Income/(Loss), Net of Tax	192	154	1,533
Comprehensive Income Attributable to Common Shareholders	$ 476,761	$ 445,155	$ 433,489