THE CONNECTICUT LIGHT AND POWER COMPANY STATEMENTS OF COMMON STOCKHOLDER'S EQUITY - USD ($) $ in Thousands	Total	Adoption of New Accounting Standard	Common Stock	Capital Surplus, Paid In	Retained Earnings	Retained Earnings Adoption of New Accounting Standard	Accumulated Other Comprehensive Loss	The Connecticut Light and Power Company	The Connecticut Light and Power Company Adoption of New Accounting Standard	The Connecticut Light and Power Company Common Stock	The Connecticut Light and Power Company Capital Surplus, Paid In	The Connecticut Light and Power Company Retained Earnings	The Connecticut Light and Power Company Retained Earnings Adoption of New Accounting Standard	The Connecticut Light and Power Company Accumulated Other Comprehensive Loss
Beginning balance (in shares) at Dec. 31, 2018			316,885,808							6,035,205
Beginning balance at Dec. 31, 2018	$ 11,486,817		$ 1,669,392	$ 6,241,222	$ 3,953,974		$ (60,000)	$ 4,199,317		$ 60,352	$ 2,410,765	$ 1,727,899		$ 301
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accounting Standards Update [Extensible Enumeration]	Accounting Standards Update 2016-13 [Member]							Accounting Standards Update 2016-13 [Member]
Net Income	$ 916,572				916,572			$ 410,852				410,852
Dividends on Preferred Stock	(7,519)				(7,519)			(5,559)				(5,559)
Dividends on Common Stock	(685,979)				(685,979)			(341,800)				(341,800)
Capital Contributions from Eversource Parent								125,000			125,000
Other Comprehensive Income/(Loss), Net of Tax	(5,059)						(5,059)	15						15
Ending balance (in shares) at Dec. 31, 2019			329,880,645							6,035,205
Ending balance at Dec. 31, 2019	12,629,994	$ (1,514)	$ 1,729,292	7,087,768	4,177,048	$ (1,514)	(65,059)	4,387,825	$ (900)	$ 60,352	2,535,765	1,791,392	$ (900)	316
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	1,212,686				1,212,686			457,934				457,934
Dividends on Preferred Stock	(7,519)				(7,519)			(5,559)				(5,559)
Dividends on Common Stock	(767,500)				(767,500)			(69,500)				(69,500)
Capital Contributions from Eversource Parent	25,000							275,000			275,000
Other Comprehensive Income/(Loss), Net of Tax	$ (11,352)						(11,352)	(14)						(14)
Ending balance (in shares) at Dec. 31, 2020	342,954,023		342,954,023							6,035,205
Ending balance at Dec. 31, 2020	$ 14,063,566		$ 1,789,092	8,015,663	4,613,201		(76,411)	5,044,786		$ 60,352	2,810,765	2,173,367		302
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	1,228,046				1,228,046			401,725				401,725
Dividends on Preferred Stock	(7,519)				(7,519)			(5,559)				(5,559)
Dividends on Common Stock	(828,337)				(828,337)			(341,400)				(341,400)
Capital Contributions from Eversource Parent								200,000			200,000
Other Comprehensive Income/(Loss), Net of Tax	$ 34,136						34,136	(51)						(51)
Ending balance (in shares) at Dec. 31, 2021	344,403,196		344,403,196							6,035,205
Ending balance at Dec. 31, 2021	$ 14,599,844		$ 1,789,092	$ 8,098,514	$ 5,005,391		$ (42,275)	$ 5,299,501		$ 60,352	$ 3,010,765	$ 2,228,133		$ 251