CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Net Income	$ 916,572	$ 1,040,519	$ 995,515
Other Comprehensive (Loss)/Income, Net of Tax:
Qualified Cash Flow Hedging Instruments	1,393	1,756	1,974
Changes in Unrealized Gains/(Losses) on Marketable Securities	1,166	(547)	(350)
Change in Funded Status of Pension, SERP and PBOP Benefit Plans	(7,618)	5,194	(2,745)
Other Comprehensive (Loss)/Income, Net of Tax	(5,059)	6,403	(1,121)
Comprehensive Income Attributable to Noncontrolling Interests	(7,519)	(7,519)	(7,519)
Comprehensive Income Attributable to Common Shareholders	903,994	1,039,403	986,875
The Connecticut Light and Power Company
Net Income	410,852	377,717	376,726
Other Comprehensive (Loss)/Income, Net of Tax:
Qualified Cash Flow Hedging Instruments	(26)	51	334
Changes in Unrealized Gains/(Losses) on Marketable Securities	41	(19)	(12)
Other Comprehensive (Loss)/Income, Net of Tax	15	32	322
Comprehensive Income Attributable to Common Shareholders	410,867	377,749	377,048
NSTAR Electric Company
Net Income	431,956	383,090	374,726
Other Comprehensive (Loss)/Income, Net of Tax:
Qualified Cash Flow Hedging Instruments	437	437	438
Changes in Unrealized Gains/(Losses) on Marketable Securities	12	(5)	(3)
Change in Funded Status of Pension, SERP and PBOP Benefit Plans	1,084	13	(264)
Other Comprehensive (Loss)/Income, Net of Tax	1,533	445	171
Comprehensive Income Attributable to Common Shareholders	433,489	383,535	374,897
Public Service Company of New Hampshire
Net Income	134,048	115,876	135,996
Other Comprehensive (Loss)/Income, Net of Tax:
Qualified Cash Flow Hedging Instruments	1,075	1,104	1,162
Changes in Unrealized Gains/(Losses) on Marketable Securities	69	(33)	(21)
Other Comprehensive (Loss)/Income, Net of Tax	1,144	1,071	1,141
Comprehensive Income Attributable to Common Shareholders	$ 135,192	$ 116,947	$ 137,137