CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Net Income	$ 1,212,686	$ 916,572	$ 1,040,519
Other Comprehensive (Loss)/Income, Net of Tax:
Qualified Cash Flow Hedging Instruments	1,596	1,393	1,756
Changes in Unrealized Gains/(Losses) on Marketable Securities	342	1,166	(547)
Change in Funded Status of Pension, SERP and PBOP Benefit Plans	(13,290)	(7,618)	5,194
Other Comprehensive (Loss)/Income, Net of Tax	(11,352)	(5,059)	6,403
Comprehensive Income Attributable to Noncontrolling Interests	(7,519)	(7,519)	(7,519)
Comprehensive Income Attributable to Common Shareholders	1,193,815	903,994	1,039,403
The Connecticut Light and Power Company
Net Income	457,934	410,852	377,717
Other Comprehensive (Loss)/Income, Net of Tax:
Qualified Cash Flow Hedging Instruments	(26)	(26)	51
Changes in Unrealized Gains/(Losses) on Marketable Securities	12	41	(19)
Other Comprehensive (Loss)/Income, Net of Tax	(14)	15	32
Comprehensive Income Attributable to Common Shareholders	457,920	410,867	377,749
NSTAR Electric Company
Net Income	445,001	431,956	383,090
Other Comprehensive (Loss)/Income, Net of Tax:
Qualified Cash Flow Hedging Instruments	437	437	437
Changes in Unrealized Gains/(Losses) on Marketable Securities	3	12	(5)
Change in Funded Status of Pension, SERP and PBOP Benefit Plans	(286)	1,084	13
Other Comprehensive (Loss)/Income, Net of Tax	154	1,533	445
Comprehensive Income Attributable to Common Shareholders	445,155	433,489	383,535
Public Service Company of New Hampshire
Net Income	147,312	134,048	115,876
Other Comprehensive (Loss)/Income, Net of Tax:
Qualified Cash Flow Hedging Instruments	1,075	1,075	1,104
Changes in Unrealized Gains/(Losses) on Marketable Securities	19	69	(33)
Other Comprehensive (Loss)/Income, Net of Tax	1,094	1,144	1,071
Comprehensive Income Attributable to Common Shareholders	$ 148,406	$ 135,192	$ 116,947